In a compression refrigeration system a refrigerant flows through the refrigeration circuit and is subject to different changes of state. Here, the physical effect is used that during the transition of the refrigerant from a liquid to a gaseous state energy is required which is removed from the environment (evaporation enthalpy). The experimental unit represents a typical refrigeration circuit consisting of a hermetic piston compressor, condenser, expansion valve and evaporator. The evaporator and condenser are transparent to provide good monitoring of the phase transition process during evaporation and condensation. The operation of the float valve as expansion valve is also easy to observe. Before the entry into the evaporator the aggregate state of the refrigerant can be monitored at a sight glass. A water circuit cools the condenser or supplies the cooling load for the evaporator. Cold and hot water and refrigerant flows are adjustable. The low pressure level of the refrigerant used permits the use of an evaporator and condenser out of glass.
Learning Objectives/Experiments
Design and operation of a compression refrigeration system
Observe the evaporation and condensation of the refrigerant
Represent and understand the refrigeration cycle in the log p-h diagram
Energy balances
Calculation of the coefficient of performance
Specification
Demonstration of the processes in a refrigeration circuit
For better process monitoring the evaporator and condenser are of transparent design
Evaporator and condenser with pipe coil
Expansion valve in the shape of a float valve
Pressure switch to protect the compressor
Temperature sensor, power meter, manometer in the refrigeration circuit, flow meter for hot and cold water and refrigerant
Safety valves at the evaporator and condenser
Refrigerant Solkatherm
Technical Data
Hermetic piston compressor
capacity: 18,3cm3
Evaporator capacity: approx. 2800mL
Condenser capacity: approx. 2800mL
Refrigerant
SES36
GWP: 4121
filling volume: 1,2kg
CO2-equivalent: 4,9t
Measuring ranges
temperature: 8x -20…200°C
pressure: 2x -1…1,5bar
flow rate:
2x 0…48L/h (water)
0…700L/h (refrigerant)
power: 0…1200W
230V, 50Hz, 1 phase
230V, 60Hz, 1 phase
120V, 60Hz, 1 phase
