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Home » The good, the bad and the ugly of refrigerants

The good, the bad and the ugly of refrigerants

  • marimac 

Compiled by Eamonn Ryan

Recently, new HFC refrigerants (named HFOs) with low GWPs have been appearing on the market. Of all refrigerants applied today, ammonia and CO2 are the oldest that have been used since the 19th century.

The choice of refrigerant (and technology) has become complex. In the HVAC&R industry, issues related to working fluids in many applications are ongoing. There are of course many different applications: chemical companies, manufacturers of equipment, distributors, environmental organisations, politicians and the public all make use of refrigerants.

Refrigerants play an essential role in cooling. Refrigerant gases used in all refrigeration systems are classified as natural or synthetic. Ammonia, carbon dioxide and propane (though less so in South Africa) are the most widely used natural refrigerants due to their excellent thermodynamic properties.

While useful, refrigerants are considered to be a significant contributing factor in global warming and so advancement in technology has brought about the initiation of environment-friendly refrigerants.

Andrew Perks is a subject expert in ammonia refrigeration. Image credit: Andrew Perks

Andrew Perks is a subject expert in ammonia refrigeration. Image credit: Andrew Perks

Regular Cold Link Africa contributor Andrew Perks writes1: “It was noted in a recent Global Cold Chain Alliance webinar in Cape Town, in an open discussion on ‘manage the moment’, that plant operator errors account for on average 80% of all the incidents recorded. The engineer from the site that had the incident was quite open and shared the impact to the site with the escalating circumstances related to turbulent variable wind direction moving the released ammonia around the site so much that they had to relocate to different assembly points three times during the incident. This not only escalated the incident but made it very difficult to maintain order with those affected that were being evacuated.

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“You just have got to get those procedures in place and do regular training. It’s all about training, training and then some more training. While you may send your technical staff for SAQCCGas training, you still need to comply with current regulations that require an annual site incident response training/evacuation plan that complies with SANS 1514,” says Perks.

So, what do we do about getting prepared for your worst nightmare?

“It was agreed (in the discussion during the webinar) that having an up-to-date emergency plan is the first step. Thereafter, you need to undertake yearly site incident response/evacuation training exercises to get your emergency teams up to speed which also keeps you in line with the MHI regulation’s requirements. It’s important so that in the event of an incident there are no surprises.”

As Perks says in the article, “[h]indsight is an exact science”, however in practice nothing is as valuable as having hands-on experience when dealing with potentially dangerous refrigerants such as ammonia. Nonetheless, despite the risks Perks emphasises that there are many advantages to using ammonia due to the fact that it is extremely efficient and holds the potential to solve future energy requirements. As ammonia is a natural refrigerant it will not damage the ozone layer and is a clean source of energy.

“Lest you have forgotten, ammonia’s chemical formula is NH3. That is one particle of nitrogen and three parts of hydrogen. It’s the hydrogen that makes ammonia hazardous but it’s also the hydrogen that makes it useful as an energy source. As ammonia, all the particles are bound together, so it is easy to transport – as illustrated in the images within this article,” writes Perks.

“The fact that hydrogen is one of the lightest gases we know after helium allows us, with the correct process, to split ammonia into its base components. Starting to make sense? So much so that we now have an ammonia energy industry. Back in the day who would have thought this to be the reality of today?”

Perks goes on to highlight the fact that there are various ‘green’ ammonia projects which are currently being undertaken across the globe which will open up a multitude of possibilities for using ammonia as a fuel source. In fact, such ‘bunkering’ studies have been underway for decades to find ways of using ammonia experimentally to fuel cars and ships. One of the advantages identified by Perks is that the only emission produced by cars using ammonia is water vapour, making it extremely clean as a fuel source.

“A couple of years ago, the Ammonia Safety & Training Institute (ASTI) took the decision to develop training programmes for use in the ammonia energy industry. ASTI realised that the skill set required in the ammonia energy industry is quite different to the ammonia refrigeration industry in that the level of prior knowledge is negligible for those attending the training courses. In order to cope with that, ASTI developed a course ‘ammonia 101’ for the energy industry. At Perks Enterprises we believe that we are in the unique position along with ASTI to bring this specialised safety training for the ammonia energy industry to South Africa.”

“The fact is that we are developing a new ammonia industry in Gqeberha – projected to come online in 2025 and at full capacity in 2026 means that we need to be in a position to supply this type of training and certification. The project is said to be looking at filling up to 10 000 jobs when completely operational. The need for safety and operational training is therefore massive.”

“One of the problems with the current training programmes in South Africa is that we really only have a skills programme for artisan training. You have to start somewhere but we also need to add those specific skills required to actually operate in the field,” writes Perks.

CAREL know-how in Natref solutions

t-Store is CAREL’s modular and scalable solution. Image credit: CAREL

t-Store is CAREL’s modular and scalable solution. Image credit: CAREL

Euroshop, held in Düsseldorf from 26 February to 2 March, was all about demonstrating how to improve the performance of refrigeration systems while at the same time reducing the carbon footprint of the applications these solutions are integrated into.

