Present Experimental work shows result obtain from experimentation of heat transfer enhancement in
circular horizontal tube by using clockwise and counterclockwise corrugated twisted tape inserts with
working fluid is air. Experiments conducted on plain circular tube with or without c-cc corrugated
twisted tube. During experiment constant heat flux and different mass flow rate condition. The c-cc
corrugated twisted tape are of same pitch and twist ratio but three different angle of rotation in
clockwise and counter clockwise direction as 30˚, 60˚, 90˚ respectively. The Reynolds no. varied from
4000 to 10000. Heat transfer coefficient and pressure drop are calculated and results are compared with
the plain tube without inserts. Finally heat transfer enhances with clockwise and counterclockwise
corrugated twisted tape inserts as compared to plain tube varied from 8 % to 44 % for various inserts.
Plain twisted tape results are also compared with the same results.
An Experimental Research on Heat Transfer Enhancement of a Circular Tube with...IRJESJOURNAL
ABSTRACT:- In the literature, internal tube baffles are widely studied. There is a lack of data for baffles mounted on outside of the tubes. This study aims to fill this gap. Therefore, the effect of baffle inclination angles on heat transfer improvement has been studied experimentally. The experiments were carried out for forced convection of air on a circular tube with inclined baffles. Air has been used as the cold fluid. Experimental results for eight different velocities of air flow (2 – 20 m/s) are presented. Pitch between baffles is 12 mm.The baffle inclination angles with respect to the tube axis were 45º, 60º and 80º. Water temperature is fixed as 65 °C. According to the experimental results, the baffles with an inclination angle of 45º enhance the heat transfer over 60º and 80º around 13.7 % and 10.5 %, respectively. However, pressure drop values for 45º and 60º are 18 % higher than pressure drop values for 80º. The empirical correlations of the Nusselt number have also been obtained for each angle.
Comparison of Shell and Tube Heat Exchanger using Theoretical Methods, HTRI, ...IJERA Editor
This document compares the design of a shell and tube heat exchanger with baffles using four different methods: 1) Kern's theoretical method, 2) ASPEN simulation software, 3) HTRI simulation software, and 4) SOLIDWORKS simulation software. The same input parameters were used to design a shell and tube heat exchanger with single segmental baffles in each method. The results from all four methods for shell side pressure drop and heat transfer coefficient were found to be in close agreement. The theoretical Kern method design results closely matched the simulation software results, showing proven theoretical methods can accurately model shell and tube heat exchanger performance.
Review Paper on Experimental Analysis of Vortex TubeIRJET Journal
The document summarizes research on the experimental analysis of vortex tubes. It discusses several studies that examined how the geometric parameters and operating conditions of vortex tubes, such as nozzle diameter, tube length, inlet pressure, and cold fraction, influence the temperature separation and energy separation efficiency. Computational fluid dynamics (CFD) models are used to study the internal flow phenomena and energy separation mechanisms. The studies found that there is an optimal tube length and nozzle diameter that maximize energy separation. Increasing the inlet pressure or decreasing the cold fraction also increases the temperature difference between the cold and hot outlets.
Irjet v4 i12326Effect of External Threaded Inside Tube on Heat Transfer Rate ...IRJET Journal
This document reviews the use of an internal threaded tube in a concentric tube heat exchanger to enhance heat transfer rates. It discusses how passive heat transfer augmentation techniques like threaded tubes can increase turbulence and disrupt boundary layers to improve heat transfer efficiency. The review analyzes previous studies that experimentally compared heat transfer performance and pressure drop between plain and threaded inner tubes. Results indicated that threaded tubes increased heat transfer coefficients and Reynolds numbers while potentially reducing fouling compared to plain tubes. Further experimentation and CFD simulation were proposed to validate theoretical predictions and determine the threaded tube design's feasibility for applications like radiators and air conditioners.
Experimental Analysis of Heat Transfer Enhancement in a Double Pipe Heat Exch...IRJET Journal
This document describes an experimental analysis of heat transfer enhancement in a double pipe heat exchanger using an inserted rotor assembled strand. The study measures heat transfer rate and pressure drop using water as the working fluid in both a plain tube and tube with the rotor insert. Results show that the rotor insert increases turbulence, leading to higher heat transfer coefficients and Nusselt numbers but also increases pressure drop compared to the plain tube. Correlations are developed for Nusselt number and friction factor as functions of Reynolds and Prandtl numbers.
The document summarizes an experimental study on heat transfer and flow characteristics of air flowing through a trapezoidal duct with and without delta wing vortex generators (VGs). Three cases of VGs with angles of 30°, 45°, and 60° were tested and compared to a smooth duct. Key findings include:
- Friction factor increased 14-21% for 30°, 19-36% for 45°, and 31-49% for 60° compared to the smooth duct.
- Heat transfer rate was enhanced 29-67% for 30°, 23-43% for 45°, and 14-27% for 60° compared to the smooth duct.
- Nusselt number, Stanton number, friction
IRJET- Experimental Analysis of Convective Heat Transfer Augmentation of Bi-M...IRJET Journal
This document provides a literature review of research on bi-metallic plate heat exchangers to enhance convective heat transfer. It discusses 8 studies that experimentally analyzed heat transfer coefficients and pressure drops of different combinations of bi-metallic plates under forced convection. The goal of improving heat transfer efficiency while minimizing pressure losses is important for industries using such heat exchangers like power plants, refrigeration, and chemical processes. The document focuses on reviewing work done to optimize the design of bi-metallic heat exchangers.
Heat transfer enhancement and friction factor analysis in tube using conical ...eSAT Journals
Abstract Role of the conical spring array for the heat transfer enhancement and pressure drop change in a pipe with constant heat flux boundary condition was investigated. Three different arrangements of conical spring array inserts were used in the experimental setup. Conical spring inserts with diverging conical spring, converging-diverging conical spring and converging conical spring array inserts arrangements were used. Water was used as a working fluid in the experimental setup. It was found that use of conical spring array inserts arrangement leads to enhancement in heat transfer. Higher heat transfer rate was achieved in the divergent spring array arrangement than the converging-diverging and converging arrangement. However, maximum friction factor is achieved in the diverging spring array insert arrangement. By increasing the Reynolds Number for different turbulator arrangement, the significant increase in Nusselt number was obtained. The enhancement in Nusselt Number for the diverging, converging-diverging, converging conical spring array arrangement was 645% ,431% and 259% respectively. The heat transfer enhancement efficiency can be evaluated based on the power consumption per unit mass of fluid. Heat transfer enhancement efficiencies were found for the divergent spring array arrangement up to 277% and for the convergent-divergent spring arrangement up to 212% and for the convergent spring array arrangement up to 153%. Keywords— Heat exchanger, Heat transfer enhancement, Friction factor, Conical spring turbulator, Heat transfer enhancement efficiency
An Experimental Research on Heat Transfer Enhancement of a Circular Tube with...IRJESJOURNAL
ABSTRACT:- In the literature, internal tube baffles are widely studied. There is a lack of data for baffles mounted on outside of the tubes. This study aims to fill this gap. Therefore, the effect of baffle inclination angles on heat transfer improvement has been studied experimentally. The experiments were carried out for forced convection of air on a circular tube with inclined baffles. Air has been used as the cold fluid. Experimental results for eight different velocities of air flow (2 – 20 m/s) are presented. Pitch between baffles is 12 mm.The baffle inclination angles with respect to the tube axis were 45º, 60º and 80º. Water temperature is fixed as 65 °C. According to the experimental results, the baffles with an inclination angle of 45º enhance the heat transfer over 60º and 80º around 13.7 % and 10.5 %, respectively. However, pressure drop values for 45º and 60º are 18 % higher than pressure drop values for 80º. The empirical correlations of the Nusselt number have also been obtained for each angle.
Comparison of Shell and Tube Heat Exchanger using Theoretical Methods, HTRI, ...IJERA Editor
This document compares the design of a shell and tube heat exchanger with baffles using four different methods: 1) Kern's theoretical method, 2) ASPEN simulation software, 3) HTRI simulation software, and 4) SOLIDWORKS simulation software. The same input parameters were used to design a shell and tube heat exchanger with single segmental baffles in each method. The results from all four methods for shell side pressure drop and heat transfer coefficient were found to be in close agreement. The theoretical Kern method design results closely matched the simulation software results, showing proven theoretical methods can accurately model shell and tube heat exchanger performance.
Review Paper on Experimental Analysis of Vortex TubeIRJET Journal
The document summarizes research on the experimental analysis of vortex tubes. It discusses several studies that examined how the geometric parameters and operating conditions of vortex tubes, such as nozzle diameter, tube length, inlet pressure, and cold fraction, influence the temperature separation and energy separation efficiency. Computational fluid dynamics (CFD) models are used to study the internal flow phenomena and energy separation mechanisms. The studies found that there is an optimal tube length and nozzle diameter that maximize energy separation. Increasing the inlet pressure or decreasing the cold fraction also increases the temperature difference between the cold and hot outlets.
Irjet v4 i12326Effect of External Threaded Inside Tube on Heat Transfer Rate ...IRJET Journal
This document reviews the use of an internal threaded tube in a concentric tube heat exchanger to enhance heat transfer rates. It discusses how passive heat transfer augmentation techniques like threaded tubes can increase turbulence and disrupt boundary layers to improve heat transfer efficiency. The review analyzes previous studies that experimentally compared heat transfer performance and pressure drop between plain and threaded inner tubes. Results indicated that threaded tubes increased heat transfer coefficients and Reynolds numbers while potentially reducing fouling compared to plain tubes. Further experimentation and CFD simulation were proposed to validate theoretical predictions and determine the threaded tube design's feasibility for applications like radiators and air conditioners.
