The first designers of refrigeration machines, Jacob Perkins in 1834, and others later in the 19th century, used ethyl ether (R-610) as the first commercial refrigerant. The reason is easy to understand if one has ever spilt this liquid on the hand and felt the effect. In fact, it was not particularly suitable to the purpose, however, being dangerous as well as requiring an excessive compressor volume. Other and more appropriate refrigerants, e.g. ammonia (R-717), carbon dioxide (R-744), ethyl chloride (R-160), isobutane (R-600a), methyl chloride(R-40), methylene chloride (R-30) and sulfur dioxide (R-764) were soon introduced, including air (R-729). Three of these refrigerants became very popular,i.e.,ammonia for refrigerators and other small units,sulfur dioxide for refrigerators and other small units, and carbon dioxide preferably for ships' refrigeration. A large number of substances were tried over the following years, with varying success.(制冷机的第一位设计者珀金斯(1834年)和后来者们(19世纪)使用乙二乙醚(R610)作为第一代商业制冷剂｡理由很简单,如果你曾经将这种液体溅在手上,你就会感觉到这种效果｡然而事实上二乙醚不是特别适合于做制冷剂,它不仅要求过多的压缩机容积,而且还很危险｡进而出现了更为合适的制冷剂,如氨(R717),二氧化碳(R744),氯乙烷(R160),异丁烷(R600a),氯甲烷(R40),二氯甲烷(R30)以及二氧化硫(R764),其中也包括空气(R729)｡这些制冷剂当中有三种被普遍使用,即氨用于冷库和其它小型制冷装置,二氧化硫用于冰箱和其它小型制冷装置,二氧化碳用于船用制冷装置｡后来,大量的物质也被尝试,并取得了不同程度的成功｡)

In the early 1930s, the introduction of chlorofluorocarbons (CFCs) was revolutionary compared with the natural substances. In addition to their uses as refrigerants in refrigeration and air-conditioning systems, CFCs have been utilized as foam-blowing agents, aerosol propellants and cleaning solvents since 1950. The main arguments put forward in their favor were complete safety and harmlessness to the environment. Both of these claims have been proved wrong. Many accidents have occurred due to suffocation in the heavy gas, without warning, in below threshold spaces. It was evident that CFCs and related compounds contribute tremendously to the destruction of the stratospheric ozone layer and to the greenhouse effect (i.e., global climate change) which are considered among the most significant environmental problems. In fact, CFCs are greenhouse gases which give a combined contribution to incremental global warming of the same magnitude. The most abundant greenhouse gas is CO2 and the others are CH4, N2O, CFCs,etc. The effect of CFCs on global climate change may vary considerably, roughly contributing in the range 15–20% as compared to 50% for CO2. The interesting point is that in order to minimize global climate change, making reductions in CFC utilization seems to be easier than reducing fossil fuel use.Therefore,a full ban on these substances was essential.(在20世纪30年代初期,相对于自然工质而言,氯氟烃(CFCs)被用作制冷剂是具有革命性的｡自1950年以来,氯氟烃除被用作制冷系统和空调系统中的制冷剂外,它还被用作为发泡剂､气溶胶喷射剂和洗涤剂｡对其有利的主要论据是完全安全并对环境无害的｡这两种论据被证明是错误的｡在没有得到任何警示的情况下,许多在有限空间内因重气体窒息死亡的事件发生｡很显然,CFCs和相关的混合物对臭氧层有极大的破坏作用,并有助于导致温室效应(即全球性气候变化,被认为是最严重的环境问题之一)｡实际上,CFCs只是对全球性变暖有同样贡献的温室气体｡量最大的温室气体是二氧化碳,其他的还包括CH4､N2O､CFCs等｡CFCs对全球性气候变化的影响变化非常大,大致贡献比例在15-20%范围内,而二氧化碳的贡献比例为50%｡有趣的是,为了使全球性气候变化减到最小,减少CFC的利用比减少矿物燃料的使用似乎更容易｡所以,对CFCs类物质的全面禁止使用是至关重要的｡在过去十年里,由于CFCs对臭氧层和全球气候变化的影响,它在全世界范围被禁止使用,尽管它曾经是应用最为广泛的化学物质｡)

During the past decade CFCs have been banned worldwide as a result of their alleged effect on the stratospheric ozone layer and global climate change despite the fact that CFCs have been among the most useful chemical substances ever developed. During the past decade, research activities have been expanded tremendously to conduct ozone level measurements using various types of ground based or airborne equipment; of course, more recently satellite technology has become a prominent technique to provide more accurate findings about the ozone levels indifferent locations.(在过去十年里,基于地面设备或空中设备测量臭氧含量的研究活动被极大的拓展｡当然,最近卫星技术成为了一个突出的技术,它能从不同方位更精确的测量臭氧水平｡)

It is well known that the stratospheric ozone layer acts as a shield against harmful UV solar radiation. Nearly two decades ago, researchers discovered that chlorine released from synthetic CFCs migrates to the stratosphere and destroys ozone molecules and hence the ozone layer which was recognized as ozone layer depletion,known as one of the biggest environmental problems.In1987, 24 nations and the European Economic Community signed the Montreal Protocol to regulate the production and trade of the ozone depleting substances. This is considered as a landmark in refrigeration history.(众所周知,平流层的臭氧层是防止有害的太阳紫外线辐射的防护物｡近20年以前,研究员发现,从CFCs释放出的氯运动到平流层,破坏了臭氧分子及臭氧层｡因此臭氧层衰减被认为是最大的环境问题之一｡1987年,24个国家和欧洲经济共同体签署了蒙特利尔协议,用以控制臭氧衰减物质的生产和交易｡这被认为是制冷史上的一个里程碑｡)

This is by no means a unique experience. Similar predicaments have occurred following release to the environment of many other new chemicals. The extensive use of ever more new compounds is one of the big problems of our time. In this situation it does not seem very sensible to replace the CFC/HCFCs with a new family of related halocarbons, equally foreign to nature,to be used inquantities of hundreds of thousands of tons every year.(这绝不是唯一的｡相似的困境还发生在许多排放到环境中的新化学物质之上｡对更多新化合物的广泛的使用是我们这个时代最大的一个问题｡在这种情况下,抛开物质本性不说,用一种新的卤烃取代每年成千上万吨使用的CFC/HCFCs看起来是不明智的｡)

Ingeneral,refrigerants are well known as the fluids absorbing heat during evaporation.These refrigerants, which provide a cooling effect during the phase change from liquid to vapor, are commonly used in refrigeration,air conditioning,and heat pump systems.(一般而言,制冷剂被认为是在蒸发过程中吸收热的流体｡这些制冷剂,在从液态向气态转换的过程中产生冷却效果,通常在制冷､空调和热泵系统中被使用｡)