CFD Analysis of Heat Transfer in Helical CoilIRJET Journal
This document presents a computational fluid dynamics (CFD) analysis of heat transfer in a helical coil. The study aims to analyze the effect of coil diameter and inlet steam temperature on the heat transfer coefficient. CFD simulations are conducted for helical coils of different diameters with varying inlet steam temperatures and water flow rates. Results show that the heat transfer coefficient increases with increasing inlet steam temperature. Prior research on heat transfer in helical coils is also reviewed, focusing on studies utilizing CFD to analyze parameters like coil diameter, pitch, curvature ratio, and Reynolds number. The CFD methodology and boundary conditions used in this study are described. Contour plots of the simulated surface heat transfer coefficient are presented and discussed.
IRJET- Design the Shell and Tube Heat Exchanger with the Help of Programming ...IRJET Journal
This document discusses the design of a shell and tube heat exchanger using MATLAB software. It begins with an abstract that outlines how heat exchangers transfer heat between fluids and research into increasing heat exchanger effectiveness. It then provides background on heat exchangers and discusses prior research on improving shell and tube heat exchanger design, notably methods developed by Kern, Tinker, Bell, Saunders, Taborek, Wills and Johnston, and others. The document indicates that while hand calculations were used historically, computer programs are now widely employed for heat exchanger design.
The document discusses heat exchangers, including their definition as equipment that transfers heat between mediums. It describes the main types - tube and shell and plate, and flow arrangements - parallel, counter, and cross flow. Key concepts covered include log mean temperature difference (LMTD), number of transfer units (NTU) method, effectiveness, and the purpose of performance testing to determine heat transfer coefficients and identify any fouling issues. The document was submitted by two students for their seminar and technical writing course.
THE EFFECT OF GEOMETRICAL PARAMETERS ON HEAT TRANSFER AND HYDRO DYNAMICAL CHA...ijmech
Compact size and high heat transfer coefficient of helical coil heat exchangers causes them to have an
important role in various industrial applications. This paper investigate numerically on the influence of
different parameters such as coil radius, coil pitch and diameter of tube on the hydrodynamic and
heat transfer characteristics of helical double tube heat exchangers using the CFD software which is
based on the principles of heat transfer, fluid mechanics and thermodynamics. The results indicated that
heat transfer augmentation occurs by increasing of the inner Dean Number, inner tube diameter, curvature
ratio and by the reduction of the pitch of heat exchanger coil. By increasing the radius of coils, the
secondary flow effects due to centrifugal forces diminishes and flow of fluid through the coils tends to flow
in a straight path and as a result, the friction coefficient decreases consequently.
Obtain average velocity from a knowledge of velocity profile, and average temperature from a knowledge of temperature profile in internal flow.
Have a visual understanding of different flow regions in internal flow, and calculate hydrodynamic and thermal entry lengths.
Analyze heating and cooling of a fluid flowing in a tube under constant surface temperature and constant surface heat flux conditions, and work with the logarithmic mean temperature difference.
Obtain analytic relations for the velocity profile, pressure drop, friction factor, and Nusselt number in fully developed laminar flow.
Determine the friction factor and Nusselt number in fully developed turbulent flow using empirical relations, and calculate the heat transfer rate.
1. Heat exchanger pressure drop analysis is important because pumping power required is directly related to pressure drop and pressure drop affects heat transfer, operation, size, and cost.
2. Major contributions to pressure drop include friction in the core and distribution devices, with core pressure drop dominated by friction, momentum effects, and entrance/exit effects.
3. Core pressure drop is analyzed using assumptions of steady, isothermal flow and accounting for friction, momentum effects, and entrance/exit contractions based on flow geometry and properties.
Convective heat transfer and pressure drop in v corrugatedMohamed Fadl
New energy system development and energy
conservation require high performance heat exchanger, so
the researchers are seeking to find new methods to enhance
heat transfer mechanism in heat exchangers. The objectives
of this study are investigating heat transfer performance
and flow development in V-corrugated channels, numerical
simulations were carried out for uniform wall heat flux
equal 290 W/m
2
using air as a working fluid, Reynolds
number varies from 500 to 2,000, phase shifts,
0 \ Ø \ 180, and channel heights (S = 12.5, 15.0, 17.5
and 20 mm). Governing equations of flow and energy were
solved numerically by using finite volume method. The
numerical results indicated that, wavy (V-corrugated)
channels have a significant impact on heat transfer
enhancement with increase in pressure drop though chan-
nel due to breaking and destabilizing in the thermal
boundary layer are occurred as fluid flowing through the
corrugated surfaces and the effect of corrugated phase shift
on the heat transfer and fluid flow is more significant in
narrow channel, the goodness factor (j/f) was increased
with increasing channel phase shift, the best performance
was noticed on phase shift, Ø = 180 and channel height,
S = 12.5 mm.
IRJET- Numerical Investigation of the Forced Convection using Nano FluidIRJET Journal
This document summarizes research on using computational fluid dynamics (CFD) simulations to analyze heat transfer and friction factors for turbulent flow of titanium dioxide, iron oxide, and silicon dioxide nanofluid in semi-circle corrugated channels. The simulations were conducted at Reynolds numbers of 10,000-30,000, nanoparticle volume fractions of 0-6%, and constant heat flux conditions. Results showed that the Nusselt number, a measure of heat transfer, increased with higher nanoparticle volume fraction and Reynolds number. Maximum Nusselt number enhancement of 2.07 was found at a Reynolds number of 30,000 and volume fraction of 6%.
