Project First has helped Tesco make its new ECO store at Wick, Scotland even greener. The innovative refrigeration project management company was set the challenge of reducing the HFC Refrigerant Charge for the store by a minimum of 50 per cent. It was asked to use natural refrigerants wherever possible, and deliver a heat recovery system that did not compromise the efficiency of the refrigeration system.
The cold rooms at the store were designed to operate with R744 (CO2), which is a natural refrigerant and were designed to operate via dedicated Trans critical CO2 condensing units. The units were designed in conjunction with an Italian manufacturer and connected to conventional evaporators.
Project First achieved the reduction in the percentage HFC by providing an integralised direct expansion water-cooled system that consisted of slim-line Refrigeration Pods placed on top of each display case and coldroom. Each Pod has a hermetically sealed horizontal scroll compressor, water-cooled by a plate heat exchanger. The display cases and cold rooms are connected radically to two independent water-cooling systems (to provide diversity), which consist of a dual pump and roof mounted dry air coolers. This proved the following benefits;
The plate heat exchangers provide up to 280 kW of heat recovery.
The heat exchangers supply low-grade heat (between 20 to 31 degrees C) to pre-heat coils sited in the main air-handling units.
The dry air coolers use low energy EC Fan motors that are by-passed at a pre-set temperature, with the cooling medium then being diverted to the heat reclaim system.
The installation of this Integralised HFC R404a system has led to the ECO stores refrigerant charge being 55 per cent lower than if a conventional DX system had been used.
Overall Tesco Wicks carbon footprint is heading towards 50% of an equivalent store using technology that will be repeatable in future stores.Delivering 800 Tonnes Carbon saving (Energy and Materials) on Refrigeration.
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