螺旋折流板换热器流动特性研究

用激光测速仪详细测量了螺旋折流板换热器的流场特性，着重研究了旋流角对速度分布和对脉动速度的影响及其与流量的偶合关系，并对速度分布对换热性能及阻力的影响做了详细的分析和讨论。模型换热器采用有机玻璃制作，壳体尺寸为200mm×6mm×3000mm(外径×壁厚×长度),换热管外径为15mm，共52根，均匀布置。折流板倾斜角度取30,35,40,42°四种，双头布置。实验介质为常温下自来水，流量测量采用转子流量计，流量范围为3～20m

Studies on Flow Characteristic of Heat Exchangers With Helical Baffles

The flow field in shell-and-tube heat exchan gers with helical baffles was measured using LDV, The influence on the velocity distribution , impulsive speed by helix inclination angle and flow rate was inve stigated. The influence on heat-exchanging capability and flow resistance of vel ocity distribution was also investigated. The dimension of heat-exchanger used i n experiments is 200 mm×6 mm×3 000 mm(outer diameter ×wall thickness×lengt h) and is made of organic glass. The tube bundle was consists of 52 tubes with externa l diameter 15 mm. There are four kinds of baffle inclination angles designed in double helix style, namely 30,35,40,42°. The actuating medium working unde r normal temperature is service water. The rotator flowmeter is chosen to measur e the volume of flow varying from 3 to 20 m3/h. Generally, the line spe ed and impulsive speed will increase with helix inclination angle decreasing correspon dingly, which promotes the heat-exchanging capability. The flow volume increasin g makes velocity distribute along diameter uniformly. But flow loss will increas correspondingly with helix inclination angle decreasing , especially when helix inclination angle is less than 35°, the loss increases sharply.With a comprehe nsive consideration, it is proposed that the helix inclination angle be 35°.