Heat Exchanger

Heat exchangers are one of the important devices that are generally present in various industrial locations. This device has a dual function as a heating and cooling system. However, in many industrial sectors, especially in factories, heat exchangers are more often used as cooling systems. So, how does the heat exchanger work? To find out the answer, you can see the complete description below.

What is a Heat Exchanger?

In simple terms, a heat exchanger is a device designed to transfer heat from one fluid to another fluid. The fluid can be a liquid or a gas, depending on the application and intended use. The heat exchanger functions to optimize heat utilization, so that efficiency and performance increase significantly.

Heat exchangers can be found in various shapes and sizes, ranging from simple to complex, depending on the needs and scale of use. However, the working principle remains the same, namely exchanging heat between two different fluids.

The importance of heat exchangers in industry cannot be ignored. Its ability to transfer heat efficiently makes this tool play a role in maximizing the performance of heating and cooling systems. This not only improves energy efficiency, but also helps maintain the continuity of production on a large scale. Therefore, understanding how heat exchangers work and application is very important.

Heat Exchanger Function

Heat exchangers have a very wide range of industrial applications. This tool can be used as a cooling system (recuperator) or heater (regenerator). This is because many industrial processes require a certain level of heat to work properly.

In industrial plants, this system helps keep machines, chemicals, water, gas and other substances at safe temperatures.

Apart from that, this tool can also be used to capture and transfer steam or waste heat released as a by-product of a process or operation, so that the steam or heat can be better utilized elsewhere to increase efficiency and save factory operational costs.

In industrial processes, heat exchangers can be used in almost all sectors, including industry, food, beverage, medicine, metallurgy, gas and oil, and many more.

Basically, this tool can help optimize the heating and cooling process in an efficient way, thereby saving resources and energy significantly.

• Condenser

Functions to change gas fluid into liquid.
The cooling fluid can be air/gas or liquid/water

• Evaporator

Functions to change liquid fluid into gas
The heating fluid can be air/gas or liquid/water

• Heat Exchangers

Lowering or increasing fluid temperature without phase change.
The heater or cooler is air/gas or liquid/water

• Heaters

Increase the temperature of liquid fluid or gas / air.
The heater can be liquid; Steam or Thermal Oil

Types of Heat Exchangers

Heat exchangers are very important devices in industry, and there are various types of heat exchangers used for various purposes. Each type of heat exchanger has its own characteristics and advantages, so choosing the right one is important so that it can be adapted to its use. If so, take a look at the various types of heat exchangers below.

1. Shell & Tube Heat Exchangers

Shell & tube heat exchangers are the most commonly used type. This heat exchanger consists of small tubes in a shell. One fluid flows in the tubes while the other fluid flows around the tubes. Typically, hot fluid fills the large tube and small fluid fills the small tube.
Jenis Heat Exchanger

Shell and Tube Heat Exchanger

Shell and Tube Heat Exchanger Design

Shell and tube heat exchangers are engineered using sophisticated and technical computer design parameters. The components of the device include the shell, shell cover, tubes, channel, channel cover, tube sheet, baffles, and nozzles. The specifications and standards for STHEs have been established by the Tubular Exchanger Manufacturers Association (TEMA).

Prior to producing a shell and tube heat exchanger, there are several pieces of data manufacturers require such as flow rates, inlet and outlet temperatures, pressure, pressure drop, resistance factors, physical properties of substances to be processed, line sizes, and the shell diameter. Added to these basic factors are more technical requirements that are used to determine the best process to produce the correct heat exchanger for the application.

2. Double Pipe Heat Exchanger / Hairpin Heat Exchanger

Double pipe heat exchanger is a simple type of heat exchanger that uses two pipes arranged in parallel. One pipe functions as a pathway for hot fluid, while the other pipe is for cold fluid. Double pipe heat exchangers are often used in systems that require low heat exchange.

Hairpin exchangers are jacketed ‘U’ tube exchangers operating in a true countercurrent flow, allowing also temperature cross (hot fluid outlet temperature is below cold fluid outlet temperature) with a very efficient design.
Another important feature of hairpin exchangers is the closure type, which allows the removal of the tube bundle and accommodate thermal expansion without requiring expansion or packed joints.

Hairpin Heat Exchanger or Double Pipe Heat Exchanger

3. Air Cooled Heat Exchanger

Air cooled heat exchangers, as the name suggests, use air as a medium to cool hot fluid. The form includes the use of a fan which has the main function of cooling the fluid flowing in the pipe. Make sure you care for and maintain the fan well so that its performance is always in optimal condition.

3.1. Fin Fan Cooler

Fin Fan Cooler, often referred to as Air Cooled Heat Exchanger (ACHE), consists of a series of Fin Tubes arranged in parallel.
Air taken from the surrounding environment is channeled through the fins of the fin tube.

Fin Fan Cooler

The cooled fluid flows through the inside of the pipe, while the fins expand the heat transfer surface area to increase the efficiency of the heat exchange equipment.

Fin fan coolers are generally used to cool liquid or gas fluids where the availability of water as a coolant is not available or is not good.

3.2. Fin Tube Coil / Fin Tube Heat exchanger

Fin Tube is classified to the Extended Surface Tube group for Heat Exchangers.
Fin Tube is generally in the form of a tube with fins on the outside which function as an extension of the surface of the outside of the tube.

