A heat exchanger is a technical component that enables the transfer of heat between two media - typically liquids or gases - without mixing. This makes heat exchangers indispensable in industrial processes where efficient temperature control and energy recovery are crucial.

What is a heat exchanger?

The heat exchanger transfers heat from one medium to another without the two media coming into direct contact. This is done through a thermally conductive wall that separates the media. The purpose is to utilise heat energy efficiently - for example, by recovering waste heat from one process and using it to heat another fluid.

A practical example is district heating systems where hot water from the district heating network transfers heat to the home's heating system via a heat exchanger without the district heating water mixing with the internal water.

How does a heat exchanger work?

Heat exchangers work by passing two media of different temperatures past each other, separated by a thermally conductive surface. Heat flows naturally from the warmer medium to the colder medium until a thermal balance is achieved

There are two main principles of flow:

Countercurrent principle: The media flows in opposite directions, resulting in high heat transfer efficiency.

Co-current principle: Media flows in the same direction, which is simpler but less efficient.

The choice between these depends on the heat transfer requirements and design complexity of the application.

What types of heat exchangers are there?

There are several types of heat exchangers, each with specific properties and applications:

Plate heat exchangers

Consists of thin, corrugated metal sheets that create channels for the media. They are compact and have high heat transfer efficiency, making them suitable for the food, pharma and chemical industries.

Tube heat exchangers

Consists of a bundle of tubes inside a jacket, with one medium flowing through the tubes and the other outside. They are robust and can withstand high pressures and temperatures, making them ideal for steam and oil applications.

Spiral heat exchangers

Consists of two spiral channels where the media flows in countercurrent. They are compact and efficient for viscous liquids and media with particles.

Scraped surface heat exchangers

Features a rotating scraper that prevents clogging and ensures even heat transfer. They are suitable for products with high viscosity or a tendency to deposit, such as in the food industry.

Pros and cons of heat exchangers

Benefits:

• Energy efficiency: Heat recycling reduces energy consumption.
• Temperature control: Precise control of process conditions.
• Compact design: Plate heat exchangers in particular require less space.
• FlexibilityAdaptable to different media and applications.

Disadvantages:

• Clogging: Narrow channels can block particle-rich media.
• Corrosion: Inappropriate material choices can lead to material degradation.
• Maintenance: Some types require regular cleaning and inspection.

The choice of heat exchanger should be based on an assessment of these factors in relation to the specific application.

What to consider when choosing a heat exchanger?

When choosing a heat exchanger, it is important to take into account:

• Media type: Is it liquid, gas, viscous or particulate?
• Temperature and pressure: What operating conditions should the heat exchanger withstand?
• Heat transfer requirements: What efficiency is needed?
• Spatial conditions: Are there any restrictions in the installation area?
• Maintenance: How easy should it be to clean and service the device?

A correctly dimensioned and selected heat exchanger ensures optimal operation and long service life.

How Alflow can help you with your heat exchanger

At Alflow, we have over 25 years of experience with flow components for the pharmaceutical, food and chemical industries. We offer a wide range of heat exchangers, including plate, tube, spiral and scraped surface heat exchangers that fulfil high demands on hygiene, documentation and reliability.

Our counselling is based on your specific needs and we offer:

• Technical sparring: Help for choosing the right heat exchanger.
• Dimensioning: Calculating capacity and efficiency.
• Documentation: Provision of necessary certificates and declarations of conformity.
• Service: Onsite and offsite maintenance and testing.

Contact us for a no-obligation conversation about how we can optimise your process with the right heat exchanger.

FAQ

What is a heat exchanger used for?

A heat exchanger transfers heat between two media without mixing them, which is essential in processes where temperature control and energy efficiency are important.

What does it cost to replace a heat exchanger?

The price varies depending on type, size and specifications. A simple model can cost a few thousand dollars, while advanced industrial heat exchangers can cost significantly more.

Which is better, hot water tank or heat exchanger?

It depends on the need. Hot water tanks store heated water, while heat exchangers heat the water on demand, which can be more energy efficient in certain applications.