Thermal performance escalation of cross flow heat exchanger using in-line elliptical tubes

2019 ◽  
Vol 33 (7) ◽  
pp. 587-612 ◽  
Author(s):  
Chidanand K. Mangrulkar ◽  
Ashwinkumar S. Dhoble ◽  
Pawan Kumar Pant ◽  
Nitin Kumar ◽  
Ashutosh Gupta ◽  
...  
Author(s):  
Kiran Lankalapalli ◽  
Ahmed ElSawy ◽  
Stephen Idem

A steady state sensible performance analysis of multi-pass cross-flow finned-tube heat exchangers is reported. The investigation considers various flow circuiting, such as counter cross-flow, parallel cross-flow, and cross-flow where the tube-side flow is in parallel. A previously developed matrix approach is used to evaluate the heat exchanger performance in each tube pass. The equations required to model the thermal performance of these configurations are presented, and the thermal performance is compared for each type of flow circuiting. Thereafter a parametric study on cross-flow heat exchanger performance is performed by varying physically significant parameters such as number of transfer units (NTU) and capacity rate ratios, and the graphical results for each type of flow circuiting are presented both for both two-pass and three-pass arrangements. A consistent criterion is proposed for each case, wherein increasing the NTU beyond a certain threshold value does not significantly improve heat exchanger thermal performance.


2006 ◽  
Vol 129 (3) ◽  
pp. 282-290 ◽  
Author(s):  
Luben Cabezas-Gómez ◽  
Hélio Aparecido Navarro ◽  
José Maria Saiz-Jabardo

A thorough study of the thermal performance of multipass parallel cross-flow and counter-cross-flow heat exchangers has been carried out by applying a new numerical procedure. According to this procedure, the heat exchanger is discretized into small elements following the tube-side fluid circuits. Each element is itself a one-pass mixed-unmixed cross-flow heat exchanger. Simulated results have been validated through comparisons to results from analytical solutions for one- to four-pass, parallel cross-flow and counter-cross-flow arrangements. Very accurate results have been obtained over wide ranges of NTU (number of transfer units) and C* (heat capacity rate ratio) values. New effectiveness data for the aforementioned configurations and a higher number of tube passes is presented along with data for a complex flow configuration proposed elsewhere. The proposed procedure constitutes a useful research tool both for theoretical and experimental studies of cross-flow heat exchangers thermal performance.


2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Hengyun Zhang ◽  
Zhaoqiang Wang

A formulation of the unit cell model and the corresponding thermal performance analysis for the cross-flow heat exchanger are carried out, with the design goal of dissipating 175 W from a high-power electronic chip in a compact space. A liquid to liquid heat exchanger in the cross-flow arrangement is preferred due to its compact size and high effectiveness. The unit cell model is formulated based on the volume-averaging method to determine the heat transfer coefficient involving two heat exchanging fluids and a solid. The various factors such as channel shape, channel edge length, channel size, and heat exchanger material can be examined based on the unit cell model. The obtained heat transfer coefficients are used for the estimation of the heat exchanger thermal performance based on the effectiveness–number of transfer units (NTU) correlation. To verify the model formulation, the heat and fluid flow over the cross-flow heat exchangers are investigated through the full-field numerical computation. The amount of heat exchanged from the numerical computation is extracted and compared with the predicted results from the unit cell model. A fairly good agreement is obtained between the two approaches. Based on the unit cell model, an aluminum cross heat exchanger with eight channel layers for the hot and cold fluids, 15 channels in each layer with a channel diameter of 2 mm, is able to meet the design target.


Author(s):  
Hengyun Zhang ◽  
Zhaoqiang Wang ◽  
Yansong Wang

An analysis for the cross-flow heat exchanger is conducted for electronic cooling applications, with the design goal of dissipating 175W from high power chip by maintaining the chip temperature within 85 °C in a compact space. Liquid to liquid heat exchanger in cross flow arrangement is preferred due to its compact size and high effectiveness. A volume averaging formulation is developed to determine the heat transfer coefficient at the unit cell level. The effects of channel shape, channel size, and heat exchanger material are examined through the heat transfer in the unit cell model. The obtained heat transfer coefficients are also used for the estimation of the heat exchanger thermal performance based on the effectiveness-NTU method. To verify the volume averaging formulation, a full field heat and fluid flow over the cross-flow heat exchangers are investigated through numerical computation. The amount of heat exchanged is extracted and compared with the unit cell model prediction. A fairly good agreement is obtained between the two approaches. Fabrication of cross-flow heat exchanger is further discussed to meet the design target.


Author(s):  
Wamei Lin ◽  
Jinliang Yuan ◽  
Bengt Sundén

Due to the increasing power requirement and the limited available space in vehicles, placing the heat exchanger at the roof or the underbody of vehicles might increase the possibility to handle the cooling requirement. A new configuration of the heat exchanger has to be developed to accommodate with the position change. In this paper, a countercurrent heat exchanger is developed for position on the roof of the vehicle compartment. In order to find an appropriate configuration of fins with high thermal performance on the air side, the computational fluid dynamics approach is applied for a comparative study among louver fin, wavy fin, and pin fin by using ANSYS FLUENT software. It is found that the louver fin performs high thermal performance and low pressure drop. Thus, the louver fin is chosen to be the configuration of the countercurrent flow heat exchanger. It is also found that the countercurrent flow heat exchanger presents higher heat transfer coefficient than the cross flow heat exchanger. Furthermore, the overall size and the air pumping power of the countercurrent flow heat exchanger are lower than those in the cross flow heat exchanger. Several suggestions and recommendations are highlighted.


Author(s):  
Wamei Lin ◽  
Jinliang Yuan ◽  
Bengt Sunde´n

Due to the increasing power requirement and the limited available space in vehicles, placing the heat exchanger at the roof or the underbody of vehicles might increase the possibility to handle the cooling requirement. A new configuration of the heat exchanger has to be developed to accommodate with the position change. In this paper, a countercurrent heat exchanger is developed for position on the roof of the vehicle compartment. In order to find an appropriate configuration of fins with high thermal performance on the air side, the CFD (computational fluid dynamics) approach is applied for a comparative study among louver fin, wavy fin, and pin fin by using ANSYS FLUENT software. It is found that the louver fin has high thermal performance and low pressure drop. Thus, the louver fin is chosen to be the configuration of the countercurrent heat exchanger, which presents higher heat transfer coefficient than a cross flow heat exchanger. For a specific case, the overall size and the air pumping power of the countercurrent flow heat exchanger is lower than that one for a cross flow heat exchanger. Several suggestions and recommendations are highlighted.


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