ABOUT THE SERVICE
A heat exchanger is a device used to transfer heat between two or more fluids. The fluids can be single-phase or two-phase and may be separated or in direct contact, depending on the type of heat exchanger. Devices containing energy sources such as nuclear fuel rods or fire-resistant heaters are not normally considered heat exchangers, although many of the principles involved in their designs are the same.
To better understand heat exchangers, it is necessary to make a classification. Typically, there are two approaches considered. The first looks at the flow configuration within the heat exchanger, while the second is primarily based on the classification of the type of structure and equipment.
Heat Exchangers Classified by Structure
Heat exchanger types are primarily categorized under two main headings: recuperative and regenerative. A Recuperative Exchanger has separate flow paths for each fluid, with the fluids flowing simultaneously through the heat exchanger along a wall that separates the flow paths. A Regenerative Exchanger, on the other hand, has a single flow path through which hot and cold fluids alternately pass.
Regenerative Heat Exchangers
In a regenerative heat exchanger, the flow path consists of a matrix that is heated when the hot liquid passes through it (this is known as "hot blow"). This heat is then released to the cold liquid as it flows through the matrix ("cold blow"). However, regenerative heat exchangers tend to be more common, as they aim to increase energy efficiency and recover lower-grade heat for specialized applications.
Recuperative Heat Exchangers
There are many types of recuperative heat exchangers that can be grouped into indirect contact, direct contact, and specific categories. The heat exchanger allows the fluids to be exchanged separately using tubes or plates. Direct contact heat exchangers do not separate the fluids.
