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Simulation of Leak/Recharge Process of Refrigerant Mixtures.


pdf icon Simulation of Leak/Recharge Process of Refrigerant Mixtures. (853 K)
Kim, M. S.; Didion, D. A.

HVAC&R Research, Vol. 1, No. 3, 242-254, July 1995.

Keywords:

refrigerants; leak process; mass fraction; recharge; refrigerant mixtures; zeotrope; flammable refrigerant

Abstract:

As alternatives to ozone-depleting refrigerants, zeotropic and near-azeotropic mixtures of nonflammable and flammable hydrofluorocarbon (HFC) refrigerants are being evaluated for use in most refrigeration/air conditioning machines that do not have flooded evaporators. Refrigerant leakage from these systems is very important because a mixture composition may shift to a flammable range. After a recharging process, the mixture composition changes, as does the performance of the system. A model simulating isothermal and adiabatic leaks was presented by the authors in the first issue of this journal. This paper presents an isothermal or adiabatic leak simulation with a recharge process which is capable of simulating up to five cycles. Case studies of an isothermal leak of vapor and liquid phases, with a liquid or vapor recharge process were conducted for binary and ternary refrigerant mixtures at the specified overall composition of R-32/134a (30/70% by mass) and R-32/125/134a (23/25/52% by mass). Mass fraction changes in both vapor and liquid phases are presented. A theoretical machinery system performance change after each recharge was evaluated using another NIST simulation model. Changes in capacity and COP are presented.