Assessment of refrigerant selection for ejection system driven by low-grade heat.

Selection of the working fluid for the refrigeration and solar air-conditioning systems is the crucial problem because of the strong influence of the thermodynamic properties on the system efficiency. Moreover, the working fluids should fulfil the environmental criteria such as zero ODP (Ozone Depletion Potential) and as low GWP (Greenhouse Warming Potential) as possible. Therefore the natural fluids or new synthetic fluids are thought as the best option. The paper deals with theoretical analysis of operation of the ejection refrigeration systems driven by low grade heat. The aim of the paper is comparison of the operating parameters of the system for isobutane as a natural refrigerant with other popular in air-conditioning systems refrigerants such as R134a, and one of the most promising fluid from HFO group, i.e. HFO-1234. Three types of HFO-1234 have been investigated: 1234yf, 1234ze(E), and 1234ze(Z).