含R227ea的混合制冷剂替代R22研究

由于R410，R407系列混合制冷剂在替代R22方面的不足，更多新型的制冷剂列入了研究。R227ea具有良好的环境性能，最典型的特点是具有很好的阻燃性。文章对含R227ea各种混合物进行了理论计算和比较，并对其安全性进行了分析。计算结果表明，混合物R32／R134a／R227ea及R32／R125／R227ea不论是COP还是Qv值，都能和R22相匹配，而且优于R410A的最大特点是其冷凝压力大大降低，甚至低于R22，非常有利于原装置替代。     

R245fa阻燃特性理论与试验研究

分析了R245fa的阻燃,试验研究了R245fa在电打火(点火能约为100 J)和普通打火机点火两种条件下对R290、R152a、DME、R600a的阻燃特性,提出了新的评判阻燃组分阻燃特性强弱的指标(阻燃系数K),并对R245fa作用于各可燃工质的阻燃效果进行分类．试验结果表明,点火能大小、点火源形式对可燃工质燃爆极限影响很大；R245fa对碳氢类可燃工质阻燃效果差；对HFC类的阻燃效果相对较好；R245fa的阻燃效果比R134a的差．     

新型制冷剂R1234yf/R134a可燃性实验研究

根据美国材料试验学会标准研制可燃性实验装置,对实验装置进行性能和误差分析,并进行校验。R1234yf环境性能好,臭氧消耗潜能值为零,其三元混合物R1234yf/DME/R134a可作为一种新型空调制冷剂。测试不同体积比时二元混合工质R1234yf/R134a的可燃性数据,得到其爆炸极限和临界抑爆比,并给出三元混合物R1234yf/DME/R134a的临界爆炸极限曲线图。结果表明:当R134a和R1234yf的体积比约为2时,二元混合物R1234yf/R134a达到临界抑爆点。     

环保型制冷机R600a/R290的应用研究

以碳氢化合物R600a/R290,1:1的配比直接灌注冰柜系统,比较两种工质的运行特性,研究了其充注量对冰柜性能的影响.R600a/R290作为氟利昂R12的替代工质,其循环性能与R12系统非常相似,实验结果为寻找环保型长期替代制冷剂提供了依据.     

-150℃四级自复叠制冷系统的实验与分析

搭建了一种四级自复叠制冷系统,采用由R600a、R134a、R23、R14、R50和R740等6种工质组成的非共沸混合制冷剂,经过调试与实验,成功得到了-150℃的柜内温度。讨论了该低温箱体的降温特性、压缩机的运行特性和混合工质的节流特性。研究表明,压缩机的吸、排气压力和温度关乎系统能否安全稳定的运行,每级毛细管的长度关乎系统的降温特性。     

太阳能有机朗肯循环发电系统模拟优化研究

针对低温太阳能集热器出水温度为65～90℃的特点，根据有机朗肯循环发电原理，选取R134a、R152a、R600a、RC318、R600、R245fa共6种工质，利用EES平台进行仿真模拟和比较分析。分析结果表明：在此温度范围内，蒸发压力、蒸发温度、系统净发电功率、热电效率及系统吸热量与热源温度变化呈正比关系，且当热源温度为90℃时，RC318系统净发电功率与热电效率最高，分别为12.27 kW、15.42%。当热源温度为85℃时，RC318系统效率达到最高值82.52%。     

环保型制冷剂R600a／R290的应用研究

以碳氢化合物R600a/R290 ,1∶1的配比直接灌注冰柜系统,比较两种工质的运行特性,研究了其充注量对冰柜性能的影响。R600a/R290作为氟利昂R12的替代工质,其循环性能与R12系统非常相似,实验结果为寻找环保型长期替代制冷剂提供了依据。     

一种适用于逆向布莱顿制冷循环的多元非共沸混合工质

针对采用空气作工质的逆向布莱顿循环在空调温区效率较低的缺点，文章提出了将非共沸混合工质应用于逆向布莱顿循环这一新的解决思路。基于循环的热力学分析和从热力学角度选择的工质，采用RKS方程对多元非共沸混合工质进行了模拟计算，详细讨论了工质成分对系统性能的影响，并在自己搭建的实验台上进行了验证。结果表明，由R290、R152a、R600a组成的混合物具有较大的单位质量制冷量、单位质量输出功和COP值，是逆向布莱顿循环较理想的工质。     

