Heat Exchangers play an important role in managing thermal energy within an application and allow processes to run at a specific temperature. The heat transfer process can be between two mediums which can be liquid to liquid or liquid to gas or gas to liquid form. Materials that have good thermal conductivity are selected for manufacturing heat exchangers. Copper, Aluminum, and stainless steel are used widely to manufacture these devices.

The design of a heat exchanger depends upon factors like the amount of heat to be transferred, budget, and application type. Depending on the design, these devices can be classified into different types, which include plate, plate fin, tube, tube fin, double pipe, and shell and tube types. Depending on the medium these devices can be classified into different types like liquid to liquid, liquid to gas, and gas to liquid. Heat exchangers which use the liquid as a medium for transferring heat are called liquid heat exchangers. Liquid to liquid and liquid to air types of devices belongs to this category.

Liquid as a heat transfer medium

Many factors are considered while deciding which liquid is ideal as a heat transfer medium for the heat exchanger. The liquid should be compatible with the components used for manufacturing heat exchangers. Properties like high thermal conductivity, low viscosity, low corrosivity, and low freezing temperature are considered ideal properties for a heat transfer liquid.

Water and synthetic oils are ideal materials as heat transfer medium in the liquid heat exchangers. Fresh water is used widely as a heat transfer medium because of the cost factor and it is available in ample quantity. Water also has the property of good thermal conductivity. Fresh water has some disadvantages also because it contains ions that can easily conduct electricity. So, to prevent the incidents of the short circuits, heat exchangers used in the electronics devices don’t use fresh water as a heat transfer medium. Deionized water is considered an ideal solution for devices used in electronics equipment because it contains less ions compared to fresh water and it reduces the chances of the electrical short circuits.

Corrosion is another factor that should be considered while selecting heat transfer liquid for the heat exchangers. Usually, components like plates, fins, or tubes are manufactured using materials like copper and aluminum because these materials have good thermal conductivity. If heat transfer liquid has corrosive properties, the use of stainless steel is ideal for manufacturing plates of tubes used in the devices. This is because stainless steel offers good corrosion resistant properties against corrosive liquids. Calcium and Magnesium in the water can form the scale on the surface of the plates or tubes and the thermal conductivity of these components can go down.

In the cold countries during the winter temperature goes below freezing points. In this type of situation Ethelyne Glycol and Water (EGW) is considered ideal material as a heat transfer medium because of its low freezing point. EGW offers good thermal conductivity and has a low viscosity. Propylene Glycol and Water (PGW) is used as a heat transfer medium in heat exchangers used in the food industries because it addresses the issue of toxicity.