To ensure a consistent quality of foodstuffs, it is essential to ensure an uninterrupted cooling chain. More than 60 percent of all foods such as meat, milk and fruit would otherwise perish very quickly. Cooling these goods is a challenge for cold store operators: The method used needs to be safe. At the same time, economic pressures force them to minimise the energy needed to deliver the vast amount of cooling required. "Refrigeration systems that use natural refrigerants play an important role", says Mark Bulmer, board member of eurammon, the European initiative for natural refrigerants. “Thanks to the thermodynamic properties of ammonia, carbon dioxide and hydrocarbons, systems run with natural refrigerants are very energy efficient and offer potential for saving energy by up to 30%.”
Germany – Fresh fruits and vegetables from farm to store to consumer
The international logistics services company Gartner KG, headquartered in Lambach, Austria, has recently begun operating a modern distribution centre for fruits and vegetables in Kehl, Germany. A long-lasting and dependable refrigeration plant with low energy consumption and environmentally friendly with a sustainable refrigeration concept were the key specification requirements. The cold store has been designed by KWN Engineering GmbH according to state-of-the-art technology using the natural refrigerant Ammonia (NH3) R717 in the chillers and complies with the requirement of the customer for a long-term environmentally friendly refrigeration concept. The system uses a secondary loop to distribute the energy to the cooling points, the food-safe coolant propylene glycol is the secondary refrigerant fluid.
The chillers generate cold using two separate liquid cooling units from Grasso in flooded operation – two NH3-reciprocating compressors with 220kW and two NH3-reciprocating compressors with 640kW. Heat is removed via an evaporative condenser from Evapco that is situated directly above the chiller units. In designing the plant, special consideration was given to the very low partial loads which can occur in a food storage facility. The air coolers from Güntner used in the stock area are speed-controlled and can be regulated individually. The plant designers made sure that air distribution was constant and with no blockages, even though high humidity is possible.
In selecting a suitable piping system for the refrigerant, several criteria were decisive, namely; long lifetime, efficiency, light weight and ease of installation. Due to its excellent price and performance ratio the pre-insulated plastic piping system Cool-fit from Georg Fischer was chosen. The system consists of fittings and pipes, pre-insulated by the manufacturer, which can be installed easily with a simple reliable pipe jointing technique. The piping system was installed in the mechanical equipment room without pre-insulation. These ABS fittings, pipes and valves (butterfly valves, filters, compensators) were post-insulated using a rubber based insulation.
With this new distribution centre, the Gartner Company has constructed a state-of-the-art cold store with lowest possible carbon foot- print cost effectively.
Consistent refrigeration for guaranteed freshness
For meat-processing companies, it is particularly vital to maintain the cold chain throughout all phases of production. In order to fulfil this demand, KÄLTETECHNIK Dresen + Bremen planned and produced a modern refrigeration system for the new building under construction for Großmetzgerei Gruninger [industrial butcher], thus providing provide optimum temperatures in all production areas. The refrigeration supply system for the entire production area was successfully commissioned in April 2010, consisting of a complex NH3 / glycol refrigeration system with total refrigerating capacity of 1,800 kW. The condensation energy generated by operation of the refrigeration system is recovered for the most part and used for heating purposes and for producing hot water. Speed-controlled screw compressors in a combined system ensure maximum operational reliability. One special feature includes equipping the production rooms with a system for intensive dehumidification after wet cleaning. The refrigeration system is fitted with a process control unit with network link and remote data transmission for simple, clearly structured operation and monitoring.
Altogether the refrigeration system with 69 air coolers is responsible for the production rooms together with the chilled deep-freeze and storage rooms with a total surface area of 6,000 m2. Corresponding distribution takes place through a ramified glycol cooling and heating circuit in the technical mezzanine with a total volume of approx. 25,000 l. Actual refrigeration takes place in the central machine room using the economical natural refrigerant ammonia (NH3) with a filling of 2,500 kg.