This document summarizes an experimental study on enhancing heat transfer in a circular double tube heat exchanger using rectangular inserts. Air was passed through the inner tube while hot water flowed through the outer tube. Heat transfer coefficients and friction factors were determined for the plain tube and with inserts. The results showed that heat transfer was enhanced by 0.9 to 1.9 times with the inserts due to flow disruption, while friction factors increased by 1 to 1.7 times. Heat transfer coefficients increased with Reynolds number whereas friction factors decreased. Validation experiments on a plain tube agreed well with theoretical predictions within 10% uncertainty.
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.
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- Effect of Wavy Tube on Heat Transfer in a Concentric Tube Heat Exch...IRJET Journal
This document provides a review of research on using a wavy inner tube in a concentric tube heat exchanger to enhance heat transfer. It first discusses different heat transfer augmentation techniques, including active, passive and compound methods. It then reviews several previous studies that experimentally and numerically examined heat transfer performance of wavy tube heat exchangers. These studies found that a wavy inner tube could increase heat transfer by over 100% compared to a plain tube by generating swirl flow and turbulence. The document also reviews research on other passive techniques like wire coil inserts and their effects on heat transfer and pressure drop. Overall, the review shows that wavy tube and other passive inserts can significantly enhance heat transfer in heat exchangers.
The document summarizes an experimental investigation of convection heat transfer for laminar flow in an inclined annulus. An annular copper pipe was exposed to a constant heat flux and rotated through inclination angles from 0° to 90° in 10° increments. Results showed that the heat transfer coefficient decreased inversely with inclination angle, with a maximum 6.6% reduction at 90°. Reynolds number also decreased inversely with angle from 1750 to 1700. Experimental results closely matched a correlation up to 40° inclination. The study found inclination angle had a small effect on heat transfer for laminar flow in the annulus.
This document summarizes an experimental study on heat transfer augmentation from surfaces with dimples. Six steel plates with varying dimple densities and arrangements were tested to analyze heat transfer and pressure drop characteristics. Temperature and pressure measurements were taken under varying air flow rates and heat inputs. It was found that heat transfer, as indicated by Nusselt number, increased with increasing dimple density. Staggered dimple arrangements provided greater enhancement than inline arrangements. Mathematical equations are presented for calculating key parameters like heat transfer coefficient, Reynolds number, and friction factor. Results are discussed and heat transfer is seen to increase with Reynolds number for all plates, with the 50 dimple plate performing best.
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.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Natural convection heat transfer in inclined open annulus passege heated from...IAEME Publication
This document summarizes an experimental study on natural convection heat transfer in an open cylindrical annulus heated from both the inner and outer sides. The study examines the effects of inclination angle (0°, 30°, 60°, 90°) and heat flux (70-600 W/m2) on the local and average Nusselt number. The results show that the Nusselt number increases with both increasing heat flux and inclination angle from horizontal to vertical. Empirical correlations between the average Nusselt number and Rayleigh number are developed from the results.
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.
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- Effect of Wavy Tube on Heat Transfer in a Concentric Tube Heat Exch...IRJET Journal
This document provides a review of research on using a wavy inner tube in a concentric tube heat exchanger to enhance heat transfer. It first discusses different heat transfer augmentation techniques, including active, passive and compound methods. It then reviews several previous studies that experimentally and numerically examined heat transfer performance of wavy tube heat exchangers. These studies found that a wavy inner tube could increase heat transfer by over 100% compared to a plain tube by generating swirl flow and turbulence. The document also reviews research on other passive techniques like wire coil inserts and their effects on heat transfer and pressure drop. Overall, the review shows that wavy tube and other passive inserts can significantly enhance heat transfer in heat exchangers.
The document summarizes an experimental investigation of convection heat transfer for laminar flow in an inclined annulus. An annular copper pipe was exposed to a constant heat flux and rotated through inclination angles from 0° to 90° in 10° increments. Results showed that the heat transfer coefficient decreased inversely with inclination angle, with a maximum 6.6% reduction at 90°. Reynolds number also decreased inversely with angle from 1750 to 1700. Experimental results closely matched a correlation up to 40° inclination. The study found inclination angle had a small effect on heat transfer for laminar flow in the annulus.