Experimental Analysis of Heat Transfer Enhancement in a Double Pipe Heat Exch...IRJET Journal
This document describes an experimental analysis of heat transfer enhancement in a double pipe heat exchanger using an inserted rotor assembled strand. The study measures heat transfer rate and pressure drop using water as the working fluid in both a plain tube and tube with the rotor insert. Results show that the rotor insert increases turbulence, leading to higher heat transfer coefficients and Nusselt numbers but also increases pressure drop compared to the plain tube. Correlations are developed for Nusselt number and friction factor as functions of Reynolds and Prandtl numbers.
The document summarizes an experimental study on heat transfer and flow characteristics of air flowing through a trapezoidal duct with and without delta wing vortex generators (VGs). Three cases of VGs with angles of 30°, 45°, and 60° were tested and compared to a smooth duct. Key findings include:
- Friction factor increased 14-21% for 30°, 19-36% for 45°, and 31-49% for 60° compared to the smooth duct.
- Heat transfer rate was enhanced 29-67% for 30°, 23-43% for 45°, and 14-27% for 60° compared to the smooth duct.
- Nusselt number, Stanton number, friction
IRJET- Experimental Analysis of Convective Heat Transfer Augmentation of Bi-M...IRJET Journal
This document provides a literature review of research on bi-metallic plate heat exchangers to enhance convective heat transfer. It discusses 8 studies that experimentally analyzed heat transfer coefficients and pressure drops of different combinations of bi-metallic plates under forced convection. The goal of improving heat transfer efficiency while minimizing pressure losses is important for industries using such heat exchangers like power plants, refrigeration, and chemical processes. The document focuses on reviewing work done to optimize the design of bi-metallic heat exchangers.
Heat transfer enhancement and friction factor analysis in tube using conical ...eSAT Journals
Abstract Role of the conical spring array for the heat transfer enhancement and pressure drop change in a pipe with constant heat flux boundary condition was investigated. Three different arrangements of conical spring array inserts were used in the experimental setup. Conical spring inserts with diverging conical spring, converging-diverging conical spring and converging conical spring array inserts arrangements were used. Water was used as a working fluid in the experimental setup. It was found that use of conical spring array inserts arrangement leads to enhancement in heat transfer. Higher heat transfer rate was achieved in the divergent spring array arrangement than the converging-diverging and converging arrangement. However, maximum friction factor is achieved in the diverging spring array insert arrangement. By increasing the Reynolds Number for different turbulator arrangement, the significant increase in Nusselt number was obtained. The enhancement in Nusselt Number for the diverging, converging-diverging, converging conical spring array arrangement was 645% ,431% and 259% respectively. The heat transfer enhancement efficiency can be evaluated based on the power consumption per unit mass of fluid. Heat transfer enhancement efficiencies were found for the divergent spring array arrangement up to 277% and for the convergent-divergent spring arrangement up to 212% and for the convergent spring array arrangement up to 153%. Keywords— Heat exchanger, Heat transfer enhancement, Friction factor, Conical spring turbulator, Heat transfer enhancement efficiency
A Review on Comparison between Shell And Tube Heat Exchanger And Helical Coil...ijiert bestjournal
The curved shape of the tube causes the flowing fluid to experience centrifugal force. The
extent of centrifugal force experienced depends on the local axial velocity of the fluid particle
and radius of curvature of the coil. The fluid particles flowing at the core of the pipe have
higher velocities than those flowing near to the pipe wall. Thus the fluid particles flowing
close to the tube wall experience a lower centrifugal force than the fluid particles flowing in
the tube core. This causes the fluid from the core region to be pushed towards the outer wall.
This stream bifurcates at the wall and drives the fluid towards the inner wall along the tube
periphery, causing generation of counter-rotating vortices called secondary flows which
produce additional transport of the fluid over the cross section of the pipe. This additional
convective transport increases heat transfer and the pressure drop when compared to that in a
straight tube.
Experimental study on heat transfer and friction factor characteristics in la...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
CFD Analysis of Plate Fin Tube Heat Exchanger for Various Fin InclinationsIJERA Editor
ANSYS Fluent software is used for three dimensional CFD simulations to investigate heat transfer and fluid flow characteristics of six different fin angles with plain fin tube heat exchangers. The numerical simulation of the fin tube heat exchanger was performed by using a three dimensional numerical computation technique. Geometry of model is created and meshed by using ANSYS Workbench software. To solve the equation for the fluid flow and heat transfer analysis ANSYS FLUENT was used in the fin-tube heat exchanger. The fluid flow and heat transfer are simulated and result compared for both laminar and turbulent flow models k-epsilon and SST k-omega, with steady state solvers to calculate heat transfer, flow velocity and temperature fields of variable inclined fin angles (Ɵ = 00,100 , 200, 300, 400,500). Model is validate by comparing the simulated value of velocity, temperature and colburn factor with experimental and numerical results investigated by WANG [1] and GHORI KIRAR [10]. Reasonable agreement is found between the simulations and other results, and the ANSYS Fluent software is sufficient for simulating the flow fields in tube fin heat exchanger.
This document summarizes research on heat transfer augmentation techniques in circular and non-circular tubes. Both active and passive methods are used, with passive methods not requiring external power. For circular tubes, research is reviewed on using displaced inserts like twisted tapes and wire coil inserts in laminar and turbulent flow. Heat transfer enhancement of up to 36% was achieved in laminar flow and up to 9.8 times in turbulent flow compared to plain tubes. Computational fluid dynamics (CFD) analysis was also used to study flow and heat transfer with inserts. For non-circular tubes, heat transfer in ducts with triangular, rectangular, and trapezoidal cross-sections was investigated.
In day-to-day life, we come across many processes where we see the usage of heat exchangers. Some
examples where heat exchangers are extensively utilized are air conditioning plants, thermal power plants, food
processing plants etc. The basic requirement in these industries is to utilize the heat energy used in the heat
exchangers efficiently. This can be done either by developing new designs that are energy efficient or by
modifying the present designs in such a manner that they give better performance under the same working
conditions. Hence, heat exchangers that would provide more heat transfer at the minimum size and cost are
requirement of the present industries. Hence they use the various heat transfer technique for enhance the heat
transfer rate. In this paper review of research work in last decade on heat transfer enhancement.
A Review on Investigation of Shell and Tube Heat Exchanger For Different Para...IRJET Journal
This document reviews research on shell and tube heat exchangers. It discusses how researchers have studied different parameters like tube geometry, baffle arrangement, fluid types, and modeling/simulation methods. The document outlines studies on modifying tube designs with different geometries or diameters. It also reviews work on changing baffle configurations, reducing leakage flows, and comparing performance between fluids. Researchers have developed models using tools like ANSYS, Fluent and MATLAB to simulate performance. Overall the document provides an overview of past work analyzing factors that influence the design and operation of shell and tube heat exchangers.
A Review on Design and Development of Spiral Coil Heat ExchangersIRJET Journal
This document reviews research on the design and development of spiral coil heat exchangers. It discusses how spiral coil heat exchangers have a more compact design and higher heat transfer rate compared to straight tube heat exchangers. The document summarizes several studies that analyzed factors influencing the heat transfer performance of spiral coil heat exchangers, such as coil geometry, mass flow rate, and coil orientation. It concludes that spiral coil heat exchangers generally have a higher heat transfer rate and are widely used in applications like geothermal heating.
Numerical Simulations on Jet Impingement Cooling of Cylindrical SurfacesIRJET Journal
This document summarizes a numerical study on jet impingement cooling of cylindrical surfaces. Jet impingement exhibits non-uniform heat transfer on cylinders, with maximum heat transfer at the jet stagnation zone and local maxima/minima occurring along the circumference due to transition between laminar and turbulent flow. Parameters studied include jet Reynolds number and cylinder to jet diameter ratio. Results for smooth cylinders matched literature. Heat transfer decreases with Reynolds number from 100 to 1000 but increases beyond 1000. The study aims to address gaps in understanding jet impingement cooling effects on cylinders.
Heat Transfer Enhancement through Liquid Jet ImpingementIRJET Journal
This document provides a literature review on experimental and computational studies of liquid jet impingement heat transfer. It summarizes various parameters that influence jet impingement heat transfer such as flow rate, nozzle size, inlet pressure, and working medium properties. It then reviews over 30 experimental and computational studies on topics like the effects of nozzle geometry, surface roughness, nanofluids, vortex generators, swirling jets, and more. The overall goal is to provide an overview of recent approaches to studying jet impingement heat transfer processes.
FLUID FLOW ANALYSIS IN AIR DUCT FLOW WITH AND WITHOUT INTERNAL THREADS USING ...IAEME Publication
Computational heat transfer flow modeling is one of the great challenges in the classical sciences. As with most problems in engineering, the interest in the heat transfer augmentation is increasing due to its extreme importance in various industrial applications. This paper deals with the analysis of heat transfer for fluid flowing through the pipe with and without internal threads using CFD. Using CFD codes for modeling the heat and fluid flow is an efficient tool for predicting equipment performance. CFD offers a convenient means to study the detailed flows and heat exchange processes, which take place inside the tube. Simulations were carried out using commercial CFD software ANSYS Fluent version 14.5. Friction factor and Nusselt number for air flowing through the specified tube (internal diameter = 0.005 m, length = 0.1 m) were obtained first for the plain tube and then for the tube with internal threads with pitch 5mm in the Reynolds number range of 2000 to 5000. Finally results will be compared to available experimental and analytical calculations. The data obtained by simulation are matching with the literature value for a plain tube with the discrepancy of less than plus or minus 5% for Nusselt number and for the friction factor.
Enhanced heat transfer for the tube with internal threads has been observed. Heat flux is more uniform all along the tube and decreases uniformly towards the center.
IRJET- Experimental Investigation of Enhancement of Convective Heat Trans...IRJET Journal
This document presents an experimental study that investigates heat transfer enhancement in a circular tube with internally placed pin fin elements. The experiments were conducted with air as the working fluid in a circular tube fitted with 36 pin fins measuring 10mm in length and 4mm in diameter inserted orthogonally along the entire length of the tube. Theoretical and experimental heat transfer coefficients were calculated and compared between the plain tube and tube with pin fins under varying flow conditions. The results show that the tube with pin fins achieved higher Nusselt numbers and heat transfer coefficients compared to the plain tube across all Reynolds numbers, demonstrating that the pin fins are effective at enhancing heat transfer.
