石蜡/膨胀石墨复合相变储热单元的放热性能
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摘要
本工作对石蜡(PA)及石蜡/膨胀石墨(97%PA/3%EG和95%PA/5%EG)复合相变储热材料的热性能进行了探究,考察了不同直径储热单元在干燥介质温度为25℃,风速为0.8 m/s条件下的放热性能。结果表明,在石蜡中添加膨胀石墨后,复合材料导热系数较纯石蜡分别提高了178.10%和214.30%,可以有效改善石蜡的导热性能,缩短放热时间;储热单元直径对放热性能有显著影响,随着石蜡相变储热单元直径的增大,放热时间线性增加;膨胀石墨的添加可以明显缩短放热时间,随膨胀石墨含量的增加,相同直径储热单元的放热时间逐渐缩短;膨胀石墨对储热单元放热性能的改善效果随直径变化而不同,在一定范围内随储热单元直径的增大而效果逐渐显著,达到极值后随直径的增大效果逐渐减弱,本实验条件下,最优储热单元直径在35～50 mm之间。结合实际生产需求,最优直径为35 mm。
Thermal properties of paraffin wax(PA) and paraffin/expanded graphite(97% PA/3%EG and 95% PA/5%EG) composite materials were investigated. Heat release performance of thermal energy storage(TES) units with different diameters containing the phase change materials were studied at a drying media temperature of 25 ℃ and a media velocity of 0.8 m?s~(-1). The results showed that the thermal conductivity of the composites was increased by 178.10% and 214.30% respectively compared with that of PA, which could shorten the TES unit discharge time. The diameter of the TES unit had a significant effect on the heat release performance. An increase in the diameter of the PA based TES unit leads to a linear increase in the heat release time, whereas an increased EG content reduces the heat release time of the unit for a given TES unit diameter. The effect of EG on the heat release performance of the TES unit increases first and then decreases with increasing diameter, leading to an optimal TES unit diameter of 35 mm under the conditions of this study.
Thermal properties of paraffin wax(PA) and paraffin/expanded graphite(97% PA/3%EG and 95% PA/5%EG) composite materials were investigated. Heat release performance of thermal energy storage(TES) units with different diameters containing the phase change materials were studied at a drying media temperature of 25 ℃ and a media velocity of 0.8 m?s~(-1). The results showed that the thermal conductivity of the composites was increased by 178.10% and 214.30% respectively compared with that of PA, which could shorten the TES unit discharge time. The diameter of the TES unit had a significant effect on the heat release performance. An increase in the diameter of the PA based TES unit leads to a linear increase in the heat release time, whereas an increased EG content reduces the heat release time of the unit for a given TES unit diameter. The effect of EG on the heat release performance of the TES unit increases first and then decreases with increasing diameter, leading to an optimal TES unit diameter of 35 mm under the conditions of this study.
引文
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[23]汪向磊,郭全贵,王立勇,等.高导热定形聚乙烯/石蜡/膨胀石墨相变复合材料的研究[J].功能材料,2013,44(23):3401-3404.WANG Xianglei,GUO Quangui,WANG Liyong,et al.Study on high thermal conductivity shaped polyethylene/paraffin/expanded graphite phase change composites[J].Functional Materials,2013,44(23):3401-3404.
[2]BYRNE J,KURDGELASHVILI L,POPONI D,et al.The potential of solar electric power for meeting future US energy needs:Acomparison of projections of solar electric energy generation and arctic national wildlife refuge oil production[J].Energy Policy,2004,32(2):289-297.
[3]李柯,何凡能.中国陆地太阳能资源开发潜力区域分析[J].地理科学进展,2010,29(9):1049-1054.LI Ke,HE Fanneng.Regional analysis of chinese terrestrial solar energy resources development potential[J].Progress in Geography,2010,29(9):1049-1054.
[4]李永亮,金翼,黄云,等.储热技术基础(Ⅰ)-储热的基本原理及研究新动向[J].储能科学与技术,2013,2(1):69-72.LI Y L,JIN Y,HUANG Y,et al.Principles and new development of thermal storage technology(I)[J].Energy Storage Science&Technology,2013,2(1):69-72.
[5]何正斌,甘雪菲,杨洁,等.石蜡相变储热管放热时间的理论预测与验证[J].农业工程学报,2011,27(12):286-290.HE Zhengbin,GAN Xuefei,YANG Jie,et al.Theoretic prediction and verification of heat release time for paraffin phase change heat storage tubes[J].Transactions of the CSAE,2011,27(12):286-290.
[6]WEI Z,LI Y,LI D,et al.Thermal energy storage:Challenges and the role of particle technology[J].Particuology,2014,15(4):2-8.
[7]李传,葛志伟,金翼,等.基于复合相变材料储热单元的储热特性[J].储能科学与技术,2015,4(2):169-175.LI Chuan,GE Zhiwei,JIN Yi,et al.Heat transfer behavior of thermal energy storage components using composite phase change materials[J].Energy Storage Science and Technology,2015,4(2):169-175.
