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1、有关公式本文采用换热效率——传热单元数法(E-NTU法)作传热计算。通常,计算中都作如下假定,即: a.空气和烟气的流量是常数; b.空气和烟气的比热是常数(取平均值); c.传热过程中不产生相变; d.换热器入口处空气和烟气温度都是均匀的; e.传热系数K是常数(取平均值); f.忽略换热器对外界的散热(有时对换热量乘以系数)。 1.1定义式 E-NTU法中采用三个无因次量:换热效率(或称温度效率)E、热容流量比(或称
1, the formula In this paper, the heat transfer efficiency - heat transfer unit number method (E-NTU method) for heat transfer calculation. In general, calculations assume that: a. The flow of air and flue gas is constant; b. The specific heat of air and flue gas is constant (averaged); c. No phase change occurs during heat transfer; d. Heat exchanger inlet air and flue gas temperature are uniform; e. Heat transfer coefficient K is a constant (averaged); f. Ignore the heat exchanger on the outside heat (sometimes heat exchange times the coefficient ). 1.1 Definition E-NTU method uses three dimensionless quantities: heat exchange efficiency (or temperature efficiency) E, heat capacity flow ratio (or