制冷与空调专业英语第2版 林慧珠 主编 5-1新.pptVIP

Unit Five Lesson 17 Evaporative Air Cooling Lesson 18 Room Air Conditioners Lesson 19 Methods of Food Freezing Lesson 20 All-Air Systems Lesson 17 Evaporative Air Cooling Lesson 17 Text Evaporative cooling, using current technology and available equipment, can be an energy-efficient, environmentally benign, and cost-effective means of cooling. Applications are found for comfort cooling in commercial and institutional buildings, in addition to the traditional industrial applications for improvement of worker comfort in mills, foundries, power plants, and other hot operations.1 Text: Several types of apparatus cool by evaporating water directly in the air-steam. These include: (1)evaporative coolers; (2)spray-filled and wetted-surface air washers2; (3)sprayed coil units； (4)humidifiers; Text: Interest has increased in indirect evaporative cooling equipment that combines the evaporative cooling effect in a secondary air-stream with heat exchange to produce cooling without adding moisture to the primary air-stream.3 Text: In the past, indirect evaporative cooling equipment was considered too expensive when compared with assembly line refrigerated equipment, but energy conservation, increasing energy costs, concern for indoor air quality, and environmental concerns regarding chlorofluorocarbons have revived interest in both indirect and direct evaporative cooling systems. Text: 　Evaporative cooling reduces the dry-bulb temperature and provides a better environment for human occupancy and farm livestock. Evaporative cooling is also used to improve products grown or manufactured by controlling dry-bulb temperatures and/or relative humidity levels.4 When temperature or humidity must be controlled within narrow limits, mechanical refrigeration can be combined with evaporative cooling in stages; it can also be used as a backup system. 5 Text: Two common applications of evaporative cooli