Fouling is a problem that varies in space and time, but a fouling situation is commonly quantified using the integral thermal fouling resistance based on the integral heat balance and an area-averaged heat transfer assessment. However, current modeling does not take into consideration the local differences, such as constrictions, that can affect the integral fluid dynamic behavior. This work shows experimental and analytical results of local investigations of a fouled counterflow double-pipe heat exchanger. The determined local parameters are used to calculate different local fouling resistances as part of a holistic modeling approach with the aim of modeling and linking local and integral fouling resistances as well as the thermal and the mass based approaches. Therefore, mass based parameters are utilized to recalculate the obtained local thermal fouling resistances as a way to account for the heat transfer increases caused by local surface roughness and/or local constrictions. The aim of this procedure is to explain and eliminate apparent negative fouling resistances on a local basis. The local thermal fouling resistances are determined by measuring the local temperatures and then used for quantification of the local overall heat transfer coefficients. Modeling of the local mass based fouling resistances requires knowledge of the density and thermal conductivity of the local material, as well as the local layer thickness and/or the local fouling mass. The local thermal fouling resistances are recalculated using the local friction coefficients and local flow velocities resulting from local constrictions. All experimental and theoretical approaches are merged into the model presented here for the determination of local fouling resistances.

结垢是一个随空间和时间变化的问题，但结垢情况通常使用基于积分热平衡和面积平均传热评估的积分热结垢阻力来量化。然而，当前的建模并未考虑可能影响整体流体动力学行为的局部差异，例如收缩。这项工作显示了污染的逆流双管换热器的局部研究的实验和分析结果。确定的局部参数用于计算不同的局部污垢阻力，作为整体建模方法的一部分，目的是建模和链接局部和整体污垢阻力以及基于热和质量的方法。所以，基于质量的参数用于重新计算获得的局部热污染阻力，作为解释由局部表面粗糙度和/或局部收缩引起的传热增加的一种方式。该程序的目的是在局部基础上解释和消除明显的负结垢阻力。局部热污染阻力通过测量局部温度来确定，然后用于量化局部整体传热系数。基于局部质量的结垢阻力建模需要了解局部材料的密度和热导率，以及局部层厚度和/或局部结垢质量。使用局部摩擦系数和局部收缩产生的局部流速重新计算局部热污染阻力。