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Air conditioning faces flammable future

USA: A search of more than 60 million chemicals to find a replacement for R410A in air conditioning systems has found just 27 suitably-efficient fluids – but all are at least slightly flammable.

The multi-year study was carried out by researchers at the US National Institute of Standards and Technology (NIST) to identify the best candidates for future use as air conditioning refrigerants that will have the lowest impact on the climate.

The study found no ideal refrigerant that combined low GWP with other desirable performance and safety features such as being both non-flammable and non-toxic. All 27 fluids NIST identified as the best from a performance viewpoint are, at best, slightly flammable, which is not allowed under US safety codes for most end uses. And several fluids among the list of refrigerants are highly flammable.

The authors of the report, published in Nature Communications, maintains that the 27 fluids are the ‘best’ low-GWP fluids allowed by chemistry.

“It is highly unlikely that any better-performing fluids will be found, and unknown risks associated with the lesser-known fluids may further reduce the list,” the authors say.

“The takeaway is there is no perfect, easy replacement for current refrigerants,” NIST chemical engineer Mark McLinden said. “Going into the study, we thought surely there has to be something else. Turns out, not so much. So it was a bit surprising, a bit disappointing,” he said.

The recent global decision to phase-down HFCs under the Montreal Protocol, added to the pre-existing European F-gas phase-down has prompted regulations which will see the elimination of many of the highest GWP refrigerants from certain applications. These include common refrigerants like R404A and R134a where suitable alternatives are known to exist. 

R410A, a blend of R32 and R125, and currently the dominant refrigerant in small air conditioning systems, stands somewhat exposed with its relatively high GWP of around 2000 – 50% higher than R134a. Many feel that a replacement for R410A will need to be found if the global phase-down targets are to be achieved.

R32 has been introduced by Daikin and others for use in small splits and propane is also being considered in similar applications in some Far East markets. However, their flammability precludes their use under current national and international safety standards in all but the smaller systems.

“The path forward will involve tradeoffs,” said Mark McLinden. “Safety codes could be revised to allow the use of slightly flammable refrigerants. Blends of two or more fluids could yield a non-flammable refrigerant, but at a higher GWP. Carbon dioxide is nonflammable, but would require a complete redesign of AC equipment.”

Because all current refrigerants are small molecules, the NIST search was limited to molecules with 18 or fewer atoms and only eight elements that form compounds volatile enough to serve as refrigerants. This initial screen resulted in 184,000 molecules to be considered further.

Screening for energy properties corresponding to fluids usable in small AC systems and GWP of less than 1,000 yielded 138 fluids. This included the new low GWP HFOs R1234yf and 1234ze amongst an incredible number of 45 HFOs.

The researchers then simulated the performance of these 138 compounds in air conditioners. Further screening to rule out chemically unstable or very toxic compounds or those with low energy efficiency resulted in the final list of 27 low-GWP fluids.

The report focuses on single-component refrigerants (pure fluids) but recognises that refrigerant blends offer additional possibilities, although the trade-off to reducing flammability will be higher GWPs.  

 

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Mitsubishi announces European R32 launch

EUROPE: Mitsubishi Electric has announced the introduction of its first R32 air conditioners into Europe.  

The Japanese manufacturer’s M Series MSZ-LN range, first previewed at Italy’s Mostra Convegno show last year, will the first to offer the new lower GWP refrigerant. The launch of further R32 units are promised throughout the year.

The Cooling Post first revealed Mitsubishi’s intentions last year. At that time the UK company revealed plans for R32 in its residential M Series and commercial P Series air conditioning ranges and Ecodan heat pumps. An R32 version of the company’s City Multi HVRF water/refrigerant hybrid this year was also hinted at.

Commenting on today’s announcement of the M-Series launch, Donald Daw, UK commercial director, said: “This is a major product evolution which will show the market exactly how air conditioning using R32 can perform.

“R32 units have been available in Japan for over two years now and we have taken that knowledge and experience and refined it into this stylish and efficient offering, including our first ever red unit,” he added.

The MSZ-LN range offers a choice of four sizes from 2.5kW to 6.1kW, with four distinct indoor wall units which are available in red, Onyx Black, Pearl White and Natural White colours. A matching, colour co-ordinated room controller is also available.

It features a built-in Wi-Fi interface enables full control and monitoring via the company’s MELCloud app, and an i-see Sensor, which automatically monitors room occupancy, position and body temperatures to deliver customised comfort.

