Computational Fluid Dynamics (CFD) Study on Rate of Heat Transfer for an Air Side Heat Exchanger

Ong, Jia Wei (2019) Computational Fluid Dynamics (CFD) Study on Rate of Heat Transfer for an Air Side Heat Exchanger. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The title of this project is Computational fluid dynamics (CFD) study on rate of heat transfer for an air side heat exchanger and the aim of this research is to investigate the performance of the heat transfer when adding the louver fin to the air side heat exchanger fin. In this project is based on the effect provide by the louver angle, to investigate at what angle can provide better heat transfer. The angle of the louver using for the project investigation are 28, 30, 32 and 34 degree. Second model is to change the fin pitch by 1.4mm, 1.5mm, 1.1mm and 0.95mm. Furthermore, model 3 is the combination of model 1 and 2 in order to get the best results obtain. The louver angle is not directly influenced the heat transfer performance, the angle is using to disturb the air flow in order to make changes in the pressure drop and the changes in boundary layer forms on the air side heat exchanger fin. In this project, 3 different model is using to investigate the air flow characteristic and the heat transfer performance, the investigation is undergoes by using the CFD as the tools to predict the results and comparing with each of the model and the reference. The performance of the results is represented by using heat transfer coefficient, when the heat transfer coefficient increases the heat transfer performance will be increases as well. In this project SolidWorks were used to fabricate the model of the louver fin heat exchanger with different angle and fin pitch. There are four cases in each model, model one is four cases with various angle and model two is four cases with various fin pitch. Model three were fabricated by combining the best results of model one and two. After fabricated, the model will be import to CFD by using FLUENT to predict the heat transfer coefficient. First and foremost is to create an enclosure for the model to act as a computational domain, and crate Boolean function to subtract the fluid domain and the louver fin. In mesher the model is mesh under curvature shape element with minimum size of 1.5 x 10−5mm, after meshing the inlet, outlet, wall and fluid domain were created by using the name select function. In setup, K-omega was used because it can provide superior performance for flows involving rotation, boundary layers under strong adverse pressure gradients, separation, and recirculation. Besides that the solver parameters is set as Green-Gausscell based gradient options because the flow is assumed as turbulent and incompressible. Lastly the results is obtain after 200 iterations. The results have shown that in model 1 case 4(28 degree) have the highest efficiency among the four cases due to the angle have interrupt the air flow and reduces the boundary layer formation on the wall. In second model, case 4 have the highest efficiency compared with other cases, because it have the highest number of louver fin which have increases the surface area and lead to a good heat transfer performance. In model 3 is the combination of case 1 in model and case four in model 2 which the model is fabricated with 0.95mm fin pitch and 28 degree of louver angle. The efficiency of model 3 is 7.34 percent which case 1 in model one only obtain 1.83% and for model 2 case four is 2.34%. The CFD software can help to predict and study the heat transfer performance of the heat exchanger fin under various geometry parameters of the louver fin.