What is Condenser | function of the condenser | types of condenser


In a vapor compression system (vapor compression) A condenser is a component that functions to change the refrigerant phase of a high-pressure gas into a high-pressure liquid or in other words the condenser process occurs condensation. The refrigerant which has been turned into liquid is then flowed to the Evaporator through the Expansion Valve.

(Type of compressor)

Function of the Condenser

In order for this desired process of transformation to occur, the heat / heat in the high-pressure refrigerant gas must be discharged out of the system. The heat comes from 2 sources, namely:

1. The heat absorbed by the refrigerant during the evaporation process

2. The heat generated in the compressor during the compression process

Low pressure refrigerant gas is compressed so that it becomes a high pressure refrigerant gas where the condensation temperature is higher than the temperature of the condensation Condenser cooling media. Cooling media that is commonly used is usually water, air, or a combination of both.

With a higher condensation temperature from the cooling media, it will be easy to process the transfer of heat from the refrigerant to the cooling media. As we know in general "heat will flow from a substance with a higher temperature to a substance with a lower temperature".
The process of heat transfer in a condenser occurs in 3 stages, namely:

1. Decreasing the value of superheat until it reaches the condensation temperature. In this process the sensible heat transfer occurs.

2. Changes in the form of refrigerant in the form of gas into liquid. In this process a latent heat transfer occurs.

3. Release of heat from liquid refrigerant (sub-cooling) to the cooling medium. In this process the sensible heat transfer occurs.

Condenser Capacity

Capacity is the ability of the Condenser to release heat from the refrigerant to the cooling media.
There are 4 things that affect the capacity of the condenser, namely:

1. Material (material for making condensers)

Each material has a different ability to move heat. The most commonly used materials for making Condensers are copper, aluminum and iron. Copper is the most popular material used because it is very good for delivering heat and is easily formed into a pipe or coil, and also its properties are more resistant to corrosion.
The actual size of the condenser can be reduced by choosing a material that has the ability to deliver better heat and also the design of the condenser itself. Nevertheless the condenser must also be able to accommodate the volume and condense all the refrigerant that comes out of the compressor. Condenser whose volume is too small causes the condenser capacity to decrease and will increase the condensation pressure.

Note: Specifically for refrigeration systems that use Ammonia (R717) ( NH3)refrigerant, copper should not be used as a system material because of the nature of Ammonia which tends to damage / react with copper. When copper is used in the Ammonia system, the inside of the copper is usually coated with bronze to avoid corrosion.

2. Area

The greater the area that is in contact with the cooling media, the greater the heat transfer.
For air-cooled condensers, it is usually equipped with fins so that the area is larger, while for water-cooled condensers to increase the capacity, an increase in the rate of water flow into the condenser is increased.
Note: For water-cooled condensers, adjusting the flow rate of water must be observed not to exceed the allowable limit because with excessive flow rates the friction factor will be even greater.

3. Temperature Difference

What is meant here is the difference between the temperature of the condensation and the temperature of the cooling medium. The temperature of the condensation must be greater than the temperature of the cooling medium.

4. Cleanliness of the Condenser

Dust particles attached to the air-cooled condenser or mold / crust attached to the water-cooled condenser act as an insulator which will reduce the heat transfer capacity. This will also inhibit the flow rate of air / cooling water.

Types of Condenser Based on Cooling Media

Based on the cooling media Condenser is divided into 3 parts,

1. Air Cooled Condenser
2. Water Cooled Condenser
3. Evaporative Condenser

Air Cooled Condenser 

This type of condenser is made of 6mm ~ 18mm (1 / 4inch ~ 3 / 4inch) outer diameter coil.
To expand the heat transfer area, the coil is equipped with fins.
single row coil is the most efficient, but to save or reduce the size of the coil is usually made into several rows multi row coil.
Air-cooled condenser is classified into 2 parts, namely:

1. Condenser with natural air conditioner (Natural Draft Condenser)

2. Condenser with forced air cooler (Forced Air Cooled Condenser)

Condenser with natural air conditioner (Natural Draft Condenser)

Transfer of heat from the condenser to the air takes place naturally convection air flow.

Because of the low heat transfer rate, a large area is needed.

This type of condenser is only used for small capacity refrigeration systems, such as refrigerators and freezers for household applications used domestic refrigerators and small freezers

Forced Air Cooled Condenser
The transfer of heat from the condenser to the air takes place with the help of an air fan.
Its higher heat transfer rate compared to natural air-cooled condensers makes this type of Condenser smaller.

Advantages and disadvantages of air-cooled condensers

Advantages: The availability of sufficient air as a cooling medium without requiring additional costs.
Disadvantages: The refrigeration system operates at a higher working pressure when compared to water-cooled condensers, consequently the compressor will require power greater as compensation for the increase in working pressure and temperature.

Water-cooled condenser

In medium and large capacity refrigeration systems usually use water as a condenser cooling medium. This is because water has the ability to move heat better than air, so that by using water as a cooler the size of a condenser with the same capacity can be smaller compared to air-cooled ones.
The water-cooled condenser is classified into 2 parts according to how it works, namely:

1. Waste Water System

Cold water enters the condenser and then exits and is immediately discharged.
This method is allowed for systems with small capacity or if there are many sources of water. What must be considered is the provisions of the applicable laws in which this system works.

2. Circulating water

system In this system the water that comes out of the Condenser is cooled back in the Cooling Tower and then circulated back to the Condenser.

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