过热蒸汽饱和器.doc
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过热蒸汽饱和器,摘 要本文着重研究了内两相流动换热机理，尝试将单个水珠的微观蒸发过程与宏观的流动传热特性联系，在其中架设桥梁，以更好地了解内(混合管)过热度的变化规律及其主要影响因素。首先，从单一水珠角度探索分析蒸发模型。基于热质交换原理，从微观角度研究水珠蒸发模型，并系统比较了两种不同相际传热方式对水珠蒸...
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摘 要
本文着重研究了过热蒸汽饱和器内两相流动换热机理，尝试将单个水珠的微观蒸发过程与宏观的流动传热特性联系，在其中架设桥梁，以更好地了解过热蒸汽饱和器内(混合管)过热度的变化规律及其主要影响因素。
首先，从单一水珠角度探索分析蒸发模型。基于热质交换原理，从微观角度研究水珠蒸发模型，并系统比较了两种不同相际传热方式对水珠蒸发速率的影响。分析结果表明：对流换热方式下的蒸发速率要比导热方式下要高得多。并运用FLUENT软件仿真模拟了水珠蒸发过程，分析水珠直径随蒸发进程的变化规律，并研究了过热度对水珠蒸发的影响。
其次，建立了混合管内气液两相传热传质过程的简化物理模型。从单一水珠蒸发模型出发，推导出相际间不同传热方式下单位体积蒸发速率的具体表达式。并对连续方程和能量方程进行求解，获得了混合管内过热蒸汽质量流量和过热度的变化图。在此基础上， 对比分析了相际间不同传热方式对混合笯@ざ龋幢ズ推鹘峁固匦裕┑挠跋欤惶教至瞬煌槌跏贾本叮次砘柿浚┒员ズ突挠跋臁Ｑ芯糠⑾郑夯旌瞎苤械谋ズ退舴⒐炭炻钪饕【鲇谒母鲆蛩兀核槌跏贾本丁⒈ズ退柿苛髁俊⒐榷群拖喽运俣取Ｓ形尴喽运俣染龆讼嗉始洳煌拇确绞健２⒃擞肅OMSOL软件模拟了混合管内气液两相流传热传质过程，数值模拟结果与上述求解结果基本吻合。
最后，选择一具体工况，对一种新型过热蒸汽饱和器进行了结构设计，确定了饱和器的外形尺寸与内部填料函的型式和高度。并依据不同的现场安装条件及用户需要，提出了重力水箱式和机械泵式两种饱和器供液装置。新型过热蒸汽饱和器改善原有装置的缺点和不足，扩大了饱和器使用范围，提高其工作性能。
关键词：过热蒸汽饱和器；两相流，过热蒸汽，蒸发速率
Abstract
This paper is analyzed and studied the principle of flow and heat transfer in superheated steam saturator, trying to combine the microcosmic evaporation process of single water droplet and macroscopic character of flow and heat transfer, and better to understand the change regularity of superheated degrees and main influencing factors in superheated steam saturator which means in the mixing duct.
First, the evaporation process of a single droplet is explored and analyzed. Based on the principle of heat and mass transfer, the evaporation rate of a single saturated water droplet is derived according to different heat transfer mode between phases. Compared with the thermal convection, the evaporation rate is 13 times higher than one by thermal conduction. Then, the evaporation process of water droplets with no relative speed is simulated by use of the FLUENT software. The droplet diameter changing with the degree of superheat is obtained due to the evaporation process.
Secondly, the simplified two-phase model in the mixing duct is constructed between the superheated vapor and saturated liquid. On the basis of a single droplet evaporation model, the volume evaporation rate is successfully derived which established a bridge between the single droplet and macroscopic properties. Through solving continuity equation and energy equations, the mass flow and the degree of superheat changing map in the mixing duct are obtained. The influence of the inter-phase heat transfer about the mixing tube length is explored. It is found that the volume evaporation rate in the mixing tube mostly depends on three factors: the initial diameter of the droplet, the degree of superheat，the mass flow of saturated water and relative velocity between superheat vapor and saturated water. The heat and mass transfer process between two phases is also simulated by use of COMSOL software in the mixing duct. The result is consistent with the result of the aforesaid solution.
At last, the structure of superheated steam saturator is designed. The shape size of saturator and the length of internal packing box are determined according to the specific working condition. Two fluid supply devices, the gravity tank type or fluid mechanical pump type, are put forward, which depends on the field installation conditions and user needs. The new type of superheated steam saturator is to ameliorate the shortcomings of existing saturation device and to expand the application field, which improves the practical work performance.
Key words: superheated steam saturator; two-phase flow; superheated steam;
evaporation rate
目 录
摘 要 I
Abstract Ⅲ
第1章 绪论 1
1.1 课题研究的背景及意义 1
1.2 过热蒸汽饱和器简介 2
1.3 国内外研究现状与发展趋势 5
1.4 本文的主要研究工作 7
第2章 过热蒸汽中水珠蒸发模型研究 9
2.1 水珠蒸发模型的探讨与分析 10
2.1.1 气液两相流速相同情况下的水珠蒸发模型 11
2.1.2 气液两相流速不同情况下的水珠蒸发模型 14
2.2 不同传热方式下单个水珠蒸发速率确定 15
2.2.1 单个水珠全部蒸发时间的确定 15
2.2.2不同热容对后继蒸发过程的影响 16
2.2.3不同传热方式下单个水珠蒸发速率的比较分析 16
2.3过热蒸汽环境下饱和水水珠蒸发过程的仿真 18
2.3.1 蒸发模型涉及到的FLUENT软件模型板块 18
2.3.2 仿真过程及结果分析 19
2.4 本章小结 24
第3章 混合管内两相流模型的分析 25
3...
