The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform
Arun S. Mujumdar - One of the best experts on this subject based on the ideXlab platform.
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Thermal Performance of Coiled Square Tubes at Large Temperature Differences for Heat Exchanger Application
Heat Transfer Engineering, 2016Co-Authors: Jundika C. Kurnia, Agus P. Sasmito, Arun S. MujumdarAbstract:In many Heat Exchanger Applications, working fluid inside the tubes is subjected to considerable temperature changes. Coiled tubes are used widely in Heat Exchanger Applications due to the enhanced Heat transfer rate caused by secondary flows. This study examines the thermal performance of three configurations of coiled tubes of square cross-section, namely, in-plane, helical, and conical coiled tubes, subjected to a large temperature difference between the fluid and the wall and compares it with that of a straight tube of identical cross-section area and length. The concept of figure of merit (FoM) is introduced to compare the Heat transfer performance of the various configurations tested. The results indicate that FoM increases as the wall temperature is increased. In addition, the combination of temperature-induced buoyant flow and curvature-induced secondary flow significantly affects the flow behavior and Heat transfer performance inside the tubes. The coil pitch in helical and conical tubes has an a...
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Numerical Investigation of Heat Transfer Performance of Various Coiled Square Tubes for Heat Exchanger Application
Energy Procedia, 2015Co-Authors: Jundika C. Kurnia, Agus P. Sasmito, Saad Akhtar, Tariq Shamim, Arun S. MujumdarAbstract:Abstract In Heat Exchanger Application, working fluid inside the tubes is subjected to considerable temperature changes. In order to improve Heat transfer performance, various strategies are proposed and evaluated; one of them is the Application of coiled tubes. Coiled tubes have been used widely in Heat Exchanger Application mainly due to the presence of secondary flow which enhances Heat transfer considerably. This study addresses Heat transfer performance of three configurations of coiled tubes with square cross-section, i.e. in-plane, helical and conical coiled tubes, subjected to large temperature difference. Their Heat transfer performance is numerically evaluated and compared with that of a straight tube with identical cross-section and length. A concept of Figure of Merit (FoM) is introduced and utilized to fairly asses the Heat transfer performance of the coiled tube configurations. The results indicate that FoM increase as the wall temperature increase. In addition, combination of temperature-induced buoyancy flow and curvature-induced secondary flow considerably affect the flow behavior and Heat transfer performance inside the tubes.
Honglei Wang - One of the best experts on this subject based on the ideXlab platform.
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Preparation of high porous silicon nitride foams with ultra-thin walls and excellent mechanical performance for Heat Exchanger Application by using a protein foaming method
Ceramics International, 2016Co-Authors: Liuyan Yin, Xingui Zhou, Jinshan Yu, Honglei WangAbstract:Ceramic foam with excellent mechanical performance, high thermal conductivity and high surface area-to-volume ratio is thought to have great potential in Heat Exchanger Application. In this study, silicon nitride (Si3N4) foams with ultrathin cell walls were prepared by using a protein foaming method via increasing the air fraction of foamed slurry. Cell thickness of these Si3N4 foams was only 2-3 μm and the pores in the Si3N4 foams fabricated here exhibited polyhedral shapes. Thermal conductivities of these Si3N4 foams ranged from 2.427 W m-1 K-1 to 3.154 W m-1 K-1, whereas compressive strengths of these Si3N4 foams are in the range from 12.85 MPa to 19.99 MPa. Moreover, compressive load-displacement curves of the Si3N4 foams generally exhibit cellular behavior.
Jundika C. Kurnia - One of the best experts on this subject based on the ideXlab platform.
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Thermal Performance of Coiled Square Tubes at Large Temperature Differences for Heat Exchanger Application
Heat Transfer Engineering, 2016Co-Authors: Jundika C. Kurnia, Agus P. Sasmito, Arun S. MujumdarAbstract:In many Heat Exchanger Applications, working fluid inside the tubes is subjected to considerable temperature changes. Coiled tubes are used widely in Heat Exchanger Applications due to the enhanced Heat transfer rate caused by secondary flows. This study examines the thermal performance of three configurations of coiled tubes of square cross-section, namely, in-plane, helical, and conical coiled tubes, subjected to a large temperature difference between the fluid and the wall and compares it with that of a straight tube of identical cross-section area and length. The concept of figure of merit (FoM) is introduced to compare the Heat transfer performance of the various configurations tested. The results indicate that FoM increases as the wall temperature is increased. In addition, the combination of temperature-induced buoyant flow and curvature-induced secondary flow significantly affects the flow behavior and Heat transfer performance inside the tubes. The coil pitch in helical and conical tubes has an a...
