水作为制冷剂的透平冷水机组研究现状(二)

水是一种古老的制冷剂,至今仍使用在溴化锂吸收式制冷机中和蒸气喷射式制冷机中,但被认为不适合在蒸气压缩式制冷机中使用。自从科学家们发现CFCs和HCFCs制冷剂对大气臭氧层的破坏作用和产生全球气候变暖效应以后,这些CFCs和HCFCs制冷剂在大型透平冷水机组中将被淘汰使用。在寻求新的替代制冷剂时,水重新引起了人们的关注。本文综述使用水作为制冷剂在大型透平冷水机组中应用的研究和开发现状,包括制冷循环的COP分析,透平压缩机的结构和设计,以及三孔口冷凝波转子系统。     

水作为制冷剂的透平冷水机组研究现状(一)

水是一种古老的制冷剂,至今仍使用在溴化锂吸收式制冷机中和蒸气喷射式制冷机中,但被认为不适合在蒸气压缩式制冷机中使用.自从科学家们发现CFCs和HCFCs制冷剂对大气臭氧层的破坏作用和产生全球气候变暖效应以后,这些CFCs和HCFCs制冷剂在大型透平冷水机组中将被淘汰使用.在寻求新的替代制冷剂时,水重新引起了人们的关注.本文综述使用水作为制冷剂在大型透平冷水机组中应用的研究和开发现状,包括制冷循环的COP分析,透平压缩机的结构和设计,以及三孔口冷凝波转子系统.     

水作为制冷剂的透平冷水机组研究现状(三)

水是一种古老的制冷剂,至今仍使用在溴化锂吸收式制冷机中和蒸气喷射式制冷机中,但被认为不适合在蒸气压缩式制冷机中使用。自从科学家们发现CFCs和HCFCs制冷剂对大气臭氧层的破坏作用和产生全球气候变暖效应以后,这些CFCs和HCFCs制冷剂在大型透平冷水机组中将被淘汰使用。在寻求新的替代制冷剂时,水重新引起了人们的关注。本文综述使用水作为制冷剂在大型透平冷水机组中应用的研究和开发现状,包括制冷循环的COP分析,透平压缩机的结构和设计,以及三孔口冷凝波转子系统。     

水作为制冷剂的透平冷水机组研究现状(四)

水是一种古老的制冷剂,至今仍使用在溴化锂吸收式制冷机中和蒸气喷射式制冷机中,但被认为不适合在蒸气压缩式制冷机中使用.自从科学家们发现CFCs和HCFCs制冷剂对大气臭氧层的破坏作用和产生全球气候变暖效应以后,这些CFCs和HCFCs制冷剂在大型透平冷水机组中将被淘汰使用.在寻求新的替代制冷剂时,水重新引起了人们的关注.本文综述使用水作为制冷剂在大型透平冷水机组中应用的研究和开发现状,包括制冷循环的COP分析,透平压缩机的结构和设计,以及三孔口冷凝波转子系统.     

制冷剂的最新进展

0前言 HFC制冷剂的ODP值为零,已经广泛地采用于空调制冷系统中以取代会引起臭氧层破坏的CFCs和HCFCs。但是HFC的高全球变暖潜能已经在近期引起许多国家和地区,特别在欧洲,日本和美国对HFC制冷剂有了更谨慎的看法。     

满足对臭氧层与气候友善要求的一些可持续发展选择

一直被广泛用于制冷、空调与热泵的CFCs与HCFCs，由于它们对臭氧层与全球变暖的负面影响，正在被逐步淘汰。在中短期内，HFCs(具有零的ODP值）是替代CFCs与HCFCs的主要侯选替代物，但是适合于长期替代的冷媒还将要求对全球变暖只能具有有限的影响。像氢烃、二氧化碳、氨、水的这些替代物质可能成为未来的选择物质，这将取决于所取得的技术进步，但在此期间，重要的是，在按最好方案作出决定时，要考虑到一些特定的当地环境（如在一些发展中国家）。     

日本氟利昂类制冷剂的使用和管理指南

制冷空调技术的进步与发展,与热力性能优良、价格低廉、容易获取的新型制冷剂的不断出现密切相关,特别是从上世纪30年代后,以R12、R11和R22为代表的卤代烃（CFCs和HCFCs）制冷剂的出现,给低温冷冻冷藏及空调领域带来了飞跃性发展。但是,上世纪70年代中期开始,科学家发现包括氟利昂制冷剂在内的CFCs及后来以R22、R123为代表的HCFCs在大气平流层中消耗了大量的臭氧,并且在南极上空造成臭氧空洞,对地球表面的气候、生物产生了一系列不利影响。     

