回转式空气预热器非稳定换热的分析

根据回转式空气预热器的工作机理,分析了非稳定换热对其热力计算的影响,详细介绍了所建立的非稳定换热的计算模型,模型反映了空气预热器的转速、受热面的质量和比热、烟气和空气的流量和比热、各分仓的角度和受热面积、传热系数等诸多因素对非稳定换热的影响.以烟气和空气的流量、传热系数以及受热面动态热容的改变为例,给出了非稳定换热影响系数和受热面温度发生相应变化的计算结果.分析了各类因素的影响程度大小和模型的合理性.与目前仅根据空气预热器转速,插值计算非稳定换热影响系数的方法相比,该模型具有更好的合理性和广泛适用性.图6参5

Analysis of Unsteady Heat Exchange of Rotary Air Preheaters

Based on the working principle of rotary air preheaters,the influencing effect of unsteady heat exchange on thermal calculation is being analyzed and a mathematical model for obtaining the influencing coefficient of unsteady heat exchange is described in detail.The model reflects the effect of factors,that influence unsteady heat exchange,such as the preheater's rotating speed,the heat exchanging surface's mass and its specific heat,the flow volume of flue gas and air as well as their specific heat,the installation angle of each sector and its heating area,as well as its heat-transfer coefficient.For variations of flue gas and air flow as well as of heat-transfer coefficients and the dynamic heat capacity of the heating surface,the corresponding calculated variations of the unsteady heat exchange influencing coefficient and those of the heating surfaces' temperatures are presented as an example.The intensity of influence of the various factors is being analyzed,together with a discussion concerning the model's reasonableness.Compared with the currently used way of calculating the influencing coefficient of unsteady heat exchange by interpolation,which merely considers to the preheater's speed of rotation,the proposed model appears more reasonable by principle and for general applicability.Figs 6 and refs 5.