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Applications For Different Types Of Heat Exchangers

What is a Heat Exchanger?

Machines called heat exchangers are designed to transfer heat between two or more fluids having varying temperatures, such as liquids, vapors, or gases. Depending on the type of heat exchanger, the heat can be transferred from one liquid form to another, from one gas, or from one liquid to another. These fluids do not come into direct touch during this swapping since it is done through a solid divider.

The type of heat exchanger used and the materials utilized to build the exchanger determine whether a fluid is suitable for and compatible with a heat exchanger. Most liquids, including oil, water, and seawater, can be used with several standard heat exchangers. Other materials are required for corrosive fluids, such as chlorinated saltwater, refrigerants, and acids.

Distinct heat exchangers will be easier to describe and classify if they include additional features, such as building materials, parts, and different heat transfer mechanisms. These qualities also aid us in determining which one is better suited for specific applications in various industries and general use.

Less maintenance is often needed for heat exchangers. These are operating at high pressures and temperatures. An efficiency of about 80% is possible with the ideal-sized heat exchanger. They are straightforward, small, simple to maintain, and clean. When disassembling, more room is not needed. Compared to plate-type heat exchangers, shell and tube heat exchangers are less expensive.

Parts of a Heat Exchanger

  • Tubes:

The tubes are the most crucial components of the heat exchanger for exchanging fluids. Use is made of either welded or seamless tubing. The diameters of heat exchanger tubes range from around 5/8 inch to between 3/4 inch and 1 inch.

  • Tube sheet:

The tubes can be supported and separated using tube sheets. By hydraulic pressure or by the expansion of a roller, the tubes are fastened to the tube sheet. It is possible to wrap a tube sheet, which acts as an insulator and corrosion preventative.

  • Tie rods:

The heat exchanger also needs tie rods to function correctly. They are tightly fitted to the tube sheet at one end, and the end baffles at the other.

  • Front headers:

There are many types of heat exchanger front headers available, including A, B, C, D, N, and Y. The use of the front title may vary depending on the arrangement of flow pressure employed, cost, and the convenience of cleaning and repair due to the wide variety of types.

  • Rear headers:

When there is no significant mechanical stress brought on by differential expansion and the shell side does not need to be cleaned, the heat exchanger’s rear header, which comprises L, M, and N-types, is employed. A fixed back header with bellows is used when thermal expansion is possible.

  • Cooling system:

The heat exchanger’s fin fans, condensers, and chillers make up its cooling system. Fin fans effectively blow air over hot tubes to maintain their cooling. The condenser’s job is to cool the materials until they transition from a gaseous state to a liquid state. To cool the equipment without cooling the water, chillers employ water as their coolant and maintain a low water temperature.

  • Heat exchanger shell:

One fluid flows inside the tubes, and another fluid flows inside the cover in the shell and tube type. These are merely big pressure tanks housed inside a pipeline collection. Among the parts of a heat exchanger, it is the most expensive one.

  • Heat exchanger baffle:

The baffles inside the shell provide higher heat transfer rates, which increases flow turbulence—additionally, these heat exchanger components aid in supporting the tubes and minimizing vibration-related issues.

Different Types of Heat Exchangers

These devices’ flow arrangement and kind of construction are typically used to categorize them. The most basic heat exchangers are those in which the hot and cold fluids flow in parallel, perpendicular, or opposite directions. These heat exchanger types, parallel-flow, counter-flow, and cross-flow arrangements, contain two concentrically arranged pipes of varying sizes.

Parallel Flow arrangement:

Heat exchangers that use a parallel-flow understanding allow hot and cold fluids to enter at the same end, travel in the same direction, and exit at the same fate.

Counter-flow arrangement:

Contrary to parallel-flow agreements, the fluids in a counter-flow heat exchanger enter at opposite ends, move in opposite directions, and exit at opposite ends.


The configuration in which the fluids flow in opposite directions is referred to as a cross-flow arrangement. Finned and unfinned tubular are the two main varieties. Both liquids are unmixed in a finned tube heat exchanger, with the fluid between the fins being directed in the opposite direction from the tube’s flow direction. Heat exchange and fluid mixing are both possible in the unfinned exchanger.

