Refrigeration & Equipment Engineering

Unit 3 - Parts of refrigeration systems

3.3.3.1. Air-cooled condensers
An air cooled condenser is one in which the removal of heat is done by air. It consists of steel or copper tubing through which the refrigerant flows. The size of tube usually ranges from 6 mm to 18 mm outside diameter depending upon the size of the condenser. Generally copper tubs are used because of its excellent heat transfer ability. The condenser with steel tubes is used in ammonia refrigerating systems.The main disadvantage of an air cooled condenser is that it operates at a higher condensing temperature than a water cooled condenser. The higher condensing temperature causes the compressor to work more

Types of air cooled condenser

• Natural convection air-cooled condenser

In natural convection air-cooled condenser the heat transfer from the condenser coils to the air is by natural convection. As the air comes in contact with the warm condenser tubes, it absorbs heat from the refrigerant and thus the temperature of air increases. The warm air being lighter, rises up and the cold air from below rises to take away the heat from the condenser since the rate of heat transfer in natural convection condenser is slower therefore they require a large surface area as compared to forced convection condensers. The natural convection air cooled condenser are used in small capacity applications such as domestic refrigerators, freezers, water cooler and air-conditioners.

• Forced convection air cooled condenser:

In forced convection air cooled condenser, the fan is used to force the air over the condenser coils to increase the heat transfer capacity.