甲烷水蒸气重整强化管内换热的数值模拟
Numerical simulation of enhanced heat transfer in tubes using methane steam reforming
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摘要: 以圆管内壁催化剂薄层内发生甲烷水蒸气重整反应为研究对象,对层流条件下反应及换热进行了数值模拟,分析了催化剂活性、薄层厚度、入口气体流量、入口压力、入口温度以及反应物组分比对反应和换热的影响.结果表明:催化剂薄层内的吸热反应可以有效地增强换热,降低壁面温度;提高催化剂活性和增加薄层厚度,可以增加化学反应吸热量,降低壁面温度,但是当薄层厚度达到一定值时,再增加薄层厚度效果很小;入口流量越大,反应转化率越小,化学反应吸热量占总吸热量的比例越小;入口压力越大,反应吸热量越小,壁面温度越高;提高入口温度使得近入口处壁面温度升高,但是对下游壁面温度的影响很小;存在最佳的反应物组分比,从而获得较低的壁面温度和较高的出口氢气含量.Abstract: Convectional heat transfer with methane steam reforming was investigated in catalyst films on the walls of a tube.The study analyzed the effect of catalytic activity,film thickness,inlet gas flowrate,pressure,temperature and concentration on reaction and heat transfer.The results show that the heat transfer is efficiently enhanced by the endothermic reaction in the catalyst films,and the wall temperature is reduced.Increased catalytic activity and film thickness increase the reaction heat and reduce the wall temperature.However,the effect of the film thickness becomes less significant as the thickness reaches a certain value.As the inlet flowrate increases,the conversion rate and the ratio of reaction heat decrease.As the inlet pressure increases,the reaction heat decreases and the wall temperature increases.As the inlet temperature increases,the wall temperature near the inlet increases,but this effect is very small on the wall temperatures downstream.There is an optimal inlet concentration,which corresponds to the lowest wall temperature and the highest hydrogen fraction at the outlet.
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Key words:
- thermal protection /
- enhanced heat transfer /
- methane /
- steam reforming /
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