Experimental Characterization of Fault Impacts on the Functioning Variables of an Inverter Driven Heat Pump

The heat pump technology answers to the three key targets of the European Union climate action by reducing greenhouse gas emissions, increasing renewable energy share and improving energy efficiency of buildings. In standard conditions, heat pumps can reach very high coefficients of performance (COPs). However, the in-situ COPs are poorly known and they depend on many factors such as sizing, climate, quality of installation, and can also be affected by some abnormal functioning caused by faults, such as heat exchanger fouling or incorrect refrigerant charge. This paper focuses on the characterization of these faults for an inverter driven residential heat pump, for which literature is very limited, in order to be able to detect those as early as possible, and thus to facilitate maintenance operation. A series of experimental tests has been conducted to generate correlations between faults and their impact on the main functioning variables and performances. The test results obtained are presented and discussed. Further steps required to develop an operational automated fault detection and diagnostic method for inverter driven heat pumps are finally discussed, as well as the possibility to associate it with a performance assessment method for heat pumps that was previously developed and validated.