本文着重研究了过热蒸汽饱和器内两相流动换热机理，尝试将单个水珠的微观蒸发过程与宏观的流动传热特性联系，在其中架设桥梁，以更好地了解过热蒸汽饱和器内(混合管)过热度的变化规律及其主要影响因素。
首先，从单一水珠角度探索分析蒸发模型。基于热质交换原理，从微观角度研究水珠蒸发模型，并系统比较了两种不同相际传热方式对水珠蒸发速率的影响。分析结果表明：对流换热方式下的蒸发速率要比导热方式下要高得多。并运用FLUENT软件仿真模拟了水珠蒸发过程，分析水珠直径随蒸发进程的变化规律，并研究了过热度对水珠蒸发的影响。
其次，建立了混合管内气液两相传热传质过程的简化物理模型。从单一水珠蒸发模型出发，推导出相际间不同传热方式下单位体积蒸发速率的具体表达式。并对连续方程和能量方程进行求解，获得了混合管内过热蒸汽质量流量和过热度的变化图。在此基础上， 对比分析了相际间不同传热方式对混合笯@ざ龋幢ズ推鹘峁固匦裕┑挠跋欤惶教至瞬煌槌跏贾本叮次砘柿浚┒员ズ突挠跋臁Ｑ芯糠⑾郑夯旌瞎苤械谋ズ退舴⒐炭炻钪饕【鲇谒母鲆蛩兀核槌跏贾本丁⒈ズ退柿苛髁俊⒐榷群拖喽运俣取Ｓ形尴喽运俣染龆讼嗉始洳煌拇确绞健２⒃擞肅OMSOL软件模拟了混合管内气液两相流传热传质过程，数值模拟结果与上述求解结果基本吻合。
最后，选择一具体工况，对一种新型过热蒸汽饱和器进行了结构设计，确定了饱和器的外形尺寸与内部填料函的型式和高度。并依据不同的现场安装条件及用户需要，提出了重力水箱式和机械泵式两种饱和器供液装置。新型过热蒸汽饱和器改善原有装置的缺点和不足，扩大了饱和器使用范围，提高其工作性能。
关键词：过热蒸汽饱和器；两相流，过热蒸汽，蒸发速率
Abstract
This paper is analyzed and studied the principle of flow and heat transfer in superheated steam saturator, trying to combine the microcosmic evaporation process of single water droplet and macroscopic character of flow and heat transfer, and better to understand the change regularity of superheated degrees and main influencing factors in superheated steam saturator which means in the mixing duct.
First, the evaporation process of a single droplet is explored and analyzed. Based on the principle of heat and mass transfer, the evaporation rate of a single saturated water droplet is derived according to different heat transfer mode between phases. Compared with the thermal convection, the evaporation rate is 13 times higher than one by thermal conduction. Then, the evaporation process of water droplets with no relative speed is simulated by use of the FLUENT software. The droplet diameter changing with the degree of superheat is obtained due to the evaporation process.
Secondly, the simplified two-phase model in the mixing duct is constructed between the superheated vapor and saturated liquid. On the basis of a single droplet evaporation model, the volume evaporation rate is successfully derived which established a bridge between the single droplet and macroscopic properties. Through solving continuity equation and energy equations, the mass flow and the degree of superheat changing map in the mixing duct are obtained. The influence of the inter-phase heat transfer about the mixing tube length is explored. It is found that the volume evaporation rate in the mixing tube mostly depends on three factors: the initial diameter of the droplet, the degree of superheat，the mass flow of saturated water and relative velocity between superheat vapor and saturated water. The heat and mass transfer process between two phases is also simulated by use of COMSOL software in the mixing duct. The result is consistent with the result of the aforesaid solution.
At last, the structure of superheated steam saturator is designed. The shape size of saturator and the length of internal packing box are determined according to the specific working condition. Two fluid supply devices, the gravity tank type or fluid mechanical pump type, are put forward, which depends on the field installation conditions and user needs. The new type of superheated steam saturator is to ameliorate the shortcomings of existing saturation device and to expand the application field, which improves the practical work performance.
Key words: superheated steam saturator; two-phase flow; superheated steam;
evaporation rate
目 录
摘 要 I
Abstract Ⅲ
第1章 绪论 1
1.1 课题研究的背景及意义 1
1.2 过热蒸汽饱和器简介 2
1.3 国内外研究现状与发展趋势 5
1.4 本文的主要研究工作 7
第2章 过热蒸汽中水珠蒸发模型研究 9
2.1 水珠蒸发模型的探讨与分析 10
2.1.1 气液两相流速相同情况下的水珠蒸发模型 11
2.1.2 气液两相流速不同情况下的水珠蒸发模型 14
2.2 不同传热方式下单个水珠蒸发速率确定 15
2.2.1 单个水珠全部蒸发时间的确定 15
2.2.2不同热容对后继蒸发过程的影响 16
2.2.3不同传热方式下单个水珠蒸发速率的比较分析 16
2.3过热蒸汽环境下饱和水水珠蒸发过程的仿真 18
2.3.1 蒸发模型涉及到的FLUENT软件模型板块 18
2.3.2 仿真过程及结果分析 19
2.4 本章小结 24
第3章 混合管内两相流模型的分析 25
3...
