The setup of represents a typical refrigeration circuit consisting of a hermetic compressor, condenser, evaporator and expansion element. Evaporator and condenser are designed as finned tube heat exchangers. The pipes of both heat exchangers are partially transparent to visualise the process of the phase transition during evaporation and condensing. Three capillary tubes of different lengths and a thermostatic expansion valve can be compared as expansion elements.
The trainer is equipped with a receiver for refrigerant. Using the receiver, refrigerant can be added to or removed from the refrigeration circuit. This allows for the effects of overfilling or underfilling of the system to be examined.
The flow rate of the refrigerant is read from a flow meter. Temperature and pressure in the refrigeration circuit and the electrical power consumption of the compressor are recorded by sensors. The measured values can be read on digital displays. At the same time, the measured values can also be transmitted directly to a PC via USB. The data acquisition software is included. Parameter changes in the refrigeration circuit can be viewed dynamically in the softwares log p-h diagram.
The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments. The unit shall perform the following experiments and investigations:
Learning Objectives / Experiments
Function and operational behaviour of the
Refrigeration circuit components
Operation with expansion valve or with capillary
Tubes of different lengths
Underfilling or overfilling with refrigerant
Thermodynamic cycle in the log p-h diagram
From the log p-h diagram and in comparison
With the measured values
Determination of the refrigeration capacity
Determination of the coefficient of performance
Determination of the efficiency of the compressor
Specification
Investigation of a refrigeration system with different expansion elements
Refrigeration circuit consisting of a hermetic compressor, condenser, evaporator and expansion element
Transparent finned tube heat exchangers as condenser and evaporator to observe the phase transitions of the refrigerant
Expansion valve and capillary tubes of different lengths as expansion elements
Receiver for underfilling/overfilling the system with refrigerant
Sensors record pressure and temperature
Compressor equipped with two pressure switches
Software for data acquisition via USB under Windows Vista or Windows 7