CFD Analysis of Heat Transfer in Helical CoilIRJET Journal
This document presents a computational fluid dynamics (CFD) analysis of heat transfer in a helical coil. The study aims to analyze the effect of coil diameter and inlet steam temperature on the heat transfer coefficient. CFD simulations are conducted for helical coils of different diameters with varying inlet steam temperatures and water flow rates. Results show that the heat transfer coefficient increases with increasing inlet steam temperature. Prior research on heat transfer in helical coils is also reviewed, focusing on studies utilizing CFD to analyze parameters like coil diameter, pitch, curvature ratio, and Reynolds number. The CFD methodology and boundary conditions used in this study are described. Contour plots of the simulated surface heat transfer coefficient are presented and discussed.
IRJET- Design the Shell and Tube Heat Exchanger with the Help of Programming ...IRJET Journal
This document discusses the design of a shell and tube heat exchanger using MATLAB software. It begins with an abstract that outlines how heat exchangers transfer heat between fluids and research into increasing heat exchanger effectiveness. It then provides background on heat exchangers and discusses prior research on improving shell and tube heat exchanger design, notably methods developed by Kern, Tinker, Bell, Saunders, Taborek, Wills and Johnston, and others. The document indicates that while hand calculations were used historically, computer programs are now widely employed for heat exchanger design.
The document discusses heat exchangers, including their definition as equipment that transfers heat between mediums. It describes the main types - tube and shell and plate, and flow arrangements - parallel, counter, and cross flow. Key concepts covered include log mean temperature difference (LMTD), number of transfer units (NTU) method, effectiveness, and the purpose of performance testing to determine heat transfer coefficients and identify any fouling issues. The document was submitted by two students for their seminar and technical writing course.
THE EFFECT OF GEOMETRICAL PARAMETERS ON HEAT TRANSFER AND HYDRO DYNAMICAL CHA...ijmech
Compact size and high heat transfer coefficient of helical coil heat exchangers causes them to have an
important role in various industrial applications. This paper investigate numerically on the influence of
different parameters such as coil radius, coil pitch and diameter of tube on the hydrodynamic and
heat transfer characteristics of helical double tube heat exchangers using the CFD software which is
based on the principles of heat transfer, fluid mechanics and thermodynamics. The results indicated that
heat transfer augmentation occurs by increasing of the inner Dean Number, inner tube diameter, curvature
ratio and by the reduction of the pitch of heat exchanger coil. By increasing the radius of coils, the
secondary flow effects due to centrifugal forces diminishes and flow of fluid through the coils tends to flow
in a straight path and as a result, the friction coefficient decreases consequently.
Obtain average velocity from a knowledge of velocity profile, and average temperature from a knowledge of temperature profile in internal flow.
Have a visual understanding of different flow regions in internal flow, and calculate hydrodynamic and thermal entry lengths.
Analyze heating and cooling of a fluid flowing in a tube under constant surface temperature and constant surface heat flux conditions, and work with the logarithmic mean temperature difference.
Obtain analytic relations for the velocity profile, pressure drop, friction factor, and Nusselt number in fully developed laminar flow.
Determine the friction factor and Nusselt number in fully developed turbulent flow using empirical relations, and calculate the heat transfer rate.
1. Heat exchanger pressure drop analysis is important because pumping power required is directly related to pressure drop and pressure drop affects heat transfer, operation, size, and cost.
2. Major contributions to pressure drop include friction in the core and distribution devices, with core pressure drop dominated by friction, momentum effects, and entrance/exit effects.
3. Core pressure drop is analyzed using assumptions of steady, isothermal flow and accounting for friction, momentum effects, and entrance/exit contractions based on flow geometry and properties.
Convective heat transfer and pressure drop in v corrugatedMohamed Fadl
New energy system development and energy
conservation require high performance heat exchanger, so
the researchers are seeking to find new methods to enhance
heat transfer mechanism in heat exchangers. The objectives
of this study are investigating heat transfer performance
and flow development in V-corrugated channels, numerical
simulations were carried out for uniform wall heat flux
equal 290 W/m
2
using air as a working fluid, Reynolds
number varies from 500 to 2,000, phase shifts,
0 \ Ø \ 180, and channel heights (S = 12.5, 15.0, 17.5
and 20 mm). Governing equations of flow and energy were
solved numerically by using finite volume method. The
numerical results indicated that, wavy (V-corrugated)
channels have a significant impact on heat transfer
enhancement with increase in pressure drop though chan-
nel due to breaking and destabilizing in the thermal
boundary layer are occurred as fluid flowing through the
corrugated surfaces and the effect of corrugated phase shift
on the heat transfer and fluid flow is more significant in
narrow channel, the goodness factor (j/f) was increased
with increasing channel phase shift, the best performance
was noticed on phase shift, Ø = 180 and channel height,
S = 12.5 mm.
IRJET- Numerical Investigation of the Forced Convection using Nano FluidIRJET Journal
This document summarizes research on using computational fluid dynamics (CFD) simulations to analyze heat transfer and friction factors for turbulent flow of titanium dioxide, iron oxide, and silicon dioxide nanofluid in semi-circle corrugated channels. The simulations were conducted at Reynolds numbers of 10,000-30,000, nanoparticle volume fractions of 0-6%, and constant heat flux conditions. Results showed that the Nusselt number, a measure of heat transfer, increased with higher nanoparticle volume fraction and Reynolds number. Maximum Nusselt number enhancement of 2.07 was found at a Reynolds number of 30,000 and volume fraction of 6%.
IRJET - Performance Analysis of a Double Pipe Heat Exchanger with and wit...IRJET Journal
This document presents a study on the performance of a double pipe heat exchanger with and without triangular baffles. Experiments were conducted with the heat exchanger in both parallel flow and counter flow configurations, and with varying hot and cold fluid flow rates. The results showed that heat transfer rate, log mean temperature difference (LMTD), and effectiveness were highest when triangular baffles were used compared to no baffles. This is because baffles promote better fluid mixing and heat transfer. The conclusions indicate that triangular baffles can significantly improve the performance of a double pipe heat exchanger.
