含不凝气体的蒸汽凝结换热数值研究

doi:10.12382/bgxb.2022.0225

摘要/Abstract

摘要：

为研究水下半闭式循环动力系统中高压换热器的性能,建立适用于高压下含大比例不凝气体的蒸汽凝结过程的数值模型,并考虑重力对水平套管式换热器的燃气流道进行多工况仿真计算与试验验证。研究结果表明:由于重力的存在,管道顶部和底部的液膜厚度不均匀,同时管内气相工质会产生二次旋流,两种作用将导致管内换热的不均匀特性;管径的减小将使管内工质流速增加,增大雷诺数的同时也使底部液膜变薄,有助于增强换热;流速增加削弱了重力的影响,使管道顶部和底部换热强度的差距变小;在所设工况下,即使考虑总换热面积的缩减,减小管径仍有助于总换热功率的提升;试验与仿真的管内温度最大误差为19.5%。所得成果可为水下半闭式循环动力系统高压换热器的设计提供参考。

关键词: 冷凝换热, 不凝气体, 蒸汽凝结, 计算流体力学

Abstract:

In order to study the performance of a high-pressure heat exchanger in an underwater semi-closed cycle power system, we establish a numerical model to analyze the condensation process of steam containing a significant proportion of non-condensable gas under high pressure. The model is verified through a specific experiment, and we conduct simulations of the gas flow channel in the heat exchanger under different working conditions, taking gravity into consideration. The results show that due to the gravity, the liquid film thicknesses at the top and bottom of the pipe are not uniform, resulting in swirling flow within the gas phase. These two effects lead to uneven heat transfer characteristics in the pipe. Additionally, the flow velocity increases with the decreasing pipe diameter, causing a rise in the Reynolds number and a thinning of the bottom liquid film. This contributes to heat transfer. The increased flow velocity also reduces the effect of gravity, reducing the disparity in heat transfer intensity between the top and bottom sections of the pipe. Under the working conditions in this paper, even with a reduced total heat transfer area, reducing the pipe diameter remains conducive to the improvement of the total heat transfer power. The maximum temperature error between the experimental and simulated results is 19.5%. The conclusions contribute to the design of high-pressure heat exchangers in underwater semi-closed cycle power systems.

Key words: condensation heat transfer, non-condensable gas, steam condensation, computational fluid dynamics

郭庆, 罗凯, 耿少航, 秦侃. 含不凝气体的蒸汽凝结换热数值研究[J]. 兵工学报, 2023, 44(7): 2080-2091.

GUO Qing, LUO Kai, GENG Shaohang, QIN Kan. Numerical Study of Condensation Heat Transfer of Steam with Non-condensable Gas[J]. Acta Armamentarii, 2023, 44(7): 2080-2091.

图/表 21

图1 半闭式循环动力系统结构示意图

Fig.1 Schematic diagram of a semi-closed cycle power system

表1 HAP三组元推进剂燃烧产物组成

Table 1 Combustion products of the HAP tri-component propellant

组分	质量分数/%	特性
CO	0.26	不溶于水
CO₂	20.47	不溶于水
H₂	0.12	不溶于水
N₂	5.48	不溶于水
HCl	8.44	可溶于水
H₂O	65.18	可凝结

图2 套管式换热器结构示意图

Fig.2 Schematic diagram of a double-pipe heat exchanger

表2 部分已有研究涉及的工况范围

Table 2 Working conditions of the research mentioned above

研究者	研究类型	工质种类	压力/MPa
Kuhn^[7]	试验研究	空气、氦气	0.1~0.5
Lee等^[8]	试验研究	氮气	0.1~0.13
Ren等^[9]	试验研究	空气	0.1~0.4
马喜振^[10]	试验研究	氮气、氩气	0.2~5.6
Park等^[11]	试验研究	空气	0.19~0.49
Ji等^[12]	试验研究	未注明	0.02~0.07
Groff等^[15]	数值研究	空气	0.1
Bian等^[16]	数值研究	空气	0.1~0.4
耿少航等^[19]	数值研究	CO₂	10

图3 套管式换热器试验设备

Fig.3 Casing heat exchanger test equipment

图4 高温换热器结构示意图

Fig.4 Schematic diagram of the heat exchanger

图5 换热器管道流域示意图

Fig.5 Flow domain of the heat exchanger pipe

表3 仿真计算的边界条件

Table 3 Boundary conditions for simulations

参数	数值
入口质量流量/(g·s^-1)	10
入口温度/K	575
入口水蒸气过热度/K	2.5
出口压力/MPa	10
壁面温度/K	545
工质种类	水蒸气、CO₂
CO₂质量分数	0.3