Diffuser in Steam Vent Silencer By Using Computational Fluid DynamicsIJERA Editor
This document summarizes a research paper that investigated the shape optimization of the pressurized inlet diffuser in a steam vent silencer using computational fluid dynamics (CFD). The researchers analyzed the pressure drop through the silencer with different hole geometries (circular, square, square extrusion) in the inlet diffuser. The results showed that square extrusion geometry had the lowest pressure drop compared to the other geometries. Therefore, the researchers concluded that optimizing the shape of the inlet diffuser to use square extrusion holes can reduce pressure drop in the steam vent silencer.
Heat Transfer Enhancement using Herringbone wavy & Smooth Wavy fin Heat Excha...IRJET Journal
This document presents a study on heat transfer enhancement using herringbone wavy and smooth wavy fin heat exchangers for hydraulic oil cooling. Two fin configurations - smooth wavy fin and herringbone wavy fin - are experimentally investigated. The performance of two heat exchangers, one with each fin type, are analyzed by passing hot oil through them and studying the cooling effect. Test results show that the smooth wavy fins provide more efficient cooling of hot oil compared to the herringbone fin heat exchanger. Tables of observations recorded during experiments on both heat exchangers are presented.
A Review on “Investigation of Heat Transfer Enhancement of Flow over the dimp...IRJET Journal
This document reviews investigations into using triangular dimple shapes on the internal surface of a divergent duct to enhance heat transfer. A divergent duct promotes fluid mixing and reduces pressure drop compared to a cylindrical pipe. The addition of triangular dimples, which act as an extended surface, can further increase heat transfer by 40-50% over a plain divergent duct. Previous studies have found triangular dimple shapes provide the highest heat transfer enhancement compared to other surface shapes like cylinders or fins. The enhanced mixing in a divergent duct with internal triangular dimples can improve heat transfer for applications in industries like food processing and chemicals.
Effect of Wavy (Corrugated) Twisted Tape Inserts on Heat Transfer in a double...ijiert bestjournal
This document summarizes an experimental study on heat transfer in a double pipe heat exchanger with the use of wavy twisted tape inserts in the inner tube. Various wavy twisted tapes with different twist ratios were inserted into the inner copper tube to enhance turbulence and heat transfer. Temperature and pressure measurements were taken at varying flow rates and Reynolds numbers. The results showed that heat transfer, as measured by Nusselt number, increased with decreasing twist ratio of the insert. The wavy twisted tape with a twist ratio of 7.1 produced the highest 172% increase in Nusselt number but also the highest 32.11% increase in friction factor compared to the smooth tube. Correlations were developed for Nusselt number
EXPERIMENTATION ON COPPER TUBE WITH INTERNAL THREADING FOR A HEAT EXCHANGER P...Journal For Research
Experimental model has been carried out to study the effect of heat transfer, thermal enhancement factor and friction factor in a smooth copper tube and different test copper tube having internal threads of pitch ( p=3.5mm), with water as a working fluid media. For such experimentation purpose Reynolds number were varied in the range of 4000 to 8000. The copper tube (OD=38mm, ID=25mm, t=6.5mm) was subjected to constant and uniform heat flux. The experimental data obtained from test tube having different surface geometry i.e. by internal threading of different pitch (p=3.5mm) were compared with smooth circular copper tube. The effect of different surface geometry of inside copper tube i.e. by threading with varying pitch on thermal enhancement factor, heat transfer and friction factor were presented. In that experimental we also calculate Nusselt number, Prandtl number, pitch like heat transfer parameter. The heat transfer rate for copper tubes having internal threads was found to be much higher than smooth circular copper tube for a given value Reynolds number. So simply by changing the internal surface geometry the performance of circular section copper tube is improved.
IRJET- An Experimental Investigations of Twisted Tape Inserts in Square and C...IRJET Journal
This document describes an experimental investigation of twisted tape inserts in square and circular helical coil heat exchangers. The study aims to compare the heat transfer performance of square and circular patterned helical coils with twisted tape inserts. Experiments were conducted to calculate heat transfer coefficients, develop Nusselt number correlations, and analyze how Nusselt number varies with Reynolds number for each coil geometry. The results will provide insights into which geometry and twisted tape configuration performs better to enhance heat transfer in helical coil heat exchangers.
CFD Analysis of Concentric Tube Heat Exchanger Using Twisted TapesIJARIIT
In this paper, the three dimensional CFD modeling studies on heat transfer, friction factor and thermal performance
of concentric tube heat exchanger using twisted tapes (Plain, V-cut, , Jagged V-cut) with different twist ratios (y=2.0, 4.0) are
used. Twisted tapes are used to augment the heat transfer by creating turbulence in the fluid flow. Various methods are applied
to increase thermal performance of heat transfer devices such as treated surfaces, rough surfaces, swirling flow devices, coiled
tubes, and surface tension devices. Out of these twisted tape method is used to increase the thermal performance. Twisted tape
inserts on effectiveness of heat exchanger has analyzed for different Reynolds Number. The maximum thermal performance
factor was obtained by the Jagged V-cut twisted tape (H=50) insert compare to other twisted tapes. Simultaneously the friction
factor has been analyzed
1) The document presents a computational fluid dynamics (CFD) analysis of a fin tube heat exchanger with rectangular winglet vortex generators.
2) It finds that adding vortex generators with angles of 30° and 45° can increase the overall Nusselt number (heat transfer coefficient) of the four row tubes by 18.68-46.38% and 38-55.86% respectively, but also increases pressure drop by 9.26-56.35% and 38-190.3%.
3) The study examines the effects of varying the winglet angle of attack, width, and placement location on heat transfer and fluid flow characteristics.
PERFORMANCE ENHANCEMENT OF HEAT EXCHANGERS USING VORTEX FLAPSIRJET Journal
The document discusses performance enhancement of heat exchangers using vortex flaps. It proposes designing a heat exchanger with twisted internal flaps to produce counter-rotating vortices inside the tube, increasing turbulence and convection of colder fluid. This is meant to improve heat transfer rate. Previous studies on using inserts like twisted tapes, coiled wires, and conical rings to enhance heat transfer in tubes are summarized. Numerical simulations will be conducted to analyze heat transfer and pressure drop characteristics of the designed heat exchanger.
This document summarizes a study on improving heat transfer in tubes by using different types of twisted tape inserts. Experiments were conducted to assess heat transfer and pressure drop in a tube fitted with alternating clockwise and counter-clockwise twisted tapes (C-CC tapes) as well as serrated twisted tapes (STT). For C-CC tapes, heat transfer increased with higher twist ratios and lower twist angles. For STT, heat transfer increased with higher serration depth ratios but decreased with higher serration width ratios. Thermal performance factors above unity indicated STT provided advantages over plain tubes or twisted tapes. Correlations for Nusselt number and friction factor were determined for both C-CC and STT.
A Review on Comparison between Shell And Tube Heat Exchanger And Helical Coil...ijiert bestjournal
The curved shape of the tube causes the flowing fluid to experience centrifugal force. The
extent of centrifugal force experienced depends on the local axial velocity of the fluid particle
and radius of curvature of the coil. The fluid particles flowing at the core of the pipe have
higher velocities than those flowing near to the pipe wall. Thus the fluid particles flowing
close to the tube wall experience a lower centrifugal force than the fluid particles flowing in
the tube core. This causes the fluid from the core region to be pushed towards the outer wall.
This stream bifurcates at the wall and drives the fluid towards the inner wall along the tube
periphery, causing generation of counter-rotating vortices called secondary flows which
produce additional transport of the fluid over the cross section of the pipe. This additional
convective transport increases heat transfer and the pressure drop when compared to that in a
straight tube.
Experimental study on heat transfer and friction factor characteristics in la...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
CFD Analysis of Plate Fin Tube Heat Exchanger for Various Fin InclinationsIJERA Editor
ANSYS Fluent software is used for three dimensional CFD simulations to investigate heat transfer and fluid flow characteristics of six different fin angles with plain fin tube heat exchangers. The numerical simulation of the fin tube heat exchanger was performed by using a three dimensional numerical computation technique. Geometry of model is created and meshed by using ANSYS Workbench software. To solve the equation for the fluid flow and heat transfer analysis ANSYS FLUENT was used in the fin-tube heat exchanger. The fluid flow and heat transfer are simulated and result compared for both laminar and turbulent flow models k-epsilon and SST k-omega, with steady state solvers to calculate heat transfer, flow velocity and temperature fields of variable inclined fin angles (Ɵ = 00,100 , 200, 300, 400,500). Model is validate by comparing the simulated value of velocity, temperature and colburn factor with experimental and numerical results investigated by WANG [1] and GHORI KIRAR [10]. Reasonable agreement is found between the simulations and other results, and the ANSYS Fluent software is sufficient for simulating the flow fields in tube fin heat exchanger.
This document summarizes research on heat transfer augmentation techniques in circular and non-circular tubes. Both active and passive methods are used, with passive methods not requiring external power. For circular tubes, research is reviewed on using displaced inserts like twisted tapes and wire coil inserts in laminar and turbulent flow. Heat transfer enhancement of up to 36% was achieved in laminar flow and up to 9.8 times in turbulent flow compared to plain tubes. Computational fluid dynamics (CFD) analysis was also used to study flow and heat transfer with inserts. For non-circular tubes, heat transfer in ducts with triangular, rectangular, and trapezoidal cross-sections was investigated.
