Christian Heerup from the Danish Technological Institute (DTI) presented two papers related to CO2 refrigeration at the last Gustav Lorentzen Conference in Hangzhou, China: “Vortex flow sensor in CO2 refrigeration system” and “Load shifting by ice storage in retail CO2 systems.” R744.com sat down with Heerup to discuss the CO2 systems’ new areas of application and the remaining challenges for CO2 refrigerat
R744.com: Could you shortly highlight some of the key messages of your presentations?
Christian Heerup: Those presentations highlight some properties and accessories of CO2 refrigeration systems that might also be applied to other types of refrigeration systems. The focus of the two studies was on how to improve the efficiency of CO2 systems and on what measures could be taken to achieve this.
The first study described a field test of a flow meter that will help the industry to better analyse, monitor and automatise refrigeration system operations in the future. The three elements combined will lead to a greater efficiency of the systems at reasonable costs.
The second presentation explained how to load shift the power consumption of a CO2 system from day-time to night-time in different climatic regions, taking into account seasonal variations. The use of ice storage could be a solution in warm climate countries to minimise the power consumption of the plant. Those regions have to handle peak demands. If the peak period of the system can be moved to the night, it will have beneficial effects on the power grid and substantiate lower end-user tariffs.
Next year, together with the manufacturer Danfoss, we will test and measure the dynamics of load shifting on this system and try to analyse the results in terms of energy savings.
R744.com: What are the remaining challenges for CO2 refrigeration that still need to be addressed?
Heerup: CO2 system efficiency in warm climates is one. I also attended some very interesting presentations about ejectors and on how to improve the overall cooperation of all components to make systems more efficient.
But the industry still needs to address challenges such as how to make CO2 units for smaller capacities at reasonable costs. Another challenge is how to increase the size of a CO2 system to enter into the small industrial refrigeration application market.
There are still a lot of areas to explore, but the basis of all this is to increase the use of CO2 in supermarket applications. This will create the business case for component manufacturers and allow for the expansion of the applications of CO2 based technologies.
R744.com: Do you foresee a future where 100% of Danish supermarkets use natural refrigerant installations? How long before this becomes a reality?
Heerup: In Denmark, practically all new stores are already using CO2. Gradually, the technology will spread to other areas like food processing, but there will be competing technologies remaining on the market because not all installers and contractors will want to manage or handle CO2 systems.
R744.com: What impact does the revised EU F-Gas Regulation have on the uptake of natural refrigerant training courses, such as those offered by DTI?
Heerup: In Denmark, the EU F-Gas Regulation does not have a big influence because our national regulation already takes care of this. But generally speaking, the F-Gas Regulation focuses peoples’ attention on reducing the use of HFCs, which is especially important outside of Denmark. There will be great opportunities for Danish companies manufacturing components and systems compatible with natural refrigerants to address the European market because this market will grow dramatically. Until now, there have been a limited number of experts who are skilled enough to handle CO2 systems. This number must increase. And of course, there will be a need for training all over Europe.
R744.com: What are your plans for the future regarding natural refrigerants?
Heerup: Some challenges will be hard to meet in the near future. For instance, the ban on HFCs in Denmark left a window open for systems with a charge up to 10kg. This lead contractors to replace DX system applications with HFC chillers to meet requirements for higher capacity.
A current proposal in preparation from the Danish EPA is expected to contain regulation of the use of HFCs possibly by limiting the acceptable GWP rate of a single system, similar to the EU F-Gas Regulation. This would influence the market towards natural alternatives but also towards low GWP HFC solutions such as HFOs.
There is currently no natural solution available on the market at a reasonable cost, for applications between regular super market installations with CO2 and plugin units with hydrocarbons. Natural refrigerant alternatives in this capacity window are still 2-3 times more expensive than the available HFC technology. The application area would typically be small supermarkets, convenience stores, catering and cold rooms.
We need to fill that gap with alternative technologies that users can afford. There is an uncertainty on how to handle safety issues with HFOs and many stakeholders would like to promote natural refrigerants in this context. However, market volumes outside of Denmark are not yet big enough to support this effort. We can foresee that there will be more competition to come between natural and non-natural low GWP refrigerants.