HVACR chillers - Supporting refrigerant choice
Climalife UK
Dave Richards, Head of Sales at Climalife discusses.
Chillers play a vital role in the Heating, Ventilation, Air Conditioning and Refrigeration (HVACR) industry. They have become an essential part of a whole range of commercial facilities such as offices, hotels, restaurants, and hospitals. Most commercial buildings nowadays, use HVACR systems as a means to cool and dehumidify the building and similar to other areas of the industry, there is a growing need for these systems to be both efficient and sustainable.
As always legislation is driving and influencing the choice of refrigerant. With the next phase down step due in January 2024, chiller manufacturers are already moving to lower GWP refrigerants.
There are many different types of chiller, however in terms of refrigerant they can be split into three types based on the pressure of the refrigerant.
Low Pressure Refrigerant Chillers
Although non-ozone depleting R-245fa has been used in some equipment, more recently the use of low-pressure chillers has increased with the use of very low GWP R-1233zd (GWP = 4.5), an A1 safety class single component refrigerant and R 514A (GWP = 7), an azeotropic B1 safety class refrigerant blend.
Medium Pressure Chillers
R-134a has been used extensively in chiller applications, mainly in larger end of the chiller market with equipment manufacturers still offering a range of equipment with R-134a as the primary option.
Whilst R-134a has a GWP of 1430 and isn’t subject to any current bans in the EU, there are already lower GWP alternatives readily available. Many of the leading manufacturers of chillers produce a range of air cooled, water cooled and remote condenser chillers that have a wide range of cooling capacities from 20kW up to 2MW most now have options designed for use with the refrigerants mentioned below.
R-513A has a GWP of 631, is non-flammable, has been quickly adopted by a number of manufacturers and can easily be used for retrofitting R-134a systems, with very similar cooling capacity and performance. The GWP of R-513A is less than half of the GWP of R‑134a which effectively means that twice as much becomes available compared to R‑134a in terms of the F-Gas phase-down.
R-1234ze is a single component HFO with a very low GWP (7) making it a very sustainable long-term refrigerant. It has been available since 2012 and has been used in chiller applications where R-134a was previously used but is not suitable as a retrofit option for R-134a due to a lower cooling capacity. The positives of using R-1234ze are the good energy efficiency, better than R-134a, and even though it is classed as A2L under the ASHRAE 34 and ISO 817 standards, since it is non-flammable below 30°C, for transportation (ADR) and manufacturing (PED/PE(S)R) purposes it can be treated as non-flammable. Whilst the switch to R-513A historically has been easier to implement, Climalife advises to always look to the longer-term solution in new equipment, with many manufacturers offering equipment using R-1234ze.
R-515B was new to the market in 2020, it can be best described as an A1 (non-flammable) version of R-1234ze with almost identical performance characteristics. R-515B offers a low GWP alternative (293) in applications where the long-term solution R-1234ze (GWP<1) cannot be used.
R-1234yf is another single component HFO with a very low GWP (4) and therefore can be considered a long-term sustainable refrigerant. Some chiller options are available for use with R-1234yf which in terms of performance is very close to R-134a. Since the safety class is different to R-134a, R-1234yf is ideally suited for use in new equipment. Under the Pressure Equipment Directive (PED) R-1234yf is in fluid safety group 1. Although retrofitting from R‑134a may be possible, any changes to the equipment PED classification need to be thoroughly considered as well as charge size restrictions from EN 378 and a suitable risk assessment will be required, which takes into account any possibility of the formation of flammable zones.
The very low GWP of both R-1234ze and R-1234yf effectively mean they provide an unrestricted solution as the phase-down tightens on higher GWP refrigerants in the years ahead.
High Pressure Chillers
R-410A has been extensively used in chillers, however with a GWP of 2088, it is not sustainable in new equipment as the F-Gas phase down steps impact. The leading contenders are currently R-454B and R-32 neither of which are suitable as R-410A retrofit options and should only be used in equipment designed for these products. Some manufacturers are also looking at the medium pressure refrigerants previously mentioned as an alternative for this technology, for example scroll compressors for R‑1234ze are now available and able to deliver the same capacity as for R-410A.
R-454B with a GWP of 466 appears to be currently leading the way with a number of manufacturers as it is a close match to R-410A in terms of operating performance and properties and has the lowest GWP. We are seeing an increasing number of chiller manufacturers making this option available to the market.
R-32 with a GWP of 675 has seen rapid growth as a replacement for R-410A in split AC systems and some manufacturers have also opted for R-32 in chillers. The properties of R-32 have meant that more equipment re-design may be required by equipment manufacturers.
Other refrigerants worthy of a mention are R-290 (propane) and R-717 (ammonia). Some manufacturers are offering HVAC systems using R-290 but the requirements for using an A3 highly flammable refrigerant can be a little more restrictive than using a lower or non-flammable option. Whilst EN 378 does not restrict charge sizes if the system is in the open air, suitable risk assessment taking into account the potential formation of flammable zones is required and likely to be significantly more restrictive than using a lower flammability option.
The use of R-717 is widespread in industrial chillers where the toxicity and flammability can be more easily managed but is rarely seen for general HVAC applications.
Looking to the future
Changing the refrigerant used in chillers is not always a quick process as it must meet a range of criteria, such as operating at the desired pressure and temperature, provide the correct levels of cooling and be more energy efficient than its predecessors. New chillers installed now need to be viable over their lifetime, which can be 20-30 years, so it’s important to choose a chiller that uses a sustainable refrigerant. The chiller manufacturers are moving quickly in the right direction and already have a number of lower GWP options available to them to be able to meet the restrictions F‑Gas legislation creates.
There are many leading manufacturers that have released or are releasing equipment that is high performing, energy efficient and cost effective with the use of very low GWP refrigerants These offer a long-term solution in order to future proof a buildings air conditioning system and to take steps towards tackling the pressing issue of climate change.
As these chillers become more established in the market, it’s important to make sure your refrigerant supplier is up to date on handling, use and performance of the new refrigerants and have availability. Climalife have a stock of all the refrigerants discussed.
