竖管渗流降膜蒸发式冷凝器传热特性分析

doi:10.16085/j.issn.1000-6613.2022-0838

摘要/Abstract

摘要：

为研究竖管渗流降膜蒸发式冷凝器，通过仿真和实验相结合的手段，探究了冷凝器单管在不同管外温度、空气雷诺数与液体雷诺数等多工况下的传热特性。结合此前研究中存在的问题，合理选择了物理模型与边界条件，获得了降膜过程的轴向温度、热通量分布等并对径向位置进行了时间序列分析。结果表明逆向通风传热效果优于顺向通风，但易加剧管段下部液膜不稳定甚至出现干壁。通过时间序列分析发现干壁区域会被液膜快速覆盖，因此短暂干壁对整体传热影响并不十分明显，仍需注意逆向通风强度过高会对管子下部液膜的稳定性造成显著影响，本文工况下推荐单管空气雷诺数不宜超过3500。此外，测试结果显示本文单管传热量约为2200W，与模拟结果相差6.7%，单管综合传热系数为1400W/(m²·K)左右。

关键词: 降膜蒸发, 冷凝器, 竖直管, 传热特性

Abstract:

In order to study the vertical pipe seepage falling film evaporative condenser, the heat transfer characteristics of the single condenser tube under different external temperature, air Reynolds number and liquid Reynolds number were explored by using the combination of simulation and experiment method. Combined with the problems in previous research, the physical model and boundary conditions were selected reasonably, the axial distribution of temperature and heat flux density of the falling film process were obtained, and the radial position was analyzed in time series. The results showed that the heat transfer effect of reverse ventilation was better than that of co-directional ventilation, but it was easy to aggravate the instability of the liquid film in the lower part of the pipe section and even cause dry wall. It was found that the dry wall area would be covered by the liquid film immediately through time series analysis. Therefore, the effect of short-term dry wall on the overall heat transfer would not very obvious. It was still necessary to pay attention to the great influence of the high reverse ventilation intensity on the stability of the lower liquid film. It was recommended that the single-pipe air Reynolds number should not exceed 3500 under the working conditions of this paper. In addition, the test results showed that the heat transfer of a single tube in this paper was about 2200W, which was 6.7% different from the simulation results, and the comprehensive heat transfer coefficient of the single tube was about 1400W/(m²·K).

Key words: falling film evaporation, condenser, vertical tube, heat transfer characteristics

中图分类号:

TK172

谢迎春, 马洪亭, 徐畅, 马硕, 陈默, 刘军, 孙国强. 竖管渗流降膜蒸发式冷凝器传热特性分析[J]. 化工进展, 2023, 42(3): 1187-1194.

XIE Yingchun, MA Hongting, XU Chang, MA Shuo, CHEN Mo, LIU Jun, SUN Guoqiang. Analysis of heat transfer characteristics in vertical tube of seepage falling film evaporative condenser[J]. Chemical Industry and Engineering Progress, 2023, 42(3): 1187-1194.

图/表 15

图1 单管物理模型与网格划分

图2 网格无关性验证

图3 单管实验装置流程

表1 被测参数的相对不确定度

被测参数名称	相对不确定度/%
流量/kg·s^-1	2.236
风速/m·s^-1	9.177
温度/℃	0.530
相对湿度/%	2.108
换热量/W	8.009
综合传热系数/W·m^-2·K^-1	8.014

图4 不同水套温度下液膜温度与壁面热通量的轴向分布

图5 不同气体雷诺数的液膜温度轴向分布

图6 不同气体雷诺数下液膜速度轴向分布

图7 空气流向对热通量的影响

图8 空气流向对液膜流动状态的影响

图9 不同气体雷诺数下进出口空气参数实验结果

表2 单管变工况测试参数汇总

空气流速 /m·s^-1	Re_g	冷水入口流量 /L·h^-1	质量流量 /kg·s^-1	喷淋密度 /kg·s^-1·m^-1	Re_l
0.5	1156	40	0.011	0.111	440
1.0	2312	60	0.017	0.166	661
1.5	3467	80	0.022	0.221	881
2.0	4623	100	0.028	0.276	1 101
2.5	5779
3.0	6935

