Heat exchangers are devices used for transferring heat. In the heat exchangers, heat transfer takes place between two mediums that can be liquid to liquid or liquid to gas, or gas to gas. The design of a heat exchanger depends upon several aspects like the required heat transfer rate, cost, and available size to fix it in the application.
Water as a heat transfer medium
Liquid to liquid or liquid to gas heat exchangers uses various liquids as a heat transfer medium and these include synthetic oil and water because both are good conductors of heat. Since water is a good conductor of heat, it is available in abundant quantity, and it is cheap, it is considered an ideal option as a heat transfer medium. There are several designs of the heat exchangers including tube fin, plate fin, and plate types that use water as a heat transfer medium.
Water to air heat exchangers
In the water, to air heat exchangers heat transfer takes place between hot water and cold air. In the tube fin heat exchangers, tubes and fins are manufactured using material that is a good conductor of heat. Hot water flows inside the tube which is a good conductor of heat so the tube and fins get hot and release the heat into the ambient. As a result, the hot water flowing inside the tube cools down. In the plate fin heat exchangers, plates and fins are manufactured using materials that are good conductors of the heat. When hot water flows inside the passage created by two subsequent plates. As a result, the plates get heat from the hot water which they release into the ambient. The plates are attached to the fins and when plates get heat from the hot water, the fins also get heat which they release into the ambient. As a result, the water flowing inside the passage created by the two fins gets cool.
Water to water heat exchangers
Water to water heat exchangers transfer heat from the hot water to the cold water. In cold countries use of wood boilers are common for heating fresh water for domestic purposes. Wood boilers are surrounded by pipes that are filled with glycol mixed liquids that have a low freezing temperature. The tank with the fresh water is connected with the brazed fin heat exchanger. The hot glycol mixed liquid coming from the boiler enters the heat exchanger from one end and on the other end cold fresh water coming out of the tank enters the heat exchanger. The heat from the glycol mixed liquid gets transferred to the cold fresh water in the heat exchanger without the two liquids coming in contact with each other.
Disadvantages of using water in the heat exchanger
Though there are distinct advantages of using fresh water in the heat exchanger, there are also disadvantages of using fresh water in the heat exchanger. Fresh water contains several minerals which are good conductors of electricity. So, using fresh water in the heat exchangers that are used for cooling electronics devices can be risky because it can cause short circuits and destroy costly equipment.