Influence of Parameters on the Estimation of Coefficient of Performance for R410a Refrigerant

Abstract

Simple equipment for measuring the coefficient of performance (COP) requires a basic thermodynamics approach and many coefficients of the gas state equation and saturated liquid line equation are affected by factors such as pressure, temperature, and volume. The coefficients used in these equations vary depending on the literature. In this study, the influence of a change in the coefficients on the precision of the COP calculation was examined. The enthalpy was calculated at seven points on the heat pump cycle, which were all reproduced adequately, with low errors, compared to the reference values. The errors of the calculated enthalpies increased when the coefficients deviated from their original values. The coefficients were changed by 14 different values between − 10 % and 10 %. However, the observed enthalpy differences between two points with similar states for either wet vapor or superheated vapor were consistent with the reference values for low values, because the same equations were used for Hou–Martin or saturated liquid lines, respectively. The absolute mean error of the COP exceeded 1.0 when the coefficients were increased by 2 %, and 0.793 at the maximum value when the coefficient decreased negatively. This worse precision could mean that different enthalpy equations were used in the process of the COP calculation, whose states were a mixture of wet and superheated vapor.