Impact of Air and Refrigerant Maldistributions On the Performance of Finned-Tube Evaporators With R-22 and R-407C.
Impact of Air and Refrigerant Maldistributions On the
Performance of Finned-Tube Evaporators With R-22 and
Lee, J.; Domanski, P. A.
DOE/CE/23810-81; Final Report; 38 p. July 1997.
Sponsor:Air Conditioning and Refrigeration Technology Inst.,
Inc., Arlington, VA
Available from: National Technical Information Service
air conditioning; evaporator; heat transfer; modeling;
refrigeration; refrigerant mixtures
The report presents basic features of the evaporator
model, EVAP5M, and simulation results for an evaporator
operating with R-22 and R-407C at non-uniform air and
refrigerant distributions. EVAP5M was developed under
this project to provide a tool for simulating a
finned-tube air-to refrigerant evaporator operating with
single-component refrigerants and refrigerant mixtures.
The tube-by-tube modeling approach allowed for
one-dimensional non-uniformity in the air velocity
profile and arbitrary maldistribution on the refrigerant
side. The model uses the Carnahan-Starling-DeSantis
equation of state for calculating refrigerant
thermodynamic properties. Simulations were performed
for three evaporator slabs with different refrigerant
circuitry designs. For the maldistributions studied,
maldistributed air caused much more significant capacity
degradation than maldistributed refrigerant. In some
cases capacity decreased to as low as 57 percent of the
value obtained for uniform velocity profile. Simulation
results showed that R-22 and R-407C have similar
susceptibility to capacity degradation. Relative change
of capacity varied depending on the evaporator design
and maldistribution studied.