Surface Condenser Definition, Working Principle, Construction, 4 Types, Applications, Advantages, and Disadvantages [PDF]

In this article, we shall learn about the definition, working principle, construction, types, applications, advantages, and disadvantages of Surface Condensers. We have also provided a PDF for the same.

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What is a Surface Condenser?

A surface condenser is a device used in thermal power plants which converts steam into water without any physical contact between steam and coolant. It is one of the most important devices used in thermal power plants. If they are not used in a thermal power plant, a large amount of water will be needed to run the plant. 

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Construction of a Surface Condenser

A cylindrical type surface condenser consists of a large cylindrical vessel. Water tubes are fitted horizontally inside the cylinder, and there is a continuous flow of water inside the tubes. The direction of the flow of water in the upper half of the tubes is opposite to that of the lower half of the tubes.

There are water inlets and water outlets. There are two water storage tanks located at two horizontal ends of the cylindrical vessel. A baffle is provided for separation. Steam enters the cylinder from the exhaust steam inlet. There is a valve at the bottom of the condenser from where condensate can be extracted. Two perforated tubes are perpendicular to the water-carrying tubes.

Single Pass Surface Condenser
Diagram of a Surface Condenser, Dizz

Principle and Working of Surface Condenser

The Basic working principle of a surface condenser is the transfer of heat from a higher-temperature body to a lower-temperature body. In this, the steam (high-temperature body) liberates its heat to the cooling water tubes (low-temperature body). In the process of heat transfer, the hot steam gets converted to water. 

Working Principle of Surface Condensers
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The steam enters from the exhaust Steam inlet and comes in contact with the water carrying tubes. The water in the tubes has a circulating flow.  As soon as the exhaust steam comes in contact with the water-cooled tubes, the process of heat transfer begins. The heat from the steam is removed and converted into a liquid which Is known as condensate. This condensate is then removed from the cylindrical vessel through a valve located at the bottom of the cylinder.

Types of Surface Condenser

There are 4 basic types of surface condensers, which are as follows

  • Downflow surface condenser
  • Central flow surface condenser
  • Evaporative surface condenser
  • Regenerative surface condenser

Down-Flow Surface Condenser

In a downflow condenser, the hot steam enters from the top of the condenser. The flow of steam in the ‘downflow surface condenser’ is in the y (-ve) direction which is in a downward direction concerning the whole system. The flow of steam is downwards because of gravity and the vacuum created by the air pump.

The water tubes are present in between, where the flow of water is perpendicular to the direction of the flow of steam, that is in z(-ve) and z(+ve) directions simultaneously. A baffle is present in the condenser, which does not allow the steam to reach the air filters.

Down Flow Surface condenser
Diagram of Down-flow surface condenser, Dizz

As soon as the exhaust steam comes in contact with the water-cooled tubes, the process of heat transfer takes place as a result of which steam loses its heat to the cooling water tubes and condensate gets deposited at the bottom. This condensate is then extracted through a valve.

Central Flow Surface Condenser

A central flow condenser is an advanced and improved version of a downflow condenser. The only difference is that in the central flow condenser, the air pump is situated at the center of the system, unlike the downflow condenser. The exhaust steam enters from the top due to gravity.

Surface condenser Central Flow type
Diagram of Central-flow surface condenser, Dizz

The direction of the exhaust steam is changed and forced towards the center of the system with the help of an air pump. This is the reason why this system is named a central flow condenser. The direction of the flow of steam and cooling water is perpendicular to the surface of the tube. Heat transfer between water and steam takes place when steam and cooling tubes come in contact with each other, hence there is a formation of condensate.

Evaporative Surface Condenser

This type of condenser is known as an Evaporative condenser because the cooling water gets evaporated in such types of condensers. In Evaporative condensers, the hot steam flows inside the tubes, and cooling water is sprayed on them. The cooling water from the cooling tank reaches the header with the help of a pump.

The header sprays water over the tubes carrying hot steam. As soon as the water comes in contact with the hot tubes it evaporates and steam inside the tubes gets converted to liquid. Fins are attached to the tubes to increase the surface area and decrease the time for cooling.

Evaporative Surface condenser
Diagram of Evaporative condenser, Learn Mechanical

Regenerative Surface Condenser

A regenerative surface condenser is a type of condenser that is particularly suited for use in high-temperature plants. This is because it employs a unique method of condensate cooling that allows for the efficient reuse of hot condensate. In a regenerative condenser, the condensate is known as regenerative condensate. This condensate is produced by passing steam through the tubes of the condenser.

As the steam condenses, the resulting condensate is heated by the exhaust steam that is released from the plant’s processes. This hot condensate is then passed through a heat exchanger, which allows it to transfer its heat to the incoming steam. By doing this, the temperature of the incoming steam is increased, which helps to improve the efficiency of the condenser. Additionally, the hot condensate can be reused in other parts of the plant, further improving the overall efficiency of the system.

Applications of Surface Condensers

Thermal power stations

  • In thermal power stations, water is heated more than its boiling point to generate steam which in turn is used to rotate the turbine. After passing through the turbine the steam is fed into a surface condenser where it is converted into water and then reused. 

Caustic recovery plants

  • In a caustic recovery plant, weak soda lye is converted to strong caustic soda by treating it. This treatment involves the emission of heat in the form of steam. Here they are used to convert the steam into condensate (weak lye) which is to be reused. 

Treatment of contaminants

  • Contaminated water is a general problem for any industry these days. This alone cannot fulfill the requirement hence Ejectors using surface condensers are used for treatment.
Surface Condenser
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Advantages of Surface Condenser

Quality of cooling water

  • Any quality of cooling water can be used in surface condensers because there is no direct contact between cooling water and exhaust steam. 

Suitable for high capacity plants

  • Due to their large size and better efficiency than jet condensers, surface ones can be used for heavy industrial purposes. 

Pure condensation

  • Pure condensation is possible in the case of these condensers as there is no mixing of exhaust steam and cooling water, so the quality of condensate obtained is pure. This condensate can also be used as boiler feedwater. 

High vacuum

  • The vacuum created by the air pump is high in the case of surface condensers. This helps in removing uncondensed air and lowers the pressure inside the condenser. This low pressure in turn increases the thermal efficiency of surface condensers.

Air pump power

  • The power required to drive the air pump in a surface condenser is much less than the power required to drive a pump in a jet condenser. 

Disadvantages of Surface Condenser

Complex design

  • The design of a this condenser is quite complex. Several mechanical parts are working at the same time. It is difficult to understand the complex design of a surface condenser. 


  • Handling these condenser is not easy; it requires skilled labor. Due to the complex engineering involved, the handling should be done with care to avoid any human injuries. 

Large size of the condenser

  • It is used for heavy industrial purposes hence the size of condensers is quite large. Therefore the whole setup of surface condenses requires a large area.

Cost of surface condenser

  • Due to its large size, the cost of surface condensers are high. It requires more power hence the cost of running also becomes more.

Quantity of water required

  • As the size of equipment is large and it is used for heavy industrial purposes. The amount of water required to efficiently run a condenser is also high.
Surface Condenser
Photo By Exporters India


In conclusion, surface condensers are important components used in various industries to convert steam into water. They work by transferring heat from the fluid to a cooling medium, such as water or air, and come in different types, including shell-and-tube and plate condensers.

They offer benefits such as efficiency and environmental sustainability, but also have drawbacks such as high costs and maintenance requirements. Overall, surface condensers are essential for improving energy efficiency and sustainability in industrial processes.

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