A sight glass indicates the aggregate state of the refrigerant upstream of the expansion valve.

The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

The purpose of a refrigeration system is the cooling of materials and products, e.g. to protect food from spoiling. Cooling The condensation takes place on the high pressure side after the evaporator. Here the heat is discharged into the environment. If not the cooling effect but the discharged heat is used, this is called a heat pump.

The set-up of a simple compression refrigeration system.

Evaporator and condenser have been designed as a pipe coil with each end immersed in a water-filled tank. The water simulates the environment.

can be described as a process in which heat is removed from the environment.

A commonly used refrigeration system is the so-called compression refrigeration system.

In this system refrigerant flows through four main elements: compressor, condenser, expansion element and evaporator.

The refrigeration system uses the fact that the refrigerant has a low boiling point at low pressure. This means that evaporation takes place on the low pressure side. During the evaporation of the refrigerant heat is removed from the environment and it is cooled.

Two thermometers measure the temperature of the water in the tanks. This allows for calculations of the amount of heat removed from the environment (evaporator, cold water) and added to the environment (condenser, hot water).

A thermostatic expansion valve serves as expansion element. Two manometers indicate the two system pressures on the high and low pressure sides. On an additional scale on the manometer the evaporation temperature of the refrigerant is indicated.

Specifications:

Fundamentals of refrigeration in a simplified model

Typical compression refrigeration system with piston compressor, thermostatic expansion valve, evaporator and condenser (each in the shape of a pipe coil)

Pressure switch to protect the compressor

2 manometers with temperature scale for the refrigerant show the values of the refrigerant on the high and low pressure sides

2 water-filled tanks with thermometer to demonstrate the cooling and heating effect

Sight glass to monitor the aggregate state of the refrigerant

Refrigerant R134a, CFC-free.

Learning Objectives / Experiments:

Fundamentals of a compression refrigeration circuit

Operation of a refrigeration system / heat pump

Key components of a refrigeration system

Developing a basic understanding of the thermodynamic cycle

Compressor, evaporator, condenser, expansion element

Relationship between the pressure and boiling point of a liquid

Simple energy balance.