Difference Between Evaporator and Boiler

The function of the Evaporator and Boiler is the same, i.e., to turn the liquid into a gaseous form. The evaporator works at the normal temperature, which is generally lower than the Boiler. Both these systems are basically used in the Thermal Power Plant to generate electricity. Besides this, they are also used in the manufacturing industries. Both these systems are part of the heat-exchanger.

Evaporator vs Boiler

The main difference between Evaporator and Boiler is that the evaporator works at a normal temperature. On the other hand, Boiler usually works at a higher temperature to convert the liquid into the gaseous form. The operation of the Evaporator is much slower compared to the Boiler operations.

Evaporator and Boiler

An evaporator by name means that it is a device that is used to turn the liquid state into the gaseous state. It is basically a heat exchanger which is used to transfer one form of heat into another substance. It is the major component of refrigeration systems.

The Boiler is the one in which the liquid is submerged, and it is heated to a high temperature, usually above 100 degrees Celsius, to convert the liquid into the gaseous/steam form. The process of operation is fast because of the heat of the boiler. Usually, the Industrial furnace is used, which can heat the boiler within a few minutes.

Comparison Table Between Evaporator and Boiler

Parameters of Comparison EvaporatorBoiler
Operating Temperature Temperature is usually lowTemperature is generally very high
Working Time The process is slow hereThe process is faster here
Size Can range from small to big They are very big in size as compared to Evaporator
Surface Area It generally covers the upper surface area of liquidIt covers the entire mass of the liquid 
Application Mainly used in Refrigeration systems like AC and FridgeThey are widely used in power plants to generate the electricity

What is Evaporator?

An Evaporator is basically an important component of the refrigeration system. The function of this device is to convert the liquid water into a gaseous form.

Evaporator generally works on a temperature that is lower than the boiling point of Boilers, due to which the process and operation are much slower here.

They generally use the heat source to heat the material inside the evaporator. They are covered into the coils when the electricity passes through it a produces the heat due to which the liquid material gets heat up.

The power or energy-producing by heating the coils is way much lower than that of the external heating source which is used in the Boilers. Thus, it takes time to heat the liquid in order to reach its evaporate state.

When the evaporator works, it usually performs the operation on the surface of the liquid; when the liquid is heated to the gaseous state, it starts to form the gas over the surface, the evaporator starts its work to transfer this heat to the other medium which is connected to it.

Evaporators are generally small, and sometimes they can be big also depending on the operation that is being performed. But mainly, they are small in size and can easily be installed in the location.

What is Boiler?

When it comes to producing electricity in the power plant, the Boiler is one of the main components of the process. The raw materials are heated inside the Boiler to move on to the next process.

The function of the boiler is to convert the liquid into the gaseous form, which is also called Steam. This steam is thus passed to the channel to rotate the turbines connected to a generator which produces the electricity.

The working temperature of the Boiler is usually higher when compared with the Evaporator, as the liquid which is stored in the Boiler needs to be converted into Steam which occurs above 100 degrees Celcius.

Usually, this temperature is achieved with external fuel such as coal, diesel, or industrial furnace, which can produce a temperature above 500 degrees also. The boiler generally performs its operation on the whole liquid in order to make it gaseous.

Boilers are very huge as they store millions of gallons of liquid into them, and the operation is performed on the whole liquid to achieve the gaseous state.

The operation which is performed here is faster and more rapid as compared to the Evaporator. Thus, the process is finished much faster here.

Main Differences Between Evaporator and Boiler

  1. The size of the Evaporators is generally small, while the size of the Boilers is much larger than that of it.
  2. The heat which is supplied to the Evaporator is through the electricity, i.e., through coils, whereas the heat which is supplied to the Boiler is through external sources like coal, diesel, or furnace.
  3. The operating temperatures of the Evaporator are lower than the boiling point of the liquid, while the temperature is higher in the Boiler to heat the liquid.
  4. Operations in Evaporator are very slow when compared with the Boiler, which has fast operations.
  5. Evaporators work by working over the surface of the liquid only, while the Boiler works on the overall liquid surface, which is stored in it.


Both Evaporator and Boiler are part of the heat exchanger system. The function is the same, i.e., to transfer the heat from one source to another which is connected to it.

These devices play a major in various applications ranging from refrigeration to power plants. In the Refrigeration system, the Evaporator transfers cool gases into the system, thus producing chilled air.

The boilers are a major part of the power plants system. Raw materials are heated inside it to generate the steam and thus make the turbines rotate it and form electricity.

The operating temperature of both devices is different. The evaporator usually works at a low temperature while the Boiler adds up the temperature above 100 degrees Celcius.

In both, the process of the water which is in the liquid state is converted into the gaseous state. Both work on different vapor pressure to generate the gaseous state.

When performing the Boiler operation, the vapor bubbles are formed, which is the sign that liquid has reached the gaseous state, but there is no bubble formation in the Evaporator.


  1. https://books.google.com/books?hl=en&lr=&id=qKGLDKgav8UC&oi=fnd&pg=PA13&dq=Evaporator+vs+Boiler&ots=u_MriDbPeJ&sig=Ztj2j7RYVbXMbwpZohf7hXZgdyU
  2. https://www.sciencedirect.com/science/article/pii/S0017931018336093
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