双螺旋盘管内膨胀石墨对相变材料的传热强化机制与蓄放热性能  

Investigation of heat transfer enhancement mechanism and performance of phase change materials using expanded graphite in double helical coils

作　　者：郭艳芹[1] 曾镇 张弘光 凌子夜[1,2] 张正国 方晓明[1,2] GUO Yanqin;ZENG Zhen;ZHANG Hongguang;LING Ziye;ZHANG Zhengguo;FANG Xiaoming(Key Laboratory of Enhanced Heat Transfer and Energy Conservation,Ministry of Education,School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China;Guangdong Engineering Technology Research Center of Efficient Heat Storage and Application,Guangzhou 510640,Guangdong,China;Foshan Shunde Midea Electric Heating and Electric Appliance Manufacturing Co.Ltd.,Foshan 528311,Guangdong,China)

机构地区：[1]华南理工大学化学与化工学院,教育部强化传热与节能重点实验室,广东广州510640 [2]广东省热能高效储存与利用工程技术研究中心,广东广州510640 [3]佛山市顺德区美的电热电器制造有限公司,广东佛山528311

出　　处：《储能科学与技术》2023年第12期3678-3689,共12页Energy Storage Science and Technology

基　　金：佛山市重点领域科技攻关项目(2120001008795)。

摘　　要：本工作提出了一种双螺旋盘管与膨胀石墨强化传热的相变蓄热器结构,通过建立双螺旋管相变蓄热器模型,模拟了双螺旋管的螺距、材料热物性对蓄放热性能的影响规律。探讨了限制空间下相变材料自然对流与材料导热增强在传热强化过程中的控制作用。结果表明,在加工螺距限制条件下,减小螺距及增加螺旋数可以提升蓄热器放热性能。膨胀石墨可以提升相变材料热导率,同时会导致材料黏度增大,因此添加膨胀石墨能增强蓄热器的导热换热,但抑制自然对流换热。通过对比分析发现,在限制空间下材料的导热增强带来的传热强化程度能够弥补由于材料自然对流不足导致的传热损失。因此,本工作揭示了相变蓄热器传热强化的控制步骤在于材料热导率强化。基于实验和仿真结合的方式,本工作设计了一款用于加热生活热水的蓄热器结构,验证了所设计的蓄热器在宽进口温度、进口流量等操作工况下具有优异的放热性能。该蓄热器与电加热器相结合,能够在电热功率小于2200 W的条件下实现热水加热功率超3500 W,突破了家用电热设备的功率限制。This paper presents a novel structure for a phase change heat storage system incorporating double spiral coils and expanding graphite to enhance heat transfer.A model of the double spiral coil phase change heat storage system is established to simulate the impact of coil pitch and thermal properties of materials on heat storage and release performance.The study delves into the influence of natural convection of phase change materials and the enhancement of material thermal conductivity on heat transfer in confined spaces.Results indicate that reducing the pitch and increasing the number of spiral coils within limited pitch conditions can enhance the heat release performance of the heat storage system.Incorporating expanded graphite boosts the thermal conductivity of phase change materials,albeit with an increase in material viscosity.Consequently,adding the expanded graphite improves the heat transfer and exchange efficiency of the heat storage system,albeit at the cost of suppressing natural convection heat transfer.Comparative analysis reveals that,under confined space conditions,the enhanced heat transfer resulting from material thermal conductivity enhancement compensates for the heat loss attributed to inadequate natural convection heat transfer.This study underscores that the key to controlling heat transfer enhancement in phase change heat storage systems lies in the thermal conductivity enhancement of materials.Drawing on experimental and simulation approaches,this article presents a designed heat storage system structure for heating domestic hot water.The proposed system exhibits excellent heat release performance across a broad range of inlet temperatures and flow rates.When combined with an electric heater,this heat storage system achieves a heating power exceeding 3500 W with electric power consumption below 2200 W,surpassing the power limitations of typical household electric heating equipment.

关 键 词：双螺旋管 相变蓄热器 数值模拟 导热增强 自然对流 

分 类 号：TK02[动力工程及工程热物理]