Potential Coefficient of Performance Improvements Due to Glide Matching With R-470C.
Potential Coefficient of Performance Improvements Due to
Glide Matching With R-470C.
Marques, M. E.; Domanski, P. A.
International Refrigeration Conference at Purdue, 7th.
Proceedings. July 14-17, 1998, West Lafayette, IN,
alternative refrigerants; air conditioner; coefficient
of performance; glide matching; heat pumps;
refrigerants; thermodynamics; zeotropic mixtures
Potential improvements of the Coefficient of Performance
(COP) were investigated for R-407C at cooling and
heating conditions of a residential heat pump. The
study used CYCLE-11, a semi-theoretical
vapor-compression cycle model, which was upgraded to
simulate cross-flow, counter-flow, and parallel-flow
evaporator and condenser with no restructions on
specifying superheated vapor and subcooled liquid
regions. The COP benefit of using counter-flow heat
exchangers in a low-life air-conditioning application
was found to be 7.1% when compared to a system with a
cross-flow evaporator and condenser. For heating
conditions (high-life application), the predicted
benefit was 3.6%. These results are representative of a
water-to-water system, where counter-flow heat
exchangers are suitable for implementing glide matching.
Since air-to-refrigerant heat exchangers are not
counter flow but rather cross-counter flow (in the best
case), the potential to improve COP in a practical air
conditioner is lower. The COP penalty caused by glide
mismatch (parallel flow) is approximately twice as
severe as the benefit that can be realized from glide