Heat Exchanger

Heat exchanger or heat exchanger performs heat exchange processes between heat carriers. In manufacturing processes, for example boilers for steam generation, condensers and evaporators in refrigeration equipment, heat recovery units, etc. A common example is a car radiator, where water is is used to transfer heat to the radiator and is cooled by air, which then cools the engine.

What is a heat exchanger?

The process of transferring heat between fluids through devices has been used by humans for a long time to apply to production processes. Since heat can normally exist in undesirable states, it must be converted into states suitable for its intended use. From here, heat exchangers were born with many different types, suitable for each production process.

Heat exchanger
Heat exchanger

A heat exchanger can be understood simply as a device used to transfer heat from one place, substance, or environment to another place, substance, or environment. Depending on the different purposes, the process can be either cooling or heating.

Types of heat exchangers

Based on the method of heat exchange, heat exchangers can be divided into two types, direct or indirect. Direct could be air-cooling processes, where the two systems interact directly. Indirect can be heat exchange processes through metal surfaces, where the two systems are not in direct contact with each other. In particular, the process of indirect heat exchange through the metal surface is more popular because they prevent contamination between the two media, thereby making the process more efficient.

Today, the process of industrialization – modernization takes place at a rapid pace, requiring heat transfer processes to be improved accordingly to suit new and specific applications. Heat exchangers must also be constantly improved and renewed to make processes faster, safer, and more efficient.

Heat exchange process
Heat exchange process

What material is the best conductor of heat?

You might think that heat exchangers always need to be made of metal, which quickly absorbs and conducts heat — and many of them are. But heat exchangers can also be made of ceramics, composites (based on metals or ceramics), and even plastics (polymers).

All these materials have their advantages. Ceramics are an especially good choice for high-temperature applications (above 1000°C). These temperatures will melt metals such as copper, iron, and steel, although they are also popular for use with corrosive and abrasive fluids at high or low temperatures.

Plastics are generally lower in weight and cost than metals, resistant to corrosion and staining, and can be engineered to have good thermal conductivity, although they tend to be mechanically weak and can decompose. cancel over time. Practically speaking, plastic is not at all suitable for high-temperature applications, but heat exchangers with plastic construction can be a good choice for applications such as heating water for swimming pools or showers. lotus, operating at room temperature daily.

Composite heat exchangers combine the best features of their parent materials — such as the high thermal conductivity of metals with the reduced weight and better corrosion resistance of plastics.
In addition, much research is currently being done to find even more interesting materials in heatsinks. For example, carbon nanotubes (thin hexagonal sheets of carbon wrapped around to make “tubes”), have amazing thermal conductivity properties and have been used in heatsinks of electronic devices.

Overview of types of heat exchangers

The reason that heat exchangers are being used more and more in the food industry is because of the increasing demand of people for quality products. Food and beverages, if thoroughly heat treated, will eliminate harmful bacteria and microorganisms, thereby prolonging the shelf life of products as well as increasing their quality. In addition, heat transfer processes also need to be fast and efficient to minimize the impact on the nutritional and sensory quality of the product, while also minimizing fuel costs and saving money. save time. In the food and beverage industry, there are many types of heat exchangers used, typically the following three types of equipment:

Tubular heat exchanger

Tubular heat exchanger
Tubular heat exchanger

This is the most basic form of device in heat exchange processes. The tubular heat exchanger is designed to consist of a small tube concentrically positioned and placed inside a larger tube. Such a dual tube design allows unrestricted fluid flow, making it ideal for applications with high viscosity products. In the food industry, it is applied to the heat exchanger for products such as honey, jam, confectionery.

Beam tube heat exchanger

Tubular heat exchangers
Tubular heat exchangers

Shell and tube heat exchangers are one of the most common and common types in the food processing industry. It is composed of many small tubes that are bundled together into a tube bundle and enclosed inside a large tube shell. With such a design, it will increase the efficiency of heat exchange between the two fluids. This type of equipment is used a lot in the dairy industry, it is used to pasteurize or pasteurize milk. In addition, this device is also used to heat other foods such as ketchup, chili sauce, chocolate, vegetable oil, etc.

Plate heat exchanger

Plate heat exchanger
Plate heat exchanger

This type of heat exchanger is also quite common in the food processing industry, used a lot in multi-pot condensate systems. The biggest feature of this type of device is that it has a large heat transfer surface area. This results in high heat exchange efficiency, as well as a much more compact size than the beam tube form. Plate heat exchangers are suitable for heat exchange applications of low-pressure, low-viscosity fluids. However, it also has the disadvantage that it will need regular cleaning if the heat exchanger is for fluids containing fiber, residue, and easy adhesion in the openings of the heat exchanger plate such as coconut milk, coconut milk. …

Factors affecting heat exchanger efficiency

The efficiency of a heat exchanger can be determined in several ways. And several factors can affect the heat exchanger performance of the device such as:

Temperature difference: The difference between hot liquid and coolant is very important when designing heat exchangers. The coolant is always needed at a lower temperature than the hot liquid. A lower coolant temperature takes more heat out of the hotter liquid, which in turn warms up the coolant temperature. For example, if you have a glass of room temperature drinking water, it is much more efficient to cool it with ice instead of just cool water, the same principle applies to the heat exchanger.

Flow rate: Another important factor is the flow of fluid on both the primary and secondary sides of the heat exchanger. A larger flow rate will increase the heat transfer capacity of the exchanger, but a larger flow rate also means more mass, which can make it more difficult to remove heat as well as heat. speed increase and pressure loss.

Installation: Heat exchangers should always be installed according to the manufacturer’s instructions. In general, the most efficient way to install a heat exchanger is with the fluid flowing in an upstream arrangement (so if the coolant moves from left to right, the hot liquid goes from right to left) and for plate and tube heat exchangers, the coolant should enter at the lowest inlet to ensure the heat exchanger is always full of water. For air-cooled heat exchangers, it is important to watch the airflow when installing the cooler, any blocked part of the core will compromise cooling capacity.

Advantages of tubular heat exchangers

The tubular design in the heat exchanger demonstrates flexibility and high working efficiency. They became commonly used heat exchangers. The main advantages of tubular heat exchangers can be named as follows:

    • Low maintenance cost
    • High working pressure
    • High working temperature
    • Suitable for granular or fibrous products
    • Meets the standards in the aseptic process
    • Easy to check and disassemble

Heat exchanger application

Today’s heat exchangers are not only applied in industrial production processes, but also everyday life applications.

Heat exchanger application
Heat exchanger application

Especially among them, within the last few decades, heat exchangers applied in the food and beverage industry have been developed very strongly because of the increasing needs of people. Typical applications include:

    • Widely used in space heating. It is also used in refrigeration, air conditioning, power plants, chemical plants. Petrochemical, natural gas, processing, and wastewater plants are also heavily used
    • Processes of pasteurization, pasteurization of milk or dairy products such as cream, yogurt, butter, whey, cheese
    • Processes requiring cooling or heating of beverages such as beer, soft drinks, fruit juices, wine, fruit puree
    • Processes that require pasteurization and heating of foods such as chili sauce, ketchup, vegetable oil, margarine, caramel, chocolate, sauce
    • The process of concentrating sugar, fruit juice, coconut milk, milk, fresh coconut water
    • Processes that need to cool, quickly freeze meat, fish, seafood products…

Are you looking for a heat exchanger? Please contact Thai Khuong for advice and quick support. Some typical heat exchanger product lines as below information that you can refer to!

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