Some 350 experts from over 150 companies and 25 countries gathered at the Crowne Plaza Fira Center Hotel on 19-20 April to hear how new technological innovations are bringing high-efficiency CO2 refrigeration systems to higher ambient temperature regions than had previously been considered technically and economically feasible.
“CO2 transcritical systems should operate in the same way whether they are in a northern European climate or a southern one,” declared Jonas Schönenberger of Frigo-Consulting.
A combination of liquid ejectors, vapour ejectors and heat exchangers together led to an efficiency increase of between 15-25% at Swiss retailer Migros’ Mythencenter superstore, for example. With site-specific customisation, the Mythencenter demonstrates that CO2 transcritical systems can be very successful, Schönenberger argued.
“One final barrier limiting the full deployment of CO2 transcritical systems is the question of efficiency and sustainability in warmer climates,” said Diego Malimpensa, Business Unit Manager – Retail Solutions at CAREL Industries S.p.A.
With this in mind, CAREL and Carrier Commercial Refrigeration Europe have joined forces to develop and industrialise a range of modulating ejectors in a bid to put an end to the so-called ‘CO2 equator’: the previously accepted geographical limit for cost-effective construction of CO2 systems in all food retail store formats. “We’re now moving from concepts to real industrial sustainability solutions,” Malimpensa argued.
Presenting a new series of adjustable CO2 ejectors for commercial refrigeration systems, Sascha Hellman – project leader for systems development at Carrier Commercial Refrigeration – said that the company’s transcritical CO2 system with the CO2Oltec ejector rack was capable of reducing the average energy consumption of a total refrigeration system by 13%.
“Carrier provides optimised energy solutions with sustainable refrigeration technologies for every food retail store format,” said Hellman, explaining that the CO2OLtec system’s three working modes were suitable for all seasons.
EU F-Gas Regulation boosting natural refrigerant uptake
Danfoss, meanwhile, argued that the EU’s F-Gas Regulation is encouraging greater uptake of natural refrigerants for supermarket refrigeration. Torben Funder-Kristensen, Danfoss’ Head of Public and Industry Affairs, showed how variable capacity ejectors improve the efficiency of CO2 as a refrigerant in supermarket applications.
Funder-Kristensen explained how fixed, optimsed geometry ejectors operating in parallel can vary the capacity by operating only partially. Ejector efficiency can reach up to 25% even in high ambient temperature conditions, he argued.
R774 can also be used as a refrigerant for direct space heating and cooling applications, reducing energy consumption and related costs still further when used in conjunction with refrigeration and freezing equipment, revealed a case study presented by Sergio Girotto, president of enEX.
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