In day-to-day life, we come across many processes where we see the usage of heat exchangers. Some
examples where heat exchangers are extensively utilized are air conditioning plants, thermal power plants, food
processing plants etc. The basic requirement in these industries is to utilize the heat energy used in the heat
exchangers efficiently. This can be done either by developing new designs that are energy efficient or by
modifying the present designs in such a manner that they give better performance under the same working
conditions. Hence, heat exchangers that would provide more heat transfer at the minimum size and cost are
requirement of the present industries. Hence they use the various heat transfer technique for enhance the heat
transfer rate. In this paper review of research work in last decade on heat transfer enhancement.
A Review on Investigation of Shell and Tube Heat Exchanger For Different Para...IRJET Journal
This document reviews research on shell and tube heat exchangers. It discusses how researchers have studied different parameters like tube geometry, baffle arrangement, fluid types, and modeling/simulation methods. The document outlines studies on modifying tube designs with different geometries or diameters. It also reviews work on changing baffle configurations, reducing leakage flows, and comparing performance between fluids. Researchers have developed models using tools like ANSYS, Fluent and MATLAB to simulate performance. Overall the document provides an overview of past work analyzing factors that influence the design and operation of shell and tube heat exchangers.
A Review on Design and Development of Spiral Coil Heat ExchangersIRJET Journal
This document reviews research on the design and development of spiral coil heat exchangers. It discusses how spiral coil heat exchangers have a more compact design and higher heat transfer rate compared to straight tube heat exchangers. The document summarizes several studies that analyzed factors influencing the heat transfer performance of spiral coil heat exchangers, such as coil geometry, mass flow rate, and coil orientation. It concludes that spiral coil heat exchangers generally have a higher heat transfer rate and are widely used in applications like geothermal heating.
Numerical Simulations on Jet Impingement Cooling of Cylindrical SurfacesIRJET Journal
This document summarizes a numerical study on jet impingement cooling of cylindrical surfaces. Jet impingement exhibits non-uniform heat transfer on cylinders, with maximum heat transfer at the jet stagnation zone and local maxima/minima occurring along the circumference due to transition between laminar and turbulent flow. Parameters studied include jet Reynolds number and cylinder to jet diameter ratio. Results for smooth cylinders matched literature. Heat transfer decreases with Reynolds number from 100 to 1000 but increases beyond 1000. The study aims to address gaps in understanding jet impingement cooling effects on cylinders.
Heat Transfer Enhancement through Liquid Jet ImpingementIRJET Journal
This document provides a literature review on experimental and computational studies of liquid jet impingement heat transfer. It summarizes various parameters that influence jet impingement heat transfer such as flow rate, nozzle size, inlet pressure, and working medium properties. It then reviews over 30 experimental and computational studies on topics like the effects of nozzle geometry, surface roughness, nanofluids, vortex generators, swirling jets, and more. The overall goal is to provide an overview of recent approaches to studying jet impingement heat transfer processes.
FLUID FLOW ANALYSIS IN AIR DUCT FLOW WITH AND WITHOUT INTERNAL THREADS USING ...IAEME Publication
Computational heat transfer flow modeling is one of the great challenges in the classical sciences. As with most problems in engineering, the interest in the heat transfer augmentation is increasing due to its extreme importance in various industrial applications. This paper deals with the analysis of heat transfer for fluid flowing through the pipe with and without internal threads using CFD. Using CFD codes for modeling the heat and fluid flow is an efficient tool for predicting equipment performance. CFD offers a convenient means to study the detailed flows and heat exchange processes, which take place inside the tube. Simulations were carried out using commercial CFD software ANSYS Fluent version 14.5. Friction factor and Nusselt number for air flowing through the specified tube (internal diameter = 0.005 m, length = 0.1 m) were obtained first for the plain tube and then for the tube with internal threads with pitch 5mm in the Reynolds number range of 2000 to 5000. Finally results will be compared to available experimental and analytical calculations. The data obtained by simulation are matching with the literature value for a plain tube with the discrepancy of less than plus or minus 5% for Nusselt number and for the friction factor.
Enhanced heat transfer for the tube with internal threads has been observed. Heat flux is more uniform all along the tube and decreases uniformly towards the center.
IRJET- Experimental Investigation of Enhancement of Convective Heat Trans...IRJET Journal
This document presents an experimental study that investigates heat transfer enhancement in a circular tube with internally placed pin fin elements. The experiments were conducted with air as the working fluid in a circular tube fitted with 36 pin fins measuring 10mm in length and 4mm in diameter inserted orthogonally along the entire length of the tube. Theoretical and experimental heat transfer coefficients were calculated and compared between the plain tube and tube with pin fins under varying flow conditions. The results show that the tube with pin fins achieved higher Nusselt numbers and heat transfer coefficients compared to the plain tube across all Reynolds numbers, demonstrating that the pin fins are effective at enhancing heat transfer.
Diffuser in Steam Vent Silencer By Using Computational Fluid DynamicsIJERA Editor
This document summarizes a research paper that investigated the shape optimization of the pressurized inlet diffuser in a steam vent silencer using computational fluid dynamics (CFD). The researchers analyzed the pressure drop through the silencer with different hole geometries (circular, square, square extrusion) in the inlet diffuser. The results showed that square extrusion geometry had the lowest pressure drop compared to the other geometries. Therefore, the researchers concluded that optimizing the shape of the inlet diffuser to use square extrusion holes can reduce pressure drop in the steam vent silencer.
Heat Transfer Enhancement using Herringbone wavy & Smooth Wavy fin Heat Excha...IRJET Journal
This document presents a study on heat transfer enhancement using herringbone wavy and smooth wavy fin heat exchangers for hydraulic oil cooling. Two fin configurations - smooth wavy fin and herringbone wavy fin - are experimentally investigated. The performance of two heat exchangers, one with each fin type, are analyzed by passing hot oil through them and studying the cooling effect. Test results show that the smooth wavy fins provide more efficient cooling of hot oil compared to the herringbone fin heat exchanger. Tables of observations recorded during experiments on both heat exchangers are presented.
A Review on “Investigation of Heat Transfer Enhancement of Flow over the dimp...IRJET Journal
This document reviews investigations into using triangular dimple shapes on the internal surface of a divergent duct to enhance heat transfer. A divergent duct promotes fluid mixing and reduces pressure drop compared to a cylindrical pipe. The addition of triangular dimples, which act as an extended surface, can further increase heat transfer by 40-50% over a plain divergent duct. Previous studies have found triangular dimple shapes provide the highest heat transfer enhancement compared to other surface shapes like cylinders or fins. The enhanced mixing in a divergent duct with internal triangular dimples can improve heat transfer for applications in industries like food processing and chemicals.
Effect of Wavy (Corrugated) Twisted Tape Inserts on Heat Transfer in a double...ijiert bestjournal
This document summarizes an experimental study on heat transfer in a double pipe heat exchanger with the use of wavy twisted tape inserts in the inner tube. Various wavy twisted tapes with different twist ratios were inserted into the inner copper tube to enhance turbulence and heat transfer. Temperature and pressure measurements were taken at varying flow rates and Reynolds numbers. The results showed that heat transfer, as measured by Nusselt number, increased with decreasing twist ratio of the insert. The wavy twisted tape with a twist ratio of 7.1 produced the highest 172% increase in Nusselt number but also the highest 32.11% increase in friction factor compared to the smooth tube. Correlations were developed for Nusselt number
EXPERIMENTATION ON COPPER TUBE WITH INTERNAL THREADING FOR A HEAT EXCHANGER P...Journal For Research
Experimental model has been carried out to study the effect of heat transfer, thermal enhancement factor and friction factor in a smooth copper tube and different test copper tube having internal threads of pitch ( p=3.5mm), with water as a working fluid media. For such experimentation purpose Reynolds number were varied in the range of 4000 to 8000. The copper tube (OD=38mm, ID=25mm, t=6.5mm) was subjected to constant and uniform heat flux. The experimental data obtained from test tube having different surface geometry i.e. by internal threading of different pitch (p=3.5mm) were compared with smooth circular copper tube. The effect of different surface geometry of inside copper tube i.e. by threading with varying pitch on thermal enhancement factor, heat transfer and friction factor were presented. In that experimental we also calculate Nusselt number, Prandtl number, pitch like heat transfer parameter. The heat transfer rate for copper tubes having internal threads was found to be much higher than smooth circular copper tube for a given value Reynolds number. So simply by changing the internal surface geometry the performance of circular section copper tube is improved.
IRJET- An Experimental Investigations of Twisted Tape Inserts in Square and C...IRJET Journal
This document describes an experimental investigation of twisted tape inserts in square and circular helical coil heat exchangers. The study aims to compare the heat transfer performance of square and circular patterned helical coils with twisted tape inserts. Experiments were conducted to calculate heat transfer coefficients, develop Nusselt number correlations, and analyze how Nusselt number varies with Reynolds number for each coil geometry. The results will provide insights into which geometry and twisted tape configuration performs better to enhance heat transfer in helical coil heat exchangers.
CFD Analysis of Concentric Tube Heat Exchanger Using Twisted TapesIJARIIT
In this paper, the three dimensional CFD modeling studies on heat transfer, friction factor and thermal performance
of concentric tube heat exchanger using twisted tapes (Plain, V-cut, , Jagged V-cut) with different twist ratios (y=2.0, 4.0) are
used. Twisted tapes are used to augment the heat transfer by creating turbulence in the fluid flow. Various methods are applied
to increase thermal performance of heat transfer devices such as treated surfaces, rough surfaces, swirling flow devices, coiled
tubes, and surface tension devices. Out of these twisted tape method is used to increase the thermal performance. Twisted tape
inserts on effectiveness of heat exchanger has analyzed for different Reynolds Number. The maximum thermal performance
factor was obtained by the Jagged V-cut twisted tape (H=50) insert compare to other twisted tapes. Simultaneously the friction
factor has been analyzed
1) The document presents a computational fluid dynamics (CFD) analysis of a fin tube heat exchanger with rectangular winglet vortex generators.
