资源目录
压缩包内文档预览：
编号：139627267
类型：共享资源
大小：2.93MB
格式：ZIP
上传时间：2021-08-03
上传人：qq77****057
认证信息
个人认证
李**（实名认证）
江苏
IP属地：江苏
25
积分
- 关 键 词：
-
冷藏库
制冷系统
设计
- 资源描述：
-
冷藏库制冷系统设计,冷藏库,制冷系统,设计
- 内容简介：
-
X X 学 院毕 业 设 计外文翻译资料 土木工程系04建筑环境与设备工程（2）班 系 别：_XXX 班 级：_XXX姓 名：_指 导 教 师：_2008年6月6 日外文资料Cycle performance study on R32/R125/R161 as analternative refrigerant to R407CX.H. Han, Q. Wang, Z.W. Zhu, G.M. ChenInstitute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027, ChinaReceived 22 June 2006; accepted 29 January 2007Available online 16 February 2007AbstractThis paper presents the new ternary non-azeotropic mixture of R32/R125/R161 as an alternative refrigerant to R407C. The physical properties of the ternary mixture are similar to those of R407C, and it is environmental friendly, that is, it has zero ozone-depletion potentials (ODP) and lower global warming potentials (GWP) than R407C. Theoretical cycle performances of R32/R125/R161 and R407C are calculated and analyzed rstly. Based on the theoretical study, experimental tests are performed on a vapor-compression refrigeration system with a rotor compressor which was originally designed for R407C (without any modications to system components for R407C). Experimental results under different working conditions indicate that the pressure ratio and power consumption of the new refrigerant are lower than those of R407C, and its refrigerating capacity and coeffcient of performance (COP) are superior to those ofR407C, respectively, and its discharge temperature is slightly higher than that of R407C. Therefore, the new refrigerant R32/R125/R161could be considered as a promising refrigerant to R407C.2007 Elsevier Ltd. All rights reserved.Keywords: Mixture; Cycle performance; R32/R125/R161; R407C1. IntroductionChlorodiuoromethane(R22)is an important refrigerant in refrigeration and airconditioning systems. Concern about the ozone depletion potential (ODP) and global warming potential (GWP) of R22 require the phase out of chlorine containing R22. Thus the research on refriger- ant replacement for R22 has been one of hot topics in the refrigeration and air-condition industry. However, the investigations show that a pure alternative refrigerant hardly can be found and promising refrigerants can be considered within the mixture of HFCs 17. At present, R407C that has been widely used as a working uid for refrigerators and air-conditioners 1, is being used as a replacement for R22.R407C is a ternary mixture refrigerant composed of R32/R125/R134a (23/25/52 wt%). Its evaporation pressure and condensation pressure are very similar to those of R22, and there is no any modication to system components. But it is diffcult to repair and maintain the system for its bigger variation of evaporation temperature when R407C is leaked. Thus, new promising mix- ture refrigerants should be considered and resear- ched as alternative refrigerants to R407C now and in the coming future.R161 is environmentally friendly, and has the excellent thermophysical properties. Because of its ammable char- acteristics, R161 is not considered as a suitable working uid for refrigeration and air-conditioning systems. The mixture of R161 with refrigeran- ts R32, R125, 15/34/51% as an alternative refrigerant to R407C, has many merits810 in physical thermodynamics: (1) its ODP is zero(the new refrigerant do not contain chl- orine atoms); (2) GWP of the new refrigerant is smaller than that of R407C; (3) the basic physical properties, for