An Improved Numerical Model for Thermostatic Expansion Valves Used in Automotive Air-Conditioning Systems

The TxV model presented at the VTMS 5 has been improved with new experimental measurements.

The model, inputted with the thermo-physical properties of the refrigerant at the orifice boundaries and the temperature conditions of the environment surrounding the bulb, allows to calculate the valve lift and the expanding fluid mass flow rate through the variable orifice.

A good correspondence with the AC loop data measured during a cool-down test on a vehicle has been established and is here presented.

The model allows therefore to seize the valve setting influence on the mass flow rate, giving a solid tool to automotive engineers in exploiting usefully the AC loop simulating tools which adopt the presented model to choose the correct components in both development and problem solving for the current market's good at first shot challenges.