由制冷剂替代谈起

制冷空调技术对人类社会的文明进步产生了巨大的推动作用。但是CFCs类、HCFCs类制冷剂的大量使用导致了臭氧层的破坏,也加剧了全球变暖。而替代CFCs和HCFCs类制冷剂的HFCs类制冷剂尽管不破坏臭氧层,但大部分也具有较高的温室效应。除CFCs制冷剂已经被淘汰外,HCFCs类制冷剂和HFCs类制冷剂也正在或将被逐渐削减。零ODP值、更低GWP值的替代制冷剂将成为未来的唯一选择。这些替代制冷剂尽管环境友好,但多存在或可燃或有毒或工作压力高等问题,也引起了人们的顾虑和担忧。实际上制冷空调行业使用这类制冷剂已有漫长的历史,长期的经验和当前国内外大量的科学研究和风险评估表明,只要采取和严格遵守相关的安全措施,能够保障这些替代制冷剂的安全使用。     

“针对使用弱可燃R32制冷剂的制冷空调设备制造与使用安全技术标准的前期研究”项目简介及进展

制冷空调系统中使用的HCFCs制冷剂是造成臭氧耗损及全球变暖的重要因素之一。为了解决这一问题,国际社会在《蒙特利尔议定书》框架内达成了加速淘汰HCFCs的调整案,要求各国在选择HCFCs替代品时充分考虑其对气候的影响,尽可能选择最大化气候效益的替代技术和替代制冷剂。鉴于具有良好的热工性能和比较优越的环保特性,R32制冷剂引起了制冷空调行业的高度关注,在《中国工商制冷空调行业HCFCs淘汰管理计划》中,已将R32作为R22的主要替代选择之一。该行业计划已在2011年7月举行的《蒙特利尔议定书》多边基金执委会第64次上得到批准。这一行业计划的批准意味着中国HCFCs物质淘汰行动就此拉开了全面实施的序幕。     

CFCs淘汰与加强对制冷剂的3R管理

本文在论述了中国工商制冷CFCs淘汰进程基础上，重点讨论了制冷空调行业使用制冷剂的特点及其对全球环境的影响，什么是制冷剂的3R管理?怎样做好制冷剂的3R管理工作?最后得出了在制冷空调行业做好氟烃类制冷剂3R管理工作的三点意义的结论。为了说明HCFCs与HFCs制冷剂在中国制冷空调行业中的使用前景，在文中还介绍了发展中国家淘汰HCFCs制冷剂的时间表及UNEP与ICAR—MA对使用HFCs制冷剂的政策立场。     

Experimental determination of phase diagram and modeling: Application to refrigerant mixtures

Accurate knowledge of phase diagrams is an essential step for optimized chemical engineering design and effective solution of engineering-related problem. As an example of the use of phase diagrams we have selected a topic at global concern which arose upon the discovery of the ozone depletion. In 1987, the Montreal protocol prohibited world-wide use and production of ChloroFluoroCarbons (CFCs) and of HydroChloroFluoroCarbons (HCFCs), while HydroFluoroCarbons (HFCs) were proposed as alternative refrigerants. Thus, the need arose for information required in the optimization of refrigerant production processes, particularly in the field of phase equilibria. These data can provide better evaluation of refrigerant production processes, especially with the aim of reducing global warning effects.In this communication, we present VLE equipments and the obtained phase diagrams concerning several binary systems involving R32, R290, R116, R744, R116, R134a, R227ea and other refrigerants. Cubic equations of state combining with modern mixing rules based on Gibbs excess models are used for the determination of phase diagrams.     

Shell side direct expansion evaporation of ammonia on a plain tube bundle with exit superheat effect

There are no data available on the direct expansion evaporation of refrigerant on the outside of a tube bundle. With the current ozone depletion and global warming issues it is critical to develop systems with low charge refrigerants especially with natural refrigerants such as ammonia which has zero ozone depletion potential (ODP) and zero global warming potential (GWP). This study presents results of an extensive experimental work on direct expansion of ammonia on a triangular pitch plain tube bundle with saturation temperature range −1.7 to −20 °C, heat flux range 5 to 45 kW m⁻² and exit superheat range 2 to 10 °C. The test matrix falls well within the practical operating conditions of industrial refrigeration systems. A typical increase in heat transfer coefficient was observed with saturation temperature and heat flux. The effect of exit super heat on the overall performance of the bundle was also reported. A correlation for outside boiling on a tube bundle in direct expansion mode was developed and compared with existing single tube pool, flooded bundle boiling and spray evaporation studies.     

