The Computer Controlled Refrigeration Unit with Open Compressor is arranged in a clear way and represents a typical compression refrigeration system with open compressor:
The main elements of the unit are:
- Open compressor activated by an electric motor.
- Condenser with fan.
- Expansion valve.
- Evaporator with fan.
The low pressure saturated refrigerant vapor, coming from the evaporator, is compressed in an open compressor driven by an electric motor though a V-belt. Therefore, its pressure increases, involving a temperature increment too. It causes the transformation of the workingfluid from saturated steam to superheated steam.
The number of revolutions of the electric motor is adjustable, allowing the study of the cycle at different degrees of compression. In addition, the electric motor is suspended as a pendulum, having a force sensor to determine the torque.
The high pressure superheated steam from the compressor flows inside an air condenser, where the working fluid, in vapor phase, transfers heat to atmospheric air (hot source) whilepassing through the tubes. Therefore, the working fluid undergoes a phase change, to liquid state, through a condensation process.
At the outlet of the condenser the cooling liquid passes through an expansion valve , whose function is to control the flow of refrigerant in liquid state entering the evaporator.
The low pressure cooling liquid coming from the expansion valve is introduced into an evaporator, where there is a heat transfer from the coldsource (atmospheric air) to the cooling liquid, producing a phase change of the working fluid until it becomes saturated steam. This process is isobaric (P = constant).The evaporator is located inside a refrigeration chamber, which includes a heating element with adjustable power to simulate a change in the conditions of the system and create different thermal loads.
The temperature and pressure can also be measured in the circuit at key points of the cycle. Besides, the circuit includes a sight glass to observe the state of the working fluid, a filter, a storage vessel to ensure a proper flow of refrigerant in the circuit, and a liquid separator to prevent liquid from entering the compressor.
As a safety measure, the circuit includes a combined high and low pressure switch and a bypass circuit with solenoid valve.
This Computer Controlled Unit is supplied with the EDIBON Computer Control System (SCADA), and includes: The unit itself + a Control Interface Box + a Data Acquisition Board + Computer Control, Data Acquisition and Data Management Software Packages, for controlling the process and all parameters involved in the process.