溴化锂制冷蒸发器中钛椭圆管外降膜流动及传热特性

文章导读

摘要为了提高溴化锂中央空调系统中制冷蒸发器的耐腐蚀性，采用钛管代替铜管，并提出椭圆管代替圆管方式提高钛管外制冷剂蒸发效率，数值模拟研究椭圆系数E对椭圆钛管外制冷剂流动过程、液膜厚度分布及传热系数影响规律。结果表明：在椭圆系数E=1.0~1.7范围内，随着E增大，管外液膜平均厚度减薄、液膜速度增大、干壁面积减少、传热边界层也更薄，传热效果显著提升；相比于圆管，E=1.7的椭圆管外液膜平均厚度减少26.21%，平均液膜速度增大20.81%，干壁面积减少86.00%，管外平均传热系数提高8.67%；E=1.8~2.0范围内，随着E增大，管外液膜平均厚度增大、液膜干壁面积增大，均不利于强化传热。

	Service

	把本文推荐给朋友
	加入我的书架
	加入引用管理器
	Email Alert
	RSS
	作者相关文章
	彭德其
	蒲幸禹
	俞天兰
	李广
	吴淑英

关键词：溴化锂制冷；降膜蒸发；汽液两相流；数值模拟；椭圆管

Abstract： In order to improve the corrosion resistance of refrigeration evaporator in LiBr (lithium bromide) central air conditioning system, titanium tube is used instead of copper tube. In addition, an elliptical tube instead of a circular tube is proposed to improve the evaporation efficiency of refrigerant outside the titanium tube. Effect of elliptic coefficient E on flow process, film thickness distribution and heat transfer coefficient of refrigerant outside the titanium tube was studied by numerical simulation. The results show that in the E (elliptic coefficient) range of 1.0—1.7, the average thickness of the liquid film is thinner, the flow velocity of the liquid film is increased, the area of the dry wall is reduced, the heat transfer boundary layer is thinner and the heat transfer effect is improved significantly with the increase of E. Compared with circular tube, when E=1.7, the average thickness of the liquid film is reduced by 26.21%, the flow velocity of the liquid film is increased by 20.81%, the area of the dry wall is reduced by 86.00% and the average heat transfer coefficient outside tube is increased by 8.67%. However, in the E range of 1.8—2.0, the average thickness of the liquid film and the area of dry wall are increased. Therefore, too large elliptic coefficient is not conducive to heat transfer enhancement.

Keywords： lithium bromide refrigeration； falling film evaporation； vapor-liquid two-phase flow； numerical simulation； elliptical tube

Received 2021-01-30;

Fund:湖南省战略性新兴产业项目（2019GK4021）；湘潭市科技计划项目（GX-YB20201011）

Corresponding Authors: 彭德其,教授,E-mail:pengshuaike@163.com Email: pengshuaike@163.com

About author: 彭德其(1972-)，男，教授，主要从事过程强化与节能环保研究

引用本文:

彭德其, 蒲幸禹, 俞天兰, 李广, 吴淑英.溴化锂制冷蒸发器中钛椭圆管外降膜流动及传热特性[J]. 化学工业与工程, 2022,39(1): 97-105

PENG Deqi, PU Xingyu, YU Tianlan, LI Guang, WU Shuying.Flow and heat transfer characteristics of falling film outside titanium elliptical tube in LiBr refrigeration evaporator[J]. Chemcial Industry and Engineering, 2022,39(1): 97-105

