Improvements in the characterization of the efficiency degradation of water-to-water heat pumps under cyclic conditions

Quasi-dynamic model of the energy efficiency degradation coefficient for an air-to-water heat pump

“…Although both methods base on energy consumed in the stand-by mode, the reduced COP obtained on their basis often differ significantly and show great discrepancies in relation to the measured data [2,5]. E. Fuentes et al [5], on the basis of experimental research, have observed that start-up losses have significant impact on the efficiency of the device.…”

“…E. Fuentes et al [5], on the basis of experimental research, have observed that start-up losses have significant impact on the efficiency of the device. However, this is neglected in calculations according to the current European standards (e.g.…”

“…Taking into account the results of previous work [2] and the literature [5,7,8] which challenge the method described in the EN 14825 standard, a new definition and calculation approach to the degradation coefficient were proposed. The analytical approach proposed by the authors is aimed to test the devices in semi-dynamic conditions instead of single point measurements.…”

“…Consideration of the device's efficiency ratio both at full and partial load increases the accuracy of the results. The COP reduction factor (PLF) is then calculated according to equation (5). Similarity to the equation (2) is noticeable, where parameter a corresponds to the Cc value, and b to the (1-Cc).…”

“…EN 14825) for air-to-water, water-to-water and brine-to-water systems. In order to take this effect into account, authors [5] proposed an improved equation (4) to define the COP reduction factor (PLF), adding the degradation coefficient Cd as defined in EN 14825 for airto-air and water-to-air heat pumps. They proved that the combination of these parameters could improve the accuracy of the part-load COP estimation.…”