speed is maintained at 450 rpm by controlling the inverter
frequency. It should be noted that this speed is appropriate
for this experimental set up. This speed is employed after
problems were encountered at several different speeds used
in previous experiments. It has been found that if the
compressor speeds of over 450 rpm are used, the pressure in
the liquid–vapor separator decreases. This enables the
liquid in the separator to become increasingly vaporized and
finally result in the increase of the vapor temperature. This
high temperature vapor probably causes the compressor to
become damaged. Also if the compressor speeds of lower
than 450 rpm are used, the amount of liquid in the separator
gradually increases. Finally, the liquid refrigerant floods the
outlet of the separator (see Fig. 1) and flows to the
compressor. This results in compressor failure. The water
temperatures are kept constant at the required values in both
the hot and the cold water tanks. They are then circulated
through the condenser and evaporator at constant temperatures
and constant volume flow rates by the circulating
pumps. The experiments are performed for both the TPERC
and the CRC systems. Experimental uncertainties in the
measured quantities are estimated according to Holman
[11]. The method is based on a combining of all the
uncertainties in the various primary experimental measurements.
The uncertainties of measured quanties and calculated
parameters are shown in Tables 2 and 3, respectively.