【作者】 吴玉庭； 鹿院卫； 桑丽霞； 郭航； 马重芳；

【Author】 WU Yuting;LU Yuanwei;SANG Lixia;GUO Hang;MA Chongfang;Key Laboratory of Enhanced Heat Transfer and Energy Conservation,Ministry of Education of China,College of Environmental and Energy Engineering,Beijing University of Technology;

【机构】 北京工业大学环境与能源工程学院,传热强化与过程节能教育部重点实验室暨传热与能源利用北京市重点实验室；

【摘要】 熔盐是一种在室温下是固体,但在高温下变成液相的无机盐及其混合物。高温混合熔盐具有传热性能好、工作压力低、液态温度范围宽、使用温度高、成本低、安全可靠等优点,是一种非常有前景的高温传热蓄热工质。熔盐高温传热已在核电、太阳能热发电、高温过程工业得到了应用。到目前为止已有大约20座商业化运行的太阳能热发电电站(总装机容量达到了1200 MW)采用了大规模熔盐蓄热技术。此外,熔盐大规模蓄热还可在电力储能独立熔盐蓄热电站、热电厂蓄热调峰、移动式蓄热、高温间歇余热利用、低谷电加热熔盐蓄热供暖等领域具有很好的应用前景。北京工业大学先后配制了135种混合熔盐,进行了热物性测定,优选获得了适用于不同温度范围的混合熔盐优化配方,获得了混合熔盐优化配方的黏度、密度、导热系数、比热等热物性参数随温度变化的试验关联式。建立了熔盐受迫对流传热、自然对流、槽式聚光熔盐集热传热、熔盐相变传热4个试验台。试验获得了3种熔盐在宽广雷诺数范围内不同温度下的湍流和过渡流受迫对流换热系数,综合本课题组试验数据和美国橡树岭国家实验室的6种熔盐试验数据,获得光滑管内湍流和过渡流对流换热的通用试验关联式,并与经典关联式进行了对比,验证了经典关联式对熔盐的适用性。进行了熔盐自然对流的实验和数值模拟研究,获得了不同雷诺数下的自然对流换热系数,并与经典关联式进行了对比。采用低熔点熔盐在实验室的槽式聚光集热传热实验台上实现了3000 h以上的成功运行,获得了包括真空集热管、循环管路和熔盐蓄热罐的热损失以及水-盐换热器的传热性能在内的一大批试验数据。更多还原

【Abstract】 Molten salt is salt which is solid at standard temperature and pressure but enters the liquid phase due to elevated temperature.Mixed molten salt is considered as a promising medium for both heat transfer and thermal storage at high temperature because of its many advantages such as good heat transfer performance,lower system pressure,high available temperature,wide liquid temperature range cheap and safety,etc.Molten salt heat transfer have been used in nuclear power,solar thermal power,high temperature process industry.Large scale Molten salt thermal storage have been used in more than 20 solar thermal power station with total power capacity of 1200 MW.In addition,Molten salt thermal storage can also been used in Independent thermal storage power station for large scale electrical energy storage,cogeneration plants heat storage,mobilized thermal energy storage systems,heat storage for high temperature intermittent waste heat and off-peaking central electricity heating technology.135 kinds of molten salts mixture with different salt components were prepared and thermophysical properties of these molten salts were measured and compared.Some optimized molten salts mixtures were obtained for meeting the demands of heat transfer and thermal storage at different temperature range.Correlation on temperature and thermal physical properties is also acquired.Four experimental systems including forced convective heat transfer system,Natural convection heat transfer,Trough solar collector/ heat transfer system with molten salts and Latent thermal storage system with molten salts were built to research the heat transfer and storage performance of molten salts.Convective Heat transfer coefficients with three kinds of liquid salts at wide range of Reynolds number were obtained.General Correlations Combining the experimental data from BJUT and ORNL in smooth tubes were obtained.Experimental Studies and numerical simulation on natural convection of molten salt has been carried out for the first time,acquiring heat transfer coefficient for different Rayleigh number with lithium nitrate as working fluid.A comparison of results and classical correlation is made.3000 h Successful Operation were realized in Trough Collector and Heat Transfer Cycle system with low melting point molten salt developed by our Laboratory.Heat loss of trough collector tubes,salts storage tank and loop pipes with low melting point molten salt were measured and analyzed.Experimental study of water-salt Heat transfer were also made.更多还原