A mathematical simulation model for thermostatic expansion valves

Abstract A mathematical model to simulate the steady-state operation of thermostatic expansion valves, in the range up to 30 kW refrigeration capacity, is described. Such a model is necessary in the study of component matching, over wide ranges of operating conditions, in heat pumps and refrigeration machines. The model treats the mutual dependence between the valve's throttling and control functions, and requires a few experimentally determined parameters, besides the accurate description of the geometry of the throttling section. An algorithm describing the solution of the mathematical model, as implemented in the computer program HP Design for simulation of heat pumps, is presented. The paper also shows that the data required may be obtained without the participation of the manufacturers, but stresses that such participation would ease the effort, and eventually reduce the uncertainty, in the determination of some parameters.