Investigation of refrigerant pipe pressure drop and charge reduction of mobile air conditioning units with R1234yf

Abstract

In this study, the pressure drop of automotive refrigerant pipes with the refrigerant R1234yf is investigated in detail. For this purpose, 1D and 3D simulations are compared with respect to prediction accuracy using liquid lines from a production car. It is shown that for a combined approach of the methods a very good agreement with the measured values can be obtained, whereas simplified modeling of the line as a straight pipe of equal length significantly underestimates the experimental values. The transition pieces between the pipe and the hose are of particular importance, since they account for up to 85% of the total pressure drop and therefore result in major errors if neglected. If hoses were eliminated, the lines could be designed smaller, resulting in a charge reduction of up to 56%.