NUMERICAL INVESTIGATION OF LAMINAR NANOFLUID FLOW IN MICRO CHANNEL HEAT SINKS IAEME Publication
The effect of using nanofluids on heat transfer and aerodynamics characteristics in rectangular shaped micro channel heat sink (MCHS) is numerically investigated for Reynolds number range of (100-400 ) and different value of heat flux (50 , 100, 150 ) / . In this study,the MCHS performance using tow type of nanofluid with volume
fraction 10% was used as a coolant is examined. The three-dimensional steady, laminar flow and heat transfer governing equations are solved using The computational fluid dynamics code (FLUENT). The MCHS performance is evaluated in terms of temperature profile, heat transfer,velocity profile, pressure drop and friction factor.
Wang W., Makeev A. Passive methods analysis of heat transfer intensification ...Елена Овечкина
The article analyzes the methods of passive intensification of heat exchange processes. The dependence of hydraulic resistance for fluid flow through the heat exchanger on the value of the temperature head on it is considered. The most effective ways of improvement of heat exchange processes are defined.
This document describes a thesis analyzing natural convection in a vertical microchannel using computational fluid dynamics (CFD). The thesis examines:
1) Fully developed flow conditions in a vertical parallel-plate microchannel with asymmetric wall temperatures, considering both velocity slip and temperature jump at the walls.
2) A more general approach to analyze entrance region conditions, without assumptions of fully developed flow.
3) Governing equations of continuity, momentum and energy to model the natural convection problem using the boundary layer approximations.
HEAT TRANSFER CORRELATION FOR NON-BOILING STRATIFIED FLOW PATTERN | J4RV3I11006Journal For Research
In chemical industries two phase flow is a process necessity. A better understanding of the rates of momentum and heat transfer in multi-phase flow conditions is important for the optimal design of the heat exchanger. To simplify the complexities in design, heat transfer coefficient correlations are useful. In this work a heat transfer correlation for non- boiling air-water flow with stratified flow pattern in horizontal circular pipe is proposed. To verify the correlation, heat transfer coefficients and flow parameters were measured at different combinations of air and water flow rates. The superficial Reynolds numbers ranged from about 2720 to 5740 for water and from about 563 to 1120 for air. These experimental data were successfully correlated by the proposed two-phase heat transfer correlation. It is observed that superficial.
This document provides an introduction to computational fluid dynamics (CFD) simulations of heat transfer in a tube bank heat exchanger. It discusses how CFD can be used to model the complex flow patterns and heat transfer between two fluids in a tube bank. The objectives are to examine optimal flow distribution for tubes of varying diameters and mass flow rates, and to analyze the effect of different tube materials on heat transfer rates. CFD provides insights into heat transfer phenomena at a lower cost than physical experiments.
Thermohydraulic Performance of a Series of In-Line Noncircular Ducts in a Par...Carnegie Mellon University
Heat transfer and fluid flow characteristics for two-dimensional laminar flow at low Reynolds number for five in-line ducts of
various nonconventional cross-sections in a parallel plate channel are studied in this paper.The governing equations were solved
using finite-volumemethod.CommercialCFDsoftware,ANSYS Fluent 14.5,was used to solve this problem.Atotal of three different
nonconventional, noncircular cross-section ducts and their characteristics are compared with those of circular cross-section ducts.
Shape-2 ducts offered minimum flow resistance and maximum heat transfer rate most of the time. Shape-3 ducts at Re < 100 and Shape-2 ducts at Re > 100 can be considered to give out the optimum results.
Transient Three-dimensional Numerical Analysis of Forced Convection Flow and ...IOSR Journals
A three-dimensional transient numerical study of a constant property Newtonian fluid in curved pipe under laminar flow conditions is presented for a uniform wall temperature boundary condition. Numerical solutions were obtained using the control volume method described by Patankar for the range of. The working fluid was water. The transient flow pattern and the temperature distribution on the tube section were derived for different values of the Reynolds number. Graphical results for velocity and temperature are presented and analyzed. Results have shown that the maximum velocity in center of velocity profile increase with increasing of Reynolds number. In curved pipes, time averaged results exhibited Dean circulation and a strong velocity and temperature stratification in the radial direction. Flow and heat transfer were strongly asymmetric, with higher values near the outer pipe bend.
This document reviews research on using computational fluid dynamics (CFD) to analyze coal/air flow in power plant pipelines in order to maintain uniform fuel feed rates at burners. Several studies are summarized that use CFD to simulate coal/air flow and model the effects of orifice flow restrictors placed in pipes. Correlations developed from CFD results relate pressure drop to factors like geometry, coal/gas loading ratio, and mass flux. CFD is shown to be an effective method for determining the optimal geometry and sizing of orifice flow restrictors to balance flow rates across burners.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Numerical Analysis of Header Configuration of the Plate-Fin Heat ExchangerIJMER
Numerical analysis of a plate fin heat exchanger accounting for the effect of fluid flow
maldistribution onthe inlet header configuration of the heat exchanger is investigated. In this analysis , it
was found that flow maldistribution has effect on the flow perpendicular to its velocity direction. The peak
velocity occurs in the central zone of the header while the velocityalong the perpendicular direction of the
inlet flow diminishes more and more. By this investigation,the results of the flow maldistribution are
presented for a plate fin heat exchangerwhich is reduced as compare to theexisting configuration of the
plate fin heat exchanger.