example, tb , tcrit, pcrit are similar to those of R407C; the variat- ion of evaporation temperature of the new refrigerant is smaller that of R407C; (4) the saturated vapor pressure curve of the new refrigerant is upper than that of R407C (in the- ory, the upper for the saturated vapor pressure, the bigger for the volumetric refr- igeration capacity and COP). So it may overcome the drawbacks for practical application, and few modications are required for the components and the structure of refrigeration system for R407C, which bring little additional cost. In addition, the lubricating oil (POE(polyol-est- er) used for R32/R125/R161 in the systemis the same kind for R407C. Xuan et al. 8 had an exper mental testing of the new ternary mixture on a variable capa- city heat pump using a composition varying device for R22. However, testing data were few and testing results were affected to a certain extent by the system components Theor- etical cycle performan- ces of R32/R125/R161 and R407C at nom-such as rectification, and could not exactly express cycle inated working conditions performances of the terna- rymixture. Therefore, to complepotentials as an alternative refrigerant to R407C, R22.2. Theoretical cycle performancesThe cycle performance parameters of R32/125/161 and R407C calculated by Refrop7.0 10 at nominated working condition (Table 1) were shown in Table 2 From Table 2, we can see that in nominated working condition, the volumetric refrigeration capacity and refrig- eration capacity of R32/R125/R161 is 10.37% and 10.38% higher than those of R407C, respectively; the compressor power consumption of R32/R125/ R161 are 7.31% higher than that of R407C; COP of R32/R125/R161 is 3.07% higher than that of R407C; the discharge temperature of R32/R125/R161 is slightly 0.33% higher than that of R407C and the pressure ratio (pc/pe) of R32/R125/R161is 3.78% lower than that of R407C.In order to verify the cycle performance advantages of R32/R125/R161 further, cycle performance parameters at other different working conditions are calculated, the calculation results are shown in Table 3 (in calculating, the discharge volume of compressor is 22.1 cm 3).From Table 3, we can know that the analysis results of cycle performances at other different working condi- tions match well with those at nominated working condition.3. ExperimentsTo test the effect in actual system for the new mixture R32/R125/R161 as an alternative refrigerant to R407C, an experimental study is performed.3.1. MaterialsR407C and R32/R125/R161 are supplied by a company(The Chemical Engineering Company of Zhejiang, China). No further purication is performed before use.3.2. Experimental methodThe second refrigerant calorimeter method is used according to National standard of the Peoples Republic of China (the method of performance test for positive dis- placement refrigerant compressors). The main principle of the method is that the heating capacity supplied by heateris equal to refrigerating capacity produced by evaporator in the Calorimeter when the refrigeration system is in the equilibrium state.3.3. Experimental apparatus and procedures3.3.1. Experimental apparatusAn vapor compression refrigeration apparatus established in the present study, as schematically shown in Fig. 1, to study cycle performances of the new ternary mixture, mainly consists of the rotor compressor designed for R407C with a displacement volume of 14.8 cm3, the condenser, the subcooler, the