图10 液膜厚度、壁面热通量与液膜表面温度的时序图

图11 不同水套温度下液膜表面温度与壁面热通量的概率密度

图12 互协方差计算结果

图13 变液膜流量工况测试结果

参考文献 19

1	吴学红, 陆刘记, 刘旭，等. 内翅板蒸发式冷凝器水膜流动特性[J]. 化工进展, 2017, 36(6): 2017-2022.
	WU Xuehong, LU Liuji, LIU Xu, et al. Experimental study on the water film flowing characteristics of the internal fin-plate evaporative condenser[J]. Chemical Industry and Engineering Progress, 2017, 36(6): 2017-2022.
2	赵婵, 许松林. 降膜蒸发研究进展[J]. 石油化工设备, 2013, 42(6): 54-59.
	ZHAO Chan, XU Songlin. Progress of study on falling film evaporation[J]. Petro-Chemical Equipment, 2013, 42(6): 54-59.
3	SHAH M M. A general correlation for heat transfer during evaporation of falling films on single horizontal plain tubes[J]. International Journal of Refrigeration, 2021, 130: 424-433.
4	师晋生, 陈玉宙. 自由表面摩擦和蒸发对过冷下降液膜传热的影响[J]. 热能动力工程, 2001, 16(4): 383-385, 392.
	SHI Jinsheng, CHEN Yuzhou. The effect of free surface friction and evaporation on the heat transfer of sub-cooled falling liquid film[J]. Journal of Engineering for Thermal Energy and Power, 2001, 16(4): 383-385, 392.
5	MITTERMAIER M, SCHULZE P, ZIEGLER F. A numerical model for combined heat and mass transfer in a laminar liquid falling film with simplified hydrodynamics[J]. International Journal of Heat and Mass Transfer, 2014, 70: 990-1002.
6	赵婵. 竖直管内气液逆流降膜的计算流体力学模拟[J]. 计算机与应用化学, 2014, 31(6): 745-750.
	ZHAO Chan. CFD simulation of counter-current gas-liquid falling-film flow in a vertical tube[J]. Computers and Applied Chemistry, 2014, 31(6): 745-750.
7	上官闪闪. 竖直圆管管内R113降膜流动与蒸发换热特性数值模拟[D]. 郑州: 华北水利水电大学, 2016.
	SHANGGUAN Shanshan. Numerical simulation on falling flow and evaporative heat transfer characteristics of R113 inside a vertical tube[D]. Zhengzhou: North China University of Water Resources and Electric Power, 2016.
8	CHUN K R, SEBAN R A. Heat transfer to evaporating liquid films[J]. Journal of Heat Transfer, 1971, 93(4): 391-396.
9	LYU T H, MUDAWAR I. Statistical investigation of the relationship between interfacial waviness and sensible heat transfer to a falling liquid film[J]. International Journal of Heat and Mass Transfer, 1991, 34(6): 1451-1464.
10	张猛, 周帼彦, 朱冬生. 降膜蒸发器的研究进展[J]. 流体机械, 2012, 40(6): 82-86.
	ZHANG Meng, ZHOU Guoyan, ZHU Dongsheng. Research progress of falling-film evaporator[J]. Fluid Machinery, 2012, 40(6): 82-86.
11	郝丽, 肖晓明, 张吕鸿, 等. 竖直管降膜蒸发器流动与传热过程的数值模拟[J]. 化学工业与工程, 2014, 31(2): 60-65.
	HAO Li, XIAO Xiaoming, ZHANG Lyuhong, et al. Numerical simulation of the flow and heat transfer process of vertical tube falling film evaporator[J]. Chemical Industry and Engineering, 2014, 31(2): 60-65.
12	黄阔. 降膜蒸发器传热传质强化及应用研究[D]. 广州: 华南理工大学, 2018.
	HUANG Kuo. Heat and mass transfer enhancement of falling film evaporator and its applications[D]. Guangzhou: South China University of Technology, 2018.
13	MA Hongqiang, LIU Yemin, HOU Caiqin, et al. Numerical investigation on the thermal-flow performance of humid air-water in the interspace outside staggered tube bundles[J]. International Journal of Heat and Mass Transfer, 2021, 166: 120784.
14	RAMADAN Z, PARK C W. Hydrodynamic behavior of liquid falling film over horizontal tubes: Effect of hydrophilic circular surface on liquid film thickness and heat transfer[J]. Case Studies in Thermal Engineering, 2021, 24: 100821.
15	蒋翔, 朱冬生, 吴治将, 等. 立式蒸发式冷凝器传热传质的CFD模拟[J]. 高校化学工程学报, 2009, 23(4): 566-571.
	JIANG Xiang, ZHU Dongsheng, WU Zhijiang, et al. The CFD simulation on heat and mass transfer of vertical evaporative condenser[J]. Journal of Chemical Engineering of Chinese Universities, 2009, 23(4): 566-571.
16	刘国兵, 惠宇, 王玉璋. 沿垂直壁面气-液降膜流动传质过程的数值研究[J]. 燃气轮机技术, 2012, 25(3): 34-39.
	LIU Guobing, HUI Yu, WANG Yuzhang. Numerical simulation of the mass transfer in gas-liquid falling film flow on the vertical plate[J]. Gas Turbine Technology, 2012, 25(3): 34-39.
17	谷芳, 刘春江, 余黎明, 等. 气-液两相降膜流动及传质过程的CFD研究[J]. 高校化学工程学报, 2005, 19(4): 438-444.
	GU Fang, LIU Chunjiang, YU Liming, et al. The CFD simulation of mass-transfer process in falling film with countercurrent two-phase flow[J]. Journal of Chemical Engineering of Chinese Universities, 2005, 19(4): 438-444.
18	臧丽叶, 田瑞峰, 孙兰昕, 等. 平面激光诱导荧光技术在液膜厚度波动实验研究中的应用[J]. 原子能科学技术, 2014, 48(9): 1654-1659.
	ZANG Liye, TIAN Ruifeng, SUN Lanxin, et al. Application of planar laser-induced fluorescence technique in measurement of dynamic film thickness[J]. Atomic Energy Science and Technology, 2014, 48(9): 1654-1659.
19	KARAPANTSIOS T D, PARAS S V, KARABELAS A J. Statistical characteristics of free falling films at high Reynolds numbers[J]. International Journal of Multiphase Flow, 1989, 15(1): 1-21.