A counter-flow setup has been discovered to transfer more heat than a parallel-flow heat exchanger by contrasting these two types of heat exchangers. Additionally, two significant drawbacks of the parallel-flow design are shown by the temperature profiles of the two heat exchangers.

Large thermal strains are produced by a significant temperature difference between the ends.

The hot fluid’s lowest temperature is never higher than the temperature of the cold fluid when it leaves the heat exchanger.

But when two fluids must be heated to almost the same temperature, the parallel-flow heat exchanger arrangement is advantageous.

Heat exchangers can be configured in various ways for the heat transfer surface. The different types of heat exchangers are described as follows:

Shell and tube heat exchanger:

The industry’s most popular and widely used heat exchanger is undoubtedly this type of exchanger family, with its different construction variants. Depending on how many shell and tube passes are required, shell and tube heat exchangers are further divided into several categories. High-pressure applications often use shell and tube heat exchangers that can withstand pressures more significant than 30 bar and temperatures higher than 260 °C. Because of their design allows shell and tube heat exchangers to sustain high pressures. The primary fluid passes through some small bore pipes inserted between two tube plates in this exchanger form. The secondary fluid flows over the surface of the tubes and through the shell that contains the tube bundle. The steam generator in nuclear engineering is frequently based on this design. The heat exchange surface is maximized to enhance the amount of heat transported and the amount of electricity generated. This design takes advantage of tubes to increase the surface area.

Tube-in-the-tube heat exchanger:

A heating and cooling device called a tube-in-tube heat exchanger specifically made for sludge, including fibers and other particles. A tube installed inside an outer shell tube is how tubes in tube heat exchangers are first presented

During use, the product medium in the tube floats against the current into the service medium. The product tube may be plain or folded. With this innovative design, thermal fatigue is avoided, efficiency is raised, and the overall size is decreased. They are ideal for high-pressure, high-temperature, and low-flow applications.

Double pipe heat exchanger:

Double pipe heat exchangers are among the least expensive in design and maintenance, making them a popular choice for small businesses. These heat exchangers work by having one fluid flow inside the tube and another flow outside the tube to exchange heat. The inner pipe serves as a conductive barrier in this system where one liquid flows through a smaller pipe, followed by another fluid between the two lines, and so on. Despite the ease of design and low maintenance cost of this type of heat exchanger, modern businesses now employ shell and tube heat exchangers because of their higher efficiency and fewer area requirements. It is used in many industrial processes, cooling technology, refrigeration equipment, and other industries and can offer good efficiency at a reasonable capital cost.

Direct and indirect heat exchangers:

When no separating wall is present, direct heat exchangers transfer heat between two phases of hot and cold currents. These heat exchangers directly mix hot and cold liquids while simultaneously transferring heat, replacing the need for heat exchange. A couple of examples are jet condensers and cooling towers.

By using another fluid, indirect heat exchangers measure the temperature change of one fluid while keeping the other fluid apart from it by an impervious surface. Using tubes, plates, etc., these heat exchangers maintain the separation of fluid-transferred heat.

Plate heat exchanger:

Metal plates are used in this exchanger to transfer heat between two fluids. This type of setup is used in heat exchangers that use lower velocity fluid flow, air, or gas. The most well-known instance of this heat exchanger type is in internal combustion engines, where an engine coolant circulates through radiator coils as air passes by the waves, cooling the coolant and heating the incoming air. The stacked-plate structure often has lower volume and cost when plate heat exchangers are compared to shell and tube exchangers. Another distinction between the two is that plate exchangers typically serve fluids with low to medium pressures in contrast to shell and tube exchangers.

