板式换热器在变流量工况下的相对传热系数分析
Analysis of relative heat transfer coefficient of plate heat exchangers under variable flow conditions
摘要：
对板式换热器的相对传热系数公式进行了简化，仅保留对流换热热阻部分。从板式换热器的通用对流换热特征数方程出发，推导出其在变流量工况下的相对传热系数公式，并利用Origin 8.0软件进行了公式拟合。计算结果表明，虽然板式换热器的板片及污垢热阻对其传热系数存在较大影响，但体现在相对传热系数公式里影响却很小。在通常流量变化范围内，公式简化所带来的误差小于4%，拟合误差小于5%，满足工程应用的要求。
Abstract：
Simplifies the relative heat transfer coefficient formula of plate heat exchangers with only the thermal resistance of heat convection remained. Deduces the formula under variable flow conditions based on the general correlation formula of heat convection of plate heat exchangers and obtains the fitted formula with the software of Origin 8.0. Calculating result shows that the thermal resistance of the plate and fluid fouling causes less influence on the relative heat transfer coefficient formula, even this has a greater impact on the heat transfer coefficient. In the common range of flow rate variation, the error of the simplified formula is less than 4% and that of the fitted formula is less than 5%, meeting the requirement of engineering application.
Keywords:plate heat exchanger, variable flow condition, relative heat transfer coefficient, correlation formula of heat convection