Residential Refrigeration Unit

This example models a basic refrigeration system that transfers heat between the refrigerant two-phase fluid and the environment moist air mixture. The compressor drives the R134a refrigerant through a condenser, a capillary tube, and an evaporator. An accumulator ensures that only vapor returns to the compressor.

Two fans drive moist air flow over the condenser and the evaporator. The evaporator air flow is divided between the freezer compartment and the regular compartment. The controller turns the compressor on and off to keep the compartment air temperature at around 4 degC.

Model

Compartment Subsystem

Compartment Subsystem

Freezer Subsystem

Compressor Subsystem

Controller Subsystem

Environment Subsystem

Simulation Results from Scopes

Simulation Results from Simscape Logging

This plot shows the rate of heat transfer between refrigerant and moist air in the condenser and evaporator as well as the rate of heat loss through the insulation of the compartment and freezer. It also shows the temperature of cold air and food in the compartment and freezer. At 11000 s, the compartment door is opened for 60 s, resulting in a spike in compartment temperature.

This plot shows the power consumed by the compressor and the cooling load of the refrigeration system, which is the rate of heat transfer in the evaporator. The coefficient of performance is the ratio of the cooling load and the power consumed.

This plot shows refrigerant pressure and mass flow rate. The high pressure line is at around 1 MPa and the lower pressure line is at around 0.1 MPa. The nominal refrigerant flow rate is 1 g/s. The plot also shows the liquid volume fraction in the accumulator.

Fluid Properties