不同工况下非共沸混合工质有机朗肯循环系统性能研究

采用MATLAB软件模拟非共沸混合工质在不同冷热源条件下对有机朗肯循环(ORC)系统性能的影响。选取R245fa/R1234ze和R245fa/R600a作为混合工质,热源温度取120和200℃,分别在冷凝露点温度为40℃和冷却水温升为5,10,15℃的工况条件下,利用热力学第一定律和火积理论对系统性能进行分析。结果表明：热源温度为200℃时,R245fa, R1234ze和R600a系统净输出功率分别为89.83,61.87和77.74 kW,使用R245fa系统性能优于其混合工质;热源温度为120℃、固定冷凝露点温度时,混合工质R245fa/R600a(90%∶10%)净输出功率比R245fa和R600a分别提高了27.6%和27%,R245fa/R1234ze(60%∶40%)净输出功率比R245fa和R600a分别提高了26%和20.5%;火积耗散和单位面积做功量与净输出功率变化相反,提高冷却水温升时,增大了系统火积耗散,且流向环境中的火积耗散在总火积耗散中占比增大,导致系统的传热不可逆损失增加。     

不同工质对太阳能有机朗肯循环系统性能的影响

循环工质的特性是影响有机朗肯循环系统性能的重要因素之一,在不同的蒸发温度条件下,选取R600、R600a、R245fa、R236fa、R236ea、R601、R601a、RC318及R227ea共9种有机工质,基于热力学第一定律和第二定律对其热力循环特性进行了计算分析,并对各有机工质的蒸发压力、热效率、功比和不可逆损失等进行了比较.结果表明：R245fa作为太阳能低温热发电朗肯循环系统的循环工质具有较高的热效率和效率,并且产生的系统总不可逆损失较小,是一种较理想的有机工质;其次,R236fa和R236ea作为系统循环工质也具有较为良好的性能.     

Measurement of physical properties of refrigerant mixtures. Determination of phase diagrams

Accurate knowledge of high pressure phase equilibrium is of utmost interest in designing chemical processes and separation units operating at high pressures. Moreover, these data are essential to develop optimized models in order to provide continuous representation of high pressure phase equilibrium. The best models are required to permit process simulators to be the most accurate as possible. There are many experimental ways to obtain information about the phase behaviour of fluid mixtures. They can be classified into two main categories: open and closed circuit methods. Closed circuit methods are composed of two main categories: the synthetic methods where compositions are known a priori and analytic methods where samplers are needed. The laboratory has published several data sets concerning refrigerant systems (binaries and ternaries). The more recent are:

– binary and ternary systems with 1,1,1,2,3,3,3-heptafluoropropane (R227ea), difluoromethane (R32) (two hydrofluorocarbons) and propane (R290),

– binaries of R227ea or R32 with CO₂ (R744) and an old refrigerant SO₂ (R764),

– ternary system composed of dimethyl ether (DME), pentafluoroethane (R125) and 1,1,1,2-tetrafluoroethane (R134a),

– binary systems involving DME with R134a and R32.

In this paper we have focused our attention on two types of models:

– the first one is a thermodynamic model implying equations of state and several mixing rules,

– the second one is a neural network model. It is not a “thermodynamic” model, but it can be used to calculate thermodynamics properties like enthalpy, entropy from density values. It has been used to represent density data of the R134a + R125 + DME ternary system.

闪急沸腾喷雾速度场的LDA研究

为探索代用燃料液化石油气LPG和二甲醚DME的喷雾机理,采用LDA技术测量了喷雾粒子的速度分布。为安全起见,用制冷剂R12作试验液体,它与LPG和DME有相似的物理特性。为做比较,在相同试验条件下对传统柴油喷雾进行了测量。考察了喷雾模式对速度分布的影响。结果表明,R12喷雾的速度分布比传统柴油喷雾均匀得多,前者的平均径向速度远大于后者。这被认为归因于闪急沸腾大大改善了雾化和液气混合。     

喷射制冷系统工质性能综合比较

在比较制冷工质的优劣时,不仅应考虑系统COP,还应考虑循环泵的耗功及压力容器中的压力水平。根据饱和蒸气压将八种环境友好型制冷工质分为四组(R141b&R123,R600a&R142b,R134a&R152a,R290&R717),分组的依据是每组制冷工质的饱和蒸气压曲线非常相近。比较结果表明,R123和R141b、R142b和R600a的热力性能都非常相近,但R123和R600a对环境的影响更小;R152a相比R134a,具有更低的压力和循环泵功、更小的环境影响,但性能系数却更大。     

非共沸工质双压冷凝热泵热水器性能研究

提出一种双压冷凝梯级加热热泵热水器（DPS）系统新构型,采用碳氢非共沸工质作为制冷剂,可实现热水的连续梯级低损加热,采用黄金分割法对系统热力性能进行优化。结果表明,非共沸工质的DPS系统的热力学性能优于纯质的DPS系统和单级热泵系统,双压冷凝系统在最优中间水温时取得最大COP。名义工况下,采用R600/R601a(40/60)的DPS系统COP高达5.17,相对采用纯质的DPS系统和单级系统分别提高9.45%和14.25%。采用温度滑移合理的非共沸工质可显著减少损,改善冷凝器的热匹配特性,系统效率最高提升11.70%,名义工况下推荐R600/R601a(40/60)作为工质对。     

利用低品位热能的有机物朗肯循环的工质选择

工质对低品位热能有机物朗肯循环的安全性、环保性、经济性和高效性具有很大的影响.本文首先对61种工质的热力学、物理、化学、环保、安全和经济特性进行了研究,并从中挑选出11种符合上述特性的候选工质,然后对这些候选工质的干湿性、饱和性质和循环热效率进行了研究,确定了8种适合低品位热能有机物朗肯循环且具有潜力的工质,它们是丙烷...     

