| Abstract: | This article presents a steady‐state model of a vapour compression refrigerating machine using a ternary refrigerant mixture R‐407C. When using a zeotropic mixture in a refrigerant cycle, the circulating composition does not agree with the composition of the original charged mixture. It is mainly due to the temperature glide and the vapour–liquid slip ratio. As a result of the composition shift and its magnitude, the system performance changes depending on the system design, especially the presence of liquid receiving vessels. In this paper, a method that predicts the circulating composition has been associated to a refrigerating machine model. The results obtained with this model show an enrichment in the most volatile components of about 1% for the circulating composition, which is sufficient to decrease the system performance by about 3%. Factors affecting the overall performance have been investigated. The results show a very strong performance dependence on the refrigerant charge. The COP can decrease by 25% when the refrigerant charge is insufficient. An initial charged composition variation of 2% involves variations of the cooling capacity of about 5%. Furthermore, our model was employed to compare the performance for both R‐22 and R‐407C. The cooling capacity for R‐22 is slightly greater in comparison to R‐407C and the COP is almost constant. Copyright © 2002 John Wiley & Sons, Ltd. |
