Fixing Efficiency Values by Unfixing Compressor Speed: Dynamic Test Method for Heat Pumps

Abstract

The growing market penetration of heat pumps indicates the need for a performance test method that better reflects the dynamic behavior of heat pumps. In this contribution, we developed and implemented a dynamic test method for the evaluation of the seasonal performance of heat pumps by means of laboratory testing. Current standards force the heat pump control inactive by fixing the compressor speed. In contrast, during dynamic testing, the compressor runs unfixed while the heat pump is subjected to a temperature profile. The profile consists of the different outdoor temperatures of a typical heating season based on the average European climate and also includes temperature changes to reflect the dynamic behavior of the heat pump. The seasonal performance can be directly obtained from the measured heating energy and electricity consumption making subsequent data interpolation and recalculation with correction factors obsolete. The method delivers results with high precision and high reproducibility and could be an appropriate method for a fair rating of heat pumps.

Dynamic Modelling and Techno-Economic Assessment of a Compressed Heat Energy Storage System: Application in a 26-MW Wind Farm in Spain

“…Furthermore, the possibility of working at partial load was also considered. Several studies of HTHPs found in the literature [26][27][28][29][30] have shown that variable speed compressors present an increase in the coefficient of performance (COP) (defined as the ratio between the sum of latent and…”

“…Furthermore, the possibility of working at partial load was also considered. Several studies of HTHPs found in the literature [26][27][28][29][30] have shown that variable speed compressors present an increase in the coefficient of performance (COP) (defined as the ratio between the sum of latent and sensible power heat produced and the electrical energy needed at the HTHP's compressor) when working at a partial load (especially between 30% and 50%). This is due to the fact that the mass flow rate also decreases, leading to a lower temperature lift between the evaporator and condenser, which reduces the pressure ratio [26].…”