Direct contact heat transfer process of vacuum exhaust system in wind tunnel

doi:10.16085/j.issn.1000-6613.2021-2380

Abstract

Abstract:

During the operation of the vacuum exhaust system of a wind tunnel, a large amount of mixed gas with water vapor are produced. In order to improve the exhaust efficiency and reduce energy consumption, the condensing tower process was introduced to cool and condense the mixed gas with water vapor by direct contact heat exchange and condensation. Based on the high mass transfer model of micro element tower, the direct contact heat transfer process between heat flow gas entering the condensation tower and cooling water was analyzed, and the mathematical equation expression of mass transfer coefficient was deduced. Combined with the experimental data, the effects of gas pressure and condensation cooling on the water vapor content of the discharged gas were investigated, and the mathematical expressions of gas pressure and water vapor content at a certain temperature were fitted. The effects of cooling water mass flux and gas-liquid ratio on mass transfer coefficient, volumetric heat transfer coefficient and outlet temperature were also investigated. On this basis, the mathematical relationship between gas-liquid ratio and volumetric heat transfer coefficient for direct contact heat transfer of wind tunnel airflow was fitted, and the optimal gas-liquid ratio was calculated. The rules obtained from the experiment can be a guiding role in the optimal design and application of direct contact heat transfer of wind tunnel airflow.

Key words: mass transfer, heat transfer, enthalpy, direct contact, condensation

摘要：

某风洞真空排气系统在运行过程中，会产生大量含水蒸气的混合气体。为了提高排气效率降低能耗，本文引入冷凝塔工艺，采用直接接触换热冷凝方式使来流含水蒸气的混合气体降温冷凝。基于微元塔高传质模型，对进入冷凝塔的热流气体与冷却水直接接触换热过程分析，推导出传质系数数学方程表达式。结合实验数据考察了进气压力与冷凝降温排出气体中水蒸气含量的影响，并拟合得到一定温度下进气压力与该气体水蒸气含量的数学表达式；也考察了冷却水质量通量和气液比变化对传质系数、体积传热系数、出气温度的影响，在此基础上拟合得到针对风洞气流直接接触换热气液比与体积传热系数数学关系式，并计算出最优气液比。实验得出的规律对风洞气流的直接接触换热优化设计和应用起到了指导作用。

关键词: 传质, 传热, 焓, 直接接触, 冷凝

CLC Number:

TQ05

LI Wei, QI Dawei, YANG Jiongliang. Direct contact heat transfer process of vacuum exhaust system in wind tunnel[J]. Chemical Industry and Engineering Progress, 2022, 41(9): 4618-4624.

李伟, 齐大伟, 杨炯良. 风洞真空排气系统直接接触传热过程[J]. 化工进展, 2022, 41(9): 4618-4624.

