Propane as refrigerant in food retailing

“Heating and Cooling in food retailing” was the topic of the Supermarket Symposium organised by the German Association for Refrigeration, Air-conditioning and Heat Pumps (Zentralverband Kälte Klima Wärmepumpen) in Nürnberg. On this occasion, Jörg Fuhrmann from Futron GmbH gave a presentation on his company's project of conceiving an integral system for heating/cooling/air-conditioning systems with hydrocarbons for the German food retailer Lidl.

Lidl's motivation to move to propane

Lidl was confronted with continuously rising energy costs, different energy consuming machines with individual controls, and legal requirements such as the German 2009 Renewable Energy Heat Act (EEWärmeG) and the 2009 Regulation on Energy Saving (EnEV), as well as possible future taxes on f-gases and an obligatory CO₂ balance sheet for companies.

Lidl's project specifications

The German discounter had a clear picture of what they expected from the new system:

• use of natural refrigerants
• combination of heating/cooling/air-conditioning
• integration of functions such as lighting, ventilation etc. - no additional central building control systems
• no separation of functional areas (heating, cooling, air-conditioning, control)
• compatibility of all equipment types
• no changes for the sales area
• ensure that there are no taxes, charge limitations or leakage controls for natural refrigerants in the pipeline
• regenerative use of energy for heating purposes (in compliance with the Renewable Energy Heat Act)
• service and maintenance from one provider
• same investment with faster amortisation
• decreasing costs for heating and cooling
• possibility to use the new equipment in the whole of Europe from Spain to Scandinavia

Why hydrocarbons in food retailing

Isobutane (R600a), propane (R290) and propene (R1270) have good thermodynamic properties but are flammable. The flammability factor can however be mitigated through outdoor installation (at ground level or on the roof). Large installations with important refrigerant charges require automatic ventilation to avoid the formation of explosive gas concentrations. Nonetheless, hydrocarbon refrigerators and freezers are state-of-the-art, and the segment of hydrocarbon frozen food storage cabinets and deep freezers is growing. Propane is also becoming an established refrigerant in water chillers for room air-conditioning.

Important system safety features

Safety is important and even more so with flammable refrigerants of course. Safety features inside Lidl's refrigeration plant are:

• tightness of joint pieces to prevent leakage
• the housing plays an important role for measuring the gas volume
• a gas sensor switches automatically all electrical components off in case of gas detection
• in case of average, an ATEX ventilator evacuates the gas mixture into the outside air to avoid the formation of explosive atmospheres
• system quality check by the manufacturer before delivery

Gained insights

The use of the integral system at Lidl has shown that propane can be efficiently and safely be deployed in commercial refrigeration. It is affordable and thanks to energy savings the costs can be amortised in only a few years time.

In Lidl markets, the waste heat from the cooling equipment combined with other heat loads in the market suffices to cover space heating. The rest of the heat demand is satisfied through the use of heat pumps that are also used for air-conditioning during summer.

To date, Futron has delivered around 60 systems, of which the first prototype is now operating for two years.

Award winning system

Thanks to this integral system, Lidl received in 2009 the Energy Management Award by the German EHI Retail Institute in Cologne, which honours the best projects in energy saving and resource efficient use of energy in retail stores. In the same year, Futron received the German Prize for Refrigeration Engineering from the German Environment Ministry.