This document summarizes an experimental study on heat transfer augmentation from surfaces with dimples. Six steel plates with varying dimple densities and arrangements were tested to analyze heat transfer and pressure drop characteristics. Temperature and pressure measurements were taken under varying air flow rates and heat inputs. It was found that heat transfer, as indicated by Nusselt number, increased with increasing dimple density. Staggered dimple arrangements provided greater enhancement than inline arrangements. Mathematical equations are presented for calculating key parameters like heat transfer coefficient, Reynolds number, and friction factor. Results are discussed and heat transfer is seen to increase with Reynolds number for all plates, with the 50 dimple plate performing best.
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.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Natural convection heat transfer in inclined open annulus passege heated from...IAEME Publication
This document summarizes an experimental study on natural convection heat transfer in an open cylindrical annulus heated from both the inner and outer sides. The study examines the effects of inclination angle (0°, 30°, 60°, 90°) and heat flux (70-600 W/m2) on the local and average Nusselt number. The results show that the Nusselt number increases with both increasing heat flux and inclination angle from horizontal to vertical. Empirical correlations between the average Nusselt number and Rayleigh number are developed from the results.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Natural convection heat transfer inside inclined open cylinderIAEME Publication
This document summarizes an experimental study on natural convection heat transfer inside an inclined open cylinder. The study investigated the effects of inclination angle (0°, 30°, 60°, 90°) and heat flux (70-600 W/m2) on the heat transfer. Empirical correlations were developed relating the average Nusselt number to the Rayleigh number. Results showed that heat transfer, as measured by the local and average Nusselt number, increased with increasing heat flux and inclination angle from horizontal to vertical.
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.
Experimental Investigation of Vertical Downward Flow Boiling Heat Transfer i...IJMER
The present work is carried to determine the two phase heat transfer coefficient during flowing
vertical downward in the minichannel. The minichannel test section is made up of aluminum having
hydraulic diameter 1.33mm. The experiments were carried out by varying mass flow rate from 0.1g/sec to
0.3g/sec of steam at three different vapour qualities of 0.2, 0.4 and 0.6. The result showed as the heat flux
increases there is an increase in two phase heat transfer coefficient upto 20000W/m2 0C. In addition to
that there is a decrease in treand of heat transfer coefficient for vapour quality.
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.
The document describes an experimental and numerical study to enhance heat transfer on a heat exchanger using an air flow with water droplets and Al2O3/water nanofluid. The study used a test rig with an instrumented air duct to inject water droplets via nozzles toward a finned tube heat exchanger. Experiments tested different nozzle types, droplet locations, air/water flow rates and temperatures. Numerical analysis using ANSYS FLUENT modeled the governing equations to study parameter effects. Results showed maximum heat transfer enhancement of 45% occurred at a 2% nanofluid concentration with sprayed air, agreeing within 11% of experimental data.
Evaluation of Convective Heat Transfer Coefficient of Air Flowing Through an ...Bishal Bhandari
The document evaluates the convective heat transfer coefficient of air flowing through an inclined circular duct. It describes an experimental setup used to study the effect of inclination angle and air velocity on the convective heat transfer coefficient. Tests were conducted by forcing air through a copper duct at various angles (0°, 30°, 60°, 90°, 120°, 150°) and velocities while keeping heat input constant. Temperature readings were used to calculate parameters like Reynolds number, Nusselt number, and the convective heat transfer coefficient. Results showed that the heat transfer coefficient peaks at a 90° inclination for an air velocity of 12 m/s, and is lowest at a 30° inclination for a velocity of 8.38 m/s
In compact heat exchangers, thermal resistance is generally dominant on the air-side and may
account for 80% or more of the total thermal resistance. The air-side heat transfer surface area is 8 to
10 times larger than the water-side. Any improvement in the heat transfer on air-side therefore
improves the overall performance of the heat exchanger. Due to the high thermal resistance on the
air-side, the optimization of such fins is essential to increase the performance of the heat exchangers
which results in thermal systems enhancement. This helps to reduce CO2 emissions through a
reduction of mass and fuel consumption.
Optimization of louvered fin geometry in such heat exchangers is essential to increase the
heat transfer performance and reduce weight, packaging, and cost requirements. In this study deals
with Computational Fluid Dynamics (CFD) studies of the interactions between the air flow and
louvered fins which equipped the automotive heat exchangers is carried out. 3D numerical
simulation results is obtained by using the ANSYS Fluent 14.0 code and compared with
experimental data. Finally the effect of louver angle and louver pitch geometrical parameters, on
overall thermal hydraulic performances of louvered fins is studied.
