A comparative performance study of a direct expansion geothermal evaporator using R410A and R407C as refrigerant alternatives to R22

• Direct expansion geothermal evaporator has been simulated using R22, R410A and R407C.
• R407C is the best fluid for retrofit R22 system in the field of DX GHP.
• The pressure drop in R407C DX evaporators is higher than that of R410A.
• The pressure drop in R22 DX evaporator is higher than those of R407C and R410A.
• HER does not really depend to the type of refrigerant at a given soil temperature.

This study presents a comparative performance analysis of a direct expansion geothermal evaporator using R410A, R407C and R22 as refrigerants. The main goal is to predict the best refrigerant capable of serving as a substitute for R22. A validated geothermal evaporator model developed by our research team was used. The simulation results show that for low refrigerant flow rate, the R410A DX evaporator shows better performance than that of R22, but from the pressure drop observed and superheating recorded with the former, it can be concluded that R407C is the best fluid to replace R22 in the DX GHP. That notwithstanding, to minimize pressure drop, especially for high refrigerant flow rates, R410A would be a better choice for the design of new DX systems.