低温工况下碳氢化合物替代R22 的制冷循环分析

本文对常用的碳氢化合物制冷剂与R22进行了循环性能对比分析,发现R290、R1270是R22极有潜力的纯质替代物.R1270与R290的混合物能较好的替代R22.如果能够发挥非共沸混合物温度滑移的特点,R1270分别与R600a、R600的混合物也能够作为R22的替代物.     

HCs替代HCFC22的理论空调循环分析

关联了4种二元碳氢化合物系基于PT状态方程及其混合规则的交互作用参数,对16种HCs纯质和混合物系进行了理论空调循环分析。结果表明HC1270、HC290、HC1270／HC290、HC1270／HC600a、HC290／HC600a等具有在空调系统中替代HCFC22的潜力。     

R22替代工质回热循环的性能分析

R22的替代工质的制冷性能通常比R22差，采用回热循环是改善循环性能的一种方法，但是增加回热器会带来成本的增加，而且不同的制冷剂在回热循环中的COP及容积制冷量的变化也是不同的。针对上述问题，分析回热循环的特性和6种制冷剂（R290，R1270，R134a／R1270（0．45／0．55），R134a／R290（0．6／0．4），R407C和R410A）在回热循环中的容积制冷量和COP的变化特点。研究结果表明，R134a,／R1270，R290和R134a／R290系统使用回热器后，性能改善较大，R410A系统只有在高冷凝温度、高过热度时才有必要使用回热器，其余替代工质系统使用回热器，其系统性能改善不明显。     

新型混合制冷剂R1270/R152a/R13I1的理论研究

针对制冷剂R22的替代问题,提出了一种适用于空调等制冷设备的环保型混合制冷剂R1270/R152a/R13I1。基于Refprop8.0,对R1270/R152a/R13I1的基本热物理性质和制冷系统循环性能进行了分析,研究表明:在标准工况下,R1270/R152a/R13I1混合制冷剂的COP和单位容积制冷量均与R22相当,非常有利于直接灌注式替代;在变工况下,R1270/R152a/R13I1的滑移温度较小,性能优于R407C,单位容积制冷量与R407C和R22相当,是一种优良的R22替代物。     

环保制冷剂R1270/RE170/R13I1的热力学性能分析

针对制冷剂R22的替代问题,提出一种适用于空调等制冷设备的环保型混合制冷剂R1270/RE170/R13I1。基于Refprop8.0,对R1270/RE170/R13I1的基本热物理性质和制冷系统循环性能进行分析,研究表明:在标准工况下,R1270/RE170/R13I1混合制冷剂的COP和单位容积制冷量均与R22相当,非常有利于直接充注式替代;在变工况下,R1270/RE170/R13I1的滑移温度较小,性能优于R407C,单位容积制冷量与R407C和R22基本相当,排气温度和压比均低于R22和R407C,是一种优良的R22和R407C制冷设备的替代物,具有充注式替代的潜力。     

采用R290和R32的家用空调器全生命周期碳排放研究

运用全生命周期评价方法分别对R290和R32分体式家用空调进行碳排放对比研究。结果表明:R290空调生命周期碳排放约为R32空调的85%;在原材料获取和回收处置阶段,虽然R32在所有材料中重量占比不到1.1%,却产生了高达78%的碳排放,说明用R290替代R32具有显著的环境效应。虽然提高制冷剂回收率和降低泄漏率有利于降低采用高GWP值制冷剂的空调碳排放,但考虑R32和R290都具有可燃性,需要谨慎采用制冷剂回收策略。     

分体式房间空调器R290和R1270替代R22实验研究

现今空调器中广泛使用的R22因环保问题而遭淘汰,HFCs(氢氟碳化物)会加剧温室效应,亟需寻求更为合适的制冷剂,HCs(碳氢)初见端倪.采用空气焓值法,在R22分体式房间空调器中充注R290和R1270,进行性能实验研究.结果表明,标准工况下,用R290直接灌注式替代R22时,系统制冷量降低5.0％,EER升高10.3％,而换用排量大20％的压缩机能提高制冷量8.9％,而EER降低8.5％,但性能较原R22系统要好;R1270系统性能要优于R290系统.结果还表明,随着室外温度降低,碳氢系统制冷量和EER的增加速率和增幅均大于原R22系统,且室外温度低时碳氢系统性能更优,有利于节能.研究结果表明,HCs适合在空调器中替代R22,具有广阔的应用前景.     

