Possible solution to the R407C composistion variation owing to leaks

In this paper the problem related to the refrigerant fluid leaks in the vapour compression plants is considered; possible leaks can vary the mixture composition. Referring to the R407C zeotropic mixture it is experimentally observed that the percentage of the less volatile component (R134a) increases, while the percentage of the more volatile components (R32 and R125) decreases. The experimental tests have been realized determining refrigerant leaks from the liquid receiver placed at the condenser outlet and measuring the properties in the steady state condition. The principal aim of this paper is to test experimentally if, imposing proper leaks, the initial conditions in terms of the energetic performances are restored with a proper recharge. This recharge is realized in different ways: with R407C, with R134a and R410A or with R32 R125 and R134a. The different solutions are then compared in terms of COP, refrigeration power and the air temperature at the evaporator outlet by means of an iteration method which allows to determine the real composition of a zeotropic mixture working in a vapour compression plant subjected to a cold store, when only the pressure and temperature values at the expansion valve inlet and outlet are known.