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
This document summarizes a numerical simulation study of heat transfer enhancement in a tube fitted with rod helical tape swirl generators. The study uses ANSYS Fluent to model heat transfer and flow characteristics of air flowing inside a circular tube with different tube insert configurations. Results are compared to experimental and analytical calculations from other studies. Enhanced heat transfer is observed with decreasing twist ratio of the helical tape inserts. Heat flux is also found to be more uniform along the tube length with the inserts.
STUDY OF HEAT TRANSFER ON BROKEN ARC ROUGHNESS ELEMENTS ON THE ABSORBER PLATE...IAEME Publication
Performance of solar air heater can be enhanced by adding roughness to the inner periphery. The present study on the effect of various shape parameters for broken arc roughness elements of heat transfer and friction factor characteristics of rectangular duct. The duct has Reynolds number (Re) range of 3000-22300, respective roughness height (e/D) values is 0.045, arc angle (α) is 60˚ and roughness width (W/w) is 5 and relatively roughness pitch is 8.
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.
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.
EXPERIMENTAL INVESTIGATION OF CONVECTION HEAT TRANSFER FOR LAMINAR FLOW IN AN...IAEME Publication
The document summarizes an experimental investigation of convection heat transfer for laminar flow in an inclined annulus. An annular copper pipe was exposed to a constant heat flux and rotated through inclination angles from 0° to 90° in 10° increments. Results showed that the heat transfer coefficient decreased inversely with inclination angle, with a maximum 6.6% reduction at 90°. Reynolds number also decreased inversely with angle from 1750 to 1700. Experimental results closely matched a correlation up to 40° inclination. The study analyzed the effect of inclination angle on heat transfer in laminar flow through an annulus.
EFFECT OF BAFFLES GEOMETRY ON HEAT TRANSFER ENHANCEMENT INSIDE CORRUGATED DUCTIAEME Publication
The turbulent heat transfer and friction inside a corrugated square duct inserted
with various baffles geometries have been studied experimentally. Five types of baffles
(flat, rectangular, semicircular, triangular and trapezoidal) are attached on top and
bottom walls of the duct. The effects of duct wavy surface, baffle geometry, baffle
position and flow Reynolds number are examined. Air is used as the working fluid
with Reynolds number ranged from 3442.6 to 17213.19 under constant wall heat flux.
Experimental results show obtained for average Nusselt numbers and friction factor.
The results indicate that the trapezoidal baffled geometry provides a higher thermal
performance than the other type baffled one. The present work showed that the highest
thermal performance factor under the same pumping power obtained from the
experiments, is about 2.26 times more than that of plain duct. Also, it is found that the
thermal performance of the baffles attach on the bottom wall of the duct is higher than
the other baffles attach on the top
Prediction of friction factor and non dimensions numbers in force convectionIAEME Publication
This document summarizes an experimental study on heat transfer in an insulated cylindrical pipe. The study measured parameters like Nusselt number, Reynolds number, and frictional factor under different flow conditions. Experiments were conducted with air flow through a 40mm diameter pipe with 5mm insulation. Measurements were taken for 1/3, 2/3, and full opening of a control valve, and results were validated against analytical calculations using common heat transfer equations. Experimental values matched well with theoretical predictions.
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.
THERMO HYDRAULICS PERFORMANCE OF TURBULENT FLOW HEAT TRANSFER THROUGH SQUARE ...IAEME Publication
This paper describes the experimental study of square ducts with inserts. Experiments are conducted for air with uniform heat flux condition. The top wall surface is made rough with metal ribs of square section. The roughened wall is uniformly heated and other walls are insulated. The heat transfer coefficient enhances square channel at injection of different inserts. The performance of the geometry under investigation has been evaluated .The heat transfer coefficient of air is increase by 46% than plane square ducts with inserts. The heat transfer and pressure drop measurements have been taken in separate sections .
This document summarizes an experimental study on heat transfer augmentation from surfaces with dimples. Six steel plates with varying dimple densities and arrangements were tested to analyze heat transfer and pressure drop characteristics. Temperature and pressure measurements were taken under varying air flow rates and heat inputs. It was found that heat transfer, as indicated by Nusselt number, increased with increasing dimple density. Staggered dimple arrangements provided greater enhancement than inline arrangements. Mathematical equations are provided for modeling heat transfer rate, Reynolds number, Nusselt number, and friction factor. Results showed that plates with 50 dimples had the highest average heat transfer coefficient and Nusselt number across all test conditions.
