Transient response of plate heat exchangers considering effect of flow maldistribution
Transient response of plate heat exchangers considering effect of flow maldistribution
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DOI：
10.1016/j.ijheatmasstransfer.2005.02.032
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发表时间：
2005-07
影响因子：
5.2
通讯作者：
N. Srihari;B. P. Rao;B. Sundén;Sarit K. Das
中科院分区：
文献类型：
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作者：
N. Srihari;B. P. Rao;B. Sundén;Sarit K. Das
近年来，板式换热器在电力和加工工业中发挥着重要作用。因此，准确开发板式换热器的仿真策略非常重要。该分析代表了单通道板式换热器的动态行为，考虑了从端口到通道的流量分布不均。除了分布不均之外，流体轴向分散还用于表征返混和活塞流的其他偏差。由于流体分布不均匀，各通道的流体速度各不相同，因此还需要考虑传热系数的变化。利用拉普拉斯变换和频域数值反演的方法获得了控制方程的解。结果显示了流量分布不均和常规换热器参数对 U 型和 Z 型配置的温度瞬变的影响。研究发现，流动分布不均的影响是显着的，它恶化了换热器的热性能以及动态响应的特征。与之前的研究相比，这里的轴向色散仅描述了通道内返混，而不是分布不均，这在物理上更合适。本方法是使用分析方法来描述分布不均和返混对板式换热器瞬态响应的影响的有效且一致的方法，而无需通过完整的数值模拟执行大量计算。
Plate heat exchangers have been playing important role in the power and process industries in the recent past. Hence, it is important to develop simulation strategies for plate heat exchangers accurately. This analysis represents the dynamic behaviour of the single pass plate heat exchangers, considering flow maldistribution from port to channel. In addition to maldistribution the fluid axial dispersion is used to characterise the back mixing and other deviations from plug flow. Due to unequal distribution of the fluid, the velocity of the fluid varies from channel to channel and hence the heat transfer coefficient variation is also taken into consideration. Solutions to the governing equations have been obtained using the method of Laplace transform followed by numerical inversion from frequency domain. The results are presented on the effects of flow maldistribution and conventional heat exchanger parameters on the temperature transients of both U-type and Z-type configurations. It is found that the effect of flow maldistribution is significant and it deteriorates the thermal performance as well as the characteristic features of the dynamic response of the heat exchanger. In contrast to the previous studies, here the axial dispersion describes the inchannel back mixing alone, not maldistribution, which is physically more appropriate. Present method is an efficient and consistent way of describing maldistribution and back mixing effects on the transient response of plate heat exchangers using an analytical method without performing intensive computation by complete numerical simulation.