摘 要
本文著重研究了過熱蒸汽飽和器內(nèi)兩相流動換熱機理，嘗試將單個水珠的微觀蒸發(fā)過程與宏觀的流動傳熱特性聯(lián)系，在其中架設橋梁，以更好地了解過熱蒸汽飽和器內(nèi)(混合管)過熱度的變化規(guī)律及其主要影響因素。
首先，從單一水珠角度探索分析蒸發(fā)模型?；跓豳|(zhì)交換原理，從微觀角度研究水珠蒸發(fā)模型，并系統(tǒng)比較了兩種不同相際傳熱方式對水珠蒸發(fā)速率的影響。分析結(jié)果表明：對流換熱方式下的蒸發(fā)速率要比導熱方式下要高得多。并運用FLUENT軟件仿真模擬了水珠蒸發(fā)過程，分析水珠直徑隨蒸發(fā)進程的變化規(guī)律，并研究了過熱度對水珠蒸發(fā)的影響。
其次，建立了混合管內(nèi)氣液兩相傳熱傳質(zhì)過程的簡化物理模型。從單一水珠蒸發(fā)模型出發(fā)，推導出相際間不同傳熱方式下單位體積蒸發(fā)速率的具體表達式。并對連續(xù)方程和能量方程進行求解，獲得了混合管內(nèi)過熱蒸汽質(zhì)量流量和過熱度的變化圖。在此基礎上， 對比分析了相際間不同傳熱方式對混合笯@ざ齲幢ズ推鶻峁固匭裕┑撓跋歟惶教至瞬煌槌跏賈本叮次砘柿浚┒員ズ突撓跋?。研究发相嵑混合管中抵\ズ退舴⒐炭炻鈧饕【鲇謁母鲆蛩兀核槌跏賈本?、饱和水质量流量、过热度和蠂D運俁?。有螌绹D運俁染齠訟嗉始洳煌拇確絞?。并詳\肅OMSOL軟件模擬了混合管內(nèi)氣液兩相流傳熱傳質(zhì)過程，數(shù)值模擬結(jié)果與上述求解結(jié)果基本吻合。
最后，選擇一具體工況，對一種新型過熱蒸汽飽和器進行了結(jié)構(gòu)設計，確定了飽和器的外形尺寸與內(nèi)部填料函的型式和高度。并依據(jù)不同的現(xiàn)場安裝條件及用戶需要，提出了重力水箱式和機械泵式兩種飽和器供液裝置。新型過熱蒸汽飽和器改善原有裝置的缺點和不足，擴大了飽和器使用范圍，提高其工作性能。


關(guān)鍵詞：過熱蒸汽飽和器；兩相流，過熱蒸汽，蒸發(fā)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 錄
摘 要 I
Abstract Ⅲ
第1章 緒論 1
1.1 課題研究的背景及意義 1
1.2 過熱蒸汽飽和器簡介 2
1.3 國內(nèi)外研究現(xiàn)狀與發(fā)展趨勢 5
1.4 本文的主要研究工作 7
第2章 過熱蒸汽中水珠蒸發(fā)模型研究 9
2.1 水珠蒸發(fā)模型的探討與分析 10
2.1.1 氣液兩相流速相同情況下的水珠蒸發(fā)模型 11
2.1.2 氣液兩相流速不同情況下的水珠蒸發(fā)模型 14
2.2 不同傳熱方式下單個水珠蒸發(fā)速率確定 15
2.2.1 單個水珠全部蒸發(fā)時間的確定 15
2.2.2不同熱容對后繼蒸發(fā)過程的影響 16
2.2.3不同傳熱方式下單個水珠蒸發(fā)速率的比較分析 16
2.3過熱蒸汽環(huán)境下飽和水水珠蒸發(fā)過程的仿真 18
2.3.1 蒸發(fā)模型涉及到的FLUENT軟件模型板塊 18
2.3.2 仿真過程及結(jié)果分析 19
2.4 本章小結(jié) 24
第3章 混合管內(nèi)兩相流模型的分析 25
3...