2) It finds that adding vortex generators with angles of 30° and 45° can increase the overall Nusselt number (heat transfer coefficient) of the four row tubes by 18.68-46.38% and 38-55.86% respectively, but also increases pressure drop by 9.26-56.35% and 38-190.3%.
3) The study examines the effects of varying the winglet angle of attack, width, and placement location on heat transfer and fluid flow characteristics.
PERFORMANCE ENHANCEMENT OF HEAT EXCHANGERS USING VORTEX FLAPSIRJET Journal
The document discusses performance enhancement of heat exchangers using vortex flaps. It proposes designing a heat exchanger with twisted internal flaps to produce counter-rotating vortices inside the tube, increasing turbulence and convection of colder fluid. This is meant to improve heat transfer rate. Previous studies on using inserts like twisted tapes, coiled wires, and conical rings to enhance heat transfer in tubes are summarized. Numerical simulations will be conducted to analyze heat transfer and pressure drop characteristics of the designed heat exchanger.
This document summarizes a study on improving heat transfer in tubes by using different types of twisted tape inserts. Experiments were conducted to assess heat transfer and pressure drop in a tube fitted with alternating clockwise and counter-clockwise twisted tapes (C-CC tapes) as well as serrated twisted tapes (STT). For C-CC tapes, heat transfer increased with higher twist ratios and lower twist angles. For STT, heat transfer increased with higher serration depth ratios but decreased with higher serration width ratios. Thermal performance factors above unity indicated STT provided advantages over plain tubes or twisted tapes. Correlations for Nusselt number and friction factor were determined for both C-CC and STT.
This document describes an experimental study of heat transfer in a rectangular duct with and without internal V-shaped ribs. Experiments were conducted with air flow in turbulent regime (Reynolds numbers 3000-18000) in smooth duct and ducts with continuous or discrete internal V-shaped ribs. Temperature and pressure measurements were taken to determine heat transfer coefficients and friction factors for different configurations. Results showed that continuous ribs enhanced heat transfer more than discrete ribs, but also increased pressure drop more substantially. Heat transfer enhancement was dependent on rib geometry and position.
IRJET- Numerical Analysis for Effect of Different Length Combination of Turbu...IRJET Journal
This document describes a numerical analysis of the effect of different length combinations of twisted tape and wire coil turbulators on heat transfer, pressure drop, and friction factor in a double pipe heat exchanger. Five combinations of twisted tape and wire coil lengths were analyzed (25-75%, 30-70%, 35-65%, 40-60%, 45-55%) using computational fluid dynamics software. The results were compared to existing studies on enhancing heat transfer using twisted tape and wire coil inserts in heat exchanger pipes. Key findings included increased heat transfer coefficients and Nusselt numbers but also higher friction factors compared to a plain pipe.
Effect of Geometric Modifications on the Performance of Vortex Tube - A ReviewIJERA Editor
This document summarizes research on modifying the geometric parameters of vortex tubes and analyzing their effects on performance. It discusses experiments that studied the impact of factors like cold orifice diameter, number of nozzles, hot end valve angle, and inlet air pressure. The key findings are that there is an optimum cold orifice diameter for maximum energy separation; performance is best with 4 nozzles; larger temperature differences are seen with hot end valve angles of 30-60°; and temperature difference increases with inlet pressure up to 380 kPa. The document reviews several past studies on modifying and analyzing vortex tube design parameters.
Analysis of Double Pipe Heat Exchanger With Helical FinsIRJET Journal
This document analyzes a double pipe heat exchanger with helical fins through computational fluid dynamics (CFD). It aims to study the flow and temperature fields inside the tubes for different helical fin angles. The geometry of the double pipe heat exchanger is modeled in CATIA V5 and meshed in Hypermesh. CFD simulations are performed in ANSYS Fluent to analyze the flow and temperature distributions for fin angles of 0, 5, 10, 15, 20, and 25 degrees. The results determine that heat transfer rate and overall heat transfer coefficient increase with helical fins compared to a smooth tube, with fins providing additional surface area to enhance heat transfer.
IRJET-Enhancement of Heat Transfer through Pipe with the Help of Various Type...IRJET Journal
This document reviews research on enhancing heat transfer through pipes using various types of turbulators. It begins with an abstract discussing using active or passive techniques to increase heat transfer rates in heat exchangers. The paper then discusses using modified baffled twisted tape inserts to change heat transfer rates. It provides equations for heat transfer and reviews several studies that experimentally analyzed heat transfer and pressure drop when using twisted tapes, baffled twisted tapes, and other turbulator inserts in pipes. The studies found that inserts can increase heat transfer by inducing swirl and disrupting boundary layers, but also increase pressure drop. The level of increased heat transfer and pressure drop depended on turbulator design and fluid properties like Reynolds number.
Comparative Study and Analysis between Helical Coil and Straight Tube Heat Ex...IJERA Editor
The purpose of this study is to determine the relative advantage of using a helically coiled heat exchanger against a straight tube heat exchanger. It is found that the heat transfer in helical circular tubes is higher as compared to Straight tube due to their shape. Helical coils offer advantageous over straight tubes due to their compactness and increased heat transfer coefficient. The increased heat transfer coefficients are a consequence of the curvature of the coil, which induces centrifugal forces to act on the moving fluid, resulting in the development of secondary flow. The curvature of the coil governs the centrifugal force while the pitch (or helix angle) influences the torsion to which the fluid is subjected to the centrifugal force results in the development of secondary flow. Due to the curvature effect, the fluid streams in the outer side of the pipe moves faster than the fluid streams in the inner side of the pipe. In current work the fluid to fluid heat exchange is taken into consideration. Most of the investigations on heat transfer coefficients are for constant wall temperature or constant heat flux. The effectiveness, overall heat transfer coefficient, effect of cold water flow rate on effectiveness of heat exchanger when hot water mass flow rate is kept constant and effect of hot water flow rate on effectiveness when cold water flow rate kept constant studied and compared for parallel flow, counter flow arrangement of Helical coil and Straight tube heat exchangers. All readings were taken at steady state condition of heat exchanger. The result shows that the heat transfer coefficient is affected by the geometry of the heat exchanger. Helical coil heat exchanger are superior in all aspect studied here.
Biodiesel, Brake thermal efficiency, Brake specific fuel consumption Honge, J...IJMER
Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the impact of flow and thermal boundary conditions for the heat transfer rate in laminar and transitional flow regimes. Calculated results have been compared to existing empirical formula and experimental tests to investigate the validity of the numerical results in case of common helical tube heat exchanger and additionally results of the numerical computation of corrugated straight tubes for laminar and transition flow have been validated with experimental tests available in the literature. Comparison of the flow and temperature fields in case of common helical tube and the coil with spirally corrugated wall configuration are discussed. Heat exchanger coils with helically corrugated wall configuration show 80–100% increase for the inner side heat transfer rate due to the additionally developed swirling motion while the relative pressure drop is 10–600% larger compared to the common helically coiled heat exchangers. New empirical Co-relation has been proposed for the fully developed inner side heat transfer prediction in case of helically corrugated wall configuration.
Analysis of Coiled-Tube Heat Exchangers to Improve Heat Transfer Rate With Sp...IJMER
Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the impact of flow and thermal boundary conditions for the heat transfer rate in laminar and transitional flow regimes. Calculated results have been compared to existing empirical formula and experimental tests to investigate the validity of the numerical results in case of common helical tube heat exchanger and additionally results of the numerical computation of corrugated straight tubes for laminar and transition flow have been validated with experimental tests available in the literature. Comparison of the flow and temperature fields in case of common helical tube and the coil with spirally corrugated wall configuration are discussed. Heat exchanger coils with helically corrugated wall configuration show 80–100% increase for the inner side heat transfer rate due to the additionally developed swirling motion while the relative pressure drop is 10–600% larger compared to the common helically coiled heat exchangers. New empirical Co-relation has been proposed for the fully developed inner side heat transfer prediction in case of helically corrugated wall configuration.
HEAT TRANSFER AND FLOW FRICTION CHARACTERISTICS OF SOLAR WATER HEATER WITH IN...IAEME Publication
Experimental investigation of friction factor and heat transfer characteristics of thermosyphone solar water heater with flat plate solar collector fitted with full length baffle of 10cm
pitch have been presented. The flow regime is laminar for this study with the Reynolds number range 124 to 258. The experimental data obtained were compared with those obtained from plain tube data. The effects of full length baffle inside the tube on heat transfer and friction factor were presented.
This document summarizes an experimental study on heat transfer and flow friction characteristics of a solar water heater with inserted baffles inside tubes. The study found that inserting full-length baffles inside tubes enhanced heat transfer and improved solar water heater performance compared to plain tubes. Maximum collector efficiency and outlet fluid temperature occurred at 12:45 hours for both baffled and plain tubes, but values were higher for baffled tubes. Friction factor was also lower for the baffled tube design at the point of maximum outlet temperature. The baffled tube design improved heat transfer and solar water heater performance relative to the plain tube design.
Review Over The Effects Of Baffle Orientation And Shape Factor Over Pressure ...IRJET Journal
This document reviews research on using baffles and other obstructions inside heat exchanger tubes to improve heat transfer and pressure drop. It summarizes 18 scientific studies that examined the effects of baffle orientation, shape, and other factors on heat transfer coefficients and pressure drop in tube heat exchangers. The studies tested baffles of different shapes, such as circular, trapezoidal, rectangular, and twisted bands, and found that baffles can increase heat transfer by up to 187% compared to smooth tubes by disturbing the fluid flow. The document concludes that baffle design parameters like size, arrangement and material properties influence heat exchange and more research is needed.
An experimental study of heat transfer in plane circular tube fitted with the V-Shaped Aluminum
turbulators is performed for plane circular tube. The objective of this Project work is to analyses heat transfer
coefficient and friction characteristics in a plane circular tube fitted with the V-Shaped Aluminum turbulators.