表4 试验工况参数

Table 4 Operation parameters of the experiment

参数	数值
燃气通道入口压力/MPa	10
燃气通道入口温度/K	1100
燃气通道出口温度/K	340
冷却水通道入口压力/MPa	5
冷却水通道入口温度/K	280
冷却水通道出口温度/K	600
燃气通道入口水蒸气体积分数/%	7

图6 高温热交换器的流域示意图

Fig.6 Flow domain of the high-temperature heat exchanger

图7 仿真计算与试验的管内温度分布对比

Fig.7 Comparison of temperature distribution between simulation and experimental results

表5 网格无关性研究中各工况计算网格设置参数

Table 5 Mesh setting parameters in grid independence study

工况	网格数	近壁面第1层网格厚度/mm	径向网格增长率	平均y⁺
网格1	242万	0.012	1.2	1.09
网格2	389万	0.010	1.2	0.92
网格3	627万	0.008	1.2	0.86

图8 网格无关性研究中的液膜厚度与换热系数对比

Fig.8 Film thickness and heat transfer coefficient of the grid independence study

图9 换热器管道中z取值分别为1.0m、1.2m、1.4m和1.6m处的速度分布

Fig.9 Velocity distrubutions at z=1.0m, 1.2m, 1.4m and 1.6m of the heat exchanger pipe

图10 换热器管道的液膜厚度和z=1.0m、1.2m、1.4m和1.6m处的液相体积分数-流线图

Fig.10 Water film thickness and water volume fraction-streamline contours at z=1.0m, 1.2m, 1.4m and 1.6m of the heat exchanger pipe

图11 热流密度和换热系数沿换热器管道的轴向变化

Fig.11 Heat flux and heat transfer coefficient distributions along the axial direction of the heat exchanger pipe

图12 变管径工况下主流温度与热流密度的变化

Fig.12 Bulk temperature and heat flux under conditions of different pipe diameters

图13 变管径工况下z=1.2m处速度分布

Fig.13 Velocity distubutions at z=1.2m with different pipe diameters

图14 变管径工况管道液膜厚度

Fig.14 Film thickness with different pipe diameters

图15 变管径工况气相主流平均雷诺数与壁面平均热流密度的关系

Fig.15 Relationship between average gas Reynolds number and wall heat flux with different pipe diameters

