A hybrid transient model for simulation of air-cooled refrigeration systems: Description and experimental validation

• A hybrid dynamic model for refrigeration systems is proposed.
• Flows through heat exchangers are approximated by a cascade of CSTRs.
• All the refrigerant thermodynamic properties are analytically determined.
• Phase transition within heat exchangers is performed by matrix operations.
• Pressure losses in evaporator are taken into account by lumped models.

In this paper are described a hybrid dynamic model for transient simulation of refrigeration systems as well as dynamic experiments that have been performed on an air/water heap pump. The machine under consideration is made of an evaporator, a condenser, an expansion valve, a variable speed scroll compressor and a receiver. The refrigerant and second fluid flows in heat exchangers are approximated by a cascade of Continuous Stirred Tank Reactors (CSTRs). This model is quite flexible since a unique structure is used for the evaporator and the condenser models according to different boundary conditions. This is due to the use of a switching procedure between different configurations based on a phase stability test that is designed to ensure the continuity of the system simulation. An analytical thermodynamic model of the refrigerant based on an equation of state is used. Good agreement between simulation results and experimental data is achieved.