Refrigerating with water? Why not!

No matter whether buildings, machines, processes or data centres are at stake: the conventional refrigeration generates an alarming quantity of CO₂ emissions. The problem is worsening owing to the fast world growth of the demand for cold – both as refrigeration and as conditioning 

Air refrigeration and conditioning units already today cause about 8% of global CO₂ emissions. According to Green Cooling Initiative (GCI) of the German Association for international cooperation (GIZ) GmbH Proklima, within 2050 about 9.5 billion cooling devices will be in operation worldwide. This is over 2.5 times the current number. If the refrigeration industry does not succeed in implementing important energy efficiency ameliorations, it will increase its energy consumption by 90%. In a “business as usual” scenario, yearly emissions of greenhouse gases by the refrigeration industry will have more than tripled by 2050.The global legislation has already reacted to this dilemma. Kigali Resolution on October 15^th2016 started the gradual reduction of noxious refrigerants for climate all over the world. In Europe, the EU Regulation (regulation on fluorinated gases n. 517/2014) rules the use of refrigerants with high GWP and, according to such regulation, the use of greenhouse-effect fluorinated gases must be gradually decreased by almost 80% within 2030. It is likely to suppose a total ban of fluorinated gases after 2030. Many users are currently wondering what solutions can allow cooling safely, permanently, in compliance with law and in sustainable way. There are already various solutions and one of them is based on the most natural refrigerant that exists: water.

Refrigerating with water: eChiller

At the end of October 2020, the German company Efficient Energy GmbH, headquartered at Feldkirchen, close to Munich, released the new eChiller120, a chiller that exploits water as refrigerant. It belongs to the family of eChiller machines, designed and implemented by Efficient Energy. They are the only refrigerating machines on the market that operate with R718 water, available as standard in a scalable power interval between 20 and 500 kW (in a modular system).

Actually, the eChiller is not the first absolute machine that exploits water as refrigerant. Water as refrigerant has already found applications for several years now in the absorption technology. Moreover, in the sector of turbo-chillers they have sometimes manufactured water machines, but they are very large and powerful – from 500kW up to even MW – and therefore they are both very bulky and very expensive. For this reason, they have never reached a real status of product available on trade as standard and mass-produced.

With eChiller, on the contrary, for the first time they have implemented a compact chilling machine, mass-produced, which uses water as refrigerant and is deemed both commercially and technically interesting. «Using water as refrigerant needs a change of point of view. Today the refrigeration industry is not used to thinking of water as refrigerant, but it has instead very useful features for refrigeration and cooling» states Peter Kader, Product Manager of Efficient Energy at the press conference on the occasion of the launch of eChiller120. The change of perspective, on the other hand, is neither so excessive, considering that a standard steam compression cycle is maintained with eChiller. With the difference that in this case it occurs in vacuum a very low pressures, around 20 mBars, and at temperatures ranging from 10 to 40°C, with components optimized according to the refrigerant.

Blue^zero®: technology with pioneering value for sustainable refrigeration

The technology developed by Efficient Energy, which allows using water as refrigerant, is marketed under the trademark Blue^zero® and to understand its innovative scope we should just consider that there are around 200 patents by the Efficient Energy company behind it.

Besides the use of water as refrigerant, characteristics of such technology are for instance the use of a new high-efficiency turbo-compressor specifically developed for this application, of specific exchangers and the fact the whole cycle takes place in vacuum. Components are integrated in innovative manner in a very compact cooling module. In the design of eChiller “35” and “45”, two cooling modules are connected so that the refrigerant is simultaneously cold water in evaporators and chilling water in condensers. Therefore, inner volume flows occur with minimal energy losses. The modular system design allows operating just the necessary parts of the system to supply the respective cooling capacity demanded, according to both the internal thermal load and the outer temperature. Transitions are fluid and range from the two-stage operation at full load to single-stage one and to the pure free cooling operation. The management of machines is very user-friendly. They are plug&play and centrally controlled. The installation of the eChiller is the same as for standard machines.

eChiller120: a new generation of Chiller

With the release of eChiller120, the eChiller family, which until now included machines with 35/45 kW cooling capacity, is widened. «With eChiller120, we are expanding our portfolio to include a more powerful version that, however, has maintained its compactness through a design change and then can be used more flexibly», explains Georg Dietrich, managing director of Efficient Energy GmbH.

The eChiller120 will be prompt for delivery since Summer 2021. The first orders have already been sent. It has a higher power than its “little brothers”. In addition to better energy efficiency – up to 82% versus conventional systems – the new Chiller also stands out for its low maintenance requisites and flexible installation options. Using water as refrigerant, it is possible to reach many companies’ legal requisites and climatic targets to reduce the CO₂ footprint of synthetic refrigerants.

The cooling process principle works like in the smaller eChiller 35/45 (35 and 45 kW). During the commissioning, the softened tap water is input into the chiller as refrigerant and then it is used in a closed circuit to generate cold. However, the innovation resides in the fully redesigned structure and in an improved compressor concept. The turbo-compressor purposely developed by Efficient Energy GmbH has been widened and directly integrated into the heat exchanger module, which notably increases the efficiency of the refrigeration machine. Despite its bigger power, eChiller120 reaches a comparably low sound level compared to eChiller35/ 45. New is also the strategic introduction of some configuration options. This includes, for instance, an optional housing and a free cooling module, a

module to expand the partial load and other options for the regulation of system peripherals. Besides, the eChiller120 can be easily connected with an existing cooling system and is equipped with an energy-optimized refrigeration control. It can also work in cascade with a CO₂ plant where it executes the system post-cooling.