This document summarizes an experimental study on heat transfer augmentation from dimpled surfaces. Six test plates with varying dimple densities were used to study the heat transfer characteristics and pressure drop. It was found that the Nusselt number, a measure of heat transfer, increases with increasing dimple density. Staggered dimple arrangements produced greater increases in heat transfer than inline arrangements. The results show that dimpled surfaces can enhance heat transfer with only a small increase in pressure drop, making them useful for applications like compact heat exchangers.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Natural convection heat transfer inside inclined open cylinderIAEME Publication
This document summarizes an experimental study on natural convection heat transfer inside an inclined open cylinder. The study investigated the effects of inclination angle (0°, 30°, 60°, 90°) and heat flux (70-600 W/m2) on the heat transfer. Empirical correlations were developed relating the average Nusselt number to the Rayleigh number. Results showed that heat transfer, as measured by the local and average Nusselt number, increased with increasing heat flux and inclination angle from horizontal to vertical.
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.
Experimental Investigation of Vertical Downward Flow Boiling Heat Transfer i...IJMER
The present work is carried to determine the two phase heat transfer coefficient during flowing
vertical downward in the minichannel. The minichannel test section is made up of aluminum having
hydraulic diameter 1.33mm. The experiments were carried out by varying mass flow rate from 0.1g/sec to
0.3g/sec of steam at three different vapour qualities of 0.2, 0.4 and 0.6. The result showed as the heat flux
increases there is an increase in two phase heat transfer coefficient upto 20000W/m2 0C. In addition to
that there is a decrease in treand of heat transfer coefficient for vapour quality.
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.
The document describes an experimental and numerical study to enhance heat transfer on a heat exchanger using an air flow with water droplets and Al2O3/water nanofluid. The study used a test rig with an instrumented air duct to inject water droplets via nozzles toward a finned tube heat exchanger. Experiments tested different nozzle types, droplet locations, air/water flow rates and temperatures. Numerical analysis using ANSYS FLUENT modeled the governing equations to study parameter effects. Results showed maximum heat transfer enhancement of 45% occurred at a 2% nanofluid concentration with sprayed air, agreeing within 11% of experimental data.
Evaluation of Convective Heat Transfer Coefficient of Air Flowing Through an ...Bishal Bhandari
The document evaluates the convective heat transfer coefficient of air flowing through an inclined circular duct. It describes an experimental setup used to study the effect of inclination angle and air velocity on the convective heat transfer coefficient. Tests were conducted by forcing air through a copper duct at various angles (0°, 30°, 60°, 90°, 120°, 150°) and velocities while keeping heat input constant. Temperature readings were used to calculate parameters like Reynolds number, Nusselt number, and the convective heat transfer coefficient. Results showed that the heat transfer coefficient peaks at a 90° inclination for an air velocity of 12 m/s, and is lowest at a 30° inclination for a velocity of 8.38 m/s
In compact heat exchangers, thermal resistance is generally dominant on the air-side and may
account for 80% or more of the total thermal resistance. The air-side heat transfer surface area is 8 to
10 times larger than the water-side. Any improvement in the heat transfer on air-side therefore
improves the overall performance of the heat exchanger. Due to the high thermal resistance on the
air-side, the optimization of such fins is essential to increase the performance of the heat exchangers
which results in thermal systems enhancement. This helps to reduce CO2 emissions through a
reduction of mass and fuel consumption.
Optimization of louvered fin geometry in such heat exchangers is essential to increase the
heat transfer performance and reduce weight, packaging, and cost requirements. In this study deals
with Computational Fluid Dynamics (CFD) studies of the interactions between the air flow and
louvered fins which equipped the automotive heat exchangers is carried out. 3D numerical
simulation results is obtained by using the ANSYS Fluent 14.0 code and compared with
experimental data. Finally the effect of louver angle and louver pitch geometrical parameters, on
overall thermal hydraulic performances of louvered fins is studied.
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
This document summarizes a numerical simulation study of heat transfer enhancement in a tube fitted with rod helical tape swirl generators. The study uses ANSYS Fluent to model heat transfer and flow characteristics of air flowing inside a circular tube with different tube insert configurations. Results are compared to experimental and analytical calculations from other studies. Enhanced heat transfer is observed with decreasing twist ratio of the helical tape inserts. Heat flux is also found to be more uniform along the tube length with the inserts.
