船用蒸汽蓄热器快速充汽过程吸热特性的测量方法研究

为了满足短时间耗汽量极大用汽设备的用汽需求,选取平均过冷度和吸热系数作为船用蒸汽蓄热器吸热特性的评价指标,对快速充汽过程进行数学建模和实验研究,以期达到对吸热特性的测量。结果表明:蒸汽蓄热器在吸热过程中,其水部存在着明显的温度分布不均匀,通过对充汽流量的减小和充汽时间的延长,能够改善吸热特性。与此同时,测量方法也有效可行,完全可用于船用蒸汽蓄热器在快速充汽过程中的吸热特性测量。

两种充汽模式下船用蒸汽蓄热器动态性能数值模拟

为给船舶蒸汽动力系统设计提供技术支撑,采用考虑蒸发和冷凝的热相变模型描述蒸汽蓄热器汽、液两相的热质传递规律,并结合缓慢充汽和快速充汽计算边界条件,基于CFX实现不同充汽模式下船用蒸汽蓄热器动态性能数值模拟。计算结果表明:在缓慢充汽起始阶段,船用蒸汽蓄热器水位波动大,最终水位保持平稳且略有升高;缓慢充汽过程中,船用蒸汽蓄热器的压力和温度均呈先快速上升再下降的变化规律;在快速充汽过程中,蒸汽蓄热器的压力和温度均呈先快速上升再下降的变化规律,计算结果与试验数据基本吻合。

Pulse Quick Charger of Electric Vehicle

In order to improve the charging efficiency of lead acid battery, shorten the charging time and avoid the battery polarization, a new charging method was put forward. Based on the analyzed results of charging characteristic of lead acid battery, a pulse quick charger is designed to adjust the charging current pulse’s amplitude and pulse width automatically stage by stage according to the measured battery voltage and feedback current. Compared with other kinds of quick chargers, it has such characteristics as shorter charging time, higher charging efficiency and lower temperature increasing during the charging process. As a result, the battery polarization is reduced efficiently.