Heat Pump Experiments with Nonazeotropic Mixtures Preporatory Work
The interest of nonazeotropic mixtures as working fluids in heat pumps has increased
in the last years. This is due to the harmfulness of CFC fluids for the ozone layer and that
nonazeotropic mixtures have been found as an alternative to the use of CFCs.
A project has been started consisting of making an experimental study of an onefamily-
house heat pump working with nonazeotropic mixtures of HCFC22 and HCFCI42b.
The first part of the project is to instrument the heat pump and to make the measuring
equipment work properly before starting further experiments. This includes three steps in the
development of the work. Calibration of the measuring equipment (thermocouples, pressure
transducers, flowmeter), writing of a measuring program check that all instrumentation is
done in a correct way and works well.
Test runs of the heat pump have been done with HCFC22 as refrigerant in order to
check the measuring equipment. The results showed a misfit of the heat balance and after
verifications, it occurred that the problem was due to an incorrectly placed thermocouple.
Since the misfit was too high to be only due to heat losses, more tests run have been
undertaken to find the sources of errors. In order to get accurate results, the valve on the
radiator water side should be changed, a new temperature regulator of the brine should be
installed and the condenser should be isolated.
The first part is completed and before starting the experiments with nonazeotropic
mixtures, some work is still required. The electronic expansion valve should be placed in the
system and a regulating program to control it should be written.
Heat pump application