06 November 2008


This paper presents a detailed performance characterisation of a reversible waterto-
water heat pump operating in cooling mode (SHERHPA 2007). It was designed to be
integrated in a building air conditioning system in order to produce cold or hot water as
required (Urchueguia et. al. 2006, GEOCOOL 2005). Characterisation of the heat pump
behaviour with regard to both cooling capacity and the coefficient of performance (COP)
under variable load conditions on secondary fluid external loops has been obtained by
laboratory testing. It was possible to simulate the conditions of the real application based on:
i) variations of water inlet temperatures on both evaporator and condenser sides and ii)
variations of flow rates on the water loops. This experimental performance study has been
carried out for water flow rates between 2000 and 4200 kg/h at 10.8ºC and 13ºC water
temperatures at the inlet of evaporator. For further analysis, IMST – ART simulation software
has been used to extend the range of input parameters up to a minimum water mass flow
rate of 1000 kg/h and water inlet temperatures on the evaporator side between 8ºC up to
18ºC, as opposed to experimental tests that have restricted possibilities. As a direct result of
the comprehensive understanding of the system response under different load conditions, it
has been possible to improve system efficiency by means of optimum control of the water
mass flow rates on both evaporator and condenser side.