取代R502的非共沸混合制冷剂

一种由R22、R290(丙烷)和R218构成的非共沸混合制冷剂已由Star Refriseration公司研制成功并已取得专利权,这种用于取代R502的混合制冷剂计划在1992年投放市场。该制冷剂在研制初期仅由R22和R290两种纯工质构成,按配比60％R22和40％R290混合而成的非共沸混合制冷剂显示良好的热力性能,但由于其易燃性严重妨碍其应用,当加入R218后这项性能大大改善,由于R218良好的阻燃性,混合制冷剂中R290的比     

碳氢制冷剂应用于汽车空调的可行性分析

本文分析了碳氢制冷剂作为汽车空调制冷工质的优势和汽车空调中使用碳氢制冷剂的危险性,综合国内外的研究,得出汽车空调中使用碳氢制冷剂有很高的安全性,对比了R290、R600a的混合物和R12的性能,从理论上验证了用碳氢制冷剂替代R12作为汽车空调循环工质的可行性,计算了一些品牌汽车的空调系统碳氢制冷剂的理论充灌量,为碳氢制冷剂在汽车空调中的应用提供了参考.     

R290分体式空调器室内泄漏安全性实验研究

采用实验研究的方法,模拟出房间空调器使用中可能出现的各种制冷剂泄漏的情况,对0.5 mm和4 mm两种泄漏孔径、260 g和350 g两种充灌量以及在室内外机连接管上加装电磁阀开关等不同情况下R290制冷剂在空调房间内的分布规律进行了实验研究。实验结果表明房间空调器内制冷剂充灌量和泄漏口径的大小对房间安全性有着很大的影响,而在室内外机连接管上加装电磁阀可以有效地减缓R290的泄漏速率,提高R290分体式空调器的安全性。     

Experimental results and design procedures for minichannel condensers and evaporators using propylene

Hydrocarbons (HCs) present favorable thermodynamic and transport properties that make them attractive for use in refrigeration, air conditioning and heat pump systems. The major issue related to HCs is their flammability and hence the realization of low charge heat transfer devices is a key factor for their market placement. Although flammable refrigerants call for charge minimization, propylene heat transfer data inside minichannels is new in the open literature.In the present paper, condensation heat transfer, flow boiling heat transfer and two-phase pressure drop measurements taken with propylene (R1270) inside a 0.96 mm diameter minichannel are presented and compared against correlations.A comparative analysis of the condensation performance of R1270, R290 and two HFCs is made with the objective of minimizing the exergy losses, due to the driving temperature difference between saturation and wall and to the frictional pressure drop. An estimation of the condenser refrigerant charge is also performed. The flow boiling heat transfer performance of R1270 is discussed in comparison to the one of R290.     

Refrigeration system performance using liquid-suction heat exchangersPerformance d'un système frigorifique utilisant des échangeurs liquide-vapeur à l'aspiration

Heat transfer devices are provided in many refrigeration systems to exchange energy between the cool gaseous refrigerant leaving the evaporator and warm liquid refrigerant exiting the condenser. These liquid-suction or suction-line heat exchangers can, in some cases, yield improved system performance while in other cases they degrade system performance. Although previous researchers have investigated performance of liquid-suction heat exchangers, this study can be distinguished from the previous studies in three ways. First, this paper identifies a new dimensionless group to correlate performance impacts attributable to liquid-suction heat exchangers. Second, the paper extends previous analyses to include new refrigerants. Third, the analysis includes the impact of pressure drops through the liquid-suction heat exchanger on system performance. It is shown that reliance on simplified analysis techniques can lead to inaccurate conclusions regarding the impact of liquid-suction heat exchangers on refrigeration system performance. From detailed analyses, it can be concluded that liquid-suction heat exchangers that have a minimal pressure loss on the low pressure side are useful for systems using R507A, R134a, R12, R404A, R290, R407C, R600, and R410A. The liquid-suction heat exchanger is detrimental to system performance in systems using R22, R32, and R717.     

