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首页> 外文会议>International Conference on Compact Heat Exchangers and Enhancement Technology for the Process Industries; 20030929-20031003; Crete Island; GR >CONDENSATION OF PURE FLUIDS AND MIXTURES OF PROCESS FLUIDS IN COMPACT WELDED AND SPIRAL HEAT EXCHANGERS
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CONDENSATION OF PURE FLUIDS AND MIXTURES OF PROCESS FLUIDS IN COMPACT WELDED AND SPIRAL HEAT EXCHANGERS

机译：紧凑型焊接和螺旋换热器中纯流体和过程流体混合物的冷凝

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Condensation occurs in many industrial processes, but rarely with pure fluids. The fluids encountered are mixtures and often non-condensable gases are present, and this makes the condensation process very complex. This paper presents experimental results of the condensation in presence of inert gases of process fluids in two geometries of compact heat exchangers: welded plate and spiral heat exchangers. The tests have been performed using pentane and isopropanol in order to investigate the effect of viscosity during the condensation processes. In both cases the heat transfer coefficient increases with the Reynolds number, which reveals the effect of the inert gases. For low condensate Reynolds number (below 100), we can assume, referring to the tests with pure fluid (Thonon and Bontemps 2002), that the liquid film is almost laminar. Therefore, for a pure fluid, the heat transfer coefficient should decrease while increasing the Reynolds numbers. In presence of an inert gas, there is an additional mass transfer resistance in the gas phase near the liquid gas-interface. This mass transfer resistance is inversely proportional to the gas Reynolds number, and this latter value is proportional to the liquid Reynolds number. The increase of the heat transfer coefficient is then due to a decrease of the mass transfer resistance in the gas phase. The data will be used for the development of a predictive model, both the film model and the condensation curve method will be applied.
机译：冷凝在许多工业过程中都会发生，但很少发生在纯流体中。遇到的流体是混合物，通常存在不可冷凝的气体，这使冷凝过程非常复杂。本文介绍了在紧凑型热交换器的两种几何形状（焊接板式和螺旋式热交换器）中存在过程流体惰性气体的情况下冷凝的实验结果。为了研究缩合过程中粘度的影响，已使用戊烷和异丙醇进行了测试。在这两种情况下，传热系数都随雷诺数增加而增加，这表明了惰性气体的作用。对于低凝结雷诺数（低于100），我们可以参考纯流体的测试结果（Thonon和Bontemps 2002），假设液膜几乎是层状的。因此，对于纯流体，传热系数应降低，同时增加雷诺数。在存在惰性气体的情况下，在液态气体界面附近的气相中存在额外的传质阻力。该传质阻力与气体雷诺数成反比，而该后者值与液体雷诺数成正比。传热系数的增加则归因于气相中传质阻力的降低。数据将用于预测模型的开发，将应用薄膜模型和凝结曲线方法。

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