以热力学计算和差热分析(DTA)实验测试相结合的方法确定了月桂酸(LA)和棕榈酸(PA)的二元系低共熔物组成和相变温度;以焦粉为载体材料,制备了LA-PA/焦粉复合相变储能材料(LA-PA/焦粉CPCM)。用红外(FT-IR)、DTA、导热系数测定和储/放热循环实验测试研究了CPCM的结构和储热性能。结果表明:LA-PA低共熔物与焦粉具有良好的化学相容性;CPCM的相变温度为35.4℃,相变焓为105.6J/g;CPCM的导热性能[0.411W/(m·k)]相较于LA-PA[0.210W/(m·k)]提高了95.7%;经过800次的储/放热循环后,CPCM的相变温度和相变焓变化都不大,表现出较好的储热稳定性,具有实际应用价值。
The phase change temperature and eutectic composition of lauric acid/palmitic acid(LA-PA) system was tested by thermodynamic calculation and DTA experiment.LA-PA/coke powder composite phase change material(CPCM )was prepared.The structure and thermal properties of CPCM were studied using infrared (FT-IR),differential thermal analysis (DTA),thermal conductivity measurement,and storage/exothermic cycle test.The FT-IR results shown that the LA-PA eutectic mixture had good chemical compatibility with coke powder.The phase change temperature of CPCM was 35.4℃,and the phase change enthalpy wass 105.6J/g.The thermal conductivity of CPCM[0.411W/(m·k)] was 95.7% higher than LA-PA [0.210W/(m·k)].After 800 heat storage/release cycles,the phase change temperature and phase change enthalpy of CPCM had litter change,showing good heat storage stability,which was expected to be applied in practical projects.
[1] Sharma A,Tyagi V V,Chen C R,et al.Review on thermal energy storage with phase change materials and applications[J].Renewable and Sustainable Energy Reviews,2009,13(2):318-345.
[2] Yuan Yanping,Zhang Nan,Tao Wenquan,et al.Fatty acids as phase change materials:a review[J].Renewable and Sustainable Energy Reviews,2014,29:482-498.
[3] Jia Rui,Sun Keyan,Li Rongchun,et al.Heat capacities of some sugar alcohols as phase change materials for thermal energy storage applications[J].The Journal of Chemical Thermodynamics,2017,115:233-248.
[4] Umair Malik Muhammad,Zhang Yuang,Iqbal Kashif,et al.Novel strategies and supporting materials applied to shape-stabilize organic phase change materials for thermal energy storage-a review[J].Applied Energy,2019,235:846-873.
[5] 李飞明,武建军,韩甲业,等.冶金焦粉脱矿物质的实验研究[J].能源技术与管理,2007(4):63-64.
[6] 张振,颜炳才,周瑞,等.焦粉的综合利用途径[J].山东工,2019,48(14):160-161.
[7] 张寅平,苏跃红,葛新石.(准)共晶系相变材料融点及融解热的理论预测[J].中国科学技术大学学报,1995,25(4):474-478.
[8] Lv Shilei,Zhu Neng,Feng Guohui.Eutectic mixtures of capric acid and lauric acid applied in building wallboards for heat energy storage[J].Energy & Buildings,2005,38(6):708-711.
[9] 黄勇,崔国文.相图与相变[M].北京:清华大学出版社,1987.
[10] Yuan Huanmei,Bai Hao,Lu Xin,et al.Effect of alkaline pH on formation of lauric acid/SiO2 nanocapsules via sol-gel process for solar energy storage[J].Solar Energy,2019,185:374-386.