The experimentations are firstly carried out on the plane circular pipe and heat transfer augmentation were
recorded and then the v-shaped Aluminum turbulators are fitted in the same plane pipe and then again the heat
transfer augmentation is recorded and then both of them is compared. Experimental investigations have been
carried out to study the effects of the V-Shaped Aluminum turbulators on heat transfer, friction and
enhancement efficiency, in a circular tube. We used the V-Shaped aluminum turbulators with the turbulator
element length of 200mm, 160mm and 120mm.We found the heat transfer argumentation.The mean heat
transfer rates obtained from using the V-Aluminum turbulators are 198%, 213% and 241% for turbulator
element Length of 200mm, 160mm and 120 mm respectively. All of the experiments are carried out at the
same inlet conditions with the Reynolds number, based on the tube diameter (Re), in a range of 3000 to
10000
This document summarizes a study on the thermal analysis of circular inclined pipes subjected to natural convection using computational fluid dynamics (CFD). The study investigated the effect of parameters like tube diameter, heat supplied, and tube inclination on the temperature and heat transfer coefficient through experimental testing and CFD analysis. The experimental results were validated against CFD results, with less than 5% error found between the two. It was found that temperature increased with increasing pipe diameter and heat supply. The temperature was also strongly influenced by heat flux and diameter, and weakly dependent on tube inclination.
Thermo hydraulics performance of turbulent flow heat transfer through square ...IAEME Publication
This document describes an experimental study of heat transfer in square ducts with inserts. The study investigated the effects of inserts on heat transfer coefficient and pressure drop in turbulent air flow through square ducts. Experiments were conducted with a square duct heated on one wall to create a uniform heat flux condition, while other walls were insulated. Measurements of temperature, pressure drop, and other variables were taken to analyze heat transfer and flow characteristics for Reynolds numbers between 10,000 and 100,000. The results show that inserts can enhance the heat transfer coefficient in square ducts by up to 46% compared to plain ducts, though they also increase pressure drop.
Thermo hydraulics performance of turbulent flow heat transfer through square ...IAEME Publication
This document describes an experimental study of heat transfer in square ducts with inserts. The study investigated the effects of inserts on heat transfer coefficient and pressure drop in turbulent air flow through square ducts. Experiments were conducted with a square duct heated on one wall to create a uniform heat flux condition, while other walls were insulated. Measurements of temperature, pressure drop, and other variables were taken to analyze heat transfer and flow characteristics for Reynolds numbers between 10,000 and 100,000. The results show that inserts can enhance the heat transfer coefficient in square ducts by up to 46% compared to plain ducts, though they also increase pressure drop due to increased flow friction.
Optimization of a Shell and Tube Condenser using Numerical MethodIJERA Editor
The purpose of this study was to investigate the effect of installation of the tube external surfaces, their parameter and variable in a shell-and-tube condenser. Variation of heat transfer coefficient with each variable of shell and tube condenser was measured each test. The optimization tube outside diameter size was analyzed and use extended surface area attached tube with tube material and tube layout and arrangement (Number of tube a triangular or hexagonal arrangement) on shell-and tube condenser. The computer programming was used to get faster output in less time. Results suggest that mean heat transfer coefficient in variable condition were mainly at velocity is fixed. And also average additional surfaces and tube layout and the arrangement comparison with the quantity of the heat transfer.
Review of Heat Transfer Parameters using internal threaded pipe fitted with i...ijiert bestjournal
Many heat transfer enhanced techniques have simultaneously been de veloped for the improvement of energy consumption,material saving,size reduction and pumping power reduction. Screw tape inserts in tubes are a typical technique that offer s a higher heat transfer increase and,at the same time,only a mild pressure drop penalty. This study investi gates the heat transfer characteristics of a horizontal tube-in-tube heat exchanger having internal threaded pip e with Screw tape inserts of different materials i.e. Mild steel screw tape and Aluminum sc rew tape inserted in the inner tube. Heat transfer,flow friction characteristics in a threaded tube fitted with sc rew tape,using oil as working fluid are investigated experimentally. Influences of the changing mate rial i.e M.S screw tape and Aluminum screw tape arrangements are also described. The experiments ar e conducted using the tapes with same twist ratios and pitch over a Reynolds number range less than 2,0 in a heat exchanger.
Similar to Experimental Investigation of Heat Transfer Enhancement by Using Clockwise and Counter -clockwise Corrugated Twisted Tape Inserts (20)
Since so many years a problem occurs in KSB Pump Va mbori for casting process i.e. cracks occurs in the castings & it is repeated one. Therefore the compan y has given opportunity to me to solve this problem . In case of steel casting there are mainly cracks & also blo w holes induced due to the casting procedure. There are many factors for the casting defects .The factor is unev en material feeding in casting & also due to the mo uld material & also the core material. These cracks finally brea k directly the component of the casting i.e. in cas e of pump the casting component is like Impeller,Volute casing & casing cover. At the time of feeding of steel material in to the casting the material is in liquid us form i.e. it i s hot material & this material is feeding into casting at the time o f feeding it develop different region of heat. At o ne side the temp is high &at other side the temp is low this also pr oduce cracks. To simulate that casting we use the M AGMA SOFTWARE for simulation & validate it using NDT.
A COMPARATIVE STUDY OF DESIGN OF SIMPLE SPUR GEAR TRAIN AND HELICAL GEAR TRAI...ijiert bestjournal
The document describes the design of a simple spur gear train and helical gear train with an idler gear using the AGMA (American Gear Manufacturers Association) standard method. Key steps of the design process include selecting input parameters, creating a preliminary drawing, selecting materials, and performing theoretical calculations to determine dimensions and check for bending and contact stresses based on AGMA equations. A comparative study is carried out to select the optimal gear train design that meets the strength requirements for the given input parameters and load conditions.
COMPARATIVE ANALYSIS OF CONVENTIONAL LEAF SPRING AND COMPOSITE LEAFijiert bestjournal
A leaf spring is a simple form of spring,commonly used for the suspension in wheeled vehicles. It is also one of the oldest forms of spring. Sometimes referred to as a semielliptical l eaf spring (SELS) it takes the form of a slender ar c-shaped length of spring steel of rectangular cross section. The centre of the arc p rovides location for the axle,while tie holes are provided at either end for attaching to the vehicle body. In the present work,a seven-leaf steel spring use d in passenger cars is replaced with a composite mu lti leaf spring made of glass/epoxy composites. The dimensions sand the num ber of leaves for both steel leaf spring and compos ite leaf springs are considered to be the same. The primary objective is to compare their load carrying capacity,stiffness and weight savings of composite leaf spring. Finally,fatigue life of steel and com posite leaf spring is also predicted using life dat a
Brimmed diffuser is collection�acceleration device which shrouds a wind turbine.For a given turbine di ameter,the power augmentation can be achieved by brimmed diffuser,p opularly known as wind lens. The present numerical investigation deals with the effect of low pressure region created by wind l ens and hence to analyze the strong vortices formed by a brim attached to the shroud diffuser at exit. Also in this analysis,a c omparative numerical prediction of mass flow rates through the wind turbine has been carried out with various types of wind lens wh ich in turn helps to optimize the torque augmentati on. It has been numerically proved that there is significant increase in the wa ke formation & vortex strength when brimming effect is added to a diffuser
FINITE ELEMENT ANALYSIS OF CONNECTING ROD OF MG-ALLOY ijiert bestjournal
The automobile engine connecting rod is a high volume production,critical component. It co nnects reciprocating piston to rotating crankshaft,transmitting the thrust of the piston to the crankshaft. Every vehicle that uses an internal combustion engine requires at least one connecting rod depending upon the number of cylinders in the engine. As the purp ose of the connecting rod is to transfer the reciprocating motion of the piston into rotary motion of the crankshaft. Connecting ro ds for automotive applications are typically manufactured by forging from either w rought steel or powdered metal. the material used f or this process is Mg-Alloy and also finite element analysis of connecting rod
REVIEW ON CRITICAL SPEED IMPROVEMENT IN SINGLE CYLINDER ENGINE VALVE TRAINijiert bestjournal
1) The document discusses improving the critical speed of the valve train in a single cylinder engine from 3600 rpm to 5000 rpm. It aims to optimize the valve spring parameters to increase the speed limit without failure of contact between components.
2) An analytical and simulation-based approach is proposed. The valve spring stiffness, pushrod buckling, contact stresses, and natural frequency response will be analyzed. ADAMS multi-body dynamics software will be used to simulate the optimized design.
3) Preliminary results found that with the optimized valve spring configuration, the engine speed could be increased beyond 5000 rpm without failure, unlike with the existing design. Experimental validation of the optimized design will evaluate performance.
ENERGY CONVERSION PHENOMENON IN IMPLEMENTATION OF WATER LIFTING BY USING PEND...ijiert bestjournal
This paper consist of working of reciprocating pump which is driven by a compound pendulum. It provide s the energy required to lift the water from a tank placed approximately several meter below the ground level. Basic application of the mechanism will be for watering the garden which will be operated by means of operation opening and closing of entrance gate. Paper consists of basic concept,design of pump and compound pendulum mecha nism and fabricationed model. The concept can also be implemented in the rural areas,having the problem of electric supply. We aim at making a prototype for providing some me an for pumping of water by the pump which requires less human efforts,conside ring cost effectiveness,easy to operate and portab le mechanism.
The IC engine has seen numerous revolutionary and e volutionary modifications in technology and design over the past few decades. The sole motto behind the modifications wa s to increase the overall efficiency of the IC Engi ne including volumetric and thermal efficiency. Recently few benchmarking techn ologies like the CRDI,MPFI,HCCI,etc. in the Otto cycle and Diesel cycle engines have created an enormous revolution in the automobile industry. In spite of these technologica l and design advances,the efficiencies are not being more than a particular l imit. However,the concept of split cycle engines has dra stically increased the overall performance in all respect. The split cycle concept basically separates the fou r strokes of the conventional cycle. The Scuderi engine one of the best-in-class engine desi gns based on the split cycle concept. The Scuderi engine works on the split cycle and gives higher efficiency than the previous split cycle engines resulting overall high perform ance. It also eliminates the problems faced by previous engines based on the spl it cycle in terms of breathing (volumetric efficien cy) and thermal efficiency. This paper throws light on the greater volumetric,thermal and overall efficiency key points related t o the Scuderi Engines.
