针对电阻发热元件普遍存在加热温度分布不均匀的问题,本文采用电热耦合仿真方法对发热元件的结构和材料进行研究与优化,以降低不同区域的温度差值。首先,采用温度均匀系数作为发热元件温度均匀性的量化指标,研究发热元件的折弯间隙宽度...针对电阻发热元件普遍存在加热温度分布不均匀的问题,本文采用电热耦合仿真方法对发热元件的结构和材料进行研究与优化,以降低不同区域的温度差值。首先,采用温度均匀系数作为发热元件温度均匀性的量化指标,研究发热元件的折弯间隙宽度、内倒角和外倒角等折弯结构参数对温度分布均匀性的影响,在原发热元件基础上优化设计了一种能实现最佳温度均匀性的发热元件结构,其主要采用R1=0.3 mm的内倒圆与外直角结合的折弯结构,间隙宽度为0.5 mm。进一步研究了不同PTC(Positive Temperature Coefficient)材料对温度分布均匀性的影响,结果表明具有较高电阻率和较高热导率的铝铜合金材料有助于改善发热元件的温度均匀性。展开更多
The performance of deep oxidation of methanol on supported Ag catalysts was examined by a chromatograph-micro-reactor. The research results showed that La and/or Ce added into γ-alumina support affected greatly the a...The performance of deep oxidation of methanol on supported Ag catalysts was examined by a chromatograph-micro-reactor. The research results showed that La and/or Ce added into γ-alumina support affected greatly the activity and selectivity of methanol oxidation on Ag catalyst. La could lower light-off temperature of methanol oxidation and decreased the content of intermediate containing oxygen, but at low temperature HCOOCH3 formed. Ce had an unfavorable role. The addition of La and Ce into catalyst could cause the effects of these elements to offset. By XPS technique, it was showed that La and Ce could change the chemical valence of Ag inversely, which corresponded to the modifications of catalytic performance.展开更多
文摘针对电阻发热元件普遍存在加热温度分布不均匀的问题,本文采用电热耦合仿真方法对发热元件的结构和材料进行研究与优化,以降低不同区域的温度差值。首先,采用温度均匀系数作为发热元件温度均匀性的量化指标,研究发热元件的折弯间隙宽度、内倒角和外倒角等折弯结构参数对温度分布均匀性的影响,在原发热元件基础上优化设计了一种能实现最佳温度均匀性的发热元件结构,其主要采用R1=0.3 mm的内倒圆与外直角结合的折弯结构,间隙宽度为0.5 mm。进一步研究了不同PTC(Positive Temperature Coefficient)材料对温度分布均匀性的影响,结果表明具有较高电阻率和较高热导率的铝铜合金材料有助于改善发热元件的温度均匀性。
文摘The performance of deep oxidation of methanol on supported Ag catalysts was examined by a chromatograph-micro-reactor. The research results showed that La and/or Ce added into γ-alumina support affected greatly the activity and selectivity of methanol oxidation on Ag catalyst. La could lower light-off temperature of methanol oxidation and decreased the content of intermediate containing oxygen, but at low temperature HCOOCH3 formed. Ce had an unfavorable role. The addition of La and Ce into catalyst could cause the effects of these elements to offset. By XPS technique, it was showed that La and Ce could change the chemical valence of Ag inversely, which corresponded to the modifications of catalytic performance.
