Large Heat Pumps Nonazeotropic mixtures as working Fluids - some results from computer simulations

Nonazeotropic mixtures of working fluids have been much discussed during recent years for large heat pumps, although practically no systems have been really installed so far. Hith mixtures it is possible to achieve gliding temperatures in the condenser and the evaporator. This enables several possibilities for improvement of the performance, such as the COP, the heating capacity, variation of the heating capacity with the load, pressure levels. and compressor discharge temperatures.In the following comparisons between some mixtures and pure working fluids regarding the COP and the relative heating capacity are presented. The results shown are computer calculated ones.Most calculation results for mixtures. presented so far in the literature, are valid for a heat pump cycle with infinite heat exchanger areas. In this paper it is shown that the influence on the performance of finite heat exchanger areas and realistic compressor efficiencies is considerable