流体机械
流體機械
류체궤계
FLUID MACHINERY
2014年
4期
1-5
,共5页
窄通道%核沸腾%流型%流动沸腾%局部换热系数
窄通道%覈沸騰%流型%流動沸騰%跼部換熱繫數
착통도%핵비등%류형%류동비등%국부환열계수
narrow channel%nucleate boiling%flow pattern%flow boiling%local heat transfer coefficient
建立单面加热垂直矩形窄通道流动沸腾换热试验装置，针对截面250mm ×3．5mm的窄缝通道，对水流动沸腾换热特性进行试验研究。通过试验分析可知：（1）随着干度的增加，局部换热系数先增加后减小，有一个最大值，此时处于饱和核沸腾区域，其蒸汽干度也接近于0，同时也接近于沸腾起始点。相应地流体从单相流-泡状-块状流-搅拌-环状流转变。（2）在流动沸腾换热中，热流密度对核态沸腾换热有明显影响，而对流动沸腾液膜蒸发的影响甚小，所以可以认为由热流密度的变化而引起的换热变化，主要表现在核态沸腾。（3）入口温度的变化对单相流动的换热系数有影响，而沸腾换热系数与流型及汽泡的产生及扰动有极大关系，入口温度对流动沸腾局部换热系数基本没有影响。
建立單麵加熱垂直矩形窄通道流動沸騰換熱試驗裝置，針對截麵250mm ×3．5mm的窄縫通道，對水流動沸騰換熱特性進行試驗研究。通過試驗分析可知：（1）隨著榦度的增加，跼部換熱繫數先增加後減小，有一箇最大值，此時處于飽和覈沸騰區域，其蒸汽榦度也接近于0，同時也接近于沸騰起始點。相應地流體從單相流-泡狀-塊狀流-攪拌-環狀流轉變。（2）在流動沸騰換熱中，熱流密度對覈態沸騰換熱有明顯影響，而對流動沸騰液膜蒸髮的影響甚小，所以可以認為由熱流密度的變化而引起的換熱變化，主要錶現在覈態沸騰。（3）入口溫度的變化對單相流動的換熱繫數有影響，而沸騰換熱繫數與流型及汽泡的產生及擾動有極大關繫，入口溫度對流動沸騰跼部換熱繫數基本沒有影響。
건립단면가열수직구형착통도류동비등환열시험장치，침대절면250mm ×3．5mm적착봉통도，대수류동비등환열특성진행시험연구。통과시험분석가지：（1）수착간도적증가，국부환열계수선증가후감소，유일개최대치，차시처우포화핵비등구역，기증기간도야접근우0，동시야접근우비등기시점。상응지류체종단상류-포상-괴상류-교반-배상류전변。（2）재류동비등환열중，열류밀도대핵태비등환열유명현영향，이대류동비등액막증발적영향심소，소이가이인위유열류밀도적변화이인기적환열변화，주요표현재핵태비등。（3）입구온도적변화대단상류동적환열계수유영향，이비등환열계수여류형급기포적산생급우동유겁대관계，입구온도대류동비등국부환열계수기본몰유영향。
A single-side heating apparatus is set up to study the flow boiling and heat transfer in vertical narrow rectangular channel,experiment research on flow boiling and heat transfer characteristics in a vertical narrow rectangular channel with the section of 250mm ×5 mm is carried out.According to the experimental analysis:(1 )With the increase of dryness,the local heat transfer coefficient firstly increases then decreases ,there is a maximum,which is saturated nucleate boiling region ,the steam quality is close to zero,also it is close to the onset of boiling.Accordingly flow mode of fluid is from single phase,bubble,slug, churn to annular flow.(2)For flow boiling heat transfer,nuclear boiling heat transfer is significantly affected by heat flux,but liquid film evaporation is nearly not.So it is assumed that heat transfer is caused by the change of heat flux.(3 )The change of inlet temperature has influence on single-phase flow heat transfer coefficient,but flow boiling heat transfer coefficient has great re-lationship with flow pattern and generated bubbles,and not inlet temperature.