STUDY OF HEAT TRANSFER ON BROKEN ARC ROUGHNESS ELEMENTS ON THE ABSORBER PLATE...IAEME Publication
Performance of solar air heater can be enhanced by adding roughness to the inner periphery. The present study on the effect of various shape parameters for broken arc roughness elements of heat transfer and friction factor characteristics of rectangular duct. The duct has Reynolds number (Re) range of 3000-22300, respective roughness height (e/D) values is 0.045, arc angle (α) is 60˚ and roughness width (W/w) is 5 and relatively roughness pitch is 8.
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.
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.
EXPERIMENTAL INVESTIGATION OF CONVECTION HEAT TRANSFER FOR LAMINAR FLOW IN AN...IAEME Publication
The document summarizes an experimental investigation of convection heat transfer for laminar flow in an inclined annulus. An annular copper pipe was exposed to a constant heat flux and rotated through inclination angles from 0° to 90° in 10° increments. Results showed that the heat transfer coefficient decreased inversely with inclination angle, with a maximum 6.6% reduction at 90°. Reynolds number also decreased inversely with angle from 1750 to 1700. Experimental results closely matched a correlation up to 40° inclination. The study analyzed the effect of inclination angle on heat transfer in laminar flow through an annulus.
EFFECT OF BAFFLES GEOMETRY ON HEAT TRANSFER ENHANCEMENT INSIDE CORRUGATED DUCTIAEME Publication
The turbulent heat transfer and friction inside a corrugated square duct inserted
with various baffles geometries have been studied experimentally. Five types of baffles
(flat, rectangular, semicircular, triangular and trapezoidal) are attached on top and
bottom walls of the duct. The effects of duct wavy surface, baffle geometry, baffle
position and flow Reynolds number are examined. Air is used as the working fluid
with Reynolds number ranged from 3442.6 to 17213.19 under constant wall heat flux.
Experimental results show obtained for average Nusselt numbers and friction factor.
The results indicate that the trapezoidal baffled geometry provides a higher thermal
performance than the other type baffled one. The present work showed that the highest
thermal performance factor under the same pumping power obtained from the
experiments, is about 2.26 times more than that of plain duct. Also, it is found that the
thermal performance of the baffles attach on the bottom wall of the duct is higher than
the other baffles attach on the top
Prediction of friction factor and non dimensions numbers in force convectionIAEME Publication
This document summarizes an experimental study on heat transfer in an insulated cylindrical pipe. The study measured parameters like Nusselt number, Reynolds number, and frictional factor under different flow conditions. Experiments were conducted with air flow through a 40mm diameter pipe with 5mm insulation. Measurements were taken for 1/3, 2/3, and full opening of a control valve, and results were validated against analytical calculations using common heat transfer equations. Experimental values matched well with theoretical predictions.
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.
THERMO HYDRAULICS PERFORMANCE OF TURBULENT FLOW HEAT TRANSFER THROUGH SQUARE ...IAEME Publication
This paper describes the experimental study of square ducts with inserts. Experiments are conducted for air with uniform heat flux condition. The top wall surface is made rough with metal ribs of square section. The roughened wall is uniformly heated and other walls are insulated. The heat transfer coefficient enhances square channel at injection of different inserts. The performance of the geometry under investigation has been evaluated .The heat transfer coefficient of air is increase by 46% than plane square ducts with inserts. The heat transfer and pressure drop measurements have been taken in separate sections .
This document summarizes an experimental study on heat transfer augmentation from surfaces with dimples. Six steel plates with varying dimple densities and arrangements were tested to analyze heat transfer and pressure drop characteristics. Temperature and pressure measurements were taken under varying air flow rates and heat inputs. It was found that heat transfer, as indicated by Nusselt number, increased with increasing dimple density. Staggered dimple arrangements provided greater enhancement than inline arrangements. Mathematical equations are provided for modeling heat transfer rate, Reynolds number, Nusselt number, and friction factor. Results showed that plates with 50 dimples had the highest average heat transfer coefficient and Nusselt number across all test conditions.
This document summarizes an experimental study on heat transfer augmentation from dimpled surfaces. Six test plates with varying dimple densities were used to study the heat transfer characteristics and pressure drop. It was found that the Nusselt number, a measure of heat transfer, increases with increasing dimple density. Staggered dimple arrangements produced greater increases in heat transfer than inline arrangements. The results show that dimpled surfaces can enhance heat transfer with only a small increase in pressure drop, making them useful for applications like compact heat exchangers.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
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.
