An alternative method to estimate refrigeration system inventory

Abstract

Refrigeration system performance is directly related to the refrigerant mass charge in the equipment. This means that there is an optimum fluid amount that requires less power usage and contributes indirectly to a reduction in greenhouse gas output. Another important factor in fluid charge optimization is that it protects against compressor failure. The best approach for predicting refrigeration system inventory is to find the distribution of refrigerant mass in the evaporator and condenser. This work presents an alternative method for estimation of the refrigeration system inventory based on the first law of thermodynamics and the void fraction correlation of Hughmark. The average error of this alternative method was 5.1% and 7.2% for the first and second experimental validations, respectively, whereas the classical method of Otaki produced an error of 10%. Additionally, a convergence study and a sensitivity test were carried out. This alternative method is especially relevant for unusual heat exchanger geometries, when the external heat transfer coefficient is difficult to obtain from the literature.