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Numerical Investigation of Heat Transfer Performance of Various Coiled Square Tubes for Heat Exchanger Application
Energy Procedia, 2015Co-Authors: Jundika C. Kurnia, Agus P. Sasmito, Saad Akhtar, Tariq Shamim, Arun S. MujumdarAbstract:Abstract In Heat Exchanger Application, working fluid inside the tubes is subjected to considerable temperature changes. In order to improve Heat transfer performance, various strategies are proposed and evaluated; one of them is the Application of coiled tubes. Coiled tubes have been used widely in Heat Exchanger Application mainly due to the presence of secondary flow which enhances Heat transfer considerably. This study addresses Heat transfer performance of three configurations of coiled tubes with square cross-section, i.e. in-plane, helical and conical coiled tubes, subjected to large temperature difference. Their Heat transfer performance is numerically evaluated and compared with that of a straight tube with identical cross-section and length. A concept of Figure of Merit (FoM) is introduced and utilized to fairly asses the Heat transfer performance of the coiled tube configurations. The results indicate that FoM increase as the wall temperature increase. In addition, combination of temperature-induced buoyancy flow and curvature-induced secondary flow considerably affect the flow behavior and Heat transfer performance inside the tubes.
Liuyan Yin - One of the best experts on this subject based on the ideXlab platform.
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Preparation of high porous silicon nitride foams with ultra-thin walls and excellent mechanical performance for Heat Exchanger Application by using a protein foaming method
Ceramics International, 2016Co-Authors: Liuyan Yin, Xingui Zhou, Jinshan Yu, Honglei WangAbstract:Ceramic foam with excellent mechanical performance, high thermal conductivity and high surface area-to-volume ratio is thought to have great potential in Heat Exchanger Application. In this study, silicon nitride (Si3N4) foams with ultrathin cell walls were prepared by using a protein foaming method via increasing the air fraction of foamed slurry. Cell thickness of these Si3N4 foams was only 2-3 μm and the pores in the Si3N4 foams fabricated here exhibited polyhedral shapes. Thermal conductivities of these Si3N4 foams ranged from 2.427 W m-1 K-1 to 3.154 W m-1 K-1, whereas compressive strengths of these Si3N4 foams are in the range from 12.85 MPa to 19.99 MPa. Moreover, compressive load-displacement curves of the Si3N4 foams generally exhibit cellular behavior.
Jerry Lo - One of the best experts on this subject based on the ideXlab platform.
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flow visualization of annular and delta winlet vortex generators in fin and tube Heat Exchanger Application
International Journal of Heat and Mass Transfer, 2002Co-Authors: Chichuan Wang, Jerry LoAbstract:Abstract This study presents flow visualization and frictional results of enlarged fin-and-tube Heat Exchangers with and without the presence of vortex generators. Two types of vortex generators and a plain fin geometry were examined in this study. For plain fin geometry at Re=500, the horseshoe vortex generated by the tube row is not so pronounced, and the horseshoe vortex separates into two streams as it flows across the second row and consequently loses its vortical strength. This phenomenon may supports the “maximum phenomenon” in low Reynolds number region reported by previous studies. With the presence of annular vortex generator, the presence of a pair of longitudinal vortices formed behind the tube is seen. The strength of the counter-rotating vortices increases with the annular height and the strength of the longitudinal vortices is so strong that may swirl with the horseshoe vortices and other flow stream. For the same winlet height, the delta winlet shows more intensely vortical motion and flow unsteadiness than those of annular winlet. This eventually leads to a better mixing phenomenon. However, it is interesting to know that the corresponding pressure drops of the delta winlet are lower than those of annular winlet. Compared to the plain fin geometry, the penalty of additional pressure drops of the proposed vortex generators is relatively insensitive to change of Reynolds number.
