Abstract Fouling deposit is a common issue on the heat transfer surface caused by the impurity of working water. Many researchers conducted experimental test to study the relationship between the fouling thermal resistance and operating parameters, such as water quality, tube geometry, and liquid velocity, targeting at developing the accurate correlation of fouling thermal resistance on heat transfer tubes. The accurate test of fouling thermal resistance is critical for investigators. In fouling test, with the fouling deposit on the internal surface, both the liquid (water) velocity through the tube and the heat flux of the test tube deviated automatically. Although testers usually tried to adjust the water velocity and heat flux back to the original point, it is hard to be realized, thus the water velocity and heat flux deviated somehow inevitably. In fact, the variations of water velocity and heat flux would cause the change of overall thermal resistance of test tubes, which should be separated from the change caused by fouling deposit. This process could be named as “decoupling”. This paper analyzed the effect of deviations of water velocity and heat flux on the test results of fouling resistance quantitatively based on experimental test, and a decoupling method and formulas were developed. One set of accelerated fouling test was conducted and result shows the fouling resistance with decoupling and non-decoupling had a maximum difference of 0.000002124 m2 K/W for tube 1, and 0.000002363 m2 K/W for Tube 2, 0.000001316 m2 K/W for tube 3.

中文翻译：

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结垢热阻测试中液体流速与热通量变化的解耦分析

摘要 污垢沉积是由工作水的杂质引起的传热表面的常见问题。许多研究人员进行了实验测试，研究污垢热阻与水质、管道几何形状和液体速度等运行参数之间的关系，旨在开发传热管污垢热阻的准确相关性。污垢热阻的准确测试对研究人员来说至关重要。在结垢试验中，随着结垢沉积在内表面，通过管子的液体（水）速度和试管的热通量自动偏离。虽然测试人员通常试图将水流速度和热通量调整回原点，但很难实现，因此，水流速度和热通量不可避免地发生了某种偏离。事实上，水流速度和热通量的变化会引起试管整体热阻的变化，这与污垢沉积引起的变化是分开的。这个过程可以称为“解耦”。本文在实验测试的基础上，定量分析了水流速度和热通量的偏差对抗污能力测试结果的影响，并提出了解耦方法和公式。进行了一组加速结垢试验，结果表明，解耦和非解耦时，管 1 的污垢阻力最大差异为 0.000002124 m2 K/W，管 2 为 0.000002363 m2 K/W，管 2 为 0.000001316 m2 K/W管 3。水流速度和热通量的变化会引起试管整体热阻的变化，这与污垢沉积引起的变化是分开的。这个过程可以称为“解耦”。在实验测试的基础上，定量分析了水流速度和热通量的偏差对抗污能力测试结果的影响，并提出了解耦方法和公式。进行了一组加速结垢试验，结果表明，解耦和非解耦时，管 1 的污垢阻力最大差异为 0.000002124 m2 K/W，管 2 为 0.000002363 m2 K/W，管 2 为 0.000001316 m2 K/W管 3。水流速度和热通量的变化会引起试管整体热阻的变化，这与污垢沉积引起的变化是分开的。这个过程可以称为“解耦”。在实验测试的基础上，定量分析了水流速度和热通量的偏差对抗污能力测试结果的影响，并提出了解耦方法和公式。进行了一组加速结垢试验，结果表明，解耦和非解耦时，管 1 的污垢阻力最大差异为 0.000002124 m2 K/W，管 2 为 0.000002363 m2 K/W，管 2 为 0.000001316 m2 K/W管 3。在实验测试的基础上，定量分析了水流速度和热通量的偏差对抗污能力测试结果的影响，并提出了解耦方法和公式。进行了一组加速结垢试验，结果表明，解耦和非解耦时，管 1 的污垢阻力最大差异为 0.000002124 m2 K/W，管 2 为 0.000002363 m2 K/W，管 2 为 0.000001316 m2 K/W管 3。在实验测试的基础上，定量分析了水流速度和热通量的偏差对抗污能力测试结果的影响，并提出了解耦方法和公式。进行了一组加速结垢试验，结果表明，解耦和非解耦时，管 1 的污垢阻力最大差异为 0.000002124 m2 K/W，管 2 为 0.000002363 m2 K/W，管 2 为 0.000001316 m2 K/W管 3。