Construction and application for VLE and pressure-enthalpy diagrams of R134a/R23/R14 zeotropic mixtures

doi:10.11949/j.issn.0438-1157.20141676

Abstract

Abstract:

The thermodynamic properties of R134a/R23/R14 ternary mixtures used in three-stage auto-cascade refrigeration systems were calculated based on the PR equation, and enthalpy and entropy were calculated by using dryness. The diagrams of pressure-enthalpy and VLE of R134a/R23/R14 mixture under the typical composition were given. The deviations of bubble pressure and vapor composition between simulation results and the experimental data were less than 1.3% and 1.2% for R134a/R23, 1.0% and 2.4% for R32/R134a, respectively. The deviations of 95% calculated values of R32/R125/R134a were between ±5%. The simulation results could meet the requirements of engineering calculation. Based on the experiment, the thermodynamic properties of the auto-cascade refrigeration system were analyzed in detail. The pressure-enthalpy diagrams of R134a/R23, R23/R14 and R134a/R23/R14 under the operating compositions were given, and the diagram of spatial pressure-enthalpy described the circle of this system clearly. This simulation program could analyze the system circle effectively.

Key words: auto-cascade refrigeration, mixtures, PR equation, thermodynamic properties, computer simulation, pressure-enthalpy diagram

摘要：

基于PR状态方程,分模块模拟计算了三级自动复叠制冷系统中R134a/R23/R14三元混合工质的热物理特性参数,得到非共沸混合工质的汽液平衡数据、两相组分,并利用干度计算焓熵值,构建了典型配比下混合工质的压焓图和汽液相平衡图。二元R134a/R23和R32/R134a混合工质的泡点压力和气相组分的计算值与实验测试值的误差分别小于1.3%、1.2%和1.0%、2.4%;三元R32/R125/R134a混合工质95%的计算值与实验值的偏差在±5%之内,表明该模型能满足工程计算需要。利用理论模型,结合实验系统,对R134a/R23/R14三级自动复叠制冷系统进行详细的组分等热物性分析,并在空间压焓图上进行了详细表述。

关键词: 自动复叠制冷, 混合物, PR状态方程, 热力学性质, 计算机模拟, 压焓图

CLC Number:

TB657.3

ZHANG Qingqing, ZHANG Hua, LOU Jiangfeng, LI Jia, ZHAO Wei, WANG Xi, LIU Zhanjie. Construction and application for VLE and pressure-enthalpy diagrams of R134a/R23/R14 zeotropic mixtures[J]. CIESC Journal, 2015, 66(7): 2387-2394.

张庆庆, 张华, 娄江峰, 李佳, 赵巍, 王袭, 刘占杰. 强非共沸工质R134a/R23/R14汽液相平衡和压焓图的构建及应用[J]. 化工学报, 2015, 66(7): 2387-2394.

