Abstract When optimizing the performance of heat exchangers, it can be advantageous to introduce structures, such as dimples or ribs on the surface. One especially advantageous solution in terms of thermo-hydraulic efficiency is to use surfaces with spherical dimples, where heat transfer is increased at an only minor pressure loss increase. However, this surface structuring also influences the deposition of particles in aqueous suspensions. The resulting fouling is a serious problem for the design and operation of heat exchangers and can cause significant economic and ecological damage. Despite the knowledge of the importance of fouling and the resulting disadvantages, this knowledge has not been incorporated systematically into the design process, and the criteria of maximizing heat transfer and reducing hydraulic losses remain in the foreground during the design of heat exchangers. In this study, dimpled surfaces with a depth to diameter ration of 0.18 , 0.26 and 0.35 were evaluated by measuring and comparing their heat transfer ability and pressure loss with and without the occurrence of particulate fouling from aqueous suspensions. The fouling resistance is used to assess the reduction in heat transfer efficiency due to particulate depositions, both local and time resolved. For the first time, a row of dimples is quantitatively assessed regarding its heat transfer efficiency under fouling conditions, and the thermo-hydraulic efficiency is determined experimentally. The results are matched against numerical investigations. The interactions of turbulent flow structures, heat transfer and particulate fouling in aqueous suspension are determined for dimpled surfaces.

中文翻译：

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局部和时间解析凹坑传热表面上颗粒沉积的实验和数值方法

摘要 在优化换热器性能时，在表面引入凹坑或肋等结构是有利的。就热工水力效率而言，一种特别有利的解决方案是使用具有球形凹坑的表面，其中传热增加而压力损失仅增加很小。然而，这种表面结构也会影响颗粒在水悬浮液中的沉积。由此产生的结垢对于换热器的设计和操作来说是一个严重的问题，并且会造成重大的经济和生态破坏。尽管知道结垢的重要性和由此产生的缺点，但这些知识还没有系统地融入设计过程中，在换热器的设计过程中，最大限度地提高传热和减少水力损失的标准仍然是最重要的。在这项研究中，深度直径比为 0.18、0.26 和 0.35 的凹坑表面通过测量和比较它们的传热能力和压力损失来评估，无论是否发生来自水悬浮液的颗粒污垢。污垢阻力用于评估由于局部和时间分辨的颗粒沉积导致的传热效率降低。首次对一排凹坑在结垢条件下的传热效率进行了定量评估，并通过实验确定了热工水力效率。结果与数值调查相匹配。湍流结构的相互作用，