Irreversible loss caused by viscosity-dominated viscous dissipation is an important factor affecting high-temperature heat pump (HTHP) performance. To quantify the effect of viscosity on the coefficient of performance (COP) of HTHP systems, this study developed a contribution analysis model based on data samples from multiple working conditions, working fluids, and device types. Factor analysis and Varimax orthogonal rotation were employed to achieve multi-factor dimensionality reduction and mapping, quantitatively analyze viscosity factors, and compare the weight contribution distributions of other influencing factors with and without viscosity parameters. Results show that, in the global sample, viscosity corresponding to condensation temperature ranks among the top three negatively correlated factors, with a contribution of 7.40%. The sum of the absolute contributions of viscosity corresponding to condensation temperature and evaporation temperature reaches 9.86%, second only to temperature lift (16.10%). In the three local temperature ranges, the contributions of viscosity corresponding to condensation temperature are 6.31%, 6.75%, and 7.11%, respectively. The total contribution of irreversible loss parameters increases from 46.21% to 49.39%, and the increase reaches 12.02% in the high-temperature range. These results provide a theoretical basis for HTHP system design, working fluid selection, and performance improvement under high-temperature operating conditions.
Xu et al. (Mon,) studied this question.