【摘要】 针对纵槽矩形低肋翅片管冷凝器,换热模型中引入翅片效率计算公式,在一定程度上提高了换热计算结果的准确性。将Stefan-Maxwell方程应用于多组分传质模型,并结合实际换热过程,计算出水蒸气在烟气中的扩散系数,分析冷凝过程中的传热与传质特性。以燃气热水器产生的烟气为热源对此类冷凝器进行换热实验,作为实际算例证明计算模型的适用性,运用计算结果分析了不同工况下的冷凝换热特征,拟合冷凝率的计算公式。在实验的基础上,分析得出:在一定的冷凝器负荷范围(以600 W为界)内,负荷的升高有助于换热的增强;进水压力为0. 1 MPa时的工况换热效果最好。低烟气侧Nuf时,以水压0. 2 MPa为界,当高于此值时,烟气侧Nu_f对翅片效率的影响更为明显。Lewis关系式运用于烟气冷凝设计的合理性取决于烟气中水蒸气的含量,Lewis准则与烟气中水蒸气含量有关。拟合出冷凝率随Ja、水蒸气含量以及烟气侧Ref的关系式。更多还原

【Abstract】 For the rectangular low-ribbed finned tube condenser,the fin efficiency calculation formula is introduced in the heat transfer model,which improves the accuracy of the heat transfer calculation result to some extent. The Stefan-Maxwell equation is applied to the multi-component mass transfer model,and the diffusion coefficient of water vapor in the flue gas is calculated by combining the actual heat transfer process,and the heat transfer and mass transfer characteristics in the condensation process are analyzed.The heat transfer experiment of the condenser is carried out by using the flue gas generated by the gas water heater as the heat source. As a practical example,the applicability of the calculation model is proved. The calculation results are used to analyze the condensation heat transfer characteristics under different working conditions,and the calculation formula of condensation rate is fitted. Based on experiments, the analysis shows that within a certain condenser load range( with600 W as the boundary),the increase of the load contributes to the enhancement of heat transfer; the heat transfer effect is best when the inlet water pressure is0. 1 MPa. At the low flue gas side Nuf,the water pressure is 0. 2 MPa as the boundary. When the value ishigher than this value,the influence of the flue gas side Nufon the fin efficiency is more obvious. The rationality of the Lewis relationship applied to the design of flue gas condensation depends on the water vapor content in the flue gas,and the Lewis criterion is related to the water vapor content in the flue gas. The relationship of the condensation rate to Ja,the water vapor content and the flue gas side Refis fitted.更多还原