1. Refrigeration

2. Definition of Refrigeration
Mechanical refrigeration, often referred to simply as refrigeration, is a process by which heat is removed from a location using a man-made heat- exchange system This in everyday terms is achieved by - 1) using a refrigerator as we would find in the home. 2) using an air conditioning device as found in places such as at home or in the car 3) refrigeration on an industrial scale Wherever refrigeration occurs, it uses the same principle with the refrigeration cycle

3. Refrigeration Cycle
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6. Industrial Refrigeration System

7. Other systems
There are other systems that utilise the refrigeration cycle to achieve their own use: Air Conditioning – this is where the process can be manipulated to either provide heated or cooled air to a set and controlled temperature Heat Pump – this is used in the reverse fashion of a refrigerator / freezer, where heated air is provided as its primary function Both the above types of temperature generation can be expensive

8. Refrigeration System Components
The main components in the Refrigeration cycle are: Compressor – this is where the refrigerant is compressed to a high pressure before it flows around to the next stage Condenser- this is where the highly compressed refrigerant gas is transformed into a moist gas then liquefied state. Expansion Valve – the part where the condensed liquid passes into the valve (much like forcing it through a smaller orifice) and experiences a great drop in pressure Evaporator – being the final stage once the liquid refrigerant has passed through the expansion valve and experienced it drop in pressure; the refrigerant enters the Evaporator and goes through almost the reverse process of where it now goes from liquid to a gas. The refrigerant now goes around again to recomplete the process.

9. Refrigerant Types
These have to be a fluid that has the ability to become compressed, such fluids are as follows: Ammonia – this is widely used as a refrigerant in industrial systems, due to the facts that it is relatively easy to become liquefied by compressing or cooling and when it returns to its gaseous state it absorbs large amounts of heat from its surroundings. The down side to this refrigerant is it is a fairly corrosive to metals it comes into contact with; such as copper, brass, bronze, galvanised surfaces (zinc) aluminium alloys, mercury, gold and silver. Pure ammonia is highly toxic to humans so if a leak is detected with your refrigerator at home immediate action would need to be taken (thankfully modern refrigerators do not use pure ammonia) Ammonia has the boiling point of -33 degrees C and the freezing point of -78

10. Refrigerant Types
There are a wide range of other refrigerant gases available:
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However Ammonia is used due to its qualities being:
Environmentally compatible
Not damaging the ozone layer
Not contributing to global warming
Its having superior thermodynamic qualities
The ammonia refrigeration process itself consumes less energy
Is easily detectable via its odour if a leak occurs

11. Safety Considerations
Refrigerant gas toxicity (Ammonia)
Pipework temperature (hot / cold)
Electrical system / components
System working pressures

12. Maintenance Checks
Evaporators: check electrical connection tightness, visually check fan motors and blades, clean evaporator coil surface
Compressor: check electrical connection tightness, visually check electrical components, inspect defrost timer motor, check oil level in compressor, check all safety controls, check refrigerant levels, visually check refrigerant supply lines
Condensers: coil cleaned and washed, check fan operation, lubricate any moving parts if needed.