22 May 2008


This paper presents a detailed performance characterisation of a reversible water
to water heat pump operating in cooling mode (SHERHPA 2007). This 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). The 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 is obtained through a
laboratory experimental test campaign. 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 is obtained 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 is 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 evaporator side between 8ºC up
to 18ºC as opposed with experimental tests that have restricted possibilities. The consistent
understanding of the system response under different load conditions has as a direct result
an improved system efficiency obtained based on the optimum control of the water mass flow
rates on both evaporator and condenser side.