EXPERIMENTAL EVALUATION OF TEMPERATURE DISTRIBUTION IN JOURNAL BEARING OPERAT...ijiert bestjournal
The excessive rise of temperature in the journal be aring operating at boundary/mixed lubrication regim es. Journal bearing test set- up is used to measure the temperature along the cir cumference of the bearing specimen for different lo ading conditions. Here in this journal bearing of l/d ratio 1,diameter of jo urnal is 60mm and the bearing length is 60mm,clear ance is .06mm has been designed and tested to access the temperature rise of the bearing. The result shows that as the load o n the bearing is increasing temperature also increasing. Temperature analysis o f journal bearing is also done by the Ansys workben ch software
STUDY OF SOLAR THERMAL CAVITY RECEIVER FOR PARABOLIC CONCENTRATING COLLECTOR ijiert bestjournal
Energy is one of the building blocks of the country . The growth of the country has been fueled by chea p,abundant energy resources. Solar energy is a form of renewable ener gy which is available abundantly and collected unre servedly. The parabolic concentrator reflects the direct incident solar rad iation onto a receiver mounted above the dish at it s focal point. The conversion of concentrated solar radiation to heat takes place in receiver. The heat transfer characteristics of the receiver changes during the rotation of the receiver which affects thermal performance. The working temperature may also influence the ther mal performance and overall efficiency of the system. Thermal as well as optica l losses affect the performance of a solar paraboli c dish-cavity receiver system. The thermal losses of a solar cavity receiver include c onvective and radiative losses to the air in the ca vity and conductive heat loss through the insulation used behind the helical tube surface. Convective and radiative heat losses form the major constituents of the thermal losses. The convection heat loss from cavit y receiver in parabolic dish solar thermal power sy stem can significantly reduce the efficiency and consequently the cost effectiveness of the system. It is important to assess this heat loss and subsequently improve the thermal performance of the receiver.
DESIGN, OPTIMIZATION AND FINITE ELEMENT ANALYSIS OF CRANKSHAFTijiert bestjournal
Crankshaft is a crucial component in an engine asse mbly. Crankshaft is consisting of two web sections and one crankpin,which converts the reciprocating displacement of the pist on to a rotary motion with a four link mechanism. G enerally crankshafts are manufactured using cast iron and forged steel mater ial. In this work to design and finite element anal ysis of crankshaft of 4 cylinder petrol engine of Maruti swift Vxi. of 1200 cubic capacity. The finite element analysis in ABA QUS software by using six materials based on their composition viz. Cast iron,EN30B,SAE4340,Structural steel,C70 Alloy steel and Aluminium based composite material reinforced with silicon carbide & fly ash. The parameter like von misses stress,deformation;maximum and minimum principal stress & strain were obtained from analysis software. The results of Finite element show that t he Aluminium based composite material is best mater ial among all. Compare the result like weight and Stiffness parameter. It is resulted of 65.539 % of weight,with reduction i n deformation.
ELECTRO CHEMICAL MACHINING AND ELECTRICAL DISCHARGE MACHINING PROCESSES MICRO...ijiert bestjournal
Nowadays,necessity of small components is a common trend. These requirements encourage the researcher s to develop very minutest size components to fulfill the demand. The manufact uring of these type of components is a difficult ob ligation and for that various machining methods are develop to manufacture such c omponents. In this article the Electro Chemical mac hining and Electrical Discharge Machining is reviewed. We tried to summar ize the work of various researchers. The study show s that this type of machining processes gives good alternative.
HEAT TRANSFER ENHANCEMENT BY USING NANOFLUID JET IMPINGEMENTijiert bestjournal
This document presents an experimental study on heat transfer enhancement using nanofluid jet impingement. Key findings include:
1) The use of nanofluids (Al2O3-water) can increase heat transfer coefficients by up to 44% compared to using water alone.
2) Heat transfer coefficients are highest near the stagnation point and decrease further from the center.
3) Varying the nozzle-to-plate distance (Z/D ratio) between 2-8 results in maximum heat transfer, with little effect beyond Z/D of 12.
4) Increasing the flow rate leads to higher heat transfer coefficients, up to a 5% increase from 2 lpm to 4 lpm.
MODIFICATION AND OPTIMIZATION IN STEEL SANDWICH PANELS USING ANSYS WORKBENCH ijiert bestjournal
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Experimental Investigation of Heat Transfer Enhancement by Using Clockwise and Counter -clockwise Corrugated Twisted Tape Inserts
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ExperimentalInvestigationofHeatTransferEnhancementbyUsingClockwise
andCounter-clockwiseCorrugatedTwistedTapeInserts
K.G.KULKARNI
Appearing in ME ( HEAT POWER),
PES’s Modern College Of Engineering
Shivajinagar , Pune, Maharashtra, India
S.Y.BHOSALE
Asst. Professor , Department of Mechanical Engineering,
PES’s Modern College Of Engineering
Shivajinagar , Pune, Maharashtra, India
Abstract
Present Experimental work shows result obtain from experimentation of heat transfer enhancement in
circular horizontal tube by using clockwise and counterclockwise corrugated twisted tape inserts with
working fluid is air. Experiments conducted on plain circular tube with or without c-cc corrugated
twisted tube. During experiment constant heat flux and different mass flow rate condition. The c-cc
corrugated twisted tape are of same pitch and twist ratio but three different angle of rotation in
clockwise and counter clockwise direction as 30˚, 60˚, 90˚ respectively. The Reynolds no. varied from
4000 to 10000. Heat transfer coefficient and pressure drop are calculated and results are compared with
the plain tube without inserts. Finally heat transfer enhances with clockwise and counterclockwise
corrugated twisted tape inserts as compared to plain tube varied from 8 % to 44 % for various inserts.
Plain twisted tape results are also compared with the same results.
Introduction
Heat transfer enhancement devices have been used for increasing heat transfer rate and optimizing heat
transfer system .Many techniques investigated (ex. Passive techniques and active techniques) for
augmentation of heat transfer inside circular tube, a wide range of inserts have been used when
turbulent flow is considered. Various methods are used for increasing thermal performance such as
rough surfaces, treated surfaces, coiled tubes , swirling flow devices , surface tension devices [1].
Twisted tape is one of the commonly used passive type swirl turbulator for heat transfer augmentation
due to their several advantages as ease of installation, steady performance and simple configurations
[2].Twisted tape inserts generate swirling flow which leads to improved fluid mixing between central
region and the wall region so, the heat transfer in tubes can be enhanced by fluid mixing. Sarma et al.
[3] derived correlations are used to predict convective heat transfer coefficient and friction factor in a
tube fitted with twisted tapes for a wide range of Reynolds number and Prandtl number. The
contribution to thermal performance of the conventional, short-width and center-cleared twisted tapes
was studied numerically [2].
Configuration optimization of regularly spaced short-length twisted tapes in a circular tube for
turbulent heat transfer was carried out by Wang et al. [4] by using computational fluid dynamics
(CFDs) modeling. Eiamsa-ard et al. [5] examined experimental study on convective heat transfer in a
circular tube with short-length twisted tapes inserted inside tube under uniform heat flux.
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Akhavan-Behabadi et al [6] Experiments were conducted to study effects of twisted tapes on heat
transfer rate and pressure drop for R-134a as working fluid in horizontal evaporators Heat transfer rate
and friction factor were calculated in circular tube which is equipped with modified twisted tape
alternate axis for CuO/water nanofluid as a working fluid [7-9].
Eiamsa-ard et al. [10] performed experiment in a double pipe heat exchanger fitted with twisted tape
elements for heat transfer and friction factor characteristics. They made their analysis for both
continuously placed twisted tape and twisted tape placed with various free spaced in circular tube. The
heat transfer augmentation and pressure drop during condensation of HFC-134a in a horizontal tube
fitted with twisted tapes were experimentally analyzed [11].
Jaisankar et al. [12] Performed experiment on solar water heater to determine thermal performance
caused by twisted tape. Effect of various aspect on heat transfer and pressure drop were examined in a
circular tube fitted with regularly spaced twisted tape elements as Twist ratio, space ratio, tape width,
rod-diameter and phase angle [13].
Naphon [14] conducted experiments by using conventional twisted tape inserts in horizontal double
pipe. Ferroni et al. [15] performed experiments in circular tube equipped with physically separated,
multiple, short-length twisted tapes. Laminar convective heat transfer enhancement in twisted tape
inserted tube was observed experimentally by Sarma et al.[16]. In some studies, researchers observed
the thermal effects of twisted tape inserts in modified tube instead of smooth tube, for example;
Thianpong et al. [17] observed heat transfer enhancement in a dimpled tube with a twisted tape swirl
generator inserted. They also derived empirical correlations based on the experimental results of their
study for prediction the Nusselt number and friction factor for Reynolds number from 12,000 to
44,000. Bharadwaj et al. [18] performed experiments by using conventional type of twisted tapes to
determine pressure drop and heat transfer characteristics of water in a 75-start spirally grooved tube.
Some researchers [19] modified the conventional twisted tape geometries, for example; Murugesan et
al. [20] used V-cut twisted tapes to analyse heat transfer and pressure drop in a circular tube.
EXPERIMENTAL SET-UP
The actual diagram of experimental set-up is given in Fig.1.The experiment consist of a blower for air
flow, an orifice meter to measure the volumetric flow rate, the test tube of 700mm length, 26 mm
inner diameter (D1), 26.4 mm outer diameter (D2), and 2 mm thickness (t). The clockwise
counterclockwise corrugated twisted tapes are tested in this experiment, with three different angle of
rotation as 30˚, 60˚ and 90˚ in clockwise and counterclockwise direction but have same twist ratio
=8.333. They are fabricated from aluminium.. Also one plane twisted tape made up of aluminium is
tested.