[8]孙文鸽,韩磊,吴志根.膨胀石墨/石蜡相变复合材料有效导热系数的数值计算[J].复合材料学报,2015,32(6):1596-1601.SUN Wenge,HAN Lei,WU Zhigen.Numerical calculation of effective thermal conductivity of expanded graphite/paraffin phase change composites[J].Acta Materiae Compositae Sinica,2015,32(6):1596-1601.
[9]张钦真.膨胀石墨/石蜡复合相变蓄热材料实验研究[D].包头:内蒙古科技大学,2013.ZHANG Qinzhen.Experiment research of the expanded graphite/paraffin composite phase change thermal storage materials[D].Baotou City:Inner Mongolia University of Science and Technology,2013.
[10]肖鑫,张鹏.泡沫石墨/石蜡复合相变材料热物性研究[J].工程热物理学报,2013,34(3):530-533.XIAO Xin,ZHANG Peng.Thermal characterization of graphite foam/paraffin composite phase change material[J].Journal of Engineering Thermophysics,2013,34(3):530-533.
[11]ZHONG Y,LI S,WEI X,et al.Heat transfer enhancement of paraffin wax using compressed expanded natural graphite for thermal energy storage[J].Carbon,2010,48(1):300-304.
[12]夏莉,张鹏,周圆,等.石蜡与石蜡/膨胀石墨复合材料充/放热性能研究[J].太阳能学报,2010,31(5):610-614.XIA Li,ZHANG Peng,ZHOU Yuan,et al.Study on the heat transfer performance of paraffin and paraffin/expanded graphite composites[J].Acta Energiae Solaris Sinica,2010,31(5):610-614.
[13]杨佳霖,杜小泽,杨立军,等.泡沫金属强化石蜡相变蓄热过程可视化实验[J].化工学报,2015(2):497-503.YANG Jialin,DU Xiaoze,YANG Lijun,et al.Visualized experiment on dynamic thermal behavior of phase change material in metal foam[J].CIESC Journal,2015(2):497-503.
[14]XIAO X,ZHANG P,LI M.Preparation and thermal characterization of paraffin/metal foam composite phase change material[J].Applied Energy,2013,112(4):1357-1366.
[15]郑文娟.石蜡/铜纳米粒子复合相变材料储热性能的研究[D].青岛:青岛科技大学,2012.ZHENG Wenjuan.The study of thermal energy storgy storage characteristics of paraffin/copper nanoparticles composite phase change materials[D].Qingdao:Qingdao University of Science and Technology,2012.
[16]ETTOUNEY H M,ALATIQI I,AL-SAHALI M,et al.Heat transfer enhancement by metal screens and metal spheres in phase change energy storage systems[J].Renewable Energy,2004,29(6):841-860.
[17]冯小江.相变储热太阳能木材干燥装置设计及性能研究[D].北京:北京林业大学,2010.FENG Xiaojiang.Design and performance research of a solar wood dryer with latent heat storage system[D].Beijing:Beijing Forestry University,2010.
[18]TEMEL U N,SOMEK K,PARLAK M,et al.Transient thermal response of phase change material embedded with graphene nanoplatelets in an energy storage unit[J].Journal of Thermal Analysis&Calorimetry,2018:1-12.
[19]张娇.膨胀石墨/石蜡复合相变蓄热材的制备及性能研究[D].西安:西安建筑科技大学,2016.ZHANG Jiao.Study on preparation and properties of expanded graphite/paraffin composite phase change heat storage materials[D].Xi'an:Xi'an University of Architecture and Technology,2016.
[20]LIU X,RAO Z.Experimental study on the thermal performance of graphene and exfoliated graphite sheet for thermal energy storage phase change material[J].Thermochimica Acta,2017,647:15-21.
[21]SARI A,KARAIPEKLI A.Thermal conductivity and latent heat thermal energy storage characteristics of paraffin/expanded graphite composite as phase change material[J].Applied Thermal Engineering,2007,27(8):1271-1277.
[22]张秀荣,朱冬生,高进伟,等.石墨/石蜡复合相变储热材料的热性能研究[J].材料研究学报,2010,24(3):332-336.ZHANG Xiurong,ZHU Dongsheng,GAO Jinwei,et al.Study on thermal properties of grephtie/paraffin composites as phase change heat storage material[J].Chinese Journal of Materials Research,2010,24(3):332-336.
[23]汪向磊,郭全贵,王立勇,等.高导热定形聚乙烯/石蜡/膨胀石墨相变复合材料的研究[J].功能材料,2013,44(23):3401-3404.WANG Xianglei,GUO Quangui,WANG Liyong,et al.Study on high thermal conductivity shaped polyethylene/paraffin/expanded graphite phase change composites[J].Functional Materials,2013,44(23):3401-3404.