Some factors that affect the Coefficient of Performance of the refrigeration are; Sub Cooling of liquids
Superheating of Vapor (May be constant, increase or decrease) Change in suction pressure
Change in discharge pressure
Effect of volumetric efficiency of Compressor .
Firstly, the mass flow rate of the refrigeration cycle was determined in order to get steady values of results. Secondly, the values of temperature were recorded for the different points corresponding to the P-h chart. Once the temperature was found, it is plotted in the P-h chart to determine the values of enthalpy for the respective points. Compared the ideal values of COP with the actual values and note the significance. Apparatus:
It was noted from the above solution that the true value of COP obtained from the experiment was 4.875. The ideal value of COP as obtained directly from the P-h chart would correspond to 4.81. Also, the work of the compressor is high with superheating i.e. ( ) and is greater than the ideal cycle (). It can be notified the effect of superheating that it increases the COP of the refrigeration cycle and as well as an increase in the specific work by the compressor. Lastly, the more the needed effort to superheat a refrigerant by increasing the evaporator load to remove its liquid would greatly increase the power input of the compressor. Conclusion:
In conclusion, the value of COP of the refrigeration cycle was successfully obtained to be 4.875. Also, the effects of superheating that was reflected in the experiment have tremendously affected the work done by the compressor and also the coefficient of performance. The compressor work and COP values tends to increase when the system undergoes superheating. Superheating is needed in a refrigeration cycle because it eliminates wet compression where it can damage the compressor. The heating of suction piping outside the refrigeration space mainly from friction and a large evaporator load could be the result of superheating of this refrigeration system. References:
. Cengel, Y.A. and Boles, 2011, Thermodynamics – An Engineering Approach, McGraw Hill, Chicago.
 Prof. T. Sundararajan and Prof. J.M. Mallikarjuna., Refrigeration Cycles, viewed 15 August 2013, http://nptel.iitm.ac.in/courses/IIT-MADRAS/Applied_Thermodynamics/Module_6/6_Simple_Vapor_Compression_RS.pdf.