推荐回答(2个)
1、研究应用强化传热技术,扩展传热面积和提高传热表面的传热性能;
2、改变换热器折流板结构(折流杆技术等)以提高壳程的传热膜系数,增加介质的湍流性,防止介质走短流;
3换热管内外表面防污垢技术(防污垢涂层技术)。
4、应用数值传热技术的研究。目前研究应用强化传热技术是提高传热效率很有效的一种技术措施,本文主要讨论应用强化传热技术对换热器进行改进。所谓换热器传热强化或增强传热是指通过对影响传热的各种因素的分析与计算,采取某些技术措施以提高换热设备的传热量或者在满足原有传热量条件下,使它的体积缩小。
换热器传热强化通常使用的手段包括三类:扩展传热面积(F);加大传热温差;提高传热系数(K)。
1.扩展传热面积F。扩展传热面积是增加传热效果使用最多、最简单的一种方法。这种方法现在已经淘汰。现在使用最多的是通过合理地提高设备单位体积的传热面积来达到增强传热效果的目的,如在换热器上大量使用单位体积传热面积比较大的翅片管、波纹管、板翅传热面等材料。
2.加大传热温差△t。加大换热器传热温差△t是加强换热器换热效果常用的措施之一。但是,增加换热器传热温差△t是有一定限度的,我们不能把它作为增强换热器传热效果最主要的手段,使用过程中我们应该考虑到实际工艺或设备条件上是否允许。
3.增强传热系数(K)。增强换热器传热效果最积极的措施就是设法提高设备的传热系数(K)。换热器传热系数(K)值越低,换热器传热效果也就越差。换热器传热系数(K)值也就越高,换热器传热效果也就越好。
结合热工知识供热公司工作谈谈何提高换热器传热效率
传热速率程式Q=KS△tm知影响换热器换热效主要素:传热系数K、传热面积S平均温差△t
于给定换热器由于传热面积S定提高传热平均温差传热系数才能提高传热效
(1)由于逆流平均温差较采用逆流操作助于提高传热效率;
(2)流体流流速流传热系数使传热系数增加;
(3)降低结垢厚度提高传热系数K
换热器应用程应何提高其换热效率呢
1.提高数平均温差
板式换热器流型逆流、顺流混合流型(既逆流顺流)相同工况逆流数平均温差顺流混合流型介于二者问提高换热器数平均温差尽能采用逆流或接近逆流混合流型尽能提高热侧流体温度降低冷侧流体温度
2.进口管位置确定
于单流程布置板式换热器检修便流体进口管应尽能布置换热器固定端板侧介质温差越流体自流越强形滞留带影响越明显介质进口位置应按热流体进冷流体进布置减滞留带影响提高传热效率
3.提高传热效率
板式换热器间壁传热式换热器冷热流体通换热器板片传热流体与板片直接接触传热式热传导流传热提高板式换热器传热效率关键提高传热系数数平均温差
.提高换热器传热系数同提高板片冷热两侧表面传热系数减污垢层热阻选用热导率高板片减板片厚度才能效提高换热器传热系数
a.提高板片表面传热系数
由于板式换热器波纹能使流体较流速产湍流(雷诺数150)能获较高表面传热系数表面传热系数与板片波纹几何结构及介质流状态关板片波形包括字形、平直形、球形等经研究实验发现波纹断面形状三角形(弦形表面传热系数压力降较受压应力布均匀加工困难字形板片具较高表面传热系数且波纹夹角越板间流道内介质流速越高表面传热系数越
b.减污垢层热阻
减换热器污垢层热阻关键防止板片结垢板片结垢厚度1mm传热系数降低约10%必须注意监测换热器冷热两侧水质防止板片结垢并防止水杂物附着板片些供热单位防止盗水及钢件腐蚀供热介质添加药剂必须注意水质黏性药剂引起杂物沾污换热器板片水黏性杂物应采用专用滤器进行处理选用药剂宜选择黏性药剂
c.选用热导率高板片
板片材质选择奥氏体锈钢、钛合金、铜合金等锈钢导热性能热导率约14.4W/(m?K)强度高冲压性能易氧化价格比钛合金铜合金低供热工程使用其耐氯离腐蚀能力差
d.减板片厚度
板片设计厚度与其耐腐蚀性能关与换热器承压能力关板片加厚能提高换热器承压能力采用字形板片组合相邻板片互相倒置波纹相互接触形密度、布均匀支点板片角孑L及边缘密封结构已逐步完善使换热器具承压能力产拆式板式换热器承压能力已达2.5MPa板片厚度传热系数影响厚度减0.1mm称型板式换热器总传热系数约增加600W/(m?K)非称型约增加500W/(m?K)满足换热器承压能力前提应尽量选用较板片厚度
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