Abstract: The temperature glide of zeotropic mixtures during phase change provides the opportunity 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 a 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
experimentally in an instrumented laboratory heat pump at the cooling mode operating condition typical for a water-to-water
residential heat pumps. 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
R32/152a, 3.6% for R407C, and 1.8% for R23/152a.
Keywords: air conditioning, building technology, coefficient of performance, COP, heat pump, refrigeration, zeotropic mixture
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