4. Experimental results
The plant was run on R22 under various working conditions in
order to verify its efficiency.
The evaporator energy balance was found by evaluating the
thermal power transferred in it by determining the enthalpy difference
between the terminal sections of the exchanger of both the
water–glycol solution and the R22.
The obtained data agreed well with each others giving an indication
of reliability on the setup to be used when comparing the
different refrigerant fluids.
Seven different test conditions were run to compare the exchanged
thermal power of water–ethylene glycol mixture and
the change in the working fluid enthalpy. The results concurred
well. The same trial run again with two of the replacement fluids,
also provided good concurrence.
Fig. 3 shows the trend of COP in function of the water–ethylene
glycol mixture load for the three tested fluids. Whereas, Fig. 4
shows the trend of the COP in function of the evaporation temperature
for the corresponding conditions, obtained when changing
the water–ethylene glycol mixture load.