图16 不同管径管道总换热功率

Fig.16 Total heat transfer power of pipes with different diameters

参考文献 26

[1]	钟宏伟, 李国良, 宋林桦, 等. 国外大型无人水下航行器发展综述[J]. 水下无人系统学报, 2018, 26(4): 273-282.
	ZHONG H W, LI G L, SONG L H, et al. Development of large displacement unmanned undersea vehicle in foreign countries: a review[J]. Journal of Unmanned Undersea Systems, 2018, 26(4): 273-282. (in Chinese)
[2]	任丽彬, 桑林, 赵青, 等. AUV动力电池应用现状及发展趋势[J]. 电源技术, 2017, 41(6): 952-955.
	REN L B, SANG L, ZHAO Q, et al. Application status and development trend of power battery for AUV[J]. Chinese Journal of Power Sources, 2017, 41(6): 952-955. (in Chinese)
[3]	KIELY D. Review of underwater thermal propulsion[C]//Proceedings of the 30th Joint Propulsion Conference and Exhibit. Indianapolis,IN, US: AIAA, 1994.
[4]	白杰, 党建军, 罗凯, 等. 水下航行器闭式循环动力系统动态仿真[J]. 鱼雷技术, 2016, 24(6): 438-443.
	BAI J, DANG J J, LUO K, et al. Dynamic simulation of closed cycle power system for UUV[J]. Torpedo Technology, 2016, 24(6): 438-443. (in Chinese)
[5]	HILLS R. HAP/OTTO fuel application to torpedo engines[C]// Proceedings of the 18th Joint Propulsion Conference. Cleveland,OH,US:AIAA, 1982.
[6]	KUHN S Z, SCHROCK V E, PETERSON P F. An investigation of condensation from steam-gas mixtures flowing downward inside a vertical tube[J]. Nuclear Engineering and Design, 1997, 177(1/2/3): 53-69. doi: 10.1016/S0029-5493(97)00185-4 URL
[7]	KUHN S Z. Investigation of heat transfer from condensing steam-gas mixtures and turbulent films flowing downward inside a vertical tube[D]. Berkeley,CA,US: University of California, 1995.
[8]	LEE K, KIM M H. Experimental and empirical study of steam condensation heat transfer with a noncondensable gas in a small-diameter vertical tube[J]. Nuclear Engineering and Design, 2008, 238(1): 207-216. doi: 10.1016/j.nucengdes.2007.07.001 URL
[9]	REN B, ZHANG L, CAO J, et al. Experimental and theoretical investigation on condensation inside a horizontal tube with non-condensable gas[J]. International Journal of Heat and Mass Transfer, 2015, 82: 588-603. doi: 10.1016/j.ijheatmasstransfer.2014.11.041 URL
[10]	马喜振. 高压下非凝性气体对蒸汽冷凝传热特性影响研究[D]. 北京: 清华大学, 2017.
	MA X Z. Research on steam condensation with non-condensable gases under the high pressure[D]. Beijing: Tsinghua University, 2017. (in Chinese)
[11]	PARK S K, KIM M H, YOO K J. Effects of a wavy interface on steam-air condensation on a vertical surface[J]. International Journal of Multiphase Flow, 1997, 23(6): 1031-1042. doi: 10.1016/S0301-9322(97)00022-0 URL
[12]	JI D, LEE J, KIM D, et al. Effective reduction of non-condensable gas effects on condensation heat transfer: surface modification and steam jet injection[J]. Applied Thermal Engineering, 2020, 174:115264. doi: 10.1016/j.applthermaleng.2020.115264 URL
[13]	FU W, LI X W, WU X X, et al. Numerical investigation of convective condensation with the presence of non-condensable gases in a vertical tube[J]. Nuclear Engineering and Design, 2016, 297: 197-207. doi: 10.1016/j.nucengdes.2015.11.034 URL
[14]	ALSHEHRI A, ANDALIB S, KAVEHPOUR H P. Numerical modeling of vapor condensation over a wide range of non-condensable gas concentrations[J]. International Journal of Heat and Mass Transfer, 2020, 151(119405).
[15]	GROFF M K, ORMISTON S J, SOLIMAN H M. Numerical solution of film condensation from turbulent flow of vapor-gas mixtures in vertical tubes[J]. International Journal of Heat and Mass Transfer, 2007, 50(19/20): 3899-3912. doi: 10.1016/j.ijheatmasstransfer.2007.02.012 URL
[16]	BIAN H Z, SUN Z N, CHENG X, et al. CFD evaluations on bundle effects for steam condensation in the presence of air under natural convection conditions[J]. International Communications in Heat and Mass Transfer, 2018, 98: 200-208. doi: 10.1016/j.icheatmasstransfer.2018.09.003 URL
[17]	ZSCHAECK G, FRANK T, BURNS A D. CFD modelling and validation of wall condensation in the presence of non-condensable gases[J]. Nuclear Engineering and Design, 2014, 279(SI): 137-146. doi: 10.1016/j.nucengdes.2014.03.007 URL
[18]	顾成勇. 含不凝气的竖直管内蒸汽冷凝数值模拟研究[D]. 大连: 大连理工大学, 2016.
	GU C Y. Numerical simulation on condensation in presence of non-condensable gas in vertical tubes[D]. Dalian: Dalian University of Technology, 2016. (in Chinese)
[19]	耿少航, 党建军, 赵佳, 等. 高压下含大比例不凝气体的水蒸气对流冷凝数值仿真[J]. 水下无人系统学报, 2021, 29(1): 88-96.
	GENG S H, DANG J J, ZHAO J, et al. Numerical simulation of convective condensation of steam with large proportion of non-condensable gas under high pressure[J]. Journal of Unmanned Undersea Systems, 2021, 29(1): 88-96. (in Chinese)
[20]	HUANG J, ZHANG J X, WANG L. Review of vapor condensation heat and mass transfer in the presence of non-condensable gas[J]. Applied Thermal Engineering, 2015, 89(5): 469-484. doi: 10.1016/j.applthermaleng.2015.06.040 URL
[21]	ANSYS. Ansys help[M]. Canonsburg,PA,US: Ansys Inc., 2016.
[22]	KHARANGATE C R, MUDAWAR I. Review of computational studies on boiling and condensation[J]. International Journal of Heat and Mass Transfer, 2017, 108(A): 1164-1196.
[23]	TANG Y, ZHU S L, QIU L M. Determination of mass transfer coefficient for condensation simulation[J]. International Journal of Heat and Mass Transfer, 2019, 143 (Nov.): 118481-118485.
[24]	MENTER F R. 2-Equation eddy-viscosity turbulence models for engineering applications[J]. AIAA Journal, 1994, 32(8): 1598-1605. doi: 10.2514/3.12149 URL
[25]	李宗吉, 王树宗, 陈华东, 等. 奥托-Ⅱ单组元推进剂燃烧产物平衡组成计算模型及仿真结果[J]. 舰船科学技术, 2004, 26(5): 27-30.
	LI Z J, WANG S Z, CHEN H D, et al. Mathematical model and simulation results of equilibrium compositions of OTTO-Ⅱ monopropellant’s combustion products[J]. Ship Science and Technology, 2004, 26(5): 27-30. (in Chinese)
[26]	李晓莹. 传感器与测试技术[M]. 北京: 高等教育出版社, 2019.
	LI X Y. Sensors and test technology[M]. Beijing: Higher Education Press, 2019. (in Chinese)