The actual figure of the clockwise counterclockwise corrugated twisted tape insert is given in Fig.2.
A blower is of 0.24 hp used to force air through the test tube. Constant and uniform heat flux is applied
to external surface of the test tube by means of heating with electrical winding. The output power is
controlled by a variac transformer to supply constant heat flux along the entire section of the test tube.
The outer surface of the test tube is insulated with glass wool and cotton to minimize the convective
heat loss to the surroundings. 6 K-type thermocouples have been used for measurement of the external
surface temperatures of the test tube wall, which are placed on the outer circumference of the test tube.
Also, the inlet and outlet temperatures of the bulk air are measured by two K-type thermocouples at
given points.
An inclined manometer is used to measure pressure drop across the test tube. After air passes the test
tube, it enters to the orifice meter for determining volumetric flow rate readings. For this purpose a
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separate U-tube manometer is placed across orifice meter. The volumetric flow rate of air supplied
from the blower is controlled by varying control valve position. The experiments are conducted by
varying the flow rate in terms of Reynolds numbers from 4000 to 10000 of the bulk air. During the
experiments the test tube is heated from the external surface, and the data of temperatures, volumetric
flow rate, pressure drop of the bulk air and electrical output are recorded after the system is approached
to the steady state condition. The Nusselt number, Reynolds number, friction factor, heat transfer
enhancement are calculated based on the average outer wall temperatures and the inlet and outlet air
temperatures.
Figure 1: Experimental set up
Figure 2 : c – cc corrugated insert
DATA COLLECTION AND ANALYSIS
The data reduction of the obtained results is summarized in the following procedures:
Heat transfer calculation:
Ts = (T2 + T3 + T4 + T5 + T6 + T7)/6 …………… (1)
Tb = (T1 + T8)/2 ……………… (2)
Discharge of air,Qa = Cd * Ao* ……… (3)
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Velocity of air flow, V = Qa /A …………………… (4)
Reynolds number, Re = VD / ʋ ………………… (5)
Q = m *Cp* (T8 - T1) ………………… (6)
h = ………………… (7)
Nu = hD / k ………………… (8)
f = ……………… (9)
η = ………………. (10)
Validation of experimental result for plain tube
In this study, experimental results of Nusselt number and friction factor for the plain tube are obtained
and validated with equations of Dittus Boelter and Petukhov as given below;
Nuth = 0.023*(Re)0.8
*(Pr)0.4
………… (11)
fs = (1.82 log10Re-1.64)-2
……………. (12)
Figure 3 : c – cc corrugated inserts
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The comparisons of Nusselt number and friction factor for the present plain tube with existing
correlations are shown in Figs. 4 and 5, respectively. These figures shows that validation experiments
of heat Transfer rate in terms of Nusselt number and friction factor for the plain tube are acceptable
with the results obtained
Figure 4: Validation results for friction factor
Figure 5: Validation results for Nusselt number
Theoretical Values of Nusselt No. and friction factor are obtained by using Dittus-Boelter and
Petukhov equations. The results of present plain tube and previous equations are nearly the same and
this provides reliable results for heat transfer and friction factor in a tube with c-cc corrugated twisted
tape inserts. In this present experimental work The Reynolds numbers were ranged from 4100 to 11000
i.e. the range of Reynolds number used is for turbulent flow. The results of the tests carried for
performance checking of present clockwise counterclockwise corrugated twisted tape are discussed
further in results and discussion.
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RESULTS AND DISCUSSION
A .Heat Transfer and Overall Enhancement
The variation of Nusselt number with Reynolds number for various clockwise and counterclockwise
corrugated inserts is shown in Figure 6. Highest Nusselt number was obtained for tape with angle of
rotation = 90º , Twist ratio = 8.33 Wave width = 12 mm. The Nusselt number for these inserts varied
from 34 % to 85 % compared to plain tube. This result can be attributed to the following reasons.
Firstly, the periodic change of swirl direction from clockwise to counterclockwise directions and vice
versa, causes the sudden change of fluid arrangement, giving better fluid mixing and uniform
temperature. Secondly corrugations on tape provide more efficient interruption of thermal boundary
layer resulting in to superior chaotic mixing of the flow causing heat transfer enhancement. The
variations of friction factor with Reynolds number for inserts are presented in Figure 7. It is observed
that the friction factor gradually reduced with rise in Reynolds number. It is observed to be minimum
friction factor for insert having angle = 90 º ,wave width = 12 mm and twist ratio =8.33. It is evident
from Figures 6, 7 and 8 that when a c-cc corrugated twisted tape is inserted into a plain tube there is a
significant improvement in Nusselt number because of secondary flow, with greater enhancement
being realized at lower Reynolds numbers and 90º angle of rotation.
.
Figure No. 6 Variation of Nusselt number for
different insert configurations
Figure 7: Variation of friction factor for different insert
Configurations
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Figure 8: Variation of Enhancement for different insert configurations
It is observed that the increment in angle of rotation causes increment in Nusselt numbers as well as
rise in pressure drop. From Figure 6, the percentage rise in Nusselt numbers for c-cc corrugated
twisted tapes compared to plain tube are about 31- 95%, 31-87% and 25-88% respectively for tape with
angle of rotation 90º , 60 º , 30 ºrespectively for twist ratio =8.33 and wave width = 12mm. The overall
enhancement ratio is useful to evaluate the quality of heat transfer enhancement obtained over plain
tube at constant pumping power. It is found to be more than unity for all the c-cc corrugated twisted
tape inserts used.
Variations of overall enhancement ratio h against Reynolds number for various tapes are shown in
figure 8. It is observed that overall enhancement tended to decrease gradually with the rise of Reynolds
number for all twist ratios. The maximum value of overall enhancement is 1.65 c-cc corrugated twisted
tape insert having angle of rotation = 90º with twist ratio equal to 8.33 and wave width is 12 mm It is
seen in Figure 8 that, for tapes of angle 30º , 60º , 90 º are of decreasing order for a given pitch in the
range of Reynolds number from 4000 to 9500.
This enhancement is mainly due to the larger portions of fluid are directed to the opposing direction in
the region of the change, leading to the stronger collision
of the recombined streams. Moreover, the higher twist angle shows the larger difference of plane
direction for the adjacent twist lengths, providing more effective disturbance to the flowing fluid. This
directly impacts on the developing thermal boundary layer, resulting in enhancement of heat transfer
inside the heat exchanger.
CONCLUSIONS
The present experimental work has been conducted investigate the potential of clockwise and
counterclockwise corrugated twisted tape inserts to enhance the heat transfer rate in a horizontal
circular tube with inside diameter 26mm with air as working fluid. The Reynolds number varied from
4000 to 9500. The effects of parameters such as angle of rotation and corrugation, Reynolds number on
the heat transfer and overall enhancement ratio have been studied.
The following conclusions can be drawn:
A. The enhancement of heat transfer with clockwise and anticlockwise corrugated twisted tape inserts
as compared to plain tube varied from 12 to 46% for 90 º angle of rotation and 10 to 39% for 60ºangle
of rotation. This enhancement is mainly due to the larger portions of fluid are directed to the opposing
direction in the region of the change, leading to the stronger collision of the recombined streams and
the spiral motion of the fluid.
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B. Increment in angle of rotation causes rise in Nusselt numbers as well as friction factors. The
maximum friction factor rise was about 175% for 60º angle of rotation. and 150% for 30 º angle of c-
cc corrugated twisted tape inserts compared to plain tube.
C. The overall enhancement for the tubes with c-cc corrugated twisted tape inserts is 1.65 for 90 º
angle of rotation and 1.4 for 60º angle of rotation c-cc corrugated twisted tape insert. Thus the
enhanced performance can be achieved using Clockwise and counterclockwise corrugated twisted tapes
as compared to plane twisted tape.
Thus, from the considerations of enhanced heat transfer and savings in pumping power by using
Clockwise and counterclockwise corrugated twisted tapes inserts are seen to be attractive for enhancing
turbulent flow heat transfer in a horizontal circular tube with air as working fluid
Future work may be extended to:
A. Change the tape material from Aluminium to copper
B. Internal corrugated test tube can be used with different inserts.
C. Compound enhancement techniques maybe applied i.e. the tape inserts can be coupled with spring
coil inserts for better enhancement.
NOMENCLATURE
A0 - area of orifice, (m2)
A - test section inner tube area, (p/4 D2) (m2)
Cp - specific heat of air, (J/kg K)
Qa - air discharge through test section (m3/sec)
D - Inner diameter of test section, (m)
H - pitch, (mm)
w - width of wavy tape insert,(mm)
H/D - twist ratio
fth - friction factor(theoretical) for plain tube
f - friction factor(experimental) for plain tube
fi - friction factor obtained using tape inserts
h - experimental convective heat transfer coefficient, (W/m2K)
hw - manometer level difference,(m)
hair - equivalent height of air column, (m)
k - thermal conductivity, (W/mK)
L - length of test section, (m)
m - mass flow rate of air, (Kg/sec)
Nui - Nusselt number (experimental) with tape inserts, (hD/k)
Nu - Nusselt number (experimental) for plain tube
Nuth - Nusselt number for plain tube (theoretical)
Pr - Prandtl number
p - pitch, (m)
DP - pressure drop across the test section, (Pa)
Q - total heat transferred to air (W)
Re - Reynolds number, (r V D/m)
T1, T8 - air temperature at inlet and outlet, (_k)
T2, T3, T4, T5 - tube wall temperatures, (_K)
Ts - average Surface temperature of the working fluid, (_K)
Tb - bulk temperature, (_K)
V - air velocity through test section, (m/sec)
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