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机构地区:[1]抚顺石油学院化工机械系,辽宁抚顺113001
出 处:《石油化工高等学校学报》2001年第1期64-67,共4页Journal of Petrochemical Universities
摘 要: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2 0 0mm× 6mm× 3 0 0 0mm(外径×壁厚×长度 ) ,换热管外径为 1 5mm ,共 52根 ,均匀布置。折流板倾斜角度取 3 0 ,3 5,4 0 ,4 2°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~ 2 0m3/h。一般情况下 ,随着旋流角的减小 ,切向速度分量增大 ,脉动速度也相应增大 ,有利于换热 ;流量增加使速度沿径向分布趋于均匀。但螺旋角减小 ,流动损失也随之增加 ,尤其在旋流角小于 3 5°以后 ,流动损失增加幅度加快。综合考虑 ,建议使用螺旋板角度为 3 5°。The flow field in shell-and-tube heat exchangers with helical baffles was measured using LDV, The influence on the velocity distribution, impulsive speed by helix inclination angle and flow rate was investigated. The influence on heat-exchanging capability and flow resistance of velocity distribution was also investigated. The dimension of heat-exchanger used in experiments is φ200 mm × 6 mm × 3 000 mm (outer diameter × wall thickness × length) and is made of organic glass. The tube bundle was consists of 52 tubes with external 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 under normal temperature is service water. The rotator flowmeter is chosen to measure the volume of flow varying from 3 to 20 m3/h. Generally, the line speed and impulsive speed will increase with helix inclination angle decreasing correspondingly, which promotes the heat-exchanging capability. The flow volume increasing makes velocity distribute along diameter uniformly. But flow loss will increase correspondingly with helix inclination angle decreasing, especially when helix inclination angle is less than 35°, the loss increases sharply. With a comprehensive consideration, it is proposed that the helix inclination angle be 35°.
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