Double vanes on the indoor unit operate independently to distribute airflow evenly throughout the room and the MSZ-LN offers a whisper-quiet operation as low as 19 dB(A). A Plasma Quad Plus filter also uses powerful plasma technology to filter out even microscopic particles, whilst the dual-barrier coating on the heat exchanger, fan and air duct prevents dust and grease accumulation.

The line-up also includes Mitsubishi Electric’s Replace technology which can utilise existing pipework, making it ideal for office and retail refurbishments.

“We see this model as ideal for high-end, stylish situations and have already had a lot of interest from our customers,” Daw added. “R32 is expected to quickly become the standard for split type air conditioning systems and we have more products lined up for the UK market in the coming months.”

Mitsubishi Electric, like many of its rivals, has introduced air conditioners using R32, the non-ozone-depleting lower GWP alternative to R410A, in the Far East and Australasia but, until now, the Japanese manufacturer has remained silent on its intentions for Europe.

It has now been revealed that it is to challenge its main rival Daikin, the R32 pioneer, with new products across its main product platforms from 2017. This will include a move to R32 on Mitsubishi Electric’s residential M Series and commercial P Series air conditioning ranges and Ecodan heat pumps.

Only Mitsubishi Electric’s VRF products will remain on R410A for the time being, although an R32 version of the company’s recently relaunched City Multi HVRF water/refrigerant hybrid will be launched in 2017.

Speaking at yesterday’s Hampshire Refrigeration Society breakfast meeting, Martin Crawford, Mitsubishi Electric’s wholesaler VAR manager, said: “R32 will be the predominant refrigerant within our business in the coming years.”

He described it as the next generation refrigerant and a good substitute for R410A, despite its slightly higher pressure and mild flammability.

For those concerned about the new gas, he said: “There are millions of R32 units already installed in Japan and Asia, so you here in the UK will not be guinea pigs.”

On the plus side, he told the audience that R32 benefits from being a single component refrigerant, making it easier to reuse and recycle, easier to handle, won’t separate, has no glide and exhibits higher efficiency than R410A.

With limits on charge sizes due to its “mild flammability”, R32 is currently proving a challenge for VRF, which is why Mitsubishi has developed its hybrid HVRF solution.

“The timing for R32 VRF will be advised in due course,” a Mitsubishi Electric UK spokesman later told the Cooling Post. “Our plans are about offering a harmonised solution for customers because we need to avoid the situation where as an industry, we are using different refrigerants on different systems in the same buildings.”

The spokesman also indicated that limited use of CO2 is being considered especially for heat pumps where the predominant load is on hot water.

It seems likely that Mitsubishi Electric will roll out similar R32 introductions across Europe but, so far, there have been no announcements of timings for individual countries.

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CO2 refrigeration now mainstream

USA: The growing acceptance of CO2 refrigeration as a mainstream technology amongst both OEMs and end users in the USA is highlighted in a new study by Danfoss.

According to the new survey of over 1,000 individuals with an interest in commercial and industrial refrigeration in North America, 82% of OEMs and 91% of consultants said they saw CO2 as a viable mainstream refrigeration technology.

In addition, about half of the OEMs who responded saw CO2 refrigeration as being at least 16% of their business within the next five years. In a similar study conducted in 2012, less than 20% of OEMs saw CO2 comprising at least 16% of their business. 

The majority of commercial refrigeration consultants and end users are today engaged in CO2 projects, citing pending legislation/regulations and corporate sustainability goals as key drivers in the decision to use CO2. However, at the same time, they identified the high initial system cost as a primary barrier to deployment. 

The survey also identified similar acceptance in the industrial refrigeration market. 57% of responding OEMs and contractors and 43% of consultants and end users indicated that they have already either been involved in a CO2 refrigeration project or have plans to be. However, OEMs and contractors do not see CO2 becoming a significant part of their business in the near future. 

OEMs and contractors identified the removal of ammonia, in terms of improved safety and reduced ammonia charge, as key drivers in using CO2. Consultants and end users agreed, but also cited pending legislation/regulation as important factors. In contrast to the commercial refrigeration industry, industrial refrigeration respondents said the primary barrier to further CO2 use is the result of end user and contractor familiarity and training. 

This industry indicator on CO2 was conducted as a follow up to a similar survey conducted by Danfoss in 2012 to gauge the market acceptance of CO2 refrigeration. The survey was distributed via email to approximately 1,100 people that do business in commercial or industrial refrigeration applications.

“The results of this survey validate the ongoing growth we are seeing in CO2 projects across North America,” said Peter Dee, Danfoss’ sales and services director – food retail. Globally, Danfoss says it has been involved in more than 10,000 CO2 refrigeration projects.

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