Answer:
The two large divisions of heat exchangers are direct contact between fluids and indirect contact between fluids.
Explanation:
A heat exchanger is one of the most used equipment at the level of thermal installations, both at the building, tertiary and industrial levels. A heat exchanger is a device designed to transfer heat between two fluids. These two fluids (liquids, gases) can be in contact or separated by a solid barrier. Its use is basic in all types of air conditioning or refrigeration, air conditioning, energy transfer or chemical processes. Heat transmission occurs through convection and conduction.
Classifying heat exchange systems can be carried out using many different criteria. When classifying different types of heat exchangers, different criteria can be taken into account. Taking into account the degree of contact between the fluids, they are grouped into two different types:
Direct Contact Heat Exchanger:
In direct contact exchangers, heat transfer occurs through a physical mixture of the fluids involved in the process. An example of this type of exchangers are the cooling towers. In this case, direct contact occurs between a stream of hot water (fluid to be cooled) using dry and colder air.
Indirect Contact Heat Exchanger
:
In a direct type exchanger there is no direct contact between the fluids and they never mix. The fluids are separated by a solid barrier and may also not coincide at the same time.
Indirect contact heat exchangers can be of various types, being the most used, according to their constructive typology:
- Concentric tubes or double tube
.
- Shell and tubes
.
- Of plates
.
- Compact heat exchangers
.
- Regenerators
.
The concentric tube equipments are the simplest that exist since they are composed of two concentric tubes of different diameter so that one of the fluids circulates inside the smaller one and the other does it through the annular space between both tubes.
Shell and tube exchangers are widely used at an industrial level and use a housing with a multitude of tubes inside.
The equipment of plates are formed by a succession of sheets of metal, armed in a frame and separated by joints, which are fixed with a steel shell. The fluid circulates between these sheets.