As part of the heat exchange equipment, the fin tube functions to transfer heat from one side to the other, from the inside tube to the outside tube or vice versa.

Fin Tube Coil

The outer part of the tube or Fin is used for fluids that have a lower heat transfer coefficient than the fluid inside the tube. Such as air, flue gas or other gases. The inside of the tube can be liquid, pressurized gas or saturated steam or other gas. Fin and Tube materials are depend on the fluid used, the temperature and pressure of the fluid

Finned tube heat exchangers is a kind of heat exchange equipment most widely used in gas and liquid. To achieve the purpose of strengthening heat transfer, the fins with horizontal and vertical are added in the surface of base tube. Although there are many forms of physical structure, the basic structure is made up of parallel plate and assembled plate bundle consist of various forms of fins.

3.3. Plate-Fin Coil / Plate Fin Heat Exchanger

Is a type of heat exchanger design that uses plates and finned chambers to transfer heat between fluids, most commonly gases. It is often categorized as a compact heat exchanger to emphasize its relatively high heat transfer surface area to volume ratio.

Aluminum alloy plate-fin heat exchangers, often referred to as Brazed Aluminum Heat Exchangers, have been used in the HVAC for more than 60 years and adopted into the cryogenic air separation industry around the time of the second world war and shortly afterward into cryogenic processes in chemical plants such as Natural Gas Processing. They are also used in railway engines and motor cars. Stainless steel plate fins have been used in aircraft for 30 years and are now becoming established in chemical plants.

Plate Fin Coil

3.4. Plate Heat Exchanger

Plate heat exchangers use metal plates as surfaces for heat exchange. These plates will form many small channels for fluid flow, and maximize heat exchange efficiency. This heat exchanger is efficient and often used in the food, beverage and HVAC (heating, ventilation and air conditioning) industries.

Gasket plate heat Exchanger

Brazed plate Heat Exchanger

3.5. Spiral Heat Exchanger

Spiral heat exchangers have a unique design in the form of spirals that are wound repeatedly. This type of heat exchanger has two channels, one for hot fluid and one for cold fluid. Its unique shape makes this heat exchanger often used in the chemical industry. Spiral heat exchangers are usually used for heating or cooling processes with large temperature differences.

Spiral Heat Exchanger

How Heat Exchangers Work

The way a heat exchanger works is based on the principle of heat transfer between two different fluids. The heat exchange occurs through the separation wall between the two fluids. Heat exchangers can work in three ways, more details will be explained below.

1. Transfer Process

The heat transfer process can occur through conduction, convection, or radiation. In a heat exchanger, heat transfer usually occurs through conduction and convection. Conduction is the process of direct heat transfer between two adjacent objects, while convection involves heat transfer through fluid flow.

2. Based on the amount of working fluid

Heat exchangers can work using two or more fluids. In a heat exchanger with two fluids, heat is transferred from one fluid to the other. Meanwhile, in heat exchangers with more than two fluids, heat can be transferred from one fluid to several other fluids.

3. Based on Fluid Flow

Fluid flow in a heat exchanger can be concurrent, countercurrent, or cross-flow. In concurrent flow, the two fluids flow in the same direction as each other, whereas in countercurrent flow, the fluids move in opposite directions. Cross-flow occurs when both fluids flow perpendicular to each other.

Working Principle of Shell and Tube Heat Exchangers

A shell and tube heat exchanger is a device that can transfer heat, and can function as a cooler or heater. This type of heat exchanger works by transferring heat between two or more fluids, and has a tube system as a place for the fluid to flow. The first set of tubes contains a liquid that will be heated or cooled, while the second set of tubes contains a liquid that is capable of transmitting heat or absorbing heat.

The working principle of a shell and tube heat exchanger is based on the flow and thermal contact between two fluids. In this case, the hot liquid will flow and transfer heat to the cold liquid. According to the laws of thermodynamics, when two liquid surfaces touch, heat transfer will occur by conduction.

When the heat exchange process occurs, one fluid will flow through the tube, while the other fluid flows through the shell. Because this type of heat exchanger has two compartments, namely the shell side and the tube side, the heat exchanger user needs to know which side the hot fluid and cold fluid will be inserted into.

Working Principle of Double Pipe Heat Exchanger

Double pipe heat exchangers work on the principle of conduction, where heat originating from one flow will be transferred through the inner pipe walls, which are of course made of conductive material. This type of heat exchanger is often used for counter flow, but can also be used for fluids with unidirectional flow.

Double pipe heat exchangers are able to handle high pressures and temperatures because they have the ability to expand and have simple construction. This type of heat exchanger is also capable of experiencing cross temperatures, namely when the cold stream output temperature becomes hotter than the hot stream output temperature. Depending on the application, this may or may not be beneficial for the user.

Due to the efficient way heat exchangers work and the various types available, heat exchangers have become an important component in various applications, including in the oil and gas industry, chemical plants, power plants, engine cooling, and household heating and cooling systems.
Selecting the right type of heat exchanger depends on the needs and characteristics of the fluid used. For example, when using fluids with large temperature differences, spiral heat exchangers are very suitable because their design maximizes contact between fluids.

Apart from that, the efficiency of the heat exchanger is also greatly influenced by good care and maintenance. It is important to keep the heat exchanger surface clean to avoid dirt buildup which can reduce heat transfer efficiency.

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