Steady-state model of vapour compression systems for refrigeration applications

This work focuses on the model of steady-state vapour compression systems (VCSs), to provide a useful and simple tool to evaluate their performance, both during the design and tuning phase, but also for the control strategy definition and automatic fault detection applications. The main issue faced in the modelling of such systems is related to the dependence of the thermophysical properties of the fluids on the local temperature conditions, which in turn determines a dependence of the transport coefficients which must be solved iteratively. In this work, a solution algorithm for the non-linear system of equations that describes the system behaviour is developed. The model is validated through experimental data obtained for an experimental refrigeration loop employing a zeotropic mixture, R450A. Comparison of the experimental and computed data of pressure, temperature and mass flowrate is demonstrated to be quite satisfactory.