CAREL in particular had three main tools on demonstration2.

The first tool available to the commercial refrigeration market is the use of natural refrigerants, considered the most future-proof alternative for reducing the harm caused to the environmental by synthetic refrigerants. Specifically, CO2 and propane are the most widely-used in retail applications.

To help its customers, especially OEMs, reduce the considerable research and development required, CAREL can now supply complete HeosBox units for semi plug-in cabinets operating on CO2. The same offering is available for manufacturers who prefer to implement Heos solutions using the individual components, in this case for both CO2 and propane. Semi plug-in systems, above all when cooled by a water loop, are cost-effective and sustainable, as the risk of leakages is drastically lower than in the traditional centralised approach with compressor racks and remote cabinets.

Furthermore, the refrigerant charge can be reduced by up to 80% and the energy saving and maintenance options, including preventive maintenance, can be managed via Cloud. There is now increasing demand for devices that can maximise energy usage and minimise waste.

Sustainability is one of the key aspects in all the different stages of design and implementation of technologies in a food retail store. t-Store is CAREL’s modular and scalable solution that guarantees the highest levels of integration and optimisation of all the systems typically installed in a retail store, whatever the format. More specifically, it is a combined proposal of solutions and services that simplifies synergy between the typically highest energy consuming areas, reducing operating costs not only of food refrigeration, but also of heating and air conditioning systems, lighting and energy management, i.e. reading and monitoring the electrical parameters and overall consumption of the connected loads, so as to monitor demand and avoid critical situations that can lead to hidden waste.

CAREL’s third tool for achieving sustainability is to no longer consider each ‘individual’ unit but rather the concepts of connections and systems, and consequently multiple devices that exchange information with each other. All CAREL solutions feature a high level of connectivity, simplifying commissioning, monitoring and maintenance through specific software and dedicated apps.

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Training is key in ammonia for safety reasons

Isolde Dobelin, director of Open Trade Training Centre (OTTC). Image credit: © Eamonn Ryan | Cold Link Africa

Isolde Dobelin, director of Open Trade Training Centre (OTTC). Image credit: © Eamonn Ryan | Cold Link Africa

OTTC has that rarity – a fully-fledged ammonia training course in South Africa up to diploma level, says Isolde Döbelin, director of Open Trade Training Centre (OTTC), which attracts the bulk of its student enrolment.3

“Peter Döbelin, founder of OTTC and Ammonia expert from Germany saw the need for the course, developing the OTTC Ammonia Diploma in 1993 for safeguarding people and their lives,” she explains, referring to her late husband.

“This was the first private training centre worldwide to offer training on ammonia refrigeration. Until now there have been more than 500 OTTC Ammonia Technician graduates working in high positions worldwide in the ammonia industries.”

Its courses include:

  • OTTC has a full new programme for ammonia training
  • OTTC Ammonia Qualification for apprentice (new)
  • OTTC Ammonia Maintenance (new)
  • OTTC Ammonia Technician Diploma
  • OTTC Ammonia Safe Handling
  • OTTC Risk Assessment (new)
  • OTTC Ammonia Design
  • OTTC has a fully functional Ammonia Training Plant since 2001 sponsored by the German and South African Industry.

Döbelin explains that ammonia refrigeration is mainly used in big cold stores for the food industries but is also used for manufacturing and especially mining industries. In South Africa ammonia has been used since 1930 and there are +/- 3 800 ammonia plants in use. These are mainly large plants, but even smaller plants are today using ammonia, where an owner insists on using a natural refrigerant.

“One client like this is Nestle. The reason for their use of a natural refrigerant is that they don’t contribute to global warming nor ozone depletion and therefore are environment friendly. Nestle’s new head office in Johannesburg is indirectly cooled with ammonia refrigeration. Ammonia cools the water and a second circuit is cooled with this water to cool the water being used in the building. The possibility to get ammonia into the second circuit is thereby minimised,” she adds.

Ammonia is produced in South Africa and is much cheaper than other refrigerants, with Sasol producing about 610 000 tons annually.

Students on one of OTTC’s ammonia courses. Image credit: ©Eamonn Ryan Cold Link Africa

Students on one of OTTC’s ammonia courses. Image credit: ©Eamonn Ryan Cold Link Africa

Döbelin lists bigger plants using ammonia as:

  • Large cold stores used for export of fruit – citrus, apples and pears
  • Decidua sub-tropical fruit uses exclusively ammonia
  • Breweries
  • Wineries
  • The chicken industry uses ammonia for spiral and holding freezers
  • Cold stores for holding imports and exports from other countries
  • The food distribution industry uses ammonia for freezer holding rooms (one plant was build and commissioned in 2015 in Johannesburg to hold 45 000 pallets of frozen goods)
  • Abattoirs mainly use ammonia for large and smaller plant – for instance, City Deep slaughters 6 000 to 8 000 heads a day
  • Using ammonia for freezing products in plate freezers
  • The ice cream industry
  • The fishing industry to produce flake and slush ice
  • In gold mines flake and slush ice are also used
  • Ice skating rinks
Ammonia plant at OTTC. Image credit: ©Eamonn Ryan Cold Link Africa

