【摘要】 对来流温度不均匀叉流换热器,本文进行了熵产生和（火用）效率的数值分析。结果表明:①在相同的传热单元数和热容量比值下,对应于换热效果最好的来流温度分布,其熵产生单元数最小,（火用）效率最高。②在给定的条件下,换热器的（火用）效率并不是随传热单元数的增加而单调增加,而是存在一个极大值,它所对应的传热单元数要小于有效度ε_max对应的传热单元数。③熵产生单元数也并不是随传热单元数的增加而单调减少,而是有时单调增加,有时有极大值。并对以上现象作了一些物理机理的分析和讨论。更多还原

【Abstract】 A numerical analysis of thermal performance of crossflow heat exchanger withnonuniform inlet fluid temperature in terms of entropy generation and exergetic efficiencyis presented. From the results it is shown that （1） the distribution of inlet temperaturecorresponding to the least entropy generation and the highest exergetic efficiency isconsistent with that corresponding to the highest performance of heat transfer under thesame values of NTU and MC_P/mc_P; （2） under the given condition, the exergetic efficiencydoes not increase monotonically with the increase of NTU. There is a maximum valueand the NTU corresponding to the maximum exergetic efficiency is less than thatcorresponding to the ε_max; （3） entropy generation number does not always decreasemonotonically along with the increase of NTU, but sometimes increases monotonicallyand sometimes emerges a maximum value. The physical mechanism about suchphenomena above are discussed.更多还原