﻿ 水下航行器小通道内蒸汽冷凝换热计算分析
 舰船科学技术  2016, Vol. 38 Issue (6): 86-91 PDF

1. 中国船舶重工集团公司 第七〇五研究所, 陕西 西安 710077 ;
2. 水下信息与控制重点实验室, 陕西 西安 710077

Calculation analysis on condensation heat transfer of small channel steam of underwater vehicle
BAI Chao1,2, HAN Yong-jun1, YI Yin1, SHI Xiao-feng1, GUO Zhao-yuan1, FENG Qi-xi1, LU Jun1
1. The 705 Research Institute of CSIC, Xi'an 710077, China ;
2. Science and Technology on Underwater Information and Control Laboratory, Xi'an 710077, China
Abstract: According to the underwater environment and use structural characteristics of the condenser of underwater vehicle, the paper develops the the model of enthalpy, the model of convective heat transfer coefficient and the model of pressure. Based on the four kinds of formula of heat transfer coefficient, the paper solves the simulation value of the enthalpy, temperature, pressure and dry degree, and compared them with the experimental data. The results show that using the D-B correlation in the single-phase region and using A-R correlation in two-phase region, the simulation results is most consistent with experimental data. And based on this, this paper calculates and analyzes the cross section size of the small channel. The results show that when the width is 6 mm, the small channel has a good flow and heat transfer capability, and provide an important reference for the engineering design of underwater vehicle.
Key words: condenser     small channel     heat transfer and condensation     heat transfer coefficient calculation formula     section size design
0 引 言

1 蒸汽凝结换热模型

1.1 凝结换热模型

1）冷却通道间壁认为是强化传热肋片，在计算时考虑翅片效率；

2）通道外部的冷却水温度为常温；

3）小通道内流动为稳态流动；

4）内管壁视为绝热，不计导热及散热损失的影响。

5）不考虑重力的影响。

 图 1 换热过程简化模型示意图 Fig. 1 The simplified model for heat transfer process
1.2 焓值求解模型

 $\delta Q=dE+({{e}_{2}}\delta {{m}_{2}}-{{e}_{1}}\delta {{m}_{1}})+\delta {{W}_{\text{out}}}$ (1)

 ${{\dot{m}}_{in}}\text{d}H-{{h}_{cd}}({{T}_{w}}-{{T}_{cd}})\text{zd}l=0\text{,}$ (2)

 ${{\dot{m}}_{in}}\text{d}H-{{h}_{cd}}({{T}_{w}}-{{T}_{cd}})(y+2z{{\eta }_{f}})\text{d}l=0,$ (3)

 ${{\eta }_{f}}=\frac{\text{th}({{m}_{cd}}h)}{{{m}_{cd}}h}\text{,}$ (4)
 ${{m}_{cd}}=\sqrt{\frac{2{{\varsigma }_{cd}}}{{{\lambda }_{cd}}{{\sigma }_{cd}}}},$ (5)

 ${{\dot{m}}_{in}}\text{d}H-{{h}_{0}}(z+{{\sigma }_{cd}})({{T}_{sw}}-{{T}_{w}})\text{d}x=0\text{,}$ (6)

 $\frac{\text{d}H}{\text{d}x}=\frac{{{h}_{cd}}({{T}_{sw}}-{{T}_{cd}})(z+2y{{\eta }_{f}})}{{{{\dot{m}}}_{in}}+\frac{{{h}_{cd}}{{{\dot{m}}}_{in}}}{{{h}_{0}}(z+{{\sigma }_{cd}})}(z+2y{{\eta }_{f}})}\circ$ (7)
1.3 对流换热系数求解模型

1）在过热区和过冷区

 ${{h}_{cd}}=\frac{Nu\cdot {{\lambda }_{cd}}}{{{d}_{ecd}}},$ (8)

$Nu$ 数可用采用对流传热理论中的特征数方式（实验关联式）来表示：

 $Nu=C\text{Re}_{m}^{a}\underset{m}{\overset{b}{\mathop{Pr}}}\,$ (9)

2）在两相区

①Nusselt 计算关系式

Nusselt 提出了纯净蒸汽层流膜状凝结的分析解，对于水平管上的层流膜状凝结，其平均表面传热系数的计算式为[10]

