Effects of Metastable flow on Flow Characteristics of R600a in Capillary Tubes Used in Refrigeration Systems
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Abstract
This research presents a mathematical model for predicting the properties of R600a refrigerant flowing through a capillary tube, incorporating the effects of metastable flow. Metastable flow occurs because the refrigerant R600a will not change from liquid to vapor even when the pressure is lower than its vapor pressure. The location where the refrigerant R600a changes from liquid to vapor is shifted further away from its original location, resulting in a higher flow rate for the R600a refrigerant. The results of the developed mathematical model were compared with those from literature. The comparison reveals that the values are similar and trend in the same direction, ensuring a certain degree of accuracy. This study also presents the effect of metastable flow on the mass flow rate under various operating conditions. It was found that accounting for the metastable flow effect can increase the mass flow rate by up to 13.08%. Two selection charts are also presented to indicate the operating conditions and capillary tube sizes for R600a.
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References
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