According to presenters at the Technology, Market overview and Market innovation sessions of the ATMOsphere Europe 2012 conference in Brussels, held 5-7 November 2012, the solutions for Southern Europe are available today. Today’s article brings the overview of the presentations addressing this hot topic.

Increased attention at ATMOsphere Europe 2012 was paid to CO₂ systems improvement and components development for increased efficiency in countries with higher average ambient temperature - key to change the out-dated paradigm that CO₂ systems for commercial refrigeration cannot be efficiently used in southern regions. Several suppliers presented their solutions ranging from new component development to optimisation of system configuration. The message across all of the presenting suppliers is clear: HFC-free solutions are ready for the whole Europe.

Market trends & developments for CO₂ in commercial refrigeration in Europe

As presented by Lothar Serwas from Carrier in the Market overview session, the third generation of CO₂ systems are currently evaluated with respect to efficiency, safety, reliability, environmental impact and modularity. Performance comparisons between various CO₂ system configurations - including the use of expanders, economisers, ejectors or mechanical sub-coolers - indicate that there will be more than one solution depending on the application requirements. Taking into account the available components today, the most promising and straightforward solution is the CO₂ system in combination with a mechanical sub-cooler, which offers the greatest potential for efficiency gains in southern climates.

100 kW R744 compressor for commercial refrigeration

High efficient compressor is an important element to move R744 application line further south. Christian Schmälzle from Obrist Engineering presented a prototype 100kWel R744 piston compressor for commercial refrigeration and large capacity heat pumps developed in cooperation with SINTEF Energy. This first prototype of the 100kWel combines a high efficient compact permanent magnet motor, improved valve system for high speed and speed controlled flow modulation. A test conducted in specially build facility indicated after more than 500 hours of operation that efficiency gains of 10% in comparison with competitors are possible.

Sustainability of CO₂ technology and the role of control systems

Diego Malimpensa from Carel introduced a simple and cost-effective solution for warmer climates - CO₂ booster with evaporative cooling - that leads to 5% higher efficiency than a reference HFC system in tested environment of Istanbul, Turkey.

CO₂ refrigeration in warm climates, efficiency improvement

Sergio Girotto from enEx offered two practical solutions available today for the use of CO₂ transcritical systems in Southern European climate. Overfed evaporators (reducing superheat losses) contribute to 10-12% energy savings in all climatic conditions due to lower compression work, at increased reliability and reduced total cost. Combined with a flash vapour recompression and an ejector (reduction of throttling losses) the energy savings in southern climate amount to up to 22% (referred to Italian climate).

Efficiency analysis and comparison of innovative CO₂ refrigeration systems

Jonas Schönenberger from Frigo Consulting presented the analysis of several CO₂ transcritical systems examined in search for an efficiency improvement. CO₂ transcritical systems with a parallel compression, an expansion-compression unit or an adsorption chiller deliver desired improvement and prove to be efficient at high ambient temperature. The CO₂ system with the adsorption chiller provides 6% energy savings due increased subcooling and additional 6% on energy saving on compression.

Read full article: http://www.r744.com/news/view/3677