Ice storage sphere systems are favored in the field of energy storage, however, the poor thermal conductivity of phase change materials (PCM) seriously weakens their wide application. Metal foam has been shown to enhance its heat transfer. In this paper, we investigate the impact of varying the filling radius ratio of foam metal to further improve energy storage performance and reduce costs in ice storage spheres. Computational fluid dynamics are employed to analyze the heat transfer and solidification processes. The enthalpy-porosity method is used to describe PCM solidification, while the local equilibrium thermal (LET) model characterizes heat transfer between the PCM and foam metal. The study explores temperature field variations, solid phase fraction changes, solidification times, and cold storage volumes, accounting for natural convection. By comparing solidification rates and other relevant parameters, the effect of foam metal filling on the solidification process is explored. Moreover, a new evaluation index is proposed, which can assess the overall performance of ice storage systems in real-time, considering market prices. The results show that natural convection is the primary heat transfer mode in pure PCM-ffild ice storage spheres, whereas smaller foam metal filling radii significantly inhibit natural convection, resulting in heat conduction as the dominant mode. Without specific requirements, an optimal fill radius ratio of 9/13 is determined. This paper offers a comprehensive understanding of cold storage employing various foam metal filling radios, contributing to advancements in efficient thermal energy storage systems.
晶闸管在负载快速变化的过程中具有短时失控特性,输出电压容易波动.选取晶闸管整流电源作为研究对象,建立仿真模型,通过引入前馈控制器实现了对晶闸管整流电源输出电压的快速补偿,改善了电源的整体动态特性.通过仿真验证模型与控制器的有效性.研究表明,引入前馈控制器能够明显改善负载波动时整流电源的输出电压动态特性.
对利用太阳能和生物质能的联合冷热电系统(CCHP)进行热力学分析.系统由内燃机和太阳能光伏电池供电,由吸收式制冷及热水系统进行余热回收.太阳能光伏电池采用五参数模型,内燃机为零维、单区模型.分析转速和压比对内燃机输出功率、排气排放物和气缸内传热的影响.结果显示:太阳能光伏电池效率为14%,日发电量500 kWh;内燃机热效率可以达到37%.转速提高后,整体CCHP电效率提高2.8%,余热利用效率提高10%.内燃机的压缩比增大后,CCHP电效率增大0.52%,整体冷热电效率几乎不变.整个CCHP系统电效率为20%,冷热电联合效率可以达到40%.
以铝基平板微热管为研究对象,探究平板微热管微槽道形状、填充工质、冷却方式、加热功率对平板微热管传热性能的影响,分析不同参数下平板微热管平均温差和热阻的变化规律.结果显示:矩形槽道的平板微热管性能优于三角形槽道平板微热管,丙酮工质平板微热管的性能优于甲醇工质平板微热管,带翅片的平板微热管的性能优于不带翅片的平板微热管.在极限热流密度范围内,加热功率越大,平板微热管的性能越好.
"十四五"以来,随着"双碳"相关文件的陆续发布以及"两高"项目管控力度加强,固定资产投资项目节能审查制度成为各级部门加强能源消费"双控"、优化产业投资结构、提升能源利用效率的重要抓手.年综合能源消费量作为衡量项目能源消费情况的直接指标,是项目节能审查环节重点关注的指标,也是判断项目对地方能源消费总量控制的重要参考.从计算边界、方法和口径等方面,总结项目年综合能源消费量核算的相关注意事项,并提出相关建议,以期更好地推进节能报告编制工作.
