What is a condenser?
The condenser is a part of the refrigeration system, which rejects the heat energy of the refrigerant gas gained in the evaporator and the compressor.
Atmospheric air and water are the two most convenient heat sinks to which the heat can be rejected.
There are three types of condensers namely
- Air cooled condenser
- Water cooled condenser
- Evaporative condenser.
AIR COOLED CONDENSERS
In an air-cooled condenser, the heat is removed by air using either natural or forced circulation. The condensers are made of steel, copper, or aluminum tubing provided with fins (extended surfaces) to improve air-side heat transfer. The refrigerant flows inside the tubes and the air outside.
(a) Natural circulation air-cooled condenser
In this type, a large condensing surface area is required as the circulated air quantity is less. These types of condensers are used in domestic refrigerators, air-colled, deep freezers, and other small-capacity applications.
(b) Forced circulation air-cooled condensers
In this type, the air is circulated by means of a fan or blower. These types of condensers are compact in design like a radiator, called a radiator type condenser.
These types of condensers can be further classified into:
- Chassis mounted condensers – mounted on the common chassis with compressor, motor and other components.
- Remote condensers – are located away from the compressor.
Advantages & disadvantages of air-cooled condensers
|1.||Simple in construction||Suitable for small capacity units only|
|2.||Low maintenance cost||Uneven distribution of air results in poor condensation|
|3.||No piping work is involved||The heat transfer rate is low|
|4.||Corrosion & fouling effects are negligible||The capacity of the condenser is reduced with an increase in the ambient temperature.|
WATER COOLED CONDENSERS
Water-cooled condensers utilize water to condense the refrigerant in the system. These types of condensers are used especially in larger installations.
Water-cooled condensers can be of three types:
- Shell and tube condensers
- Shell and coil condensers
- Double tube(pipe) condensers
1. Shell and tube condensers
- It consists of a shell in which number of tubes are fitted. The water circulates through the tubes. On the two sides of the shell, condenser heads are provided which can be opened for periodic cleaning of the condenser tubes.
- The condenser can have any number of passes depending on its design.
- The horizontal shell and tube condenser having two passes.
- High temperature and high pressure refrigerant from the compressor enter the condenser from the top and are circulated in the shell.
- Because of the heat transfer between the hot refrigerant and water circulated in the tudes, the refrigerant condenses on the outside of the tudes and taken out of the condenser from the bottom.
2.Shell and coil condensers
- It is a modification of the shell and tube type and is often used on small packaging units.
- In this type, as the water is circulated through a coil, which is embedded in a shell.
- The high pressure and high temperature refrigerant from compressor flow down in the condenser shell come in contact with coil through which the water is circulated. The refrigerant gets condensed and is collected at the bottom of the shell.
- The shell ends are not removable, but water scale can be removed by treatment with the acid solution.
3.Double tube condensers
- It is also called tube- within- tube condenser.
- In the double tube arrangement, the refrigerant condenses in the outer tubes and water flows through the inner tube in the opposite (counter flow) direction.
- These types of condensers are easy to fabricate and can be very conveniently cleaned.
|1.||Better heat transfer rate||High maintenance cost|
|2.||Suitable for large capacity refrigeration||The problem of corrosion and fouling exists|
|3.||Even distribution of water results in better condensation||The problem of disposing of used water|
- Evaporative condenser is essentially a water conservation device, which employs both air and water for condensation of vapour refrigerant.
- In these condensers, the refrigerant first rejects its heat to water and then the water rejects its heat to air, mainly in the form of evaporated water.
- The function of the air is to increase the rate of evaporation by carrying away the water vapour as in cooling tower.
- Thus the evaporative condenser combines the functions of condenser and cooling tower.
- Evaporative condensers can be installed indoors as well as outdoors by using ductwork to discharge the exhaust air outside.
- Evaporative condensers are commonly used in large ammonia plants as they are found to be cheaper.