directly heated tube,filament-type tube是什么意思

用法例句

The research of uniform stream Fuzzy optimization control in power-plant straight-heating boiler;

电站直热锅炉均匀流量Fuzzy优化控制研究

The type of direct heating and circulation heat pump,because of the different heating way,they are many difference in energy efficiency and the efficient.

直热式和循环式热泵,由于加热方式不同,从而导致其能效比、经济性的差异。