expansion valve, the receiver, the calorimeter and the evaporator.There are two kinds of refrigerants in this apparatus. One is the rst refrigerant or main refri- gerant which cycle performance is to be tested in experiment; another is the second refrigerant lled in the calorimeter as medium of heat transfer. The evaporator is put into the upper part of the ca- lorimeter and the electric heaters are installed at the bott- om and submerged by the second refrigerant. The Dewar vessel is used for heat insulation.In order to perform accurate measurement of temperature in equilibrium state, eight Type T thermocouples, which are carefully and periodically calibrated against a 25 X reference platinum resistance thermometer in a high accuracy thermostatic bath, are placed at the measured places and connected to an Agilent data acquisition unit(Aglient 34970A). The resulting uncertainty is not higher than 0.2. Condensation pressure and evaporation pres- sure are measured by means of a precision pressure gauge(full scale, 04 MPa) and a precision pressure gauge (Full scale, 02 MPa), respectively, whose uncertainties are 10 kPa, 5 kPa. Measured places for temperatures and pres- sures are shown in Fig. 1 and measured deviations are shown in Table 4.Two digital wattmeters are used to determine the electri- cal power input to the compressor and the heating power of the electrical heaters, their uncertainty is 0.5%(02 kW (for compressor); 04 kW (for heater). The com- position of the main refrigerant is analyzed by a gaseous chromatograph (GC112A, China) equipped with a ame ionization detector (FID). The GC is calibrated with pure components of known purity and with mixtures of known composition that are prepared gravimetrically. Considering the margin of error and reproducibility of GC, we generally estimate an overall uncertainty in the measurements of the composition of 0.002 in mole fraction.3.3.2. Experimental proceduresThe experimental procedures are as follows: (1) the sys tem was rst evacuated; (2) a targeted amount of samples was introduced into system; (3) the experiment is started. Du- ring the experiment, the second refrigerant is heated by the electrical heaters. Its vapor he- ated the main refriger- ant in the evaporator upside, then condensed on the surface of eva- porator coils and returned to the bottom of calorim- eter afterward. The main refrigerant absorbs the heat and evaporates. The compressor sucks the vapor of main refrig- rant and compresses it to be high-temperature and high- pressure steam. Then the steam is cooled and condensed into liquid by water in the condenser, subcooled by waterin the subcooler (a receiver used between the condenser and the subcooler to ensure liquid refrigerant en- tering the subcooler), throttled by the expansion valve and returned to evaporator to abso- rb the heat from the second refrigerant again; (4) in order to test the cycle performances of samples at given working conditions, adjusting the heat- ing power to control the suction te- mperature of compressor, adjusting the opening de- gree of throttle valve to control the ow rate of refrigerant, that is, to control the suction pressure, adjusting the ow rate of water in the condenser to control the discharge pres- sure and adjusting the ow rate of water in the subcooler to control the subcooled tempe- rature. It is believed that 1 h or more is suffcient to obtain thermal stability state at therm- al balance. After the desired