Research And Insight

Evaporative condenser

An evaporative condenser is used to remove excess heat from a cooling system when the heat cannot be utilised for other purposes. The excess heat is removed by evaporating water.

The evaporative condenser has a cabinet with a water-sprayed condenser, and it usually has one or more fans. The excess heat is removed by evaporating water. In an evaporative condenser the primary coolant of the cooling system is cooled, which is the opposite of a cooling tower. Evaporator condensers are more expensive than dry coolers and are primarily used in large cooling systems or systems where the outdoor temperature is high. In many locations around the world, regulations limit the physical size of a cooling system and this in turn limits the use of evaporative condensers.

Spraying a condenser with water exploits the fact that the dew point temperature is lower than the air temperature and that a wet surface transfers heat more efficiently.

In comparison, an evaporator used in a cooling system absorbs heat from the surroundings, for example by cooling the surrounding air. Heat is absorbed using a cooling medium that flows through the evaporator.  The cooling medium can be one of several coolants. When the coolant flows through the evaporator and transfers heat from the surroundings, it changes phase from a liquid to a gas.

For air conditioning applications, either air-cooled or water-cooled evaporators are used.

An air-cooled evaporator is typically fitted with a copper or steel pipe, onto which aluminium fins are fitted. The cooling medium flows through the pipe, transferring heat to the fins, which in turn are cooled by a fan. A water-cooled evaporator often has an elongated tank with a built-in pipe system. The cooling medium flows around the pipes in the tank, while cold water flows inside the pipes, extracting the heat from the cooling medium.

Evaporation is the name of the process that takes place in an evaporator. The cooling media flowing through the evaporator enters the inlet in liquid form. When a cooling media is provided with enough heat in an evaporator, it reaches its boiling point, and begins to change state into gas. This change of state from liquid to gas is known as evaporation.

An expansion valve is placed between the condenser and the evaporator as shown in the diagram below. This valve reduces the pressure to the evaporation pressure point. When the cooling media has passed through the expansion valve, it enters the evaporator, where evaporation will begin when heat is added from the surroundings.

Grundfos supplies pumps and equipment to the cooling and air conditioning applications where evaporation takes place.

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