18 May 2017

O.1.9.3 Comparative analysis of two subcritical heat pump boosters using subcooling in order to increase the efficiency of systems with a high water temperature glide

This paper presents the experimental results obtained from two new heat pump prototypes for sanitary hot
water production working with R290 as refrigerant and designed for heat recovery from water sources like
sewage water or condensation loops (typical temperature condition between 10ºC to 30ºC). The heat pumps use
subcooling in order to enhance the system efficiency. With the proposed strategy it is possible to match the
water temperature glide with the refrigerant temperature in a more proper way (it should be taken into account
that typically in this kind of system the temperature glide can vary between 10 K and 50 K). The obtained
results have shown a high degree of improvement by making subcooling. COP more than 30% higher than the
same cycle working without subcooling (Nominal point: inlet water temperature at evaporator is 20ºC and the
water inlet/outlet temperature in the heat sink is 10ºC and 60ºC). In order to determine the advantages and
disadvantages of each system configuration the performance of the two different prototypes are compared fromthe point of view of control, reliability, efficiency and cost.