Heat exchangers are devices that allow heat to be transferred between two or more fluids of different temperatures (vapors, liquids, or gases). The heat transfer process can be liquid-to-gas, gas-to-gas, or liquid-to-liquid, and it can happen through a solid separator or direct fluid contact, depending on the type of heat exchanger used. Other design features, such as construction materials and components, heat transfer processes, and flow configurations, aid in classifying and categorizing the various types of heat exchangers accessible. Heat exchanger makers offer a wide range of heat-exchanging devices designed and manufactured for use in both cooling and heating processes and find applications across a wide range of industries.
This blog examines the numerous types and designs of heat exchangers, as well as their functions and mechanics. This blog also discusses the factors to consider when choosing a heat exchanger and the most popular applications for each one.
How Does Heat Exchanger Work?
As previously stated, heat exchangers come in a variety of shapes and sizes, and their sole purpose is to transfer and transmit heat in a variety of processes and scenarios, such as space heating, refrigeration, cooling, power plants, chemical plants, and other applications. But how do these machines function?
Heat is transferred from one place to another via heat exchangers. The heat exchanger receives and transports the combustion produced by the natural gas or propane fuel being burned in the furnace. The metal is heated by the hot flue gas as it makes its way to the furnace’s exhaust outlet. The air moving over the heat exchanger’s exterior is heated by the hot metal. It’s important to note that this is only one type of heat transfer that occurs in many types of heat exchangers, but it’s the entire point in practically all heat transfer devices.
Types of Heat Exchangers
There are various different types of heat exchangers available depending on the design characteristics. The following are some of the commonly used versions in the industry:
- Shell and tube heat exchangers
- Double pipe heat exchangers
- Plate heat exchangers
- Evaporators, boilers, and condensers
Shell and Tube Heat Exchangers
Shell and tube heat exchangers are made out of a single tube or a series of parallel tubes encased within a sealed, cylindrical pressure vessel (i.e., shell) and are the most popular type of heat exchangers. One fluid goes through the smaller tube(s), while the other flows around and between them inside the sealed shell. Finned tubes, single- or two-phase heat transfer, countercurrent, crossflow, or cocurrent arrangements, and single, two, or multiple pass configurations are some of the other design features available for this type of heat exchanger.
Double Pipe Heat Exchangers
Double pipe heat exchangers, a type of shell and tube heat exchanger use the simplest heat exchanger design and construction, consisting of two or more concentric, cylindrical pipes or tubes (one larger and one or more smaller tubes). One fluid runs through the smaller tube(s), while the other fluid circulates around it (s) within the bigger tube, according to the shell and tube heat exchanger design.
As the fluids remain separated and flow through their own channels throughout the heat transfer process, the design requirements of double pipe heat exchangers contain characteristics from the recuperative and indirect contact types stated earlier. Double pipe heat exchangers, on the other hand, can be constructed with concurrent or countercurrent flow arrangements and employed modularly in series, parallel, or series-parallel configurations within a system, giving them some flexibility in design.
Plate Heat Exchangers
Plate heat exchangers, also known as plate-type heat exchangers, are made up of corrugated multiple thin plates packed together. Each pair of plates forms a channel for one fluid to flow through, and the pairs are stacked and attached—via brazing, bolting, or welding—to create a second route for the other fluid to flow through.
Plate fin or pillow plate heat exchangers are examples of modifications to the conventional plate design. Fins or spacers between plates in plate-fin exchangers allow for different flow configurations and more than two fluid streams to pass through the device. Pillow plate exchangers provide pressure to the plates to improve heat transfer over the plate’s surface. Plate and frame, spiral plate, and plate and shell heat exchangers are among the various options.
Evaporators, Boilers, and Condensers
A two-phase heat transfer mechanism is used in boilers, condensers, and evaporators. As previously stated, one or more fluids in two-phase heat exchangers change phase throughout the heat transfer process, either from liquid to gas or from gas to liquid.
Condensers are heat-exchanging devices that cool a heated gas or vapor to the point of condensation, converting it to a liquid. The heat transmission process in evaporators and boilers, on the other hand, converts liquids to gases or vapors.
Other Variants
Heat exchangers are used in a wide range of industries in a variety of applications. As a result, heat exchangers are available in a variety of configurations, each tailored to the needs and specifications of a specific application. Fan-cooled heat exchangers, air-cooled heat exchangers, and adiabatic wheel heat exchangers are some of the various types available, in addition to the ones listed above.
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