History of a New Technology - Part 6
Beyond the CO2 Equator – Southern Europe and Total Integration
For years, the refrigeration sector—historically very conservative—fueled strong skepticism against carbon dioxide.
In the beginning, “experts” were saying that CO2 was simply not suitable for refrigeration at all. A few years later, faced with the evidence of the first successful plants, the criticism shifted: it was said to be a solution limited to the cold climates of Northern Europe. Detractors even spoke of a “CO2 Equator,” an imaginary latitudinal boundary below which the technology would never be cost-effective.
The challenge in that period was to tear down these prejudices, proving that with the right technical architecture (optimized cycles and ejectors), R744 was competitive even under the Mediterranean sun.
1. Conquering Southern and Eastern Europe
The turning point for the expansion in the southern Europe was 2013.
The success of these sites finally opened doors to markets where skepticism had previously reigned (France, Spain, and Italy itself). Shortly after, the wave of innovation reached Eastern Europe, with the first plants in Poland, Croatia, and Romania.
Different manufacturing techniques were studied by the manufacturers. For example some used welded carbon steel for the piping, while others adopted stainless steel. It was an important element, much different from previous refrigeration installations with HFC, where brazed copper was used.
Advansor (Dover) mainly was expanding its market, thanks to a strong effort in standardization and industrialization, while Enex was more specialized in development and R&D, thanks to the connections with Sintef and CNR of Padova. A good help for spreading CO2 technology came from Shecco, with its informative activity.
More suppliers introduced in their range components designed for CO2- compressors, valves and heat exchangers - so competition at all level started. A “new” alloy (K65) was introduced for the piping by Wieland, which for small plants allowed to use brazing process, instead of the more demanding welding.
In 2014 the new F-gas regulation was in preparation. It entered in force 1st of January 2015. It introduced clear limitations to the use of syntetic refrigerants, finally convincing most of the users that natural fluids were the right choice for the future. Of course CO2, being no toxic and non flammable, was the candidate for retail refrigeration and light industrial refrigeration.
2. Italy and the “All-in-One” System
Another decisive chapter opened in 2014 in Trentino-Alto Adige. Collaborating with Realtime, a trusted local installer for a major regional retailer, Enex began implementing revolutionary combined systems.
It was no longer just about “making things cold”: the central unit was now capable of simultaneously producing refrigeration, space heating and cooling. Summer air conditioning was integrated into the system, transforming the refrigeration rack into the true energy heart of the building.
3. The Chiller with Flooded Evaporator
In 2016, Enex introduced a radically new chiller design based on the principle of the gravity-flooded evaporator, new for CO2, but well known in industrial ammonia systems. Installations for skating rinks were done in Scandinavia by Green&Cool and Huurre, and by all the companies in general in light-industrial plants.
A new sector for CO2 chillers was the north-Italian wineries, introducing environmental advantages in this demanding sector.
Shortly after it was introduced a variant of gravity-fed chillers featuring the ejector—another Enex invention. This adjustment allowed for an efficiency improvement of approximately 10% specifically during peak thermal conditions, where CO2 refrigerant chillers typically struggle the most.
4. Zero-Cost Heat: Heat Pumps and High-Temperature Recovery
One of the most extraordinary thermodynamic advantages of CO2 in the transcritical cycle is the gas temperature at the compressor discharge. While in traditional systems the discharge heat has a low temperature and it is difficult to reuse, with CO2 the refrigerant temperature after compression can exceed 90-100°C.
- Hot Water and Heating: since 2008 solutions were developed to recover part of the heat available, so as to produce domestic hot water or space heating, practically at zero cost.
- Total Integration: In modern supermarkets, the new units eliminated the need for gas boilers or separate systems.
Essentially, the heat “extracted” from the refrigerated display cases to preserve food becomes the resource used to heat the store and the sanitary water. A perfect example of the circular economy applied to engineering.