Experimental investigation of the effect of condenser subcooling in R134a and R1234yf air-conditioning systems with and without internal heat exchanger

• An experimental study the about effect of condenser subcooling is presented.
• As condenser subcooling increases, COP undergoes a maximum.
• Results indicate that R1234yf benefits more from condenser subcooling than R134a.
• The internal heat exchanger reduces the COP benefit due to condenser subcooling.

This paper presents an experimental study about the effect of condenser subcooling on the performance of an air conditioning system operating with R134a and R1234yf, under the same operating conditions. For both refrigerants, it has been shown that the COP undergoes a maximum as a consequence of the trade-off between increasing refrigerating effect and increasing specific compression work. At a given operating condition, the system COP increased up to 18% for R1234yf and 9% for R134a. These results confirmed the trends obtained from a previous theoretical analysis, demonstrating that a system operating with R1234yf can benefit more from the condenser subcooling than that with R134a. The experimental results also showed that the presence of an internal heat exchanger significantly reduces the COP increase due to condenser subcooling, since both improvements compete towards reducing the throttling losses. Besides the interference between IHX and condenser subcooling, the use of both simultaneously still yields a more efficient air conditioning system, especially for R1234yf.