Air compressors are efficient and cost effective, which is why they are common in workshops, manufacturing, and processing. They are so common that a regularly quoted statistic is that they account for around 12% of the UK’s industrial energy usage. However, as much as 90% of that energy is wasted as heat.
Heat is an unavoidable by-product of compressed air. Generally, it is dissipated by a combination of cooling systems and natural cooling as the air moves through your compressed air system. However, heat recovery can recover as much as 94% of that heat, helping you cut your energy bills and shrink your environmental impact.
How air compressor heat recovery works
Heat recovery uses the existing cooling mechanisms to extract the heat from your system for use elsewhere, possibly from the oil circuit or aftercoolers. The heat is transferred to another medium, usually water, via heat exchangers or an integrated recovery system.
Waste heat recovery is even more direct, sometimes using the hot air from air-cooled compressors for applications like space heating.
Heat recovery efficiency differs between types of compressors, but typically ranges between 70% and 94%. The savings are such that installing heat recovery will pay for itself in 12 to 36 months.
How can air heat recovery be used?
Just like your air compressor, heat recovery can be versatile.
- Space heating: perhaps the most direct heat recovery method is ducting the hot air to warm your workshops, saving on heating system costs.
- Water heating: the water from a heat exchanger can reach 90º. It can be used in washrooms and staff facilities, to feed boilers, or even in any processes that need heated water.
- Operational processes: the heat can be used in any applications that need heat, like food processing, laundry, paint booths, or even for simple drying.
Systems can also be designed to switch uses, allowing you to save on heating in winter and hot water in summer.
Heat recovery components
Regardless of your compressor type, you can benefit from heat recovery. Most modern compressors can easily be adapted for heat recovery, and can even come with heat recovery components pre-installed. Retrofitting older compressors is also almost always possible.
- Oil-lubricated compressors use an oil circuit heat exchanger. These capture heat from the compressor’s oil loop.
- Water-to-water heat exchangers transfer the heat from water-cooled compressors. This means heated water can be used anywhere, without risk of contamination from the compressed air system.
- Ducting and louvres are used with air-cooled compressors. These help capture and redirect the warm exhaust air, allowing you to use it rather than being lost to the atmosphere.
The benefits of a heat recovery system
There are many reasons you should use heat recovery.
Energy efficiency
By recovering over 90% of the heat from your compressor, your compressed air system will be incredibly energy efficient.
Cost savings
Because you can use the recovered heat instead of generating that heat again, you can dramatically cut your energy costs. Depending on usage, you might find that heat recovery pays for itself in a year.
Environmental benefits
Increasing your energy efficiency and reducing your energy use helps the environment. It is estimated that air compressor heat recovery in the UK could save enough energy each year to power more than one and a half million houses.
Will you benefit from heat recovery?
Almost every compressed air system can benefit from heat recovery, and the most common compressors used in industry – lubricated rotary screw compressors – are ideal for heat energy recovery through their oil loop.
There are a few factors to consider. Heat recovery works best with systems that are run at a steady load. Heat recovery is always possible, but it is not as effective if the heat is not always there to recover.
You should also think about your heat requirements. There is little point in recovering heat that will not be used. For example, are there spaces that need heating, or sufficient hot water use to justify heat recovery?
Can your system use heat recovery?
It is almost always possible to retrofit heat recovery to a compressed air system. Indeed, older systems, which may be less efficient, usually bring the biggest savings through heat recovery. And, although it is easier to include heat recovery at installation, retrofitting can often be completed with minimal disruption, and sometimes with no downtime.
If you want to benefit from heat recovery, we are always happy to advise on the type suitable for your compressors, as well as the possible uses and savings it could offer.
Our engineers can also help you with installation, taking care of design, including the necessary components, and ensuring the required safety systems, like pressure reliefs and temperature controls, are in place.
Some common myths
We frequently find people have resisted heat recovery because of some common misunderstandings about heat recovery.
Myth: It is only for winter
Heat recovery works all year round. Your compressor generates heat regardless of the weather. How you use that heat at different times of the year is likely to change.
Myth: It is only for 24-hour operations
Heat recovery works whenever your compressor is on. You will still benefit because it supplements other systems, like your heating or hot water, although the return on your investment will take longer.
Myth: It will affect performance
Heat recovery can have a positive impact on performance. By helping your compressor’s cooling system remove heat, heat recovery can help your compressor continue to work at optimum levels for longer.
Getting started with heat recovery
Getting started with heat recovery could not be easier. Our team has helped hundreds of businesses design, install, and maintain their heat recovery systems, saving them money, helping the environment, and, just as important, keeping them warm!
Just contact Design Air. We can offer you a heat recovery assessment, taking you through the type of installation we can offer, the impact it will have, and even calculating the savings you can expect from it.
