【摘要】 用于烟气余热回收的板式换热器存在温度分布不均的问题。为改善烟气温度分布均匀性，有效遏制换热器腐蚀，本文通过实验测试对比碳钢与铸铁材质低阻叉流板式换热器性能差异，运用数值仿真预测局部流动传热特性并开展热阻分析，采用局部热阻调控方法设计了非均匀翅片结构。实验结果表明，在450℃高温时碳钢与铸铁材质的叉流板式换热器总传热系数分别达到32.5 W/(m~2·K)与25.1 W/(m~2·K)。通过数值仿真研究发现，叉流传热方式导致烟气侧沿程截面温度分布极不均匀，在热侧出口与冷侧入口交叉区、热侧出口与冷侧出口交叉区的热阻大，极易导致局部烟气温度低于露点温度。基于热阻分析法开发非均匀翅片结构，实施局部热阻靶向调控，最终实现维持阻力几乎不变情况下，使出口截面平均温度方差由6.9℃降至1.1℃,换热器内流体温度分布均匀性得到显著提升。更多还原

【Abstract】 Plate heat exchanger for flue gas waste heat recovery suffers from non-uniform temperature distribution. Improving the uniformity of temperature distribution can effectively suppress heat exchanger corrosion. This study experimentally investigates the performance of two low-resistance cross-flow plate heat exchangers. Meanwhile, the computational fluid dynamic(CFD) method is applied to predict the local heat transfer characteristics. By employing the targeting thermal resistance regulation strategy, a non-uniform fin structure is designed. Results demonstrate that, at a high temperature of 450 ℃, the total heat transfer coefficients of cross-flow plate heat exchangers made of carbon-steel and cast-iron reach 32.5 W/(m~2·K) and 25.1W/(m~2·K), respectively. The cross-flow heat transfer results in extremely uneven temperature distribution concern. The regions at the cross-section of hot-side-outlet and cold-side-inlet, as well as the cross-section at the hot side outlet and the cold side outlet, show dominantly high thermal resistance, which can easily cause local flue gas temperatures dropping below its dew point temperature. As the result, a non-uniform fin structure based on thermal resistance analysis is involved based on the targeting local thermal resistance regulation analysis, the average temperature variance at the outlet cross-section is significantly reduced from 6.9 ℃ to 1.1 ℃ while maintaining the flow resistance almost unchanged. The uniformity of fluid temperature distribution in the heat exchanger is significantly improved.更多还原