浅析中央空调系统替代制冷剂的选择

根据大气臭氧层耗损和温室气体对全球气候变化的影响，分析了中央空调系统几种替代制冷剂的特性，探讨了在实际使用中如何进行替代制冷剂的选择。     

制冷空调行业HCFCs工质替代的分析

立足HCFCs制冷剂替代的进程,分析对大气臭氧层破坏和温室效应,得出HCFCs作为制冷剂淘汰的必要性和进程;分析发达国家和发展中国家不同经济技术水平,提出《蒙特利尔议定书》淘汰HCFCs制冷剂的时间表,结合我国制冷空调行业的实际情况,提出相应的淘汰进程;提出HCFCs制冷剂工质替代既要开发新工质也要从制冷设备入手减少充注量和控制设备泄漏的新路线。     

Emissions and environmental impacts from air-conditioning and refrigeration systems

The impacts of air conditioning and refrigeration systems on stratospheric ozone are primarily linked to release of ozone-depleting refrigerants. Their contributions to global warming stem both from release of refrigerants and from emission of greenhouse gases (GHGs) for associated energy use. Because the energy-related component has a significantly higher warming impact, phaseout of hydrofluorocarbon (HFC) refrigerants with less efficient options will increase net GHG emissions. The same conclusion applies for perfluorocarbon (PFCs), though they are less commonly used as refrigerants. Integrated assessment of ozone depletion, global warming, and atmospheric lifetime provides essential indications in the absence of ideal refrigerants, namely those free of these problems as well as safety, stability, compatibility, cost, and similar burdens. This study examines the trend in refrigerant losses from chiller use. It documents both substantial progress in release reductions and the technical innovations to achieve them. It contrasts the impacts of current refrigerants with alternatives and with the chlorofluorocarbons (CFCs) they replaced. The study examines the sensitivity of efficiency to charge loss. It also summarizes thermodynamic and environmental comparisons of options to show that phaseout decisions based on chemical composition alone, without regard to attributes of individual substances, can result in greater environmental harm than benefit.     

The chemistry of stratospheric ozone: its response to natural and anthropogenic influences

The current rapid changes in the composition of the atmosphere reflect both the metabolism of the biosphere and the broad range of influencing human activities. However, the only known sources of CFCs are industrial. In predicting future changes in ozone depletion and global warming it is necessary to understand the role of the biosphere in regulating emissions as well as future industrial emissions. This paper discusses theoretical predictions and trends in global ozone concentrations from 1969–1986. Antarctic and Arctic ozone trends and the global implications of the Antarctic ozone hole are described in detail. It is concluded that even if the control measures of the Montreal Protocol are implemented by all nations, the atmospheric abundance of chlorine will at least double during the next few decades. Future global ozone depletion could be larger than originally predicted because the PSC-induced chemical reactions that cause ozone depletion were not included in the stratospheric ozone assessment models on which the Montreal Protocol was based. To return the Antarctic ozone layer to its natural state will require very strong measures, including a complere phase out of all fully halogenated CFCs, halons, carbon tetrachloride and methyl chloroform, as well as careful use of HCFC substitutes.     

Environmental risk assessment of hydrofluoroethers (HFEs)

Hydrofluoroethers (HFEs) are being used as third generation replacements to chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and perfluorocarbons (PFCs) because of their nearly zero stratospheric ozone depletion and relatively low global warming potential. HFEs have been developed under commercial uses as cleaning solvents (incl., HFE-7500, C7F15OC2H5; HFE-7200, C4F9OC2H5; HFE-7100, C4F9CH3; HFE-7000, n-C3F7OCH3), blowing agents (incl., HFE-245mc, CF3CF2OCH3; HFC-356mec, CF3CHFCF2OCH3), refrigerants (incl., HFE-143a, CF3OCH3; HFE-134, CHF2OCHF2; HFE-245mc, CF3CF2OCH3), and dry etching agents in semiconductor manufacturing, (incl., HFE-227me, CF3OCHFCF3). From the environmental, ecological, and health points of view, it is important to understand their environmental risks for these HFEs from a diversity of commercial applications and industrial processes. This paper aims to introduce these HFEs with respect to physiochemical properties, commercial uses, and environmental hazards (i.e. global warming, photochemical potential, fire and explosion hazard, and environmental partition). Further, it addresses the updated data on the human toxicity, occupational exposure and potential health risk of commercial HFEs. It is concluded that there are few HFEs that still possess some environmental hazards, including global warming, flammability hazard and adverse effect of exposure. The partition coefficient for these HFEs has been estimated using the group contribution method; the values of logKow for commercial HFEs have been estimated to be below 3.5.     

HFC-161混合物替代R502的理论研究

提出一种新型制冷剂HFC-161/125/143a(质量百分比10/45/45)用于替代制冷剂R502.新制冷剂环境性能良好,ODP值为0,GWP值为3466,GWP值小于R502及其常用替代制冷剂R404A和R507.采用Refprop软件计算了HFC-161混合物的基本热物理性质,以及低温工况和变工况下的理论循环性能,并与制冷剂R502、R404A、R507的相关数据进行对比.结果表明:新制冷剂的运行压力、压比、COP值、单位容积制冷量与R502相当,温度滑移小于R502常用替代物R404A,是一种性能优良的制冷剂R502的替代物.