The need for, and availability of, working fluid property data: Results from Annexes XIII and XVIII

In these days of transition to new, more environmentally friendly working fluids, there is a definite need for good data and models of basic thermodynamic and transport properties of both pure compounds and mixtures to be used for cycle calculations and equipment redesign. Two annexes of the IEA Program on Advanced Heat Pumps have dealt with such data, namely Annex XIII-State and Transport Properties of High Temperature Working Fluids and Nonazeotropic Mixtures and Annex XVIII-Thermophysical Properties of the Environmentally Acceptable Refrigerants. In this paper, highlights of these two annexes are presented. A sensitivity analysis (from Annex XIII) gives an estimate of how accurately these basic data need to be known to reach a certain accuracy in heat pump coefficient of performance (COP) and heating or cooling capacity calculations. This analysis points out the importance of measured property data. Other projects to be highlighted are a comparison of equations of state with experimental density, vapor pressure, and heat capacity data for mixtures (XIII), a survey of current research on the properties of the "new" refrigerants (XVIII), and an evaluation of equations of state for R134a and R123 which will lead to an international bulletin for the properties of these two alternative refrigerants (XVIII)