Question 1
State the function of the following accessories of a refrigeration system: overload, high pressure cut out switches, low pressure cut out switches, anti-freeze, thermostats.
Observation
The expected responses are:
(a) FUNCTION OF THE FOLLOWING ACCESSORIES OF A REFRIGERATION SYSTEM OVERLOAD:
- This is a device either temperature, pressure or current operated which will stop operation of unit if dangerous condition arise.
- It is used to protect the compressor from overheating
- HIGH PRESSURE CUT OUT SWITCHES:
- This is an electrical control switch operated by the high side pressure which automatically opens electrical circuit if too high pressure is reached.
- It is used to stop the system when the pressure exceeds safety limit.
- LOW PRESSURE CUT OUT SWITCHES:
- This is a device used to keep low side evaporating pressure from dropping below certain pressure.
- It is used to stop the system when evaporation or suction pressure becomes low.
- It also sometimes causes the compressor to produce a high vacuum at high speed.
(iv) THERMOSTAT:
- This is a device that is used to control the temperature of a refrigerator system.
- This is a device which senses ambient temperature conditions and in turn acts to control a circuit
(b) TYPES OF REFRIGERATOR
- Single door refrigerator.
- Double door refrigerator
- Single compressor
- Multi compressor.
(c) Refrigerant Blend:
- Refrigerant blend is the liquid mixture of refrigerant which
exhibit a constant maximum and minimum boiling point and these mixtures act as a single refrigerant.
- It is also the combination of two or more refrigerant to produce a single refrigerant.
Majority of the students were able to answer the questions correctly.