A Study of the Heat Transfer Coefficient of a Mini Channel Evaporator with R-134a as Refrigerant

7th International Conference on Cooling & Heating Technologies

材料科学;物理学

Dollera, E.B.^1 ; Villanueva, E.P.^2

College of Engineering, Xavier University-Ateneo de Cagayan, Cagayan de Oro City, Philippines^1

College of Engineering, Iligan Institute of Technology, Mindanao State University, Iligan City, Philippines^2

关键词: Channel hydraulics;    Computer aided simulations;    Controlled flow;    Cooling process;    Data acquisition softwares;    Experimental set up;    Temperature profiles;    Vapour compression refrigeration systems;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/88/1/012027/pdf
DOI  :  10.1088/1757-899X/88/1/012027

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

The present study is to evaluate the heat transfer coefficient of the minichannel copper blocks used as evaporator with R-134a as the refrigerant. Experiments were conducted using three evaporator specimens of different channel hydraulic diameters (1.0mm, 2.0mm, 3.0mm). The total length for each channel is 640 mm. The dimension of each is 100mm.x50mm.x20mm. and the outside surfaces were machined to have fins. They were connected to a standard vapour compression refrigeration system. During each run of the experiment, the copper block evaporator was placed inside a small wind tunnel where controlled flow of air from a forced draft fan was introduced for the cooling process. The experimental set-up used data acquisition software and computer-aided simulation software was used to simulate the pressure drop and temperature profiles of the evaporator during the experimental run. The results were then compared with the Shah correlation. The Shah correlation over predicted and under predicted the values as compared with the experimental results for all of the three diameters and high variation for Dh=1.0mm. This indicates that the Shah correlation at small diameters is not the appropriate equation for predicting the heat transfer coefficient. The trend of the heat transfer coefficient is increasing as the size of the diameter increases.