temperature is attained, the pressures and temperatures are recorded, respectively. The com position of the sample was measured by immediately injecting it into the GC. The experimental data at thermal balance are mea- sured at least four times (1 time/0.5 h) in order to ensure repea- tability.4. Experimental resultsDuring the experiment, the ambient temperature is main tained at 20 1, the total heat leakage (about 0.35 W/K) is estimated less than 1% of the cooling capacity of the sys tem and is ignored in the data process. Twenty-eight work ing conditions have been tested in the experiment within a wide range of the condensation temper- atures(3554.4).evaporation temperatures(-1010)and subcooling tempera- tures (515 ), respectively. Table 5 gives the experimental results for nominated working condition. Figs. 27 give the experimental results on different cycle perfor- manceparameters varying with evaporation temperature at differ ent condensation temperature for R32/R125/R161, R407C. At the same evaporation temperature and condensation temperature, dierent cycle performance parameters vary- ing with dtsubc are showed in Table 6.(1) . power consumption, the volumetric refrigerating capacity, the refrigerating cap acity and COP increase, the pressure ratio and the discharge temperature decrease with evaporation temperature rising at different condensation temperatures for R32/R125/ R161, R407C.(2). at the same condensation and evaporation temperature, the volumetric refrigerating capacity, the refrigerating capacity and COP of R25/R125/R161 are superior to those of R407C;(3). the pressure ratio and power consumption of R25/ R125/R161 are lower than those of R407C and the discharge temperature is slightly higher than that of R407C at the same working conditions;(4). COP and the volumetric refrigerating capacity increase with the subcooling temperature rising at the same condensation temperature.5. ConclusionsCycle performance parameters for the ternary mixture R32/R125/R161 are studied and compared with those of R407C in a vapor compressor refrigeration system designed for R407C under several working conditions. The research shows that most cycle performance parame- ters of the new refrigerant, such as the pressure ratio and power consumption, cooling capacity and COP are supe- rior to those of R407C, respectively; the discharge temper- ature is slightly higher than that of R407C under different working conditions. The new refrigerant R32/R125/R161 could be considered as a promising refrigerant to R407C.AcknowledgementsThis work has been supported by Zhejiang Provincial Natural Science Foundation of China (Z105034) and Chinese Postdoctoral Science Foundation (20060400311).References1 L. Shi, X.Y. Zhao, L.Z. Han, et al., THR03 as an alternative to HCFC22, J. Eng. Thermophys. 20 (5) (1999) 538541 (in Chinese).2 D. Jung, Y. Song, B.J. Park, Performance des melanges de frigorigenes utilises pour remplacer le HCFC22, Int. J. Refrig. 23 (6) (2000)466474.3 J.T. Mcmullan, Refrigeration and the environment-issues and strategies for the future, Int. J. Refrig. 25 (1) (2002) 8999.4 A. Cavallini, Working uids for mechanical refrigerationinvited, Int. J. Refrig. 