Analysis of fluid retention zones in heat exchangers with segmental baffle and helical baffle

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Xin Gu ◽  
Ning Li ◽  
Cheng Chen ◽  
Qianxin Zhang ◽  
Guan Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flow Pattern ◽  
Heat Transfer Performance ◽  
Fluid Retention ◽  
Transfer Performance ◽  
Distribution Method ◽  
Average Flow ◽  
Helical Baffle ◽  
Flow Velocities

Abstract By using the residence time distribution method (RTD), the fluid retention zones in the shell and tube heat exchanger with segmental baffle (STHX-SB) and the heat exchanger with helical baffle (STHX-HB) are compared and discussed. The flow pattern and fluid retention zone of the similar double helical flow heat exchanger (STHX-SDH) were analyzed by using the same method. The result shows the spiral flow can reduce the fluid retention zone. The flow pattern in the STHX-SDH likes a double helical shape and leads to a very small fluid retention zone. According to the simulation results, the location of the fluid retention zone of STHX-SDH is determined. The verification line method and the zone assessment method were adopted, to discuss the flow velocity of each point on the verification line and the average flow velocities of the selected zones. The change laws of the flow velocities on the verification lines and the average flow velocities of the selected zones at different Reynolds numbers were compared. The result reveals the distribution of the fluid retention zone of the STHX-SDH and the sensitivity of each fluid retention zone to the Reynolds number. By optimization of the angle of the baffle, the volume fraction of the fluid retention zone is reduced to 1.61%, and the heat transfer performance is improved by 13.23%. It is verified that reducing the fluid retention zone can effectively enhance the heat transfer performance. This research method provides a theoretical basis for reducing the fluid retention zone of the heat exchanger and enhancing heat transfer performance.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

scholarly journals Effect of Magnetic Nanofluids on the Performance of a Fin-Tube Heat Exchanger

2021 ◽  
Vol 11 (19) ◽  
pp. 9261
Author(s):  
Yun-Seok Choi ◽  
Youn-Jea Kim
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Magnetic Fields ◽  
Heat Transfer Performance ◽  
Permanent Magnets ◽  
Convective Heat Transfer Coefficient ◽  
Transfer Performance ◽  
Tube Heat Exchanger ◽  
Improve Heat Transfer ◽  
Fin Tube

As electrical devices become smaller, it is essential to maintain operating temperature for safety and durability. Therefore, there are efforts to improve heat transfer performance under various conditions, such as using extended surfaces and nanofluids. Among them, cooling methods using ferrofluid are drawing the attention of many researchers. This fluid can control the movement of the fluid in magnetic fields. In this study, the heat transfer performance of a fin-tube heat exchanger, using ferrofluid as a coolant, was analyzed when external magnetic fields were applied. Permanent magnets were placed outside the heat exchanger. When the magnetic fields were applied, a change in the thermal boundary layer was observed. It also formed vortexes, which affected the formation of flow patterns. The vortex causes energy exchanges in the flow field, activating thermal diffusion and improving heat transfer. A numerical analysis was used to observe the cooling performance of heat exchangers, as the strength and number of the external magnetic fields were varying. VGs (vortex generators) were also installed to create vortex fields. A convective heat transfer coefficient was calculated to determine the heat transfer rate. In addition, the comparative analysis was performed with graphical results using contours of temperature and velocity.

Heat Transfer Performance Analysis of Horizontal Ground Heat Exchanger under the Artificial Lake

2012 ◽  
Vol 516-517 ◽  
pp. 316-321
Author(s):  
Zhong Yi Yu ◽  
Yan Hua Chen ◽  
Xiao Liang Tang ◽  
Jian Ping Lei
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Performance ◽  
Simulation Method ◽  
Transfer Performance ◽  
Ground Heat Exchanger ◽  
Loop Formation ◽  
Artificial Lake ◽  
Pump System ◽  
Heat Pump System

According to the application conditions of horizontal ground heat exchanger(HGHE) under artificial lake, this paper uses numerical simulation method to do dynamic simulation research of the heat transfer performance of HGHE, analyzes the effect of connection mode and pipe flow velocity on heat transfer performance of HGHE in detail，puts forward efficient HGHE loop formation mode，and will provide effective technical support for ground-source heat pump system design with HGHE.

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