18 May 2017
The seasonal efficiency of a heat pump during on-field operation may be different from the expected performance derived from laboratory tests. In fact, the installation layout and the control strategy may influence the overall energy performance of a heating system and cause the heat pump to operate with low efficiency.
Within this work, the performance of three heating systems, all based on the same type of gas absorption heat pumps, have been monitored for a winter season, with the purpose of pointing out the critical issues, which determine, in some cases, performance much lower than the expected values.
The investigated systems include from six to ten heat pump units installed in a rail set, and provide heating power to public buildings (schools and town hall), located in the North of Italy.
The heat pump system performance of each plant, expressed in terms of Gas Utilization Efficiency (GUE), has been measured and correlated with other parameters, which characterize the specific operating conditions.
Unnecessary transient operation, small temperature difference between supply and return, poor regulation of the supply temperature and distribution losses resulted to be the main issues reducing the heat pump system monthly efficiency.