Experimental study of the combined effect of the refrigerant charge, compressor speed and expansion valve opening in a refrigeration system.

An experimental study has been performed to evaluate the effect of refrigerant charge, electronic expansion valve opening and compressor speed on the thermodynamic performance of a vapour compression refrigeration system. A testing apparatus comprised of a variable speed compressor, a pulse width modulated electronic expansion valve and a device for varying the refrigerant charge, was designed and constructed. It has been found that for a given refrigerant charge the COP at a particular compressor speed can be maximized by a proper opening of the expansion valve. It has also been shown that the optimum evaporator superheat is within a range of 1 to 3°C.