 ${{h}_{H}}=0.875{{\left[ \frac{gr\rho _{\text{l}}^{\text{2}}\lambda _{\text{l}}^{\text{3}}}{{{\eta }_{\text{l}}}d({{T}_{\text{s}}}-{{T}_{\text{w}}})} \right]}^{0.25}}\circ$ (10)

②Akers-Rosson 实验关联计算式

 ${{h}_{cd}}=0.026\ 5\frac{{{\lambda }_{cd}}}{d{{e}_{cd}}}R{{e}_{eq}}^{0.8}P{{r}_{m}}^{1/3}\circ$ (11)

 $h=\frac{\sum\limits_{{}}^{{}}{{{h}_{i}}}}{N}\circ$ (12)

1.4 压力求解模型

1）过热段和过冷段摩擦阻力压力降

 $\Delta {{p}_{cd}}=\lambda \frac{l}{d}\frac{\rho {{V}^{2}}}{2},$ (13)

 $\Delta {{P}_{cd}}={{f}_{cd}}\frac{{{L}_{cd}}^{\prime }}{d{{e}_{cd}}}\frac{{{\rho }_{\text{m}}}{{u}_{cd,m}}^{2}}{2}\circ$ (14)

 ${{f}_{cd}}=\left\{ \begin{array}{*{35}{l}} 16/R{{e}_{cd,m}}, & 0＜R{{e}_{cd,m}}＜2\ 500; \\ 0.079R{{e}_{cd,m}}^{-0.25}, & 2\ 500＜R{{e}_{cd,m}}＜20\ 000; \\ 0.046R{{e}_{cd,m}}^{-0.2}, & R{{e}_{cd,m}}>20\ 000 \\ \end{array} \right.$ (15)

2）对于饱和段即凝结段摩擦阻力压降

 $\Delta {{P}_{sa}}=4{{f}_{cd}}^{\prime }\frac{{{L}_{cd}}^{\prime }}{d{{e}_{cd}}^{3}}\frac{R{{e}_{eq}}^{2}{{\mu }_{l}}^{2}}{2{{\rho }_{l}}}\circ$ (16)

 ${{f}_{cd}}^{\prime }=0.043\ 5R{{e}_{eq}}^{0.12}{{f}_{cd}}\circ$ (17)
2 仿真计算 2.1 仿真流程

2.2 仿真模型对比

1）不同区域模型参数的选取

① 目前应用比较普遍的是 Dittus 和 Boelter 总结的实验关联式：

 $Nu=0.023R{{e}^{0.8}}Pr0.3,$ (18)

② Debray.F 等[12]于 2001 年提出了单相换热实验关联式：

 $Nu=0.059\ 3R{{e}^{3/4}}P{{r}^{1/3}}\circ$ (19)

Nusselt 计算关系式

 ${{h}_{cd}}=0.875{{\left[ \frac{gr\rho _{cd}^{\text{2}}\lambda _{cd}^{\text{3}}}{{{\eta }_{cd}}{{d}_{ecd}}({{t}_{\text{s}}}-{{t}_{\text{w}}})} \right]}^{0.25}};$ (20)

Akers-Rosson 实验关联式

 ${{h}_{cd}}=0.026\ 5\frac{{{\lambda }_{cd}}}{d{{e}_{cd}}}R{{e}_{eq}}^{0.8}P{{r}_{m}}^{1/3}\circ$ (21)

2）不同模型的计算式仿真对比

 图 2 沿程焓值对比 Fig. 2 Enthalpy value contrast

 图 3 沿程温度对比 Fig. 3 Temperature contrast
2.3 实验仿真对比

 图 4 沿程压力对比 Fig. 4 Pressure contrast

 图 5 沿程干度对比 Fig. 5 Dry degree contrast

 图 6 小通道冷凝换热装置三维图 Fig. 6 Small channel condensation heat exchange device

 图 7 不同模型与实验值对比图 Fig. 7 Comparison of model and experimental results

 图 8 不同模型误差趋势图 Fig. 8 Error trend of models

 图 9 不同模型归一化均方误差 Fig. 9 Normalized mean square error
2.4 水下航行器换热通道尺寸设计

 图 10 通道截面宽度参数对换热系数和出口压力的影响 Fig. 10 The effect of width on the heat transfer coefficient and outlet pressure

3 结 语

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