Experimental Investigation on Heat Transfer Analysis in a Cross flow Heat Ex...IJMER
Heat exchanger is devices used to exchange the heat between two liquids that are at different
temperature .These are used as a reheated in many industries and auto mobile sector and power
plants. The main aim of our project is thermal analysis of heat exchanger with waved baffles for
different types of materials at different mass flow rates and different tube diameters using FLOEFD
software and comparing the results that are obtained. The work is a simplified model for the study of
thermal analysis of shell-and-tubes heat exchangers having water as cold and hot fluid. Shell and
Tube heat exchangers are having special importance in boilers, oil coolers, condensers, pre-heaters.
They are also widely used in process applications as well as the refrigeration and air conditioning
industry. The robustness and medium weighted shape of Shell and Tube heat exchangers make them
well suited for high pressure operations. The project shows the best material, best boundary conditions
and parameters of materials we have to use for better heat conduction. For this we are chosen a
practical problem of counter flow shell and tube heat exchanger having water, by using the data that
come from cfd analysis. A design of sample model of shell and tube heat exchanger with waved baffles
is using Pro-e and done the thermal analysis by using FLOEFD software by assigning different
materials to tubes with different diameters having different mass flow rates and comparing the result
that obtained from FLOEFD software.
IRJET- Thermal and Fluid Flow Analysis of a Heat Exchanger: “A Comprehensive ...IRJET Journal
This document provides a comprehensive literature review and analysis of thermal and fluid flow performance in heat exchangers. It discusses several types of heat exchangers and techniques used to enhance heat transfer, such as surface textures, channel designs, and nanofluids. The document reviews experimental, numerical, and computational studies on fluid flow characteristics and heat transfer for different heat exchanger configurations and applications. It also provides governing equations for fluid flow and heat transfer analysis and compares experimental results to analytical predictions using correlations.
Enhancement of Heat Transfer Rate using Helix Tube and Friction FactorIRJET Journal
1) The document discusses heat transfer enhancement techniques, focusing on helical tubes. Rough surfaces, pulsating flows, and swirl flows can increase heat transfer, but also increase friction losses.
2) Helical tubes can significantly increase heat transfer rates compared to straight tubes due to secondary flows induced by centrifugal forces from the curvature. This allows for higher heat transfer with less surface area.
3) Key parameters that determine heat transfer rates are the Reynolds number, Nusselt number, Prandtl number, and friction factor. Correlations are presented relating these numbers for both straight and helical tubes. The helical tube equations account for an increased heat transfer coefficient due to secondary flows.
Computational Investigation of Fluid Flow 90o Bend Pipe using Finite Volume A...IRJET Journal
This document discusses a computational investigation of fluid flow through a 90-degree bend pipe using finite volume modeling. A two-dimensional model of a 90-degree bend pipe was developed in ANSYS and hydrodynamic characteristics were examined and compared to a straight pipe of the same length. The finite volume results were validated by comparing to published data, showing good agreement. Flow separation, boundary layer separation, friction factor, and turbulent intensity were examined for a range of Reynolds numbers.
Heat exchangers transfer heat from one medium to another. There are two main types: tube-and-shell and plate. Tube-and-shell consists of tubes in a shell, with fluids flowing inside and outside the tubes. Plate type uses plates to separate hot and cold fluids, providing a larger surface area. Heat exchangers can have parallel, counter, or cross flow arrangements. Performance is evaluated using parameters like log mean temperature difference, number of transfer units, effectiveness, and overall heat transfer coefficient.
Mixed convection heat transfer in inclined tubes with constant heat flux, eur...Ahmed Al-Sammarraie
The document summarizes previous research on mixed convection heat transfer in inclined tubes and describes an experimental study. The study investigated the effects of heat flux, tube inclination angles, and tube diameters on heat transfer for laminar to turbulent air flows in inclined circular tubes under constant wall heat flux. Local and average Nusselt numbers were measured for tube inclinations of 30°, 45°, and 60° and diameters of 0.75, 1.5, and 2 inches. The results showed that Nusselt numbers increased with higher heat flux and as the tube moved from 60° to 30° inclination, and decreased with larger diameter to length ratios.
Mixed convection heat transferin inclined tubes with constant heat fluxOzyegin University
The document summarizes previous research on mixed convection heat transfer in inclined tubes and describes an experimental study. The study investigated the effects of heat flux, tube inclination angles, and tube diameters on heat transfer for laminar to turbulent air flows in inclined circular tubes under constant wall heat flux. Local and average Nusselt numbers were measured for tube inclinations of 30°, 45°, and 60° and diameters of 0.75, 1.5, and 2 inches. The results showed that Nusselt numbers increased with higher heat flux and as the tube moved from 60° to 30° inclination, and decreased with larger diameter to length ratios.
A Review on Enhancement of Heat Transfer Rate by Various Passive MethodsIRJET Journal
This document reviews various passive methods that have been used to enhance heat transfer rates in heat exchangers. It summarizes 15 research papers that studied techniques like using corrugated tubes, twisted tapes, nanofluids, and ribbed surfaces to increase heat transfer surface area and turbulence. Computational fluid dynamics simulations and experiments on different heat exchanger designs found that these passive methods can increase heat transfer rates by up to 60% while also increasing pressure drop. The optimal designs and flow conditions depended on factors like geometry, Reynolds number, and mass flow rates. Overall, passive inserts and surface modifications were shown to effectively enhance heat transfer in heat exchangers.
