Air-water heat pump modelling for residential heating and domestic hot water in Chile

Abstract

In Chile, household heating demands are mainly provided by wood stoves and domestic hot water by gas water heater. This presents two drawbacks, the use of wood stoves for heating is responsible of severe pollution problems during winter period and another drawback is associated to the high price of the gas. To mitigate these problems, it is proposed to analyse the use of heat pumps for both heating and domestic hot water. The first step for this analysis is to determine the seasonal performance of the heat pump, which depends, among others, on the building location, building characteristics and heat pump characteristics. In this study the performance of a four occupants household located at Concepcion and Santiago are considered. The heating demand is determined by using the software TRNSYS, by obtaining an annual heating demand that varies between 5003 kWh and 8788 kWh for Concepcion and between 4388 kWh and 7883 kWh for Santiago. The domestic hot water demand is determined from a typical consumption profile, with an annual energy demand of 3721 kWh and 3541 kWh for Concepcion and Santiago respectively. These profiles are used as inputs to the heat pump model by developing an hourly simulation. The heat pump is modelled by using a modular approach decomposed in three individual models for the following components: compressor, condenser and evaporator. It is assumed that the compressor is regulated with an ON/OFF control. The system SPF varies between 2,54 and 2,60 for the six cases analysed in this study. There is no significant difference in the SPF in both cities, which is attributed to the ambient conditions, which are in average very similar.