管内介质为蒸汽状态下的填充床内置换热器外壁传热

Outer wall heat transfer of heat exchanger embedded in honeycomb ceramic packed bed under condition of steam flow medium

在填充床内置换热取热实验台上,研究了换热器管内介质分别为湿蒸汽与过热蒸汽条件下的填充床内置换热器外壁传热。实验结果表明:管内介质分别为湿蒸汽与过热蒸汽时,填充床内置换热器的外壁传热系数随蒸汽质量流量的增大而增大,随湿蒸汽换热器入口干度、过热蒸汽换热器入口过热度的增大而迅速减小;管内介质为过热蒸汽时,换热器外壁镀银后,低流速热风工况下的填充床内置换热器换热系数比镀银前减少近50%,换热器取热的50%以上来自于换热器外壁的辐射换热。

The paper investigated heat exchanger wall heat transfer embedded in the packed bed under the conditions that the medium in the tube is steam. The experimental results show the heat transfer outer wall coefficient increases with the increase of steam mass flow and declines rapidly with the heat exchanger entrance steam dryness and superheated steam heat exchanger entrance superheat degree when the medium in the pipe respectively is wet steam and superheated steam. When the medium in the pipe is superheated steam and the heat exchanger wall is plated silver and the hot gas velocity is very low,the outer wall heat transfer coefficient of heat exchanger embedded in the packed bed decreases nearly 50% heat exchanger comparing that when the heat exchanger wall is not plated silver,in the heat extraction process of the embedded heat exchanger,more than 50% of the contribution comes from the radiation of the outer wall of the heat exchanger.