This document discusses a thesis that analyzes heat transfer in a helical coil heat exchanger using computational fluid dynamics (CFD). The thesis was submitted in partial fulfillment of a Bachelor of Technology degree in Mechanical Engineering. The student conducted CFD analysis using ANSYS Fluent to simulate heat transfer between fluids flowing in parallel and counter-current directions in a tube-in-tube helical coil heat exchanger. Contours, vectors, and plots of parameters like temperature, velocity, heat flux, and Nusselt number were generated to analyze heat transfer performance under varying conditions. The overall goal was to provide data on heat transfer behavior in helical coil exchangers to address the lack of experimental results available for their
Design and Experimental Analysis of Rectangular Wavy Micro Channel Heat sinkAM Publications
An experimental investigation has been explore in order to study the flow of fluid and heat transfer characteristics on a Rectangular Wavy microchannel heat sink. Various applications are envisaged for the use of microchannel heat sink in electrical and electronic power generation and distribution. The Heat sink with microchannel is designed on an Aluminium specimen with Rectangular Wavy configuration with a channel cross section of 1mm x 0.5mm.To improve the heat transfer performance of the cooling system is achieved by using nanoparticles in the fluid passing through the microchannel heat sink. Results are presented by using different concentration (with 1% to 3%) of Nano fluids in water for the heat sink. Various cooling characteristics including thermal resistance, temperature drop and pressure drop across the microchannel heat sink are analysed for different volume concentrations, different volumetric flow rates and Reynolds number. Other significant characteristics for the measurement of heat transfer characteristics across this microchannel heat sink are also analysed and presented in this experiment.
IRJET - Performance Analysis of a Double Pipe Heat Exchanger with and wit...IRJET Journal
This document presents a study on the performance of a double pipe heat exchanger with and without triangular baffles. Experiments were conducted with the heat exchanger in both parallel flow and counter flow configurations, and with varying hot and cold fluid flow rates. The results showed that heat transfer rate, log mean temperature difference (LMTD), and effectiveness were highest when triangular baffles were used compared to no baffles. This is because baffles promote better fluid mixing and heat transfer. The conclusions indicate that triangular baffles can significantly improve the performance of a double pipe heat exchanger.
NUMERICAL INVESTIGATION OF LAMINAR NANOFLUID FLOW IN MICRO CHANNEL HEAT SINKS IAEME Publication
The effect of using nanofluids on heat transfer and aerodynamics characteristics in rectangular shaped micro channel heat sink (MCHS) is numerically investigated for Reynolds number range of (100-400 ) and different value of heat flux (50 , 100, 150 ) / . In this study,the MCHS performance using tow type of nanofluid with volume
fraction 10% was used as a coolant is examined. The three-dimensional steady, laminar flow and heat transfer governing equations are solved using The computational fluid dynamics code (FLUENT). The MCHS performance is evaluated in terms of temperature profile, heat transfer,velocity profile, pressure drop and friction factor.
Wang W., Makeev A. Passive methods analysis of heat transfer intensification ...Елена Овечкина
The article analyzes the methods of passive intensification of heat exchange processes. The dependence of hydraulic resistance for fluid flow through the heat exchanger on the value of the temperature head on it is considered. The most effective ways of improvement of heat exchange processes are defined.
This document describes a thesis analyzing natural convection in a vertical microchannel using computational fluid dynamics (CFD). The thesis examines:
1) Fully developed flow conditions in a vertical parallel-plate microchannel with asymmetric wall temperatures, considering both velocity slip and temperature jump at the walls.
2) A more general approach to analyze entrance region conditions, without assumptions of fully developed flow.
3) Governing equations of continuity, momentum and energy to model the natural convection problem using the boundary layer approximations.
HEAT TRANSFER CORRELATION FOR NON-BOILING STRATIFIED FLOW PATTERN | J4RV3I11006Journal For Research
In chemical industries two phase flow is a process necessity. A better understanding of the rates of momentum and heat transfer in multi-phase flow conditions is important for the optimal design of the heat exchanger. To simplify the complexities in design, heat transfer coefficient correlations are useful. In this work a heat transfer correlation for non- boiling air-water flow with stratified flow pattern in horizontal circular pipe is proposed. To verify the correlation, heat transfer coefficients and flow parameters were measured at different combinations of air and water flow rates. The superficial Reynolds numbers ranged from about 2720 to 5740 for water and from about 563 to 1120 for air. These experimental data were successfully correlated by the proposed two-phase heat transfer correlation. It is observed that superficial.
This document provides an introduction to computational fluid dynamics (CFD) simulations of heat transfer in a tube bank heat exchanger. It discusses how CFD can be used to model the complex flow patterns and heat transfer between two fluids in a tube bank. The objectives are to examine optimal flow distribution for tubes of varying diameters and mass flow rates, and to analyze the effect of different tube materials on heat transfer rates. CFD provides insights into heat transfer phenomena at a lower cost than physical experiments.
Thermohydraulic Performance of a Series of In-Line Noncircular Ducts in a Par...Carnegie Mellon University
Heat transfer and fluid flow characteristics for two-dimensional laminar flow at low Reynolds number for five in-line ducts of
various nonconventional cross-sections in a parallel plate channel are studied in this paper.The governing equations were solved
using finite-volumemethod.CommercialCFDsoftware,ANSYS Fluent 14.5,was used to solve this problem.Atotal of three different
nonconventional, noncircular cross-section ducts and their characteristics are compared with those of circular cross-section ducts.
Shape-2 ducts offered minimum flow resistance and maximum heat transfer rate most of the time. Shape-3 ducts at Re < 100 and Shape-2 ducts at Re > 100 can be considered to give out the optimum results.
Transient Three-dimensional Numerical Analysis of Forced Convection Flow and ...IOSR Journals
A three-dimensional transient numerical study of a constant property Newtonian fluid in curved pipe under laminar flow conditions is presented for a uniform wall temperature boundary condition. Numerical solutions were obtained using the control volume method described by Patankar for the range of. The working fluid was water. The transient flow pattern and the temperature distribution on the tube section were derived for different values of the Reynolds number. Graphical results for velocity and temperature are presented and analyzed. Results have shown that the maximum velocity in center of velocity profile increase with increasing of Reynolds number. In curved pipes, time averaged results exhibited Dean circulation and a strong velocity and temperature stratification in the radial direction. Flow and heat transfer were strongly asymmetric, with higher values near the outer pipe bend.