19 (8) (1996) 485496.5 J.M. Calm, G.C. Hourahan, Refrigerant data summary, Eng. Sys. 18(2001) 7488.6 S. Devotta, A.V. Waghmare, N.N. Sawant, B.M. Domkundwar, Alternatives to HCFC-22 for air conditioners, Appl. Therm. Eng. 21(2001) 703715.7 D.B. Jabaraj, A. Narendran, D. Mohan Lal, S. Renganarayanan,Evolving an optimal composition of HFC407C/HC290/HC600a mixture as an alternative to HCFC22 in window air cond- itioners, Int. J. Therm. Sci. 46 (2007) 276278.8 Y.M. Xuan, G.M. Chen, B. Chen, Experimental study as an new alternative refrigerant to R22, J. Eng. Thermophys. 25 (2) (2004) 201204 (in Chinese).9 G.M. Chen, Z.K. Guo, X.Z. Guo, Y.M. Xuan, Environmental refrigerant instead of HCFC-22, Invention patent, ZL 03116856.6.10 NIST (National Institute of Standard Technology) Standard Refer- ence Database 23, Version 7.0, 2002.对R407C 的一种替换制冷剂R32/R125/R161的周期性能研究X.H. 韩， Q. 王 ， Z.W. 朱， G.M. 陈浙江大学低温与制冷学院2006年6月22日收到; 2007年1月2日发表摘要：本文研究R407C一种替代制冷剂：R32/R125/R161组成的新非共沸混合物。新三元混合物的物理特性和R407C类似，但它对环境影响较小：臭氧层耗能值(ODP)为零，温室效应潜能值(GWP)比R407C低。本文的实验在以R407C为制冷剂的压缩机内进行的（没有对压缩机各元件做任何改变），在实验中，对R32/R125/R161和R407C理论循环性能进行计算和研究。实验结果表明：在不同的工作环境下，新制冷剂的压缩比和耗能值低于R407C，但它的排气温度高于R407C，总体来讲它的制冷性能更加优越。所以，新制冷剂R32/R125/R161 可以作为R407C的一种替代选择。关键字：混合物；循环性能； R32/R125/R161； R407C1.引言一氯二氟甲烷(R22)是冷藏和空调系统的一种重要制冷剂。由于R22有较高的臭氧层耗能值(ODP)和温室效应潜能值(GWP)其必将被逐步淘汰。因而在冷藏和空调领域研究R22的替换制冷剂是其中一个热门方向。然而，在氟利昂类制冷剂中想找到一种单纯的替换制冷剂是很困难的。当前，R407C是冰箱和空调器领域中广泛应用的R22一种替代物。R407C是由R32/R125/R134a（ 23/25/52每克）组成的一种三元混合制冷剂 。其蒸发压力和冷凝压力都和R22非常相似。当其替代R22用于制冷压缩机时，其系统部件不用做任何改变，但当蒸发温度、冷凝温度变化更大时，R407C容易泄漏，且较难维修和保养。因此，不管是在现在还是在将来，新的制冷性能更好制冷剂应加以考虑和研究。R161对环境没有影响，并具有优良的热力物理性能。但由于其易燃的特性，在制冷及空调系统领域中R161并不被视为一个合适的制冷剂。但如果R161、R32、 R125 以15/34/51 混合，在物理热力学方面与R407C相比有许多优点：（1）.其臭氧层耗能值为零（新制冷剂不含有氯原子）；（2）.温室效应潜能值GWP值比R407C 小；（3）.基本物理特性，例如，, 与R407C类似；其蒸发温度的变化范围比R407c稍小 ；（4）.其饱和蒸气压曲线比R407C高(从理论上讲，饱和蒸气压越高，容积制冷量越大，COP越高）。所以有可能克服R407C的弊端，而且很少改动R407C制冷系统所需D的部件和结构，节省改动系统带来的额外费用。此外，用于R32/R125/R161的润滑油（POE（多元醇酯）和R407C系统中的润滑油是相同的 。Xuan et al.进行了实验,测试新三元制冷剂在一个利用R22的变容量热泵装置的性能参数。不过，由于系统组件的改变，测试数据和测试结果受到一定程度的影响，并不能完全表达混合物的循环性能。因此，在循环性能中实验我们借鉴以往的研究，对新制冷剂R32/R125/R161和R407c循环性能参数，进行计算、测试和分析，以验证其作为R407C、R22一种替代冷媒的潜力，2 .理论周期循环性能RefRop7.0 10 在特定的工作条件下对R32/125/161和R407C循环性能参数进行研究。结果显示在表2中 。从表2中，我们可以看到，在特定工作条件下，R32/R125/R161的容积制冷量和制冷量分别比R407C高10.37 和10.38 ，R32/R125/R161的压缩机消耗功率比R407C高7.31; R32/R125/R161的COP值比R407C高3.07;排气温度R32/R125/R161比R407C略高0.33 ，R32/R125/R161的压缩比（Pc/Pe）比R407C低3.78。为了验证R32/R125/R161周期循环性能优势，在其他不同的工作条件下计算循环性能参数,计算结果列在表3 （在计算中，压缩机的容积是22.1cm3）.从表3中，我们分析其结果可以发现其周期循环性能，在其他不同的工作条件与特定工作条件相同。3.实验为了测试新的混合物R32/R125/R161在实际应用中替代R407C的效果，我们做以下试验。 3.1材料R407C和R32/R125/R161是由一个公司（中国浙江省化学工程公司）提供的，在开始使用前做进一步的净化。 3.2实验方法第二冷媒热量表的使用应根据中华人民共和国标准(全国标准容积式冷却压缩机性能测试方法)。方法的主要原理是当制冷系统在均衡状态时加热器提供的热容量与蒸发器所吸收的热量是相等的。3.3实验仪器及程序3.3.1实验仪器在本试验中用一个蒸汽压缩制冷系统研究新混合制冷剂的周期循环性能，系统原理如图1所示，主要的部件有：制冷剂为R407C的转子式压缩机，容积14.8立方厘米，冷凝器，过冷器，膨胀阀，油分离器，热量表和蒸发器。在这个系统中有两种类型的制冷剂。一种是第一冷媒或称主冷媒，在实验中测试其周期循环性能参数。另一种是第二冷媒，其填充在热量表记录传热数。热量表安装在蒸发器上部和电加热器底部。为了在平衡状态时进行精确的温度测量，八个T型热电偶要定期校准，参考铂电阻温度计安装在一个高准确度恒温箱内，放置在被测地方并连接到一个安捷伦数据采集单元（ Aglient 34970A ）。由此产生的误差不会大于0.2。冷凝压力和蒸发压力的测量分别是由精密压力表（量程，0-4 MPa ）和精密压力表（量程，0-2 MPA ）测量的，其误差分别是10个千帕、5千帕。温度和压力列于图1中，测量偏差列于表4中。两个数字电力计（0-2千瓦（压缩机），0-4千瓦（加热器）是用来确定电机电源输入到压缩机和加热器中能量的，其误差在 0.5 以内。制冷剂由一个装有一个火焰离子化检测器（ FID法）的气态色谱仪（GC112A，中国）分析标定混合物的各部分组成。考虑到重复性的抽样误差和气相色谱法误差，一般来说，在测量中我们估计整体的误差在 0.002摩尔以内。3.3.2 实验程序实验程序如下：（1）.首先系统排空; （2）.在系统中加入一定制冷剂; （3）.开始试验。 在实验中，第二冷媒由电加热器加热。主冷媒在蒸发器内吸热，压缩机将制冷剂压缩成高温、高压蒸汽。然后蒸汽在冷凝器中被冷却水却冷，经膨胀阀回到蒸发器中，进行下一次的循环。（4）.为检验样品在给定工作条件下的循环性能，改变压缩机吸气温度，控制吸力压力；改变节流阀的开度控制制冷剂的流速，调节冷凝器中的水流量以控制过冷度。一般认为，1小时或以上，就足以达到热稳定状态，在达到热平衡后，分别记录压力和温度。在热平衡中，实验至少进行4次（1此/0.5h）,以确保试验的准确性4 .实验结果实验结果显示:周期循环性能参数随蒸发温度差异而不同。实验过程中，周围环境的温度为20 1，在数据处理过程中散热量(约0.35W/ K）估计不到的系统冷却能力的1,可
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号