Cool Farnborough— Carrier’s air show
What really captures attention at the Farnborough International Airshow is flying displays by the likes of the Airbus 380 (below) and the wow of this year’s show, the Lockheed Martin/Boeing F-22 Raptor.
The world’s aviation industry meeting at Farnborough in July expects a comfortably cool indoor environment. Enter Carrier Rental Systems — as Ken Sharpe describes.When the Sun comes out at Farnborough International Airshow, watching the flying displays is a very pleasant experience — albeit ear-shattering as military planes are put through their paces. This year’s show, the 60th, ran for seven days from 14 to 20 July and saw a return visit of the huge Airbus 380. In the vast areas of temporary buildings housing the exhibition stands, however, conditions would be intolerable without cooling provided by the largest collection of temporary air-conditioning put together in the UK. Managing director Keith Browse says that Carrier Rental Systems has more than three-quarters of the air-conditioning contracts on the site. The brief facts are that 14.5 MW of temporary cooling was provided by Carrier Rental Systems, 12.5 MW of which serves the four exhibition halls (see photo) and the vast majority of the corporate entertainment areas. The largest, Hall 4 toward the top left, is over 20 000 m2 and could well be the largest single cooled temporary space in Europe. The smallest is a relatively modest 10 000 m2. The power consumption of all this cooling equipment outstrips the available electricity supply, so Carrier also supplied or organised 6.9 MW of generator capacity, which runs at a conservative 75% for secure and economic operation. An indication of the scale of the generator capacity is given by the fact that 40 000 litres of diesel was delivered before the show, with two further deliveries of 20 000 litres each during it. It is a project that Carrier Rental Systems has been involved with since 2000, when the show first moved to the middle of July from its previous slot towards the end of September and it was deemed necessary to provide comfort cooling in the quality temporary structures that house the trade stands. The contract continues to the 2010 and 2012 shows. It’s a mammoth project, with the setting up beginning on 19 April and occupying a team of six throughout the build-up. During the show, a team of five engineers is resident on site to attend to any problems with the air conditioning, further supported by two generator engineers. After the show nearly all the equipment will have been removed and sent on to new hires within three weeks. Some chillers have to be put into position at an early stage before the temporary buildings arrive. The mainstay of the air conditioning in the exhibition halls is the distribution of cool air through lengths of textile ducting up to a hundred metres long. There is no target set temperature, but the benefit of the air conditioning is very apparent to people coming in from outside. It is also very quiet. In Hall 1, for example, (the longest, but not the largest hall in the aerial shot), four Aquaforce air-cooled chillers using R134a each have a cooling capacity of 450 kW. Each chiller supplies chilled water at 7/12°C to an air-handling unit that supplies 60 000 m3/h of cool air at around 19°C to the space. Virtually all the chillers are new this year and incorporate micro-channel coils to significantly reduce refrigerant charge. A 750 kW chiller, for example, has a charge of less than 100 kg, compared with 160 to 180 kg for the chillers used two years ago. There are two chiller/AHU combinations at each end of Hall 1 serving duct runs that stretch halfway along its length. Air leaves an AHU through 1.2 m square galvanised duct up the end of the temporary structure before changing direction and to a circular cross-section to pass through the end wall. This connection is Teed off to serve two lengths of textile duct. The overall effect is that Hall 1 has four lengths of flexible duct coming in from each end. The ducts start with a diameter of 1.2 m and taper down to 800 mm and finally to 600 mm. The system is similar in the other three halls. At Hall 2, the chillers and AHUs are in the middle of one side. Hall 4 has a double-ridge roof with four lengths of duct in each part. Hall 3 also has a double-ridge roof, but is rather smaller and so requires only two lengths of ducting in each part. An energy-saving feature introduced this year is for half the air-handling units in each hall to operate on 100% air recirculation, with the others on 100% fresh air as always. Keith Browse expects this measure to reduce overall energy consumption by 10 to 15%. Experience with the 2006 show, when outdoor temperatures reached 38°C, led to the installation of more cooling capability this year to avoid problems of extreme discomfort. The ducted systems enjoy the support of a considerable number of air-recirculation units with chilled-water coils. Warm air is drawn in at low level, and cool air is discharged at about head height. These air-recirculation units have capacities of 20 and 50 kW. There are around 300 such units, served by chilled water carried through flexible pipes from externally sited chillers through channels in the ground that have been excavated in previous years. At one end of a aisle running across the width of the centre of Hall 3, four 50 kW units are installed in pairs back-to-back to send a stream of cool air right across the middle of the hall. In the restaurant at ground level running along one side of Hall 1, cooling is provided by dozens of 20 kW recirculation units. They have moving louvres for more effective air distribution and 3-port valves. The prestigious restaurant on the first floor is served by a ducted system. Richard Jones, international director with Carrier Rental Systems, says of this project, ‘The nice thing from the client’s point of view is that there is a lot of trust and understanding. Problems are addressed during an extensive planning phase — unlike a lot of emergency hires.’ Pictures 1 and 2: Textile ducts carry and distribute cooled air from air-handling units to the vast temporay exhibtion halls. Pictures 3 and 4: Cooling is also provided in exhibition halls and the restaurant (right) by air-recirculation units served by chilled water. Picture 5: Up-to-date R134a chillers with a total cooling capacity of 12.5 MW served the four exhibitor halls at the recent Farnborough International Airshow.
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