C07 -- Exergy and Performance Analysis of Alternative Refrigerants with Lower GWP for the Retrofit of Heat Pumps with R410A PDF

In virtue of its high performance and capability of providing heating and cooling, Heat Pumps (HPs) technology has performed an outstanding spread within the Heating, Ventilation, and Air Conditioning (HVAC) sector. Such spread presents a projected worldwide growth that surpasses 200% in the next decade. With a constant development, the vapor compression (VC) HPs systems have been progressively evolved along with all their components, including mechanical components, control systems, and refrigerants. This latter one, due to the great focus on the decarbonization of world economies, has presented a major importance in the last years, especially when hydrofluorocarbon (HFC) refrigerants with a considerably high Global Warming Potential (GWP), are still very much in vogue. Therefore, the present work starts with a data analysis, supported by a non-supervised learning algorithm, of an extensive dataset with equipment consisting of different types of VC HPs with various features, such as different compressors, cooling and heating capacities, type of equipment, etc. The considered dataset reveals that the HFC R410A is still extremely used. Thus, with the objective of identifying feasible alternatives for the drop-in retrofit of systems that use it as primary fluid, a simulation in Python is conducted to analyse the exergy and performance of three alternative refrigerants with lower GWP, R32, R290, and R1270, in comparison to R410A. The simulation considers air-to-air and air-to-water HPs in both cooling and heating modes, with different supply and ambient temperatures. Additionally, since the retrofit process may result in a reduction of compressor isentropic efficiency (ηisen) depending on the refrigerant employed, different values for this parameter, were also considered. Summarily, all the alternatives present promising results that surpass the R410A in terms of COP and exergetic efficiency (ε). From such results, improvements up to 2.4% and 4.1% for the aforementioned parameters, respectively, may be observed, even with a ηisen reduction. The only circumstances where the original refrigerant outperformed the alternative ones more notably occurred after a reduction over 10% in the ηisen. Finally, in addition to the retrofitting refrigerant choice, the impact on the analysed parameters may also vary according to the operation mode, system, and temperature lifts.