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CARRIER ABSORPTION CHILLER SERVES NEW ARTS CENTRE
The Baltic Flour Mills — a former silo building on the banks of the River Tyne, which is being transformed into the largest UK contemporary visual arts venue outside London — will benefit from a state-of-the-art combined heat and power (CHP) system that features Carrier absorption chilling technology.
Gateshead Metropolitan Borough Council (GMBC) commissioned Aircogen to design, build and install a CHP solution to the heating, cooling and power requirements of the converted grain warehouse. Two years’ collaboration between Aircogen and engineering consultant Atelier Ten led to the development of an innovative CHP system incorporating a 400kW Carrier absorption machine.
The resulting system conceived for Baltic Flour Mills is a single pre-tested and commissioned package designed and built by Aircogen, which contains all the equipment necessary for the efficient provision of heat, chilled water and a secure supply of power sufficient for normal building operation.
The main plant is located in an energy centre at the east end of the building, and the original design included cogeneration combined with absorption refrigeration and heat rejection, via heat exchangers, into the nearby Tyne. In the event, detailed analysis and life-cycle costing revealed that the river water-cooling concept should be dropped in favour of a more conventional air-cooled arrangement. However, the CHP and absorption elements remain.
A key feature of the Aircogen system is the provision of a “no break” supply, which essentially allows the CHP unit to operate as a rotating uninterruptible power supply. This means that, in the event of instability in the electricity grid provision, the main building will be disconnected from the grid and run “island mode” until such time as a stable external supply is available once more.
The entire air and water plant incorporates variable speed drive controls, as such devices have proved to represent a wise investment — owing to significant potential savings in pump and fan power — in arts centres, which generally operate only rarely at full load.
The building’s mechanical plant — including the CHP, much of the lighting and the fire security system — is controlled through an open-architecture building management system.
Due for completion during 2001, the 42m high Baltic Flour Mills complex will eventually contain five art exhibition areas — including one 800 sq m “high art space” — a cinema, library, café, bookshop, information centre and rooftop restaurant. Once fully operational, it is expected to play host annually to some 350,000 visitors.
Carrier absorption technology
At the heart of the air conditioning element of the CHP system is a Carrier 16JB absorption chiller with a cooling capacity of 350 kW and very low electrical load — no more than 20A— a characteristic of particular importance in a CHP context.
Although Dr Willis Carrier first applied the absorption theory more than 60 years ago, in today’s increasingly environmentally conscious world, the absorption refrigeration option is proving more and more popular, owing to its high overall energy efficiency, low running costs, flexibility of application and absence of harmful refrigerants. Because an absorption machine uses water as a refrigerant and lithium bromide (a saline solution) as the prime mover – it has much less effect on global warming than conventional systems. And by utilising the waste heat which is the by-product of the CHP process, absorption machines dramatically reduce the overall generation of primary energy.
This innovative solution to cooling requirements has already been applied in a CHP context in UK applications situated as far apart as Jersey in the Channel Islands and Altrincham in the North West, and in premises as diverse as hospitals, office blocks, hotels, factories and department stores.
The cycle uses a secondary fluid to absorb the refrigerant which has been vaporised in the evaporator. A pump is then used to deliver the liquid to the generator. There, heat is used to drive off the refrigerant, which is turned back to liquid in the condenser.
The coupling of absorption and CHP can lead to overall system efficiency of an astonishing 95 per cent.
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