There are a few options available for anyone looking to replace the R22 in the refrigeration system, or indeed replace the refrigeration system completely. The first option would be to use a drop-in replacement, however this needs careful consideration because many of the drop-ins do not have the same performance as R22. So that needs to be considered carefully.
There are also a number of refrigerant blends available, but again there are some technical considerations there, and it’s something that needs to be assessed on a case by case basis.
The next option would be to move to a natural refrigerant. This is seen as an excellent option, because natural refrigerants will not be subject to future restrictions and legislation, as is the case with many of the HFC alternatives. For that reason, natural refrigerants are being seen as a future-proof solution, and something that is being considered by more and more for their R22 phase out needs.
One of the important considerations when looking at a new ammonia system is the ammonia charge. That is, to say, the amount of ammonia which is used within the refrigeration system. All Azane packages are designed to have a critical ammonia charge, which means that the absolute minimum amount of ammonia is used to ensure reliable operation. We use various technologies to reduce the ammonia charge, and the key amongst these – in the case of the Azanefreezer – is the low pressure receiver system. Coupled with this, we use an aluminum coil evaporator with an enhanced internal surface. It’s the enhanced internal surface which ensures a very low ammonia charge within the evaporators themselves. Traditionally, ammonia has been used in large scale industrial refrigeration, and that has been the case for over 100 years. Recent advances in technology mean that ammonia is now available in much more compact and smaller packaged systems. This opens up a whole new range of applications for ammonia that were not previously available. Low charge packaged ammonia systems mean that the installation of an ammonia system is greatly simplified. This is especially important in retrofit applications where an existing system may need to run in parallel while the new packaged ammonia system is installed. The fact that the package is a complete factory built system means that there is a minimum amount of disruption while the installation is taking place.
It’s typically the case that investing in an ammonia system will require a slightly higher capital investment than would be required for an HFC system. However, the good news is that an ammonia system will outperform an HFC system, and what this means is that energy bills are reduced, and typically we would be seeing a return of investment in as little as 2 or 3 years.
One of the key features of the Azane packages is their air cooled condensers. The benefit of an air cooled condenser is that it does not use any water, and that’s becoming an increasingly important consideration, especially in regions where water is becoming scarce. Air cooled condensers can be shown to be more efficient overall than an evaporative condenser when the entire seasonal running conditions are taken into account. Recent studies have shown that air cooled condensers are actually more efficient than evaporative condensers when the entire range of operating conditions is taken into account. The reason for this is that air cooled condensers have a much larger surface area available than an evaporative condenser. This means that when the ambient temperature is lower, the air cooled condenser will outperform the evaporative condensers in terms of energy consumption when the entire range of operation is taken into account.
R22 is an HCFC and it contains chlorine. It’s the chlorine in this compound which, when released into the atmosphere, can be damaging to the ozone layer. For that reason, the Montreal Protocol was signed in the 80s, and an agreement was put in place to phase out these compounds. It is now that we’re seeing this coming into effect in the US with the EPA phase down of R22.
There are a number of options available to anyone who is currently using a refrigeration system using R22. The first option available would be to use one of the various drop-in refrigerant replacements. What this means is that the system would use a different refrigerant, and again, be a manmade synthetic refrigerant to be used in place of R22. This can be an attractive option for anyone whose system has life left, and anyone who’s not keen to scrap equipment that still has some residual value. Now, the challenge comes when looking at drop-in replacements that the system will never operate exactly the same as it did when it was using R22. There are issues of material compatibility, looking at seal materials. There are also issues of oil compatibility, and this needs to be considered carefully and addressed when any drop-in refrigerant is used. The next thing to consider is the overall capacity of the system, because many of the drop-in replacements would have a capacity that is less than the capacity using R22. Finally, the efficiency of the system will almost certainly be affected when using a drop-in replacement, and this needs to be considered to see if that solution is really the best for that system.
The EPA have published a timetable for the phase down of HCFC R22. This means that they are already placing restrictions on the amount of R22 which can be produced or imported and brought onto the market in the US. This means that the availability of R22 is decreasing, and the price is increasing. This is a trend that will continue until the phase down is complete in the year 2020.
There are also a number of HFC blends available on the market as a replacement for R22. These HFC blends – as the name suggests – are a blend of more than one chemical, and this needs to be considered when assessing that this is a potential solution. The best consideration when using a blend is that the separate components in the system can lead to some changes in performance in the refrigeration system, particularly when looking at the performance of the evaporator, where the different components of the blend can evaporate at different temperatures. This can lead to what’s known as refrigerant glide, and this can have a detrimental effect on the performance of the system.
Refrigerant blends should certainly not be considered for central pump systems, where any large receiver vessels in the system can essentially act to separate the various components of the blend, and then this can lead to underperformance of the system.
The final consideration when looking at refrigerant blends is oil compatibility. Many of the blends would require that an existing system is completely flushed of any old oil and replaced with a new type of oil. That’s something that is both costly and time consuming, so it may be that that process is something that would lead to becoming uneconomical when looking at replacement refrigerant.
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