Simulation of Leak/Recharge Process of Refrigerant Mixtures.
Simulation of Leak/Recharge Process of Refrigerant
Mixtures.
(1015 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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899