Heat exchangers are devices used for maintaining specific temperature in the applications. There are many processes which needs to run at a specific temperature and heat exchangers are used for this purpose. Heat exchangers are manufactured using materials that are good conductors of heat. Materials like aluminum, copper and stainless steel are considered ideal for manufacturing these devices. In these devices heat transfer takes place between two mediums – air to gas or gas to liquid or liquid to air. These devices can be classified into liquid to liquid, liquid to gas and gas to liquid types.
Water as a heat transfer medium
Use of water is common as a heat transfer medium. Water is available in abundant quantity, it is cost effective solution and it is good conductor of the heat, so it is used widely in the heat exchangers. There are different types of heat exchangers that uses water as a heat transfer medium and these include water to water, water to air and air to water types. In the water to water type, heat transfer takes place between two water streams with different temperature. In the water to air type heat transfer takes place between hot water and cold air and in the air to water type heat transfer takes place between hot air and cold water.
Air to water types of heat exchanger
Air to water types of heat exchangers are considered efficient than air to air type of heat exchanger, because air is not considered as efficient heat transfer medium as water. Air to water heat exchangers work on simple principle of temperature difference between air and water. In this type of heat exchangers hot air is transferring heat into the cold water moving inside coils, As a result the temperature of the air surrounding the coil comes down and the temperature of the water inside the coil increases. The water with the increased temperature moves out of the application and cooled again in the closed circuit with the help of condensers and again this cold water moves inside the coils in the application.
Examples of air to water type of heat exchangers include furnace, fireplace, shell and tube, and plate types of heat exchangers.
Advantages of Air to Water type of Heat Exchangers
Compared to air to air type, air to water type of devices substantially reduce cost of energy. Use of this type of devices is common where fresh water resources are available. Applications that generate large amount of heat use this type of devices, which include mainframe computing systems and auto manufacturing facilities.
Disadvantages of Air to water heat exchangers
Though air to water type of devices are efficient than air to air type, there are also disadvantages of this type of devices. Air to air type of heat exchangers can be easily fixed inside the applications, whereas air to water type of devices needs to be attached with the source of water or there should be water circulation system. The water circulation system should provide continuous flow of cold water into the application which absorbs heat from the application and hot water coming out of the applications needs to be cooled down and circulated back into the application. This type of setup involves additional costs and there are also maintenance related issues associated with it.