This document reviews research on using computational fluid dynamics (CFD) to analyze coal/air flow in power plant pipelines in order to maintain uniform fuel feed rates at burners. Several studies are summarized that use CFD to simulate coal/air flow and model the effects of orifice flow restrictors placed in pipes. Correlations developed from CFD results relate pressure drop to factors like geometry, coal/gas loading ratio, and mass flux. CFD is shown to be an effective method for determining the optimal geometry and sizing of orifice flow restrictors to balance flow rates across burners.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Numerical Analysis of Header Configuration of the Plate-Fin Heat ExchangerIJMER
Numerical analysis of a plate fin heat exchanger accounting for the effect of fluid flow
maldistribution onthe inlet header configuration of the heat exchanger is investigated. In this analysis , it
was found that flow maldistribution has effect on the flow perpendicular to its velocity direction. The peak
velocity occurs in the central zone of the header while the velocityalong the perpendicular direction of the
inlet flow diminishes more and more. By this investigation,the results of the flow maldistribution are
presented for a plate fin heat exchangerwhich is reduced as compare to theexisting configuration of the
plate fin heat exchanger.
Experimental Investigation on Heat Transfer Analysis in a Cross flow Heat Ex...IJMER
Heat exchanger is devices used to exchange the heat between two liquids that are at different
temperature .These are used as a reheated in many industries and auto mobile sector and power
plants. The main aim of our project is thermal analysis of heat exchanger with waved baffles for
different types of materials at different mass flow rates and different tube diameters using FLOEFD
software and comparing the results that are obtained. The work is a simplified model for the study of
thermal analysis of shell-and-tubes heat exchangers having water as cold and hot fluid. Shell and
Tube heat exchangers are having special importance in boilers, oil coolers, condensers, pre-heaters.
They are also widely used in process applications as well as the refrigeration and air conditioning
industry. The robustness and medium weighted shape of Shell and Tube heat exchangers make them
well suited for high pressure operations. The project shows the best material, best boundary conditions
and parameters of materials we have to use for better heat conduction. For this we are chosen a
practical problem of counter flow shell and tube heat exchanger having water, by using the data that
come from cfd analysis. A design of sample model of shell and tube heat exchanger with waved baffles
is using Pro-e and done the thermal analysis by using FLOEFD software by assigning different
materials to tubes with different diameters having different mass flow rates and comparing the result
that obtained from FLOEFD software.
IRJET- Thermal and Fluid Flow Analysis of a Heat Exchanger: “A Comprehensive ...IRJET Journal
This document provides a comprehensive literature review and analysis of thermal and fluid flow performance in heat exchangers. It discusses several types of heat exchangers and techniques used to enhance heat transfer, such as surface textures, channel designs, and nanofluids. The document reviews experimental, numerical, and computational studies on fluid flow characteristics and heat transfer for different heat exchanger configurations and applications. It also provides governing equations for fluid flow and heat transfer analysis and compares experimental results to analytical predictions using correlations.
Enhancement of Heat Transfer Rate using Helix Tube and Friction FactorIRJET Journal
1) The document discusses heat transfer enhancement techniques, focusing on helical tubes. Rough surfaces, pulsating flows, and swirl flows can increase heat transfer, but also increase friction losses.
2) Helical tubes can significantly increase heat transfer rates compared to straight tubes due to secondary flows induced by centrifugal forces from the curvature. This allows for higher heat transfer with less surface area.
3) Key parameters that determine heat transfer rates are the Reynolds number, Nusselt number, Prandtl number, and friction factor. Correlations are presented relating these numbers for both straight and helical tubes. The helical tube equations account for an increased heat transfer coefficient due to secondary flows.
Computational Investigation of Fluid Flow 90o Bend Pipe using Finite Volume A...IRJET Journal
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Abstract
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Preliminary report on flow boiling in microchannel
1. Flow boiling heat transfer in
microchannel
A preliminary final year project report submitted in partial fulfilment of the
requirement for the degree of
B.Tech. in Mechanical Engineering (2014-2018)
By
Aritra Chatterjee(Roll No. 20)
Debanjan Baksi(Roll No. 34)
Debanjan Paul(Roll No. 35)
Debtanu Maitra(Roll No.38)
Under the guidance of
Prof. Dibyendu Mondal
Mechanical Engineering Department
Academy of Technology
G.T. Road, Adisaptagram, P.O.: Aedconagar
Hooghly-712121, West Bengal
May, 2017
2. 1
Certificate of Recommendation
This is to certify that the project entitled “Flow Boiling Heat Transfer
in Microchannel” which is being submitted by Aritra Chatterjee,
Debanjan Baksi, Debanjan Paul and Debtanu Maitra, in partial
fulfilment for the award of Degree of Bachelor in Technology in
Mechanical Engineering from Academy of Technology, Hooghly –
712121, under Maulana Abul Kalam Azad University of Technology
(MAKAUT, formerly known as WBUT) for the 2014-2018 session, is
the record of the following students’ work under my supervision.
________________ _________________
(Aritra Chatterje) (Debanjan Baksi)
(Roll No. 20) (Roll No. 34)
________________ _________________
(Debanjan Paul) (Debtanu Maitra)
(Roll No. 35) (Roll No. 38)
Prof. ________________
Supervisor, Dept. Of Mechanical Engineering. Examiners
________________
________________
Prof. ________________
Head of Dept. of Mechanical Engineering
3. 2
Abstract
The following report is a brief overview of microchannels and the
concept of flow boiling. A literature review of flow boiling in
microchannels has also been included. This is just a premiliminary
work, a part of the actual project concerning “Simulation of flow
boiling heat transfer in a single horizontal microchannel”, as assigned
by our mentor Prof. Dibyendu Mondal. Hopefully this report will form
a proper basis for further work in the project.