[1]	郭文杰, 翟玉玲, 陈文哲, 申鑫, 邢明. Al₂O₃-CuO/水混合纳米流体对流传热性能及热经济性分析[J]. 化工进展, 2023, 42(5): 2315-2324.
[2]	尚玉, 肖满, 崔秋芳, 涂特, 晏水平. CO₂捕集工艺中热再生气余热的PVDF/BN-OH平板复合膜回收特性[J]. 化工进展, 2023, 42(3): 1618-1628.
[3]	邹银才, 李清国, 吴辉, 钟小兵, 陈咸志. 弹载相变热沉传热仿真与优化[J]. 化工进展, 2023, 42(3): 1248-1256.
[4]	汪静, 武卫东, 王浩, 李振博, 刘荟. 辅助冷凝器冷却水量对闭式热泵干燥系统性能的影响[J]. 化工进展, 2021, 40(3): 1307-1314.
[5]	周智程, 魏爱博, 屈健, 关凤渤, 郭泽霖. 管板结构脉动热管冷却动力电池的传热特性[J]. 化工进展, 2020, 39(10): 3916-3925.
[6]	赵朋飞,张小辉,张汉,冯鹏,徐佳瑞. 非等温液-液对置撞击面温度分布均匀性[J]. 化工进展, 2019, 38(12): 5297-5305.
[7]	孙斌,董爽,杨迪,李洪伟. 多壁碳纳米管-水/乙二醇纳米流体在汽车散热器中的传热特性[J]. 化工进展, 2019, 38(03): 1207-1217.
[8]	李兆宁, 赵彦杰, 范亚茹. 相变蓄冷浆体材料研究进展[J]. 化工进展, 2018, 37(S1): 108-116.
[9]	马乾, 刘雪东, 温传美, 谢红笑, 尹传忠. 网纹内管双套管双管板安全型换热器的传热性能[J]. 化工进展, 2018, 37(06): 2109-2115.
[10]	徐委托, 马晓建, 马力, 陈俊英, 杨闪, 张芬芬. 脂肪酸甲酯降膜蒸发器沸腾传热性能[J]. 化工进展, 2016, 35(09): 2693-2698.
[11]	谢涛, 杨伯伦. 基于太阳能蓄热过程的甲烷二氧化碳重整研究进展[J]. 化工进展, 2016, 35(06): 1723-1732.
[12]	李连涛, 诸凯, 刘圣春, 王华峰. 带有中间分液结构的管壳式冷凝器实验研究[J]. 化工进展, 2016, 35(05): 1332-1337.
[13]	严涛, 刘玉丰, 刘丰. 液化天然气(LNG)接收站节能再冷凝器的研究与设计[J]. 化工进展, 2015, 34(s1): 51-54.
[14]	韩广明，李敏霞，马一太. 低GWP工质空调冷凝器性能模拟计算[J]. 化工进展, 2014, 33(04): 824-830.
[15]	屈健. 脉动热管技术研究及应用进展[J]. 化工进展, 2013, 32(01): 33-41.