Experimental study and numerical simulation of flow and heat transfer performance on an offset plate-fin heat exchanger

2015 ◽  
Vol 52 (9) ◽  
pp. 1791-1806 ◽  
Author(s):  
Juan Du ◽  
Zuo-Qin Qian ◽  
Zhong-yuan Dai
Machines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 72
Author(s):  
Pingting Ying ◽  
You He ◽  
Hesheng Tang ◽  
Yan Ren

The heat exchanger is widely applied to many axial piston machines, and its structure significantly affects the heat transfer performance. Flow characteristic and heat transfer performance in heat exchanger channels with different dimples geometries are numerically and experimentally analyzed in this research work. The objective is to present details of flow field structure and heat transfer mechanisms for the dimpled channel. The realizable k-ε turbulence model was employed in the numerical simulations with the Re range from 3500 to 20,000. The temperature contour, local streamlines, friction factor, and Nu were presented to illustrate the heat transfer enhancement mechanisms. From this investigation, it is found that dimples cause downward flow, improve the flow mixing and reattachment, interrupt the boundary layer and form periodic impingement flows and then greatly improve the heat transfer. The heat transfer coefficient of hemispherical dimple channels with the three kinds of dimple radius–depth ratios is the highest, and it is about 27.2% higher than that of the traditional rhombus dimple channel. Comparing to the rhombus dimpled channel, the lower flow friction performance of the hemispherical dimple channel depends on the lower dimple radius–depth ratio. The hemispherical dimpled channel present better overall thermal performance due to the strength and extent of the recirculation flow reduction.


Author(s):  
Wei Dong ◽  
Shengbao Zhang ◽  
Zhiqiang Guo ◽  
Xiao Yu

The primary surface heat exchanger (PSHE) is a kind of small size, light weight, high integration heat exchanger. The characteristics of the complex internal structure, complex flow pattern and the flow interaction have a great influence on the heat transfer of the air-air primary surface heat exchanger. Five cross-corrugated air-air primary surface heat exchangers with different core configurations are designed and fabricated applying additive manufacturing technology. The cross angle θ of upper and lower corrugated plates is 0°, 15°, 30°, 45°, respectively. An experimental investigation on the flow and heat transfer performance is carried out. The comparison of test results of overall heat transfer coefficient and the pressure drop for different primary heat exchangers is presented. The test results show that the pressure drop is significantly increased with the cross angle increasing, and the heat transfer performance does not show the linear increasing with the cross angle increasing.


Author(s):  
Bin Gao ◽  
Qincheng Bi ◽  
Zesen Nie

Different overlap configurations of discontinuous helical baffles affect the flow pattern of the shell-side fluid directly, and thus there is a significant impact on the flow and heat transfer characteristics of the shell-side fluid. In the present paper, experiments were carried out to study the impact of baffle overlap proportion on the shell-side flow and heat transfer performance of the shell-and-tube heat exchanger with helical baffles (STHEHB). Two different shell-side friction factors, the friction factor per helical pitch (fs,1B) and the friction factor per tube length (fs,1m), were defined based on different reference lengths. The results showed that, since the baffle overlap proportion leads to different helical pitch as well as flow fields in shell side, opposite conclusions are obtained by choosing different reference length. Based on the same Reynolds number, the shell-side Nusselt number of the STHEHB with 10% baffle overlap is higher than that with 50% baffle overlap. The reason is that the larger baffle overlap proportion produces more serious leak flows and weakens the heat transfer in shell side. The comparison of heat transfer coefficient per unit pressure drop versus shell-side flow rate showed that the STHEHB with smaller baffle overlap proportion has better comprehensive heat transfer performance, but the difference between the two decreases gradually with the increase of the flow rate.


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