4. 3
Table of Contents
FLOW BOILING HEAT TRANSFER IN MICROCHANNEL ......................0
CERTIFICATE OF RECOMMENDATION .............................................1
ABSTRACT......................................................................................2
TABLE OF CONTENTS......................................................................3
INTRODUCTION..............................................................................4
HEAT TRANSFER IN MICROCHANNELS ............................................6
FLOW BOILING...............................................................................7
FLOW BOILING HEAT TRANSFER IN MICROCHANNELS (LITERATURE
REVIEW) ........................................................................................9
OBJECTIVES OF THE PRESENT WORK.............................................11
KEYWORDS ..................................................................................12
CONCLUSION ...............................................................................14
REFERENCES.................................................................................15
PAPERS.............................................................................................15
SITES ................................................................................................15
5. 4
Introduction
Microchannels are essentially channels with hydraulic diameters less
than 1mm. Microchannels are being extensively used in the field of
fluid control and heat transfer. This project is concerned with the heat
transferring properties of microchannels, hence the ensuing
discussions will mostly relate to that.
As the scale of devices becomes small, thermal control and heat
dissipation from these devices can be effectively accomplished
through the implementation of microchannel passages. The small
passages provide a high surface area to volume ratio that enables
higher heat transfer rates. Smaller channel size in a heat exchanger
provides higher surface area to volume ratio and results in higher heat
and mass transfer rates and lower equipment size. Automotive and
aerospace industries embraced the use of smaller sized passages in
compact heat exchangers to meet the weight and size constraints,
while high performance requirements in cryogenic industries, for
example, necessitated the use of millimeter-sized passages in
equipment with relatively
large heat transfer rates
and higher effectiveness
requirements.
Research into
microchannels was initially
undertaken Tuckerman
and Pease in 1981, who Figure 1 – Publication histogram showing papers
related to single-phase liquid heat transfer and fluid
flow in microchannels.
6. 5
demonstrated for the first time the high heat flux removal capability
of up to
800 W/cm2 achieved with microchannels in single-phase and two-
phase flows. After a slow start, research interest in microchannels has
increased significantly in the last decade, with numerous papers
published from the 90s to the late 2000s (see Fig. 1, 2).The main thrust
during this period was on understanding the fundamental
mechanisms. Research is now focused on further refining the
theoretical concepts, generating experimental data sets, enhancing
heat transfer performance while reducing pressure drop, and
extending the use of microchannels to new applications.
Figure 2 shows the various
papers published for flow
boiling heat transfer and
two-phase flow in
microchannels. In this brief
report, we will have a
overview of microchannels
and the various studies
conducted regarding flow
boiling heat transfer in
microchannels.
Figure 2 – Publication histogram showing papers related
to flow boiling heat transfer and two-phase flow in
microchannels.
7. 6
Heat transfer in microchannels
Over the last decade, micromachining technology has been
increasingly used for the development of highly efficient cooling
devices called heat sink because of its undeniable advantages such as
less coolant demands and small dimensions. One of the most
important micromachining technologies is micro channels. Hence, the
study of fluid flow and heat transfer in micro channels which are two
essential parts of such devices, have attracted more attentions with
broad applications in both engineering and medical problems.
Microchannel heat transfer has the very potential of wide applications
in cooling high power density microchips in the CPU system, the
micropower systems and even many other large scale thermal
systems requiring effective cooling capacity. This is a result of the
micro-size of the cooling system which not only significantly reduces
the weight load, but also enhances the capability to remove much
greater amount of heat than any of large scale cooling systems. It has
been recognized that for flow in a large scale channel, the heat
transfer Nusselt number, which is defined as hD/k, is a constant in the
thermally developed region where h is the convective heat transfer
coefficient, k is thermal conductivity of the fluid and D is the diameter
of the channel. One can expect that as the size of the channel
decrease, the value of convective heat transfer coefficient, h,
becomes increasing in order to maintain a constant value of the
Nusselt number. As the size of the channel reduces to micron or nano
size, the heat transfer coefficient can increase thousand or million
times the original value. This can drastically increase the heat transfer
and has generated much of the interest to study microchannel heat
transfer both experimentally and theoretically.
8. 7
Flow Boiling
Flow boiling occurs when all the phases are in bulk flow together in a
channel; e.g., vapor and liquid flow in a pipe. The multiphase flow may
be classified as adiabatic or diabatic, i.e., without or with heat addition
at the channel wall. An example of adiabatic flow would be oil/gas
flow in a pipeline, or air/water flow. In these cases the flow patterns
would change as the inlet mass flow rates of the gas or liquid are
altered or as the velocity and void distributions develop along the
channel. Boiling would not take place and phase change would only
occur if in a one component multiphase flow (e.g., steam-water) the
pressure decreases and flashing occurs. Examples of diabatic flow are
to be found in the riser tubes of steam generators and boiler tubes in
power plants or in the coolant channels between nuclear fuel
elements in a boiling water reactor. Boiling occurs on the walls of the
channels and the flow patterns change due to vapour production as
one observes the flow
downstream in the channel
due to vapour production.