Performance variation of an R22 window air conditioner retrofitted with a HFC/HC refrigerant mixture under different ambient conditions over a range of charge quantities

R22 has been generally accepted as the most suitable refrigerant for air conditioners, due to its favorable thermodynamic properties. However, R22 is a controlled substance under the Montreal protocol. M20 is a HFC/HC refrigerant mixture that can be used as a substitute for R22. This paper presents experimental investigation on the performance comparison of a window air conditioner operated with the M20 tested under different refrigerant charge levels and outdoor conditions against that with R22. Experiments were conducted in accordance with BIS procedure in a psychrometric test facility. Refrigerant charge in the air conditioner was systematically varied from 900 to 1600 g in steps of 50 g for R22 and 697 to 1279 g in steps of 39 g [equivalent to 50 g of R22] for the M20. At each charge levels, the outdoor room conditions were changed in accordance with BIS standards. It is observed that R22 is more sensitive to deviations in charge levels as compared to the M20. A decrease in charge level of about 7% reduced the system refrigerating capacity by 11.3% with R22 while with the M20 refrigerant mixture it reduces by 6.9% only. Similarly an overcharge by 7% reduces the refrigerating capacity of the system by 13.8% with R22 while with M20 it reduces by 6.5% only. Thus M20 is less sensitive to charge deviations. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20339     

Fluid selection for a low-temperature solar organic Rankine cycle

Theoretical performances as well as thermodynamic and environmental properties of few fluids have been comparatively assessed for use in low-temperature solar organic Rankine cycle systems. Efficiencies, volume flow rate, mass flow rate, pressure ratio, toxicity, flammability, ODP and GWP were used for comparison. Of 20 fluids investigated, R134a appears as the most suitable for small scale solar applications. R152a, R600a, R600 and R290 offer attractive performances but need safety precautions, owing to their flammability.     

三级复叠式制冷系统低温级制冷剂的应用分析

为研究三级复叠制冷系统中低温循环制冷剂替代的可行性方案,采用R1150/R170/R717、R50/R170/R717和R14/R170/R717三种工质组合,对三级复叠式制冷系统的高低温循环压缩机的排气温度、压缩机输入功率、COP、热力学完善度、系统的■效率、■损失以及系统中各个部件■损失所占比例随蒸发温度的变化进行热力学分析。研究结果表明:不同蒸发温度下均存在最佳中间循环冷凝温度,使COP值最大。蒸发温度由-100.0℃升高到-80.0℃时,R1150/R170/R717的■损失最小,COP、热力学完善度和■效率最大。R1150/R170/R717的COP由0.60增大到0.82。R1150/R170/R717的COP比R14/R170/R717的COP高3.47%～4.49%。主要的■损失部件是冷凝器,冷凝器的■损失所占比例随蒸发温度的升高而升高。推荐在三级复叠式制冷系统中采用R1150/R170/R717制冷剂组合方案,研究结果为三级复叠式制冷系统工质组的选择提供理论依据。     

LPG替代R22的理论分析

本文对液化石油气LPG作为R22替代制冷工质进行了理论研究.通过对LPG热力学性能和理论循环的分析,得到了LPG替代R22后的系统性能参数.LPG和R22的热力学性能是在试验工况、空调工况和热泵工况下采用美国NIST的REFPROP软件分析的,其中包括压缩性能（压比和绝热压缩温度）、热力学特性（循环效率）和制冷量.分析结果证实LPG是一种很好的替代工质.     

基于模糊层次分析法的制冷剂选择

制冷剂选择是复叠式热泵研究的一个重要方向。在分析模糊、灰色关联在制冷空调领域应用及复叠式热泵制冷剂选择研究现状基础上,采用模糊层次分析法构建了包括安全性、热力性能、环保性能、成本和热物性5个方面共27个指标组成的制冷剂评价指标体系,建立制冷剂性能综合评价模型,利用该模型在47种纯工质范围内为复叠式热泵选择合适的工质。结果表明,综合性能较好的制冷剂组合为R134a/R601a、R134a/R601、R1234yf/R236ea等。