[1] LUO Xulu, LI Wenwu, CAO Zhixi. Research on erosion of lithium bromide solution in chiller[J]. Light Industry Machinery, 2011, 29(1): 104-107(in Chinese) 罗序禄, 李文武, 曹志锡. 制冷机中溴化锂溶液腐蚀性研究[J]. 轻工机械, 2011, 29(1): 104-107
[2] QUAN Difeng. Introduction to the application advantages of titanium in sea water cooling heat exchanger[J]. Popular Science & Technology, 2015, 17(4): 67-68(in Chinese) 全迪锋. 浅谈钛在海水冷却换热器中的应用优势[J]. 大众科技, 2015, 17(4): 67-68
[3] LI Xianjun, WANG Hao, MA Zhongxian. Application and prospect of titanium in ship field[J]. World Nonferrous Metals, 2013(8): 24-27 (in Chinese) 李献军, 王镐, 马忠贤. 钛在舰船领域的应用及前景[J]. 世界有色金属, 2013(8): 24-27
[4] TAN Qibin, JIANG Bin. Analysis on falling-film flow and heat transfer characteristics outside non-circular tube[J]. Refrigeration and Air-Conditioning, 2016, 16(12): 69-73, 30(in Chinese) 谭起滨, 蒋斌. 非圆管管外降膜流动和换热特性分析[J]. 制冷与空调, 2016, 16(12): 69-73, 30
[5] LI Zijian, JIANG Weiguo, QIU Qinggang, et al. Numerical study on falling film flow outside special shaped tube[C]//Engineering Thermophysics Committee of Chinese Society of Higher Education. Proceedings of the 20th National Conference on Engineering Thermophysics——Thermohydrodynamics. Engineering Thermophysics Committee of Chinese Society of Higher Education, 2014(in Chinese) 李子建, 蒋维国, 邱庆刚, 等. 异形管外液体降膜流动数值研究[C]//中国高等教育学会工程热物理专业委员会. 高等学校工程热物理第二十届全国学术会议论文集——热流体力学专辑. 中国高等教育学会工程热物理专业委员会, 2014
[6] LUO Lincong, PAN Jihong, TIAN Maocheng, et al. Influence of tube shape on falling water film thickness and Nusselt number outside horizontal tube[J]. CIESC Journal, 2013, 64(8): 2760-2768(in Chinese) 罗林聪, 潘继红, 田茂诚, 等. 管形对水平管降膜圆周膜厚和Nusselt数的影响[J]. 化工学报, 2013, 64(8): 2760-2768
[7] JANI S, AMINI M. Heat transfer analysis of falling film evaporation on a horizontal elliptical tube[J]. Journal of Heat Transfer, 2012, doi: 10.1115/1.4005745
[8] TAN Qibin, JIANG Bin. Analysis of falling film flow and heat transfer characteristics outside the elliptical horizontal tube[J]. Journal of Engineering for Thermal Energy and Power, 2017, 32(9): 20-25, 114, 120-121(in Chinese) 谭起滨, 蒋斌. 椭圆横管外降膜流动和换热特性分析[J]. 热能动力工程, 2017, 32(9): 20-25, 114, 120-121
[9] SUN L, YANG L, SHAO L, et al. Overall thermal performance oriented numerical comparison between elliptical and circular finned-tube condensers[J]. International Journal of Thermal Sciences, 2015, 89: 234-244
[10] PU L, LI Q, SHAO X, et al. Effects of tube shape on flow and heat transfer characteristics in falling film evaporation[J]. Applied Thermal Engineering, 2019, 148: 412-419
[11] HASAN A, SIRÉN K. Performance investigation of plain circular and oval tube evaporatively cooled heat exchangers[J]. Applied Thermal Engineering, 2004, 24(5/6): 777-790
[12] QI Chunhua, XU Ke, FENG Houjun, et al. Numerical simulation and experimental studies on falling film outside elliptical tube(Ⅰ): CFD simulation[J]. Chemical Industry and Engineering, 2012, 29(4): 74-79(in Chinese) 齐春华, 徐克, 冯厚军, 等. 椭圆管外液膜流动的数值模拟及传热实验研究Ⅰ: 数值模拟研究[J]. 化学工业与工程, 2012, 29(4): 74-79
[13] QI Chunhua, FENG Houjun, XING Yulei, et al. Numerical simulation and experimental studies on falling film outside elliptical tube(Ⅱ): Experimental study[J]. Chemical Industry and Engineering, 2012, 29(5): 43-47, 69(in Chinese) 齐春华, 冯厚军, 邢玉雷, 等. 椭圆管外液膜流动的数值模拟及传热实验研究Ⅱ: 实验研究[J]. 化学工业与工程, 2012, 29(5): 43-47, 69
[14] ZHENG Y, MA X, LI Y, et al. Experimental study of falling film evaporation heat transfer on superhydrophilic horizontal-tubes at low spray density[J]. Applied Thermal Engineering, 2017, 111: 1548-1556
[15] DING H, XIE P, INGHAM D, et al. Flow behaviour of drop and jet modes of a laminar falling film on horizontal tubes[J]. International Journal of Heat and Mass Transfer, 2018, 124: 929-942
[16] ZHU X, CHEN S, SHEN S, et al. Experimental study on the heat and mass transfer characteristics of air-water two-phase flow in an evaporative condenser with a horizontal elliptical tube bundle[J]. Applied Thermal Engineering, 2020, doi: 10.1016/j.applthermaleng.2019.114825
[17] LEE Y T, HONG S, DANG C, et al. Heat transfer characteristics of obliquely dispensed evaporating falling films on an elliptic tube[J]. International Journal of Heat and Mass Transfer, 2019, 132: 238-248
[18] QIU Q, ZHANG X, QUAN S, et al. 3D numerical study of the liquid film distribution on the surface of a horizontal-tube falling-film evaporator[J]. International Journal of Heat and Mass Transfer, 2018, 124: 943-952
[19] BRUMFIELD L K, THEOFANOUS T G. On the prediction of heat transfer across turbulent liquid films[J]. Journal of Heat Transfer, 1976, 98(3): 496-502
[20] CHEN X, SHEN S, WANG Y, et al. Measurement on falling film thickness distribution around horizontal tube with laser-induced fluorescence technology[J]. International Journal of Heat and Mass Transfer, 2015, 89: 707-713
[21] PARKEN W H, FLETCHER L S, SERNAS V, et al. Heat transfer through falling film evaporation and boiling on horizontal tubes[J]. Journal of Heat Transfer, 1990, 112(3): 744-750