Heat exchanger types
We are in the process of finding out about heat exchangers. We know that they are devices designed to transfer heat between two or more fluids—i.e., liquids, vapors, or gases—of different temperatures. Depending on the type of heat exchanger employed, the heat transferring process can be gas-to-gas, liquid-to-gas, or liquid-to-liquid and occur through a solid separator, which prevents mixing of the fluids, or direct fluid contact. Other design characteristics, including construction materials and components, heat transfer mechanisms, and flow configurations, also help to classify and categorize the types of heat exchangers available.
Let’s start by talking about two heat exchanger parts:
1. Tube Plate Heat Exchanger –
This heat exchanger is composed of tube sheets that separate steel tubes where heat flows into or out of the tubes as hot or cold fluids pass over them. The most common type of heat exchanger used today in both small and large sizes is this type. They are often seen in the form of heat exchangers that are an integral part of heat pumps, car radiators, gas heaters, air conditioners, and heat exchanger units.
2. Plate Heat Exchanger –
A heat exchanger with plates as the heat transfer device is known as a plate heat exchanger. They consist of stainless steel or aluminum plates with corrugated grooves on one side where heat travels to or from fluids with internal tubes for fluid flow between each pair of adjacent plates. These are often used in small-scale applications such as refrigeration systems.
Let’s now look at the various types of heat exchangers—gas-to-gas, liquid-to-gas, liquid-to-liquid—and how they work:
3. Gas-to-Gas heat exchangers –
heat exchangers that transfer heat between two gases are known as gas heat exchangers. These heat exchangers can be vertical or horizontal and can be cylindrical or triangular in shape.
4. Liquid-to-Gas heat exchangers –
this type of heat exchanger transfers heat from a liquid to a gas by allowing the liquid to flow through tubes and the gases on either side of them, separated by a solid wall surface such as metal plates or tube sheets.
5. Liquid-to-Liquid heat exchangers –
this is one of the most important among all the types of heat exchangers because it is very commonly found everywhere around us—in air conditioners, cooling heat exchangers, heat pumps, and heaters.
6. Plate and Shell heat exchanger –
this uses a large number of metal plates placed closely together with some free space left between them to allow the fluid to flow through them. The heat is transferred through the plates which are either welded or bolted together. In the case of plate heat exchangers, the two fluids—hot and cold—flow on either side of each plate resulting in heat transfer from one side to another whereas in shell and tube heat exchangers, both fluids flow around a common enclosed volume called a shell.
In addition, there are several other types of heat exchangers based on how they work:
7. Coil heat exchanger –
a coil heat exchanger is a type of heat exchanger that uses heat transfer fluid flowing through a closed-loop tubing system contained inside or outside heat exchangers.
8. Coil and shell heat exchanger –
this heat exchanger is made up of a coil heat exchanger enclosed in a larger heat-conducting metal shell/housing, which further contains the cooling (cold) medium such as water or oil along with any additional heat-dissipating hardware like fans to further cool the exterior housing walls.
9. Air-to-air heat exchangers –
these are used mainly for ventilation at homes, commercial buildings, and industrial plants.
10. Plate fin heat exchanger –
this heat exchanger uses two sets of metal plates with corrugated fins between them to increase the heat transfer surface. This heat exchanger is commonly found in car radiator systems where the coolant enters at one end and heat is transferred through successive plates towards the other end while heat dissipates out of the system through heat sinks (fin type heat exchangers) attached to one side of each plate.
Other types – there are several other types of heat exchangers including spherical-tube heat exchangers (STHX), plate-fin/tube bundle heat exchangers, interleaved fin-and-tube arrangements, etc., depending on how they work and their application fields. In addition, there is also a type called an induced draft heat exchanger, which is used for explosively hazardous environments.
by heat transfer fluids/fluids with heat transfer fluid inside them through corrugated tubes attached to plates instead of solid metal plates or internal tubing—used mainly for heating purposes in solar heaters and geysers where heated water flows up through the corrugated tubes whereas colder surrounding air enters from the other side at lower levels resulting ineffective heat transfer processes.
11. Stacked plate heat exchangers –
heat exchangers are made by stacking smaller heat exchangers together with each heat exchanger containing a different heat-transfer fluid on either side of the common separating wall to increase surface area for better heat transfer—which can be further increased by using fins between or around heat exchanger plates.
12. Tubular heat exchangers –
heat exchangers are made by passing heat-transfer fluids through tubes that serve as heat transfer surfaces inside a heat exchanger housing—with cool fluid usually entering from the bottom and hot fluid leaving at the top for efficient heat transfer processes.
13. Other types –
other heat exchangers include shell–and–tube heat exchangers, finned-tube bundles,
spiral-fin heat exchangers etc., with each having their own applications in various industries depending on how they function and work with different types of fluids to perform various uses/functions effectively.
Keeping this basic information about heat exchanges in mind will help you understand more about them in depth further when we go into heat exchanger types and their applications in various industries.