Scraped Surface Heat Exchangers:

Heat transfer to highly viscous or sticky goods is necessary for some applications. Because the scraping blades prevent the product from settling on the inside surfaces of the heat exchangers, scraped surface heat exchangers are the most excellent option for efficient heat transmission in certain situations. The ground surface tube’s bottom is where the product enters a cylinder. In a cylinder encircling the product channel, heating or cooling fluids move against the channel’s flow. To provide even heat flow to the product, blades inside the product channel remove the product from the channel wall. The scraping blades are created from various materials to satisfy different processing needs. They are specially made for delicate product handling to prevent compromising product quality and uniformity. It is possible to mount scraped surface exchangers either vertically or horizontally. An electric motor inside rotates a rotor with grinding blades. Rotor movement and product movement through the heat exchanger occur in the same direction, with the product entering at the bottom and exiting at the top to prevent product damage. The interior surface of the heating surface has been polished to a high quality.

Pillow plate heat exchangers:

These are employed for industrial product cooling and heating needs. These heat exchangers are entirely welded, causing an inflation process to give their surface a waved, “pillow-shaped” appearance. These kinds are frequently used in solids drying, water chillers, and reboilers, among other things. The dairy sector frequently uses this heat exchanger to cool milk in bulk stainless steel tanks. With this heat exchanger, the tank surface area can be merged without any gaps between pipes that would be welded to the tank’s exterior.

Dimple Plate Coil Heat Exchanger:

Dimple plate/plate coil technology is the most excellent option for applications where one of the fluids isn’t moving, even if its market share is significantly lower than that of the preceding two groups. Additionally, it can be used in retrofit applications, like waste heat recovery, which wasn’t initially planned for. Generally speaking, this is a cost-effective alternative to refrigeration or heating for passively cooling or heating a storage tank (such as a milk or beer tank that is brightly colored). Two steel sheets are spot-welded together, and the plates are inflated to create channels for fluid to pass through. Dimple plate/plate coil technology can usually be tailored to any specific application because of its simplicity and inexpensive materials. Tank jackets for dairy and alcoholic beverage tanks are the most common use, but dimple plates can also be cut to fit within a tank and submerged in the stored liquid for effective heat transfer. Dimple plate/plate coil heat exchangers give the best of the two heat exchangers. They are affordable, adaptable, and small, yet they can endure extremely high pressures and temperatures thanks to their design and materials. Many industrial processes might also use it as an afterthought to reduce energy costs or adhere to environmental standards.

Finned heat exchanger:

Finned tube heat exchangers are made to refer to the most significant amount of heat transfer surface area with the transferred heat, which increases the effectiveness of transmitting heat in liquids with low thermal conductivity, such as air.

It consists of tubes with fins added to enhance the area of fluid contact with the external fluid and the fluid inside the tube with the fluid outside the line to exchange heat. These fins are typically thin and constructed of either copper or aluminum. Air conditioners and automobile radiators both use these kinds of heat exchangers.

Adiabatic heat exchanger:

This kind of heat exchanger is frequently utilized in the industrial sector. The system comprises a revolving wheel and a fluid intermediary that stores heat before transferring it to the other side of the heat exchanger for release.

Threads are placed around the perimeter to expand the wheel’s surface area. It circulates fluid having two portions through which heat is delivered while it is in use. These are crucial when heat must be effectively transported across gases, which is complicated with other types.

Phase change heat exchanger:

Heat exchangers containing material that undergoes a phase transition inside its structure may be referred to as “phase” exchangers. This heat exchanger collects, transfers, and constantly dissipates heat using the natural phase-change capabilities of an eco-friendly cooling fluid.

Due to the minimal volume difference between these phases, the transition is often from a solid to a liquid state. This phase transition acts as a buffer since it happens at a fixed temperature while allowing for extra heat production. Phase shift materials’ principal benefit is their prodigious capacity for energy storage.

Microchannel heat exchanger:

These varieties of multi-pass parallel-flow heat exchangers include fins, multi-port tubes with hydraulic channels less than 1 mm wide, and manifolds (inlet and exit). A controlled environment brazing procedure is typically used to join these components.

In this kind, air flows cross-currently through joined fins while at least one fluid (such as water or a refrigerant) circulates through tubes or enclosed channels. They have a high heat transfer efficiency, are small, and have low airside pressure. The automotive sector uses it for automobile radiators, among other uses.

