汽-汽再热器内流动与换热特性数值研究

Numerical simulation of flow and heat transfer in shell and tube steam reheater

为了揭示汽-汽再热器的换热特性,首次通过三维数值模拟的方法对汽-汽再热器内的流动、换热及熵产特性进行了研究。结果显示,当高温蒸汽流速较小时,高温蒸汽侧进口处的温度梯度较大,而低温蒸汽侧出口处的温度变化不明显;随着高温蒸汽流速增大,高温蒸汽沿流程的温度梯度逐渐减小,低温蒸汽出口平均温度逐渐增大,同时换热器内局部熵产值逐渐增大;随着管壳式换热器隔板数的增加,低温蒸汽出口平均温度逐渐增大,但增幅逐渐减小。

In order to reveal the heat transfer characteristics of steam reheater,the flow,heat transfer and entropy generation characteristics in steam reheater were studied by three-dimensional numerical simulation for the first time.The results show that when the high-temperature steam flow rate is small,the temperature gradient at the inlet of high-temperature steam side is larger,while the temperature change at the outlet of low-temperature steam side is not obvious;with the increase of high-temperature steam flow rate,the temperature gradient of high-temperature steam along the flow direction gradually decreases,while the average temperature at the outlet of low-temperature steam gradually increases,and the local entropy generation increases.With the increase of the baffle number in shell and tube heat exchanger,the average temperature at the outlet of low temperature steam increases,but the rise range decreases.