Summarises experience gained with refrigerant mixtures in laboratory heat pump tests on a test facility designed to measure the steady state and cyclic performance of two air to air heat pumps. Investigates hardware modifications to utilise the temperature glide of zeotropic refrigerant mixtures. Measures the time-dependent operating concentrations of mixtures. States a large temperature glide mixture was used to examine the change in performance. Develops a simulation program for an entire heat pump system. Verifies the program with experimental data and uses it to estimate the behaviour of mixtures in different types of heat exchangers.

KEYWORDS: year 1997, Heat pumps, laboratory testing, air air heat pumps, refrigerants, computer programs, calculating, mixtures