Condenser, subcooling, COP
This paper presents a theoretical and experimental analysis of the effect of condenser subcooling on the performance of vapor-compression systems. It is shown that, as condenser subcooling increases, the COP reaches a maximum as a result of a trade-off between increasing refrigerating effect and specific compression work. The thermodynamic properties associated with the relative increase in refrigerating effect, i.e. liquid specific heat and latent heat of vaporization, are dominant to determine the maximum COP improvement with condenser subcooling. Refrigerants with large latent heat of vaporization tend to benefit less from condenser subcooling. For a typical AC system, numerical results indicate that the R1234yf would benefit the most from condenser subcooling in comparison to R410A, R134a and R717 due to its smaller latent heat of vaporization. On the other hand, the value of COP maximizing subcooling does not seem to be a strong function of thermodynamic properties. Experimental results comparing R1234yf and R134a confirmed the trends observed during the numerical study. For a given operating condition, the system COP increased up to 18% for R1234yf and only 9% for R134a.