A technology, several applications

Due to its scalability and modularity, the eChiller allows satisfying applications that need more cooling capacities.The eChiller120 is ideal for the process cooling, the chilling of machines and the technical air conditioned and therefore it can be used, for instance, in mechanical engineering, automotive, rubber or plastic industry, or for the refrigeration of data centres, control centres and sale servers. «Our technology is perfect wherever chilling without condensation is required. It is worth reminding the plastic processing industry, tires, the chemical and pharmaceutical industry, calculation centres, all applications that need bare and raw cooling between 14 and 20°C. They are all applications in which the eChiller can excellently carry out its high-efficiency zero-emission functions», states Thomas Bartmann, Sales Manager of Efficient Energy GmbH.If the cooling requirement is even higher, eChiller120, due to its modular scalable structure and an integrated optional composite control, can be installed in net and reach a chilling performance of over 500 kW.

The new Chiller marks just the beginning of the product range widening. «The market potential of Blue^zero® technology is not exhausted at all and we are already working at further developments. For 2020/2021, we have made huge investments in the infrastructure and in the development of laboratories, to introduce the green cooling on the market as quickly and widely as possible», Georg Dietrich underlines. At the same time, the company is expanding its distribution network and aims at accomplishing further collaborations with OEM. «This is the only way enabling us to exploit further the market potential of Blue^zero® and to achieve an impact in the fight against the climatic crisis”, Dietrich affirms.

What about costs? «The investment return depends on the sector, but for Germany it can be indicated as <4 years. Concerning foreign markets, we cannot express precise statements about ROI because of sometimes much lower electricity prices or maybe the presence of specific schemes of financial support for sustainable technologies», Dietrich explains.

More than a machine, a new refrigeration model

The Blue^zero® technology, which makes water usable as refrigerant, has certainly an absolute pioneering value: they are not known on the market other examples of mass-produced products that use water as refrigerant efficiently and that therefore so punctually accept the sector challenges of drastically decreasing direct and indirect emissions. Actually, what Efficient Energy proposes goes far beyond the eChiller in itself, it exceeds the machine but it is the concrete example of how this new technology can be implemented and used successfully. Ultimately, it is a new cooling model. This fact, seen in the present context where the demand for cold technologies is rising, not negligibly owing to climatic changes and to global warming, confers a milestone value to the technology. The conditioning and refrigeration industry is growing. The yearly turnover amounts to around 80 billion dollars all over the world. In the only Germany, there are about 120 million chilling machines, 3 millions of them in industry. The big number of air conditioning systems causes extremely high emissions through the use of noxious refrigerants for the environment such as fluorocarbons (HFC). Furthermore: owing to the missing energy efficiency, every year over 17% of the global energy consumption is used for the air cooling and conditioning. In the only Germany, the energy consumption for heating and cooling represents 50% of the total energy consumption. This makes the refrigeration industry a scarcely striking but powerful engine of the climatic change. With these numbers and this scenario, the urgency of sustainable solutions is more pressing than ever. Moreover, medium-term solutions are no longer acceptable: we have no more time for them! Solutions must be necessarily disruptive and long-term, Blue^zero® is precisely framed in this trend.«A refrigeration market with 100% natural and climatically neutral refrigerants is possible; technologies are available and they make sense also from the economic point of view. It is mandatory to arouse even higher awareness of the refrigeration industry importance in a global context and to defeat the lobby of big synthetic suppliers», states Thomas Bartmann, sales manager of Efficient Energy GmbH.

How does the eChiller operate?

The eChiller uses the same refrigeration principle (steam compression process) as conventional refrigeration machines. eChiller 35/45 exploits about 60 litres of softened tap water in a closed circuit. In the eChiller120, there are 80 litres of water. The heat from the client-consumer circuit is absorbed by heat exchangers and makes water evaporate in the evaporator (vacuum). This steam is compressed by the special turbo-compressor and brought to condensation – liquefaction in the condenser, which is cooled by chilling water. The cooling water absorbs the condensate heat and can be used in other ways.

The turbo-compressor installed on the machine and developed by Efficient Energy is characterized by:

• Very low noise level due to vacuum;
• Good controllability;
• High efficiency at partial loads;
• No initial current peak.

The eChiller is designed for input water temperatures between 10 and max. 40° C. However, Efficient Energy is working at a development that will allow the use of water as refrigerant in the hottest Countries, too.

Water as refrigerant

Water is probably the safest refrigerant in absolute. It will be always available everywhere and it will be never forbidden. It is not subjected to patents and it does not suffer from fluctuating costs. Direct emissions are null, the environmental impact inexistent. In incoming years, many of the refrigerants used today will disappear or strongly decrease because they cannot satisfy the environmental emergency. The cost of the electric energy is rising and will be further charged on the cold production.

Moreover: most of natural refrigerants have characteristics – flammability, toxicity and high operation pressures – used by some parties as argument to slow down their diffusion on the market and to create mistrust in them a priori. Water has none of these features and does not arise any complication. Concerning this, it might easily pave the way to the use of natural refrigerants in the applications above reported.