Intracycle Evaporative Cooling in a Vapor Compression Cycle

摘要

The temperature glide of zeotropic mixtures during phase change provides theopportunity to limit throttling losses of the refrigeration cycle by intracycle evaporative cooling of the refrigerant leaving the condenser. Intracycle evaporative cooling is similar to the use of the liquid-line/suction-line heat exchanger with the difference that a two-phase low-pressure refrigerant, instead of superheated vapor, is used to subcool the high-pressure liquid leaving the condenser. Intracycle evaporative cooling was evaluated by a semi-theoretical simulation model and in the NIST's Small Breadboard Heat Pump at the cooling mode operating condition typical for a water-to-water residential heat pump. The capacity, coefficient of performance (COP), pressures, and temperature profiles of refrigerant and heat-transfer fluid in the heat exchangers are reported. The laboratory measured improvement of the COP was 4.0% for R-32/152a, 3.6% for R-407C, and 1.8 percent for R-23/152a.