Ammonia plant at OTTC. Image credit: ©Eamonn Ryan Cold Link Africa

Döbelin describes the regulations in South Africa: “The first Ammonia Safe Handling Course was demonstrated and implemented in 2004 at OTTC, which OTTC and ACRICSA developed and registered at SAQA to enable regulation and standards for ammonia in 2014. The first assessment and cards were thereafter issued to the first participants. SARACCA is the official organisation for this regulation for South Africa

“In October 2014 the regulations of our standards became law. They are regulated in South African National Standard (SANS) 1017, the regulations being similar to those in the EU, but in some areas even stricter. Most of our pressure vessels have to be stress relieved (post weld heat treatment). Compulsory checks of all plants are in place with monthly, three monthly, annual and three yearly checks having to be done. These are to be carried out by trained persons with a license to work on ammonia plants and must be recorded in a compulsory logbook.”

“The recordings and other compulsory checks are checked by AIA (authorised inspections authority) every three years, for example, by globally recognised testing and certification body TUV. Several institutes in South Africa are authorised to train technicians to obtain the required license.

“Three levels are available and have to be renewed every three years:

  • Level A  : is the operator and cannot work on the plant
  • Level B  : is the person who can maintain and repair the plant
  • Level C  : is the designer, commissioning engineer and inspector

Döbelin suggests the future of ammonia is bright as it is the best oldest and natural refrigerant. “Most of the people are afraid of ammonia because it can be dangerous when one is exposed to it. In fact it is a very safe refrigerant because its self-alarming and even the smallest leak can be immediately detected by its odour, enabling one to be quickly cared for by professional trained technicians. Therefore don’t neglect to train your staff working in the environment and plant room.”

R32 and global warming potential

According to a White Paper4 by Daikin Corporation on R32, hydrofluorocarbons (HFCs), as the name suggests, are compounds containing hydrogen, fluorine and carbon. They are used for residential and commercial heating, ventilation, and air conditioning (HVAC) as refrigerants, by firefighters as a fire suppressant, and in aerosols as propellants.

HFCs are also greenhouse gases often described in terms of their global warming potential (GWP), which is the tendency of a substance to persist in the environment while absorbing energy and, thus, retain higher energy and temperatures in the atmosphere.

GWP ratings for substances and material that contribute to the potential of global warming are developed by the Intergovernmental Panel on Climate Change (IPCC), a United Nations body responsible for assessing the science related to climate change.1

GWP uses the same scale to evaluate all substances and materials, making comparisons of direct emissions of refrigerants easy. For example, R410A – a commonly used HFC refrigerant over the past two decades – has a GWP of 2088, which suggests that each kilogram of R410A emitted to the atmosphere is equivalent to 2088 kilograms of CO2 emissions. Different refrigerants have different GWPs:

R32, or difluoromethane (CH2F2), is an HFC refrigerant with a GWP of 675, which is markedly lower than that of R410A and many other commonly used refrigerants. However, GWP is only one refrigerant property and not the only measure of a refrigerant’s environmental impact when employed in HVAC systems.

To estimate the total emissions-related effects of a refrigerant’s use in HVAC systems, environmental researchers often employ a methodology known as Life Cycle Climate Performance (LCCP) modelling. LCCP modelling estimates the total direct and indirect greenhouse gas emissions over an HVAC’s system’s lifetime, from manufacturing to disposal and recycling.

Put differently, an LCCP analysis considers a refrigerant’s physical properties and thermodynamic performance as well as the impacts of that refrigerant’s use in an HVAC system to estimate total CO2 equivalent emissions over that HVAC system’s lifetime.

R-32’s properties can help HVAC engineers design systems that have a lower greenhouse gas emission impact than R410A. R-32 has greater latent heat capacity than R410A, which means that R-32 systems could be designed to achieve the same capacity performance by circulating less refrigerant at a lower flow rate through the compressor. A lower charge of R-32 refrigerant in comparison to R410A allows HVAC engineers the opportunity to design smaller compressors and coils.

These characteristics of R-32 help give engineers the tools they need to design R-32 systems with energy savings and a reduction in the material used. These indirect benefits can have a significant impact on the environment that are not accounted for in a GWP rating alone.

Daikin lab tests on rooftop systems equipped with inverter-driven compressors and water-cooled chillers found that full-load and part-load efficiency rating metrics improved by up to 12% by using R-32 as compared to R410A. Daikin engineers have also found that R-32 can be used in heat pump and cooling applications and extreme cold and hot climates with improved performance over R-410A. According to the EIA projections, 94% of the required energy for operating air conditioning systems was provided using electricity from non-renewable sources.

References

  1. Previous issues of Cold Link Africa – contributor Andrew Perks
  2. CAREL media release
  3. Open Trade Training Centre (OTTC)
  4. White Paper by Daikin Corporation on R32 Regrigerant – com

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