Waste heat recovery unit type:

Another kind of heat exchanger that can be used to move heat from a process’s high-temperature output to another area of the process is a waste heat recovery unit. Domestic drainage heat recovery is an easy illustration.

By coiling copper tubing around the drain pipe, this technique allows one to recover the heat that is lost through a sink or shower drain. As the water travels down the tube toward the water heater, the coil is then used to heat it. These help businesses become more efficient and cut back on waste.

Condenser, boiler, and evaporator:

Evaporators, condensers, and boilers are all different types of heat exchangers, which many people are unaware of. Two stages of heat transfer are used in these heat exchangers. In a condenser, heated gas is cooled to the point of condensation, which transforms the gas or vapor into a liquid. The process of heat transmission in evaporators and boilers involves shifting the liquid form from the liquid state to the gas or vapor form.

Applications of Heat Exchangers

Heat exchangers of the shell and tube type are employed in numerous industrial processes such as in oil refining, preheating, and cooling processes, as well as steam generation, boiler in heat recovery and vapor recovery systems, and industrial cooling processes with small heat transfer areas requirements, double pipe heat exchangers are best suited for those applications. On the other hand, furnaces and chemical processing plants frequently employ plate heat exchangers.

Heat exchangers are primarily employed to transfer heat from one medium to another. They can also harness heat from a hot fluid, leaving the system to warm up a cold fluid entering a hot process system.

The spiral heat exchanger works well for effluent cooling, heat recovery, and digester heating. These are usually employed to warm food and chill liquids.

Components and Materials of Heat Exchangers

Heat exchangers can be built from a variety of different materials. The kind of heat exchanger one needs and what goal or goals it serves to determine the elements and materials employed.

The most popular parts used to build heat exchangers are shells, tubes, coils, plates, fins, and adiabatic wheels.

While metals have a high resistance and are frequently used to make heat exchangers due to their high thermal conductivity, as in the case of heat exchangers, may offer more significant advantages depending on the needs of the heat transfer application those made of materials such as copper, titanium, and stainless steel, other materials, such like graphite, ceramics, composites, or plastics.

How does a Heat Exchanger work?

It is a device that enables heat from one liquid (or gas) to be transferred to another liquid or gas without the two fluids mixing or coming into contact. They are employed for the liquid-cooled, closed-loop cooling of water to air-cooled components.

When a cooling system employs liquid as a coolant and a heat exchanger to remove heat from the coolant, the cooling system is said to be using closed-loop liquid cooling. The most popular coolants include water, deionized water, disrupted glycol, and water solutions.

The heat exchanger enters and passes through the combustion produced by burning natural gas or propane fuel in the furnace. Hot flue gas from the stove heats the metal as it travels to the exhaust outlet. The heated metal warms the air moving over the heat exchanger’s exterior. It should be noted that although different types of heat exchangers use other methods of exchanging heat, practically all forms of heat transfer devices use the same method overall.

How to make Heat Exchanger more efficient?

There are numerous approaches to quantifying heat exchanger efficiency. However, while evaluating thermal performance, the following criteria should be taken into account.

Temperature differential:

When building a heat exchanger, it’s crucial to consider the difference in temperature between the hot fluid and coolant. The coolant should always be kept at a lower temperature than the hot fluid. More heat will be removed from the hot liquid by more excellent fluids than by warmer ones. The same logic applies to heat exchangers: if one had a glass of drinking water at room temperature, it would be much more efficient to cool it down with ice than with cool water.

Fluid flow rates on both the heat exchanger’s primary and secondary sides are also significant factors. A higher flow rate will increase the exchanger’s capacity to transfer heat. Still, it also entails a higher mass, which may make it harder to remove energy while also growing velocity and pressure loss.


The manufacturer’s instructions should always be followed when installing a heat exchanger. The best approach to establishing a heat exchanger is with the fluids running in a counter-current configuration (such that if the coolant is flowing left to right, the hot liquid is flowing right to left). The coolant should enter at the lowest inlet position for shell and tube heat exchangers to ensure that the heat exchanger is full of water. Installing a cooler on an air-cooled heat exchanger requires careful consideration of the airflow because any obstructed core area would reduce cooling capacity.

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