If you have ever tried to defrost your own freezer at home, you’ll know sometimes it’s not an easy feat! With modern freezers, this is becoming less and less common and technology helps them regulate the ice. But there were times when people used warm water, scrapers to ride the freezer of ice. This could end in damaged equipment.
Luckily on the industrial aspect, there are systems in place to do this for businesses. What you may not know is there are different types of defrosting processes that can be used. This blog looks into them and their pro’s and cons, and as always how they can benefit our customers.
Why is defrosting so important?
Like all systems, every business needs the equipment to work at maximum efficiency. If the refrigeration system has an accumulation of ice built-up on it, then this won’t be the case. It might seem strange that ice build-up can cause a problem, due to wanting ice in the first place, but excessive ice build-up means the system is not running optimally. This, of course, can mean systems more prone to failure and ultimately large cost incurred. So having planned and correct defrosting is vital to the system operation.
How does hot gas defrosting work?
The main area that needs to have accumulated ice removed from it is the evaporator coil. In a nutshell hot gas defrosting works by using already high-temperature vapour made in the system, to warm the evaporator coil and melt the ice on it. This vapour is made in the compressor and is the vapour that is naturally discharged. Although it seems straightforward to use this vapour, it is much more than simply directing at the ice. In fact, there are different methods to introduce the hot gas to the required areas, which have been developed over a number of years.
We won’t go into the full technical aspects of these, but there are three main types, a three-pipe system, reverse cycle and reverse flow. Our engineers can always discuss with you the preferred method in a given scenario.
What other types of defrosting are there?
Other than hot gas defrosting, there is one other main type – electric defrost. This system for defrosting uses electrical heating elements that are situated in or near the evaporator coils. When a defrost cycle has implemented the flow of refrigerant is interrupted by a valve, the electrical elements then are switched on automatically. They heat up and the evaporator fan blows the resulting hot air over the evaporator coil – melting the accumulated ice.
Which defrosting type is more energy efficient?
There are pro’s and con’s to both systems of defrosting, but on the energy efficiency scale, hot gas wins the race. This is because the hot gas is a heat already produced by the system as a by-product of the refrigerant. In electrical defrosting, the warmth is not directed directly at the evaporator coil, so can take a while to defrost completely. This system also has to cope with ice that can form on the heating elements themselves, so added energy is needed to deal with this situation first!
Is hot gas defrosting expensive?
Compared to electric defrosting, using hot gas is more expensive. This is because in electrical defrosting the design and installation is fairly easy to put together and install. Hot gas systems are much more complicated as they use different piping systems to deliver the vapour. The design of this can cost more money, by the very nature of the engineering required. The budgeting can even out though if the system installation requires the demand of defrosting that hot gas would be better for. Each installation is on a design by design basis, so don’t write off hot gas defrosting!
What are the time differences in defrosting?
In hot gas versus electrical defrosting, the hot gas is quicker. This is due to the gas already being hot that will be used to defrost, whereas the electrical elements take time to heat up and do their job. As the temperatures of defrosting can impact the system as a whole, the shorter method is always the best.
How much defrosting should a system need?
This is really a case by case scenario! The main thing to remember is the overall effect on the system. Defrost cycles should be kept to a minimum, as sudden changes put extra strain on all the equipment which can result in shortening the life of components.
What next?
As always our engineers and design team will be happy to chat with you and answer your questions to whether this type of system is right for your installation. We never suggest a bit of equipment that you don’t need or is not right for the plant. So please get in contact with our friendly team for more information, or to discuss this (or any other) question further.
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