Abstract:

With the development of technology, the performance of electric devices has increased, and their sizes have been miniaturized. Therefore, the heat emitted by these devices has elevated, and this increased required cooling load rates. Although the cooling performance of conventional refrigerants could meet these cooling load rates, their global warming potential and ozone layer depletion coefficients are high. Accordingly, international protocols and agreements have started to restrict these traditional refrigerants globally. Therefore, researchers have begun to work on alternative, environmentally friendly refrigerants. At this point, CO2 refrigerant stands out as a competitor to conventional refrigerants due to its non-toxic feature, low global warming potential value (1), zero ozone layer depletion coefficient, and high performance in the flow boiling regime. However, there is no high-accuracy flow boiling heat transfer coefficient in the literature due to the unique thermophysical properties of CO2. In the current study, 1084 flow boiling heat transfer coefficient data of CO2 for pipes having different diameters were taken from the literature studies. The collected flow boiling heat transfer coefficient data were tried to be predicted with the multiple regression model. For this purpose, 26 variables were analyzed and the correlation between them was examined. The results were discussed based on the literature, and suggestions were presented.

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