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Technology: Sun-dried air cuts cooling costs

Technology: Sun-dried air cuts cooling costs

作者:端噤霾  时间:2019-02-26 07:15:00  人气:

AN air-conditioning system powered only by solar energy could cut cooling costs by up to 95 per cent in hot, humid climates. The Florida Solar Energy Center in Cape Canaveral has devised a passive solar cooling system for climates such as that of the south-eastern United States. The system could reduce the energy needed to cool a house by 65 per cent a year in Miami and up to 95 per cent a year in Atlanta, says engineer Armin Rudd. However, Rudd concedes that the capital cost of the system – initially estimated at $10 000 – is too high unless conventional energy costs start to climb. The system consists of a desiccant made of silica gel which is embedded in roof panels. At night, moist air from the house flows through the panels which absorb the moisture. During the day, the sun heats the desiccant, driving out the moisture, while the air dried out the previous night keeps the house cool. Successful operation requires night temperatures that are at least 8 Degree C cooler than those in the day. Cooling systems for hot, dry climates have used desiccants before, but they have not been used for hot, humid regions, according to Rudd. The Florida researchers calculate their system’s performance with computer models which compare energy needs for air conditioning a standard house with and without the cooling system. These models indicate that the system could provide 95 per cent of the annual cooling needs in Atlanta, but only 79 per cent of cooling requirements in very hot weather because the system is overstretched by extreme conditions. The percentage savings are smaller in Miami, but the total energy savings would be larger because Miami is hotter. However, even in Miami the average conventional energy cost of cooling a house is well under $1000 a year. That is low enough to prevent the new system competing on cost terms with conventional air conditioning systems, Rudd says. He adds, however, that the system ‘is more environmentally benign, and in the event that energy costs soar, it could be very cost competitive.’ Despite the high costs,