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1、Today the refrigeration industry is a vast and essential part of any technological society, with yearly sales of equipment amounting to billions of dollars in the United States alone. 当今制冷工业是任何技术社会的庞大而重要的一部分，仅在美国制冷设备的年销售额就达到数十亿美元。,16,It is convenient to classify the applications of refrigeration int
2、o the following categories: domestic, commercial, industrial, and air conditioning. 制冷的用途可以简便的分为以下几类：民用、商用、工业用和空气调节。,17,Industrial air conditioning is used to create the air temperatures, humidity, and cleanliness required for manufacturing processes. Computers require a controlled environment. 工业空调
3、用来为生产创造所需要的温度，湿度和洁净度。计算机也是需要一个可控制的环境。,18,A compressor and condenser are required to maintain the evaporation process and to recover the refrigerant for reuse. 为了维持蒸发过程和使制冷机重复再使用，需要设置压缩机和冷凝器。,19,Refrigeration, regardless of the means by which it is obtained, may be defined as a process of the removal
4、 of heat from a substance or from a space. 制冷，不管用什么方式，可以定义为热量以物质或者空间转移的过程。,20,The advantages of ammonia over other refrigerants are its low cost, higher cops (and thus lower energy cost), more favorable thermodynamic and transport properties and thus higher heat transfer coefficients (require smalle
5、r and lower-cost heat exchangers), greater detectability in the event of a leak, and no effect on the ozone layer. 氨比其他制冷剂好的地方在于它的成本低、性能系数高、热力学和传输特性较好，热传导系数较高，如果出现泄漏比较容易检测出来，并且对臭氧层没有影响。,21,Refrigerants are the working fluids in refrigeration, air- conditioning, and heat pumping systems. They absorb
6、heat from one area, such as an air-conditioned space, and reject it into another, such as outdoors, usually through evaporation and condensation, respectively. 制冷剂是用于制冷、空调和热泵系统。它们从一个区域吸收热量，比如说一个空调房间，并且把它排到另一个区域，例如室外，通常通过蒸发器和冷凝器。,22,Variable air volume systems, in addition to helping to solve energy
7、problems, can save 20% to 30% in building energy costs over conventional constant air volume system. 除了有助于解决能量问题外，在建筑能量的成本方面，变风量系统能够节能20%-30%。,23,Furthermore, VAV system can provide beautiful comfort: when designed, maintained and operated properly. 此外，变风量系统能够提供极好的舒适感：当设计维护和操作得当。,24,Cooling of non-r
8、esidential buildings equipped with All-Air Systems significantly contributes to the electrical energy consumption and to the peak power demand. 装备全风量系统的无人居住的供冷，极大地增加了电能的消耗和增加了巅峰电量的需求。,25,HVAC systems are designed to maintain indoor air quality and provide thermal space conditioning. Traditionally, H
9、VAC systems are designed as All-Air Systems, which means that air is used to perform both tasks. Hvac系统设计的目的是维持室内空气品质和提供热力空气调节。传统上来说，hvac系统被设计为全空气系统，这意味着空气用来实现两个功能。,26,One solution to the provision of ventilation is a mechanical system, either just using fans at inlets and/or extraction points to fo
10、rce a flow through the space, or fans coupled to an air handling unit which also controls the temperature and humidity of the incoming air (air conditioning).一种通风的解决方案是使用机械系统，要么就在入口和抽起点处使用风机，强制产生气流流过空间，要么利用风机结合空调装置，这种空调装置也能控制外部进入的空气温度和湿度。,27,However they are not so easy to control as an air-conditio
11、ning system, and so we are working to understand more about natural ventilation flows, to help in the design of more comfort buildings. 然而对他们的控制并不如空调系统那么容易，因此我们正在研究以了解更多的关于自然通风的流动过程，以帮助我们设计出更加舒适的建筑。,28,This chapter describes induction units and fan-coil units used in in-room terminal unit systems. I
12、n-room terminal unit systems are applied primarily to exterior spaces of buildings with high sensible loads and where close control of humidity is not required.,29,Without control, such natural infiltration is haphazard, and the process can only legitimately be termed “ventilation” if the arrangemen
13、ts are designed to maintain the desired state of the indoor air under a variety of outdoor conditions. 不加控制，自然渗透是不规则的，只有在这个时候，这个过程可以正确的称为通风，当布置是经过设计来保持要求的室内空气状态，当室外空气状况不断变化时。,30,The great economic importance of natural ventilation is that it can bring about these air changes without expenditure of m
14、echanical energy. 自然通风的最大的经济上的重要意义，就在于它不必消耗机械能就可以产生大量的换气。,31,Continuous thermal pleasure extending over a period of hours is not possible. We are left simply with the idea of comfort as a lack of discomfort: this may seem an uninspiring definition, but nevertheless it presents a real practical chall
15、enge. 长时间的连续不断地热舒适性是不可能的。我们只能将舒适性这一概念理解为无不适应之感而已，这似乎是一个令人沮丧的定义，但是，他毕竟代表了一种现实的要求。,32,Any guide to comfort must relate these forms of discomfort to the physical variables of the environment, so that a permissible range of the variables may be recommended.,33,In non-air-conditioned buildings in warm cl
16、imates the PMV seem to overestimate the thermal sensation 在无空调热气候建筑内，pmv似乎高估了热敏感性,34,People who during their daily life are used to being exposed to very warm environments will most likely vote more moderately on the thermal sensation scale than people who rarely or never have been exposed to warmth. 经常在日常生活中接触温暖的环境人会比几乎不暴露在温暖环境下的人在热敏感上赢得更多的柔和感。,35,