The situation of interest in
nuclear reactors is flow
boiling. Consider a vertical
channel of arbitrary cross‐
sectional shape (i.e. not
necessarily round), flow area
A, equivalent diameter De,
uniformly heated (axially as
well as circumferentially) by a
heat flux q". Let Tin be the
inlet temperature (Tin<Tsat),
Figure 3 - Heat transfer and flow regimes in a vertical heated
channel
9. 8
m the mass flow rate and P the operating pressure of the fluid (e.g.
water) flowing in the channel. We wish to describe the various flow
and heat transfer regimes present in the channel as well as the axial
variation of the bulk and wall temperatures. (Ref. Fig. 3)
At axial locations below the onset of nucleate boiling, the flow regime
is single‐phase liquid. As the fluid marches up the channel, more and
more steam is generated because of the heat addition. As a result, the
flow regime goes from bubbly flow (for relatively low values of the
flow quality) to plug (intermediate quality) and annular (high quality).
Eventually, the liquid film in contact with the wall dries out. In the
region beyond the point of dryout, the flow regime is mist flow and
finally, when all droplets have evaporated, single‐phase vapor flow.
10. 9
Flow boiling heat transfer in
microchannels (literature review)
Flow boiling in microchannels was first studied by Tuckerman and
Pease in 1981, but it took more than ten years before a major effort
was undertaken by other researchers to explore this topic further. The
first major effort on understanding the thermohydraulic behavior of
flow boiling systems in microscale passages was presented by
Moriyama et al. in 1992. They used R-113 refrigerant in 35-110 μm
high and 30 mm wide rectangular passages. This geometry is
sometimes referred to as microgap in the literature.
In 1993, Peng and Wang reported one of the first studies with
subcooled flow boiling of water in minichannels. The fully developed
boiling region had little influence from subcooling or flow velocity.
These observations were helpful in determining the nature of flow
boiling in microchannels.
A more systematic study covering a large range of minichannel
diameters was conducted by Bowers and Mudawar in 1994. They
reported the average heat transfer, pressure drop and CHF data in
these channels.
In 2002, Serizawa conducted adiabatic flow experiments with steam-
water and air-water flows in microchannels and studied flow patterns,
which were affected by the surface roughness. He presented a flow
pattern map based on his experimental observations. The differences
between the adiabatic and diabatic flows were studied experimentally
by Hetsroni et al.
11. 10
Figure 4 - Historical development timeline over 25 years highlighting advances in flow boiling in
microchannels.
12. 11
Objectives of the present work
As is evident from our previous discussions, the study of flow and heat
transfer in microchannels is very important for the technology of
today and the near future as developments are following the trend of
miniaturization in all fields.
Our future work on the project will include:
I. Simulation of Flow Boiling Heat Transfer in a single horizontal
microchannel using commercial flow solver (ANSYS Fluent 13.0)
II. Validation of the CFD model by comparing the present simulated
results with the available literature.
III. The effects of various Reynolds No. on “volume fraction of
vapour”, “static temperature along the wall” and “heat transfer
coefficient” at the heated wall is evaluated.
IV. The Incipient Heat Flux is investigated as a function of fluid inlet
velocity and fluid inlet temperature.
13. 12
Keywords
• CHF (Critical Heat Flux) describes the thermal limit of a
phenomenon where a phase change occurs during heating (such
as bubbles forming on a metal surface used to heat water),
which suddenly decreases the efficiency of heat transfer, thus
causing localised overheating of the heating surface.
• Flow regime is a description of the geometrical distribution of a
multiphase fluid moving through a channel. Many different
terms are used to describe this distribution, the distinction
between each one being qualitative and somewhat arbitrary. In
vertical or moderately deviated channels, the most common
flow regimes for gas-liquid mixtures are bubble flow, dispersed
bubble flow, plug flow, slug flow, froth flow, mist flow, churn
flow and annular flow.
• Heat sink is a passive heat exchanger that transfers the heat
generated by an electronic or a mechanical device to a fluid
medium, often air or a liquid coolant, where it is dissipated away
from the device.
• Hydraulic diameter, DH, of any channel, is defined as 4A/P, P
being the wetter perimeter and A being the cross-section area.
• Macrochannel is a channel with hydraulic diameter greater than
3mm.
Minichannel is any channel with hydraulic diameter varying
from 0.2mm to 3mm.
• Micropower system is a system that generates electricity, and
possibly heat, to serve a nearby load. Such a system may employ
any combination of electrical generation and storage
technologies (e.g. small scale generators) and may be grid-
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connected or autonomous, meaning separate from any
transmission grid.
• Nucleate boiling is a type of boiling that takes place when the
surface temperature is hotter than the saturated fluid
temperature by a certain amount but where the heat flux is
below the critical heat flux.
• Nusselt number (Nu) is the ratio of convective to conductive
heat transfer across (normal to) the boundary in heat transfer at
a boundary (surface) within a fluid.
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Conclusion
An initial foray into the topic of flow boiling heat transfer in
microchannels has showed that there is a lot of potential in
conducting research work in this area. Flow boiling microchannel heat
sinks are very promising for several applications, such as, the
computer and IT industry, high power semiconductor devices,
miniature vapour compression refrigeration systems. We notice
several papers have been published regarding microchannels and flow
boiling heat transfer since the late 20th century, making it a fairly new
topic of interest.
In this brief report, we familiarized ourselves with microchannels and
the concept of flow boiling. As part of the project, we will later work
on a simulation of flow boiling heat transfer using ANSYS software and
record suitable findings.
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References
Papers
▪ “Flow Boiling Heat Transfer in Microchannels” – Dong Liu, Suresh
V. Garimella; Purdue University
▪ “History, Advances, and Challenges in Liquid Flow and Flow
Boiling Heat Transfer in Microchannels: A Critical Review” –
Satish G. Kandlikar; Rochester Institute of Technology
Sites
▪ Wikipedia: https://en.wikipedia.org/
▪ Case Study on Heat Transfer in Microchannel:
http://www.cpdlr.com/notes-articles-engineering/292-case-
study-on-heat-transfer-in-microchannel.html