机电专业英语第2版24Unit24A11-AirSystems全空气系统-杨晓磊-机电专业英语分解.ppt

A11-Air Systems There are some advantages and disadvantages of All-Air System. Advantages: (1) The central mechanical equipment room location for major equipment allows operation and maintenance to be performed in unoccupied areas and permits the maximum range of choices of filtration equipment, vibration and noise control, and the selection of high quality and durable equipment. (4) Seasonal changeover is simple and readily adaptable to automatic contro1. (5) Gives a wide choice of zoning, flexibility, and humidity control under all operating conditions, with the availability of simultaneous heating and cooling . (6) Air-to-air and other heat recovery systems may be readily incorporated Disadvantages: (1) They require additional duct clearance, which reduces usable floor space and increases the height of the building. (2) Depending on layout, vertical shaft space is needed for distribution requiring larger floor plates. (3) The accessibility of terminal devices requires close cooperation among architectural, mechanical, and structural designers. (4) Air balancing, particularly on large systems, can be more difficult. The basic function of a room air conditioner is to provide comfort by cooling, dehumidifying, filtering or cleaning, and circulating the room air. It may also provide ventilation by introducing outdoor air into the room and／or exhausting room air to the outside. Also, comfort may be provided by controlling the room temperature through selection of the desired thermostat setting. The conditioner may provide heating by heat pump operation, electric resistance elements, or by a combination of both. 家用空调的基本的功能是通过降温、除湿、过滤、净化以及循环房间空气而提供安逸舒适的环境。它还可以提供通风, 引进室外空气或排出房间空气；也可以通过设定自动调温器来控制房间温度。空调可以通过热泵、电加热器、或由两者结合向房间供热。 房间内温热的空气通过冷却盘管, 与此同时释放出显热和潜热。然后, 这些被调节过的空气由风扇或鼓风机再次在房间循环。 流过蒸发器的低温液态(低压)制冷剂, 吸收房间空气的热量而蒸发。然后, 蒸汽将这部分热量携带到压缩机, 压缩机压缩蒸汽, 使蒸汽温度提高到比室外空气的温度更高。在冷凝器内, 高温(高压)制冷剂蒸汽液化, 并且把从