Figures/Tables 11

References 20

1	齐大伟, 李伟华, 李传旭, 等. 大型风洞用离心真空泵气动设计[J]. 真空, 2021, 58(4): 49-53.
	QI Dawei, LI Weihua, LI Chuanxu, et al. Pneumatic design of centrifugal vacuum pump for large wind tunnel[J]. Vacuum, 2021, 58(4): 49-53.
2	李彦良, 张喦, 曹知红, 等. 大温差高速燃气喷水冷却器喷嘴阵列设计[J]. 工程热物理学报, 2020, 41(5): 1102-1109.
	LI Yanliang, ZHANG Yan, CAO Zhihong, et al. Design and simulation of the nozzle array for high temperature gas cooler[J]. Journal of Engineering Thermophysics, 2020, 41(5): 1102-1109.
3	蒲旭阳, 刘伟雄, 李向东, 等. 抽吸排气式高焓风洞应用实验研究[J]. 推进技术, 2018, 39(2): 450-455.
	PU Xuyang, LIU Weixiong, LI Xiangdong, et al. Applied experimental study of exhaust high enthalpy tunnel with pumping[J]. Journal of Propulsion Technology, 2018, 39(2): 450-455.
4	郭达, 祁贵生, 刘有智, 等. 错流旋转填料床的质、热同传性能及传热机理研究[J]. 化工学报, 2021, 72(11): 5543-5551.
	GUO Da, QI Guisheng, LIU Youzhi, et al. Research on mass and heat synchronous performance and heat transfer mechanism of cross-flow rotating packed bed[J]. CIESC Journal, 2021, 72(11): 5543-5551.
5	付海玲, 王一平. 直接接触汽化传热实验装置的设计与测试技术[J]. 化学工程, 2017, 45(12): 30-34.
	FU Hailing, WANG Yiping. Design and test technology of direct contact evaporation heat transfer experimental installation[J]. Chemical Engineering, 2017, 45(12): 30-34.
6	李晗, 蒲文灏, 杨宁, 等. 空气-石蜡直接接触换热特性实验研究[J]. 化工学报, 2018, 69(9): 3792-3798.
	LI Han, PU Wenhao, YANG Ning, et al. Experimental study on air-paraffin direct contact heat transfer characteristics[J]. CIESC Journal, 2018, 69(9): 3792-3798.
7	胡保亭. 空气-水直接接触高效传热过程及设备研究[D]. 青岛: 中国海洋大学, 2004.
	HU Baoting. Study on high efficient air-water direct contact heat transfer process and equipment[D]. Qingdao: Ocean University of China, 2004.
8	章学来, 卢家才, 李瑞阳, 等. 直接接触式换热技术的研究进展[J]. 能源技术, 2001, 22(1): 2-6.
	ZHANG Xuelai, LU Jiacai, LI Ruiyang, et al. There search advancement of direct contact heat transfer technology[J]. Energy Technology, 2001, 22(1): 2-6.
9	王一平, 李彦博, 张金利. 直接接触式环流换热器传热研究[J]. 化学工程, 2000, 28(4): 18-21, 31.
	WANG Y P, LI Y B, ZHANG J L. Research on heat transfer about direct contact recycling exchanger[J]. Chemical Engineering, 2000, 28(4): 18-21, 31.
10	WAGNER W, KRUSE A. Properties of water and steam: the industrial standard IAPWS-IF97 for the thermodynamic properties and supplementary equations for other properties: tables based on these equation[M]. Berlin: Springer-Verlag, 1998.
11	WALKERW H, LEWISW K, MCADAMSW H. Principles of chemical engineering[M]. NewYork: McGraw-Hill, 1923.
12	FISENKOS P, PETRUCHIKA I, SOLODUKHINA D. Evaporative cooling of water in a natural draft cooling tower[J]. International Journal of Heat and Mass Transfer, 2002, 45(23): 4683-4694.
13	魏世超, 黄群武, 蒋丽红, 等. 采用填料强化的鼓泡塔直接接触换热性能研究[J]. 化学工业与工程, 2017, 34(1): 84-89.
	WEI Shichao, HUANG Qunwu, JIANG Lihong, etal. Direct contact heat transfer performance in spray column with packing[J]. Chemical Industry and Engineering, 2017, 34(1): 84-89.
14	LI Yi, KLAUSNER J F, MEI R W, et al. Direct contact condensation in packed beds[J]. International Journal of Heat and Mass Transfer, 2006, 49(25/26): 4751-4761.
15	SPIEGEL L, BOMIO P, HUNKELER R. Direct heat and mass transfer instructured packings[J]. Chemical Engineering and Processing: Process Intensification, 1996, 35(6): 479-485.
16	倪春丽, 王一平, 黄群武. 新型规整填料换热器传热的理论与实验研究[J]. 化学工程, 2018(1): 31-36.
	NI Chunli, WANG Yiping, HUANG Qunwu. The oretical and experimental study on heat transfer performance of novel structured packing heat exchanger[J]. Chemical Engineering, 2018(1): 31-36.
17	HEYNSJ A, KRÖGERD G. Experimental investigation into the thermal-flow performance characteristics of an evaporative cooler[J]. Applied Thermal Engineering, 2010, 30(5): 492-498.
18	刘少卿. 规整填料内直接接触冷凝传热实验研究[D]. 天津: 天津大学, 2013.
	LIU Shaoqing. Experimental study of direct contact condensation instructured packing[D]. Tianjin: Tianjin University, 2013.
19	HASANA L, SIRÉN K. The oretical and computational analysis of closed wet cooling towers and its applications in cooling of buildings[J]. Energy and Buildings, 2002, 34(5): 477-486.
20	郭强, 祁贵生, 刘有智, 等. 不同规整填料旋转床的传质性能对比[J]. 化工进展, 2016, 35(3): 741-747.
	GUO Qiang, QI Guisheng, LIU Youzhi, et al. Comparative study of mass transfer performance of different structured packings in rotating packed bed[J]. Chemical Industry and Engineering Progress, 2016, 35(3): 741-747.

序号	名称	安装位置	量程/规格	数量	品牌或型号
1	文丘里流量计	冷凝塔进气管路	0~100kg·s^-1	1	罗斯蒙特
2	质量流量计	冷凝塔进水管路	0~1000kg·s^-1	1	重庆川仪
3	压力变送器	热气进气口	0~100kPa（绝压）	1	罗斯蒙特
4	温度计	冷凝塔进气口、出气口，冷凝塔进水口、出水口，填料位置	Pt100热电阻	5	重庆川仪
5	气体水分分析仪	冷凝塔进气口、出气口	0~70%	2	诺科仪器NK-300
6	测量采集系统		PLC1500	1	西门子

序号	名称	安装位置	量程/规格	数量	品牌或型号
1	文丘里流量计	冷凝塔进气管路	0~100kg·s^-1	1	罗斯蒙特
2	质量流量计	冷凝塔进水管路	0~1000kg·s^-1	1	重庆川仪
3	压力变送器	热气进气口	0~100kPa（绝压）	1	罗斯蒙特
4	温度计	冷凝塔进气口、出气口，冷凝塔进水口、出水口，填料位置	Pt100热电阻	5	重庆川仪
5	气体水分分析仪	冷凝塔进气口、出气口	0~70%	2	诺科仪器NK-300
6	测量采集系统		PLC1500	1	西门子

参数	值
热流气体进冷凝塔
F_g/kg·s^-1	18.88~92.26
T_g1/℃	58.6~91.8
W_g1/%	25.4~61.35
p_g/kPa	18~72
冷却水
F_w/kg·s^-1	100~700
L/kg·m^-2·s^-1	1.86×10^-2~1.303×10^-1
T_w1/℃	25.0
T_w2/℃	37.2~61.6

参数	值
热流气体进冷凝塔
F_g/kg·s^-1	18.88~92.26
T_g1/℃	58.6~91.8
W_g1/%	25.4~61.35
p_g/kPa	18~72
冷却水
F_w/kg·s^-1	100~700
L/kg·m^-2·s^-1	1.86×10^-2~1.303×10^-1
T_w1/℃	25.0
T_w2/℃	37.2~61.6

气体体积分数/%				F_g/kg·s^-1	G/kg·m^-2·s^-1	t_g1/℃	p_g/kPa	c_g/kJ·kg^-1·K^-1	I/kJ·kg^-1
H₂O	N₂	CO₂	O₂	F_g/kg·s^-1	G/kg·m^-2·s^-1	t_g1/℃	p_g/kPa	c_g/kJ·kg^-1·K^-1	I/kJ·kg^-1
61.35	24.4	4.81	9.38	57.7	0.0107	68.3	29	1.42	-7206