制冷剂R290的国内研究进展

对国内制冷剂R290作为R22替代工质的研究进展进行回顾,首先从热力学特性角度说明R290替代R22的可行性,并对R290在家用空调器等方面替代R22的理论分析和试验研究方面的进展进行陈述,进而对R290在复叠式制冷循环以及自行复叠制冷循环中的理论和试验研究进行论述。指出虽然R290在国内还未得到推广使用,但用来替代R22具有一定的可行性。     

Experiment and simulation on the performance of an autocascade refrigeration system using carbon dioxide as a refrigerant

The main purpose of this study is to investigate the performance of an autocascade refrigeration system using zeotropic refrigerant mixtures of R744/134a and R744/290. One of the advantages of this system is the possibility of keeping the highest pressure of the system within a limit by selecting the composition of a refrigerant mixture as compared to that in the vapor compression system using pure carbon dioxide. Performance test and simulation have been carried out for an autocascade refrigeration system by varying secondary fluid temperatures at evaporator and condenser inlets. Variations of mass flow rate of refrigerant, compressor power, refrigeration capacity, and coefficient of performance (COP) with respect to the mass fraction of R744 in R744/134a and R744/290 mixtures are presented at different operating conditions. Experimental results show similar trends with those from the simulation. As the composition of R744 in the refrigerant mixture increases, cooling capacity is enhanced, but COP tends to decrease while the system pressure rises.

Résumé

The main purpose of this study is to investigate the performance of an autocascade refrigeration system using zeotropic refrigerant mixtures of R744/134a and R744/290. One of the advantages of this system is the possibility in keeping the highest pressure of the system within a limit by selecting the composition of a refrigerant mixture as compared to that in the vapor compression system using pure carbon dioxide. Performance test and simulation have been carried out for an autocascade refrigeration system by varying secondary fluid temperatures at evaporator and condenser inlets. Variations of mass flow rate of refrigerant, compressor power, refrigeration capacity, and coefficient of performance (COP) with respect to the mass fraction of R744 in R744/134a and R744/290 mixtures are presented at different operating conditions. Experimental results show similar trends with those from the simulation. As the composition of R744 in the refrigerant mixture increases, cooling capacity is enhanced, but COP tends to decrease while the system pressure rises.     

R407C、R410A系统热力性能研究综述

本文介绍了R22制冷剂最有希望的替代物R407C和R410A的基本物性，以及国外学者对使用这两种工质的制冷系统有关换热、压降特性及对COP影响的研究成果，以帮助国内制冷、空调企业了解R22替代工质研究的新动向、加快制冷工质替代的步伐。     

Refrigerant charge reduction in vapor compression refrigeration cycles via liquid-to-suction heat exchange

This short communication reports a study of the potential for refrigerant charge reduction in vapor compression refrigeration systems by means of a liquid-to-suction heat exchanger. The analysis was carried out on purely thermodynamic grounds for refrigerants of current interest, such as R134a, R22, R290, R600a and R717, assuming the cooling capacity as a constraint so that the evaporating pressure is free to vary. It was found that the minimum amount of refrigerant can be reduced depending on the thermophysical properties of the refrigerant, the working conditions, and the charge inventory.     

R290应用于商用大容积陈列柜的性能研究

对比R290与R134a的热力学性质,分析在商用大容积陈列柜中用R290替代R134a的可行性,并对R290应用于商用大容积陈列柜的性能进行测试。试验结果表明：相对于R134a系统,R290系统的冷却速度较快,较低能耗,噪声较小,冷凝器耗材较少。对于R290的安全性,只要控制合适的充注量并采取适当的安全措施就可以达到安全使用的要求。     

R290/CO2复叠式制冷系统的性能实验

通过对R290／C02复叠式制冷系统的性能实验，对低温循环用CO2作为制冷工质，高温循环分别用R22和R290为制冷工质的性能进行比较，结果表明，随着蒸发温度的升高，冷凝温度的降低，R290／CO2复叠式制冷系统的最佳质量流量比增大，COP增加。随着高温循环压缩机入口温度的升高，R290压缩机的功耗略高于R22压缩机的功耗，R290循环的COPh要高于R22循环的COPh。结果表明自然工质R290／CO2复叠式制冷系统具有很好的发展前景。     

An evaluation of options for replacing HCFC-22 in medium temperature refrigeration systems

Due to the ongoing global phase-out of R-22, which is still the most widely used refrigerant around the world, there is a need to replace this refrigerant in many different applications. This paper focuses on a thorough evaluation of the R-22 replacement options for medium-temperature refrigeration applications. It includes a thermodynamic analysis, comparison of heat transfer and pressure drop characteristics, system performance comparisons using a validated detailed system model, safety issues, and determination of the environmental impact of refrigerant selection. Three potential alternatives to the R-22 were studied: two HFCs (404A and R-410A) and one HC (R-290). An HFC refrigerant, R-410A, is shown to be an efficient and environmentally acceptable option to replace R-22 in medium temperature applications.