An experimental study of heat transfer in a corrugated plate heat exchangerIAEME Publication
1. The document discusses an experimental study of heat transfer in a corrugated plate heat exchanger. Experiments were conducted to analyze heat transfer characteristics for different flow arrangements of hot and cold fluids through the heat exchanger.
2. The effectiveness and exergy loss of the heat exchanger were calculated for parallel and counter flow arrangements. The average effectiveness was found to be 48% higher and exergy loss 33% lower in the counter flow arrangement compared to the parallel flow arrangement.
3. Maximum heat transfer was observed at the highest hot fluid inlet temperature of 70°C, being 5% greater in the parallel flow arrangement. However, the non-dimensional exergy loss and log mean temperature difference were both lower in the
HEAT TRANSFER ANALYSIS OF EFFECTS OF LONGITUDINAL FINS ON HEAT TRANSFER IN DO...IRJET Journal
This document analyzes heat transfer in a double pipe heat exchanger with and without longitudinal fins. It was found that using longitudinal fins improves heat transfer performance. Specifically:
1) Heat transfer rate and LMTD increased by 28.42 watts and 12.5 watts respectively with fins compared to without fins.
2) Effectiveness, which is a measure of heat exchanger performance, increased from 0.3211 without fins to 0.3533 with fins.
3) Overall heat transfer coefficient and rate of heat transfer were higher with fins, showing fins enhance heat transfer in double pipe heat exchangers.
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.
AN EXPERIMENTAL STUDY OF HEAT TRANSFER IN A CORRUGATED PLATE HEAT EXCHANGER IAEME Publication
In the present work an attempt has been made to investigate the performance of a corrugated plate heat exchanger by the first law and the second law of thermodynamics. Experiments were conducted to determine the laminar convective heat transfer characteristics for fully developed flow of hot and cold fluid in alternate ducts. Experiments were conducted on a three channel 1-1 pass corrugated plate heat exchanger. Hot fluid was made to flow in the central channel to get cooled by
cold fluid in the top and bottom channels in parallel and counter flow arrangements.
EXPERIMENTAL AND THEORTICAL STUDY OF THE THERMAL PERFORMANCE OF HEAT PIPE HEA...IAEME Publication
1. An experimental and theoretical study was conducted on a four row heat pipe heat exchanger with distilled water as the working fluid.
2. Tests were performed at varying air flow rates and inlet evaporator temperatures to analyze the effect on effectiveness.
3. The maximum effectiveness occurred at a mass flow rate ratio of 2. A theoretical model was developed and showed good agreement with experimental results.
Effect of Wavy Tube on Heat Transfer in a Concentric Tube Heat Exchanger: A R...IRJET Journal
This document provides a review of research on using a wavy inner tube in a concentric tube heat exchanger to enhance heat transfer. Several studies have found that a wavy inner tube can increase the Nusselt number, friction factor, and thermal performance factor compared to a plain inner tube. Computational fluid dynamics simulations have also validated that wavy fins and tubes promote longitudinal vortices that augment heat transfer, while transverse vortices have a negative effect. Overall, experiments and models show that a wavy inner tube can enhance heat transfer in a concentric tube heat exchanger by over 100% in some cases.
AN EXPERIMENTAL STUDY OF EXERGY IN A CORRUGATED PLATE HEAT EXCHANGERIAEME Publication
In the present work an attempt has been made to investigate the performance of a 3 channel 1-1 pass, corrugated plate heat exchanger. The plates had sinusoidal wavy surfaces with corrugation angle of 450. Hot water at different inlet temperature ranging from 400C to 600C was made to flow in the central channel to get cooled by water in the outer channels.
NATURAL CONVECTION HEAT TRANSFER IN INCLINED OPEN ANNULUS PASSEGE HEATED FROM...IAEME Publication
Natural convection is investigated experimentally in an open cylindrical annulus heated with both annulus inner and outer sides under same constant heat flux condition to study the effect of angle of inclination and heat flux on heat transfer. Heat transfer results are given for inclination angles of 0o
(horizontal), 30o , 60o and 90o (vertical) using annulus diameter ratio of 1.8, inner and outer tube length 50 cm and heat flux from 70 W/m2 to 600W/m2 . The results show that the local and average Nusselt number increase as the heat flux increase and when angle of inclination changed from 0o
(horizontal) to 90o (vertical).An empirical correlations of average Nusselt number as a function of Rayleigh number were deduced.
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.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
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