The present study covers modelling of the amount of refrigerant and of the pressure drop in a rectangular copper microchannels evaporator. The evaporator has been tested in a test rig simulating a small-capacity heat pump and all the modelled parameters are compared to the measured ones. All the calculations are performed using EES software program. The void fraction was calculated in order to predict the amount of refrigerant in the evaporator. The choice of the model for the calculation of the void fraction has a big influence on the prediction of the amount. The void fraction was predicted, using several available correlations, out of which the Hughmark, UI ACRC and CISE models seem to give the best approximation. The mass of refrigerant was calculated out of these data and compared to the experimental results. The pressure drop was determined, using the Friedel, Pierre and Granryd's adjustment of Pierre models. Afterwards results were compared to the experimentally measured pressure drop. Granryd's model seems to give the closest approximation. Comparisons of the predicted results with the measured ones are presented in figures and analysed. Conclusions regarding the models tested for determination of the void fraction and pressure drop in the present application and probably other applications with rectangular microchannels are drawn.
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