NIST Time|NIST Home|About NIST|Contact NIST

HomeAll Years:AuthorKeywordTitle2005-2010:AuthorKeywordTitle

Potential Coefficient of Performance Improvements Due to Glide Matching With R-470C.

pdf icon Potential Coefficient of Performance Improvements Due to Glide Matching With R-470C. (616 K)
Marques, M. E.; Domanski, P. A.

International Refrigeration Conference at Purdue, 7th. Proceedings. July 14-17, 1998, West Lafayette, IN, 1998.


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 matching.