References 23

[1]	Kim S G, Kim M S. Experiment and simulation on the performance of an autocascade refrigeration system using carbon dioxide as a refrigerant [J]. International Journal of Refrigeration, 2002, 25(8): 1093-1101.
[2]	Gong Maoqiong, Wu Jianfeng, Cheng Quiwei, Sun Zhaohu, Liu Jiayong, Hu Qinguo. Development of a -186℃ cryogenic preservation chamber based on a dual mixed-gases Joule-Thomson refrigeration cycle [J]. Applied Thermal Engineering, 2012, 36(1): 188-192.
[3]	Wang Q, Li S H, Wang J P, Sun T F, Han X H, Chen G M. Numerical investigation on the performance of a single-stage auto-cascade refrigerator operating with two vapor-liquid separators and environmentally benign binary refrigerants [J]. Applied Energy, 2013, 112: 945-955.
[4]	Du Kai, Zhang Shaoqian, Xu Weirong, Niu Xiaofeng. A study on the cycle characteristics of an auto-cascade refrigeration system [J]. Experimental Thermal and Fluid Science, 2009, 33(2): 240-245.
[5]	Yu Jianlin, Zhao Hua, Li Yanzhong. Application of an ejector in autocascade refrigeration cycle for the performance improvement [J]. International Journal of Refrigeration, 2008, 31(2): 279-286.
[6]	Sivaakumar M, Somasundaram P. Exergy and energy analysis of three stage auto refrigerating cascade system using zeotropic mixture for sustainable development [J]. Energy Conversion and Management, 2014, 84: 589-596.
[7]	Rui Shengjun(芮胜军), Zhang Hua(张华), Huang Lihao(黄理浩). Pressure characteristics of auto-cascade refrigeration system [J]. CIESC Journal (化工学报), 2012, 63(S2): 176-180.
[8]	Rui Shengjun(芮胜军), Zhang Hua(张华), Zhang Qinggang(张庆钢), Huang Lihao(黄理浩). Characteristics of two-stage segregation auto-cascade refrigeration system [J]. CIESC Journal (化工学报), 2013, 64(6): 2019-2035.
[9]	Zhao Wei(赵巍), Zhang Hua(张华), Liu Ruixi(刘瑞希), Xiao Chuanjing(肖传晶), Zhang Shuchun(张书春). Study on mixed refrigerants selecting and matching of a four stage auto-cascade refrigeration [J]. Journal of Refrigeration(制冷学报), 2013, 34(5): 17-22.
[10]	Rui Shengjun(芮胜军), Zhang Hua(张华), Huang Lihao(黄理浩), Yu Zida(喻子达), Wang Xi(王袭), Wang Xiaoying(王晓影). Theory and experimental study of two-stage auto-cascade low temperature refrigerator [J]. Journal of Mechanical Engineering(机械工程学报), 2014, 50(2): 159-164.
[11]	Peng D Y, Robinsion D B. A new two-constant equation of state [J]. Ind. Eng. Chem. Fundam., 1976, 15(1): 59-64.
[12]	Li H, Yan J. Evaluating cubic equations of state for calculation of vapor-liquid equilibrium of CO2 and CO2-mixtures for CO2 capture and storage processes [J]. Applied Energy, 2008, 86(6): 826-836.
[13]	Lemmon E W, Jacobsen R T. A generalized model for the thermodynamic properties of mixture [J]. International Journal of Thermophysics, 1999, 20(3): 825-835.
[14]	Agelia M Abudour, Sayeed A Mohammad, Robert L Robinson Jr, Khaled A M Gasem. Generalized binary interaction parameters for the Peng-Robinson equation of state [J]. Fluid Phase Equilibria, 2014, 383:156-173.
[15]	Liu Yanni(刘燕妮), Guo Kaihua(郭开华), Lu Laiyun(鹿来运). Vapor-liquid equilibrium measurements for tetrafluoromethane + propane system [J]. CIESC Journal (化工学报), 2013, 64(10): 3514-3519.
[16]	Fang Jin(方锦), Hou Shuxin(侯树鑫), Duan Yuanyuan(段远源), Song Yixin(宋艺新). Evaluating of vapor-liquid equilibrium models for refrigeration mixture containing hydroflurocarbons [J]. J. Tsinghua Univ.: Sci. & Tech. (清华大学学报:自然科学版), 2008, 48(11): 1940-1944.
[17]	Hu Peng(胡芃), Gao Jingxuan(高静轩), Chen Longxiang(陈龙祥), Chen Zeshao(陈则韶). Prediction of vapor-liquid equilibria for binary and ternary HFC/HC mixtures using PR equation of state and vdW mixing rule [J]. CIESC Journal (化工学报), 2012, 63(2): 350-355.
[18]	Scalabrin G, Grigiante M, Cristofoli G. Modelling enthalpy and entropy of pure and mixed refrigerants with an innovative corresponding states method [J]. International Journal of Refrigeration, 2003, 26(8): 936-950.
[19]	Lim J S, Park K H, Lee B G, Kim J D. Phase equilibria of CFC alternative refrigerant mixtures: binary systems of HFC23+HFC134a and HFC23+HEC227ea at 283.15 and 293.15K. [J]. Journal of Chemical and Engineering Data, 2001, 46(6):1580-1583.
[20]	Cui Xiaolong, Chen Guangming, Li Changsheng, Han Xiaohong. Vapor-liquid equilibrium of difluoromethane+1,1,1,2-tetrafluoroethane systems over a temperature range from 258.15 to 343.15 K [J]. Fluid Phase Equilibria, 2006, 249(1/2):97-103.
[21]	Nagel M, Bier K. Vapor-liquid equilibrium of ternary mixtures of the refrigerants R32, R125 and R134a [J]. International Journal of Refrigeration, 1995, 18(8):534-543.
[22]	Lu Xiangyang(陆向阳). The experimental study of three-stage auto-cascade refrigeration system [D]. Shanghai: University of Shanghai for Science and Technology, 2004.
[23]	Gong M Q, Wu J F, Luo E C, Qi Y F, Hu Q G, Zhou Y. Research on the change of mixture compositions in mixed-refrigerant Joule-Thomson cryocoolers [J]. Advances in Cryogenic Engineering, 2002, 47(B): 881-887.