相变乳液作为一种新型的储热工质,可用于太阳能的高效集热,但使用过程中存在乳液导热性差、光热转换效率低等问题。以石蜡相变乳液(PCME)为研究对象,系统地考察了乳化剂种类、亲水亲油平衡值(HLB值)、乳化剂含量对PCME性能的影响;同时,通过向PCME中添加气相纳米二氧化硅(纳米SiO2)作为改性材料,考察其对提高乳液导热性的影响,并搭建了模拟太阳能集热装置测试相变乳液的集热性能。结果表明:当乳化剂为司班60/吐温80、HLB值为12、质量分数选用4%时,所制备出的乳液性能较好;当向该乳液中添加0.3%纳米SiO2时,改性后的SiO2/PCME导热系数由原乳液的0.2750W/(m·K)提高至0.3892W/(m·K),其光热转换效率与纯水相比提高了24.73%,与SiO2纳米流体相比提高了17.14%。
As a new thermal storage working medium,phase change emulsion can be used for efficient solar energy heat collection,but there still are some problems such as poor thermal conductivity of emulsion and low photothermal conversion efficiency.Taking paraffin phase change emulsion (PCME) as the research subject,the effects of emulsifier type, hydrophilic-lipophilic balance (HLB) value,and emulsifier content on the properties of PCME were investigated systematically in this work.Meanwhile,Nano-SiO2 was employed as a modified material and was added into PCME.The effect of nano-SiO2 on improving thermal conductivity of PCME emulsion was investigated,and a simulated solar collector was built to test the thermal collection performance of different phase change emulsions.When the emulsifier was Span 60/Tween 80,HLB was 12,and the mass fraction was selected as 4%,the properties of the prepared emulsion was better.When 0.3wt% nano-SiO2 was added into the emulsion,the thermal conductivity of the modified SiO2/PCME was increased from 0.2750W/(m·K) of the original emulsion to 0.3892W/(m·K),and the photothermal conversion efficiency was improved by 24.73% compared with pure water and by 17.14% compared with SiO2 nanofluid.
[1] Zhang X,Wu J Y,Niu J.PCM-in-water emulsion for solar thermal applications:The effects of emulsifiers and emulsification conditions on thermal performance,stability and rheology characteristics[J].Solar Energy Materials and Solar Cells,2016,147:211-224.
[2] Wazeer A,Das A,Vidya S.Phase change materials for solar energy applications[J].Transactions of the Indian Institute of Metals,2023,76(5):1155-1163.
[3] Wang Z,Qu J,Zhang R,et al.Photo-thermal performance evaluation on MWCNTs-dispersed microencapsulated PCM slurries for direct absorption solar collectors[J].Journal of Energy Storage,2019,26:100793.
[4] Naveenkumar R,Ravichandran M,Mohanavel V,et al.Review on phase change materials for solar energy storage applications[J].Environmental Science and Pollution Research,2021,29(7):9491-9532.
[5] Morimoto T,Kawana Y,Saegusa K,et al.Supercooling characteristics of phase change material particles within phase change emulsions[J].International Journal of Refrigeration,2019,99:1-7.
[6] Wang Z,Li R,Hu J,et al.Experimental study on hybrid organic phase change materials used for solar energy storage[J].Journal of Thermal Science,2020,29(2):486-491.
[7] Shi T,Zhang M,Liu H,et al.Phase-change nanofluids based on n-octadecane emulsion and phosphorene nanosheets for enhancing solar photothermal energy conversion and heat transportation[J].Solar Energy Materials and Solar Cells,2022,248:112016.
[8] Wang F,Lin W,Ling Z,et al.A comprehensive review on phase change material emulsions:Fabrication,characteristics,and heat transfer performance[J].Solar Energy Materials and Solar Cells,2019,191:218-234.
[9] Maithya O M,Li X,Feng X,et al.Microencapsulated phase change material via Pickering emulsion stabilized by graphene oxide for photothermal conversion[J].Journal of Materials Science,2020,55(18):7731-7742.
[10] Burgos J,Mondragón R,Martínez-Cuenca R,et al.Photothermal properties and performance of hybrid carbon-paraffin/water emulsions[J].Journal of Energy Storage,2023,73:109136.
[11] Barison S,Cabaleiro D,Rossi S,et al.Paraffin-graphene oxide hybrid nano emulsions for thermal management systems[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2021,627:127132.
[12] Li Z,Kan A,Wang K,et al.Optical properties and photothermal conversion performances of graphene based nanofluids[J].Applied Thermal Engineering,2022,203:117948.
[13] Zou Y,Qin C,Yang B,et al.Optical properties and photothermal conversion characterization of TiN nanofluids with different base fluids[J].Plasmonics,2024,19:1371-1382.
[14] 陈红兵,龚雨桐,姚华宁,等.添加纳米颗粒和分散剂的相变流体性能测试研究[J].功能材料,2019,50(5):5023-5027.
[15] Ma F,Zhang P.Performance investigation of the direct absorption solar collector based on phase change slurry[J].Applied Thermal Engineering,2019,162:114244.
[16] 毛凌波,梁志彬,林敬堂,等.纳米粒子与石蜡乳状液复合多相功能热流体的制备与性能[J].新能源进展,2013,1(3):257-262.
[17] 王方娴.高性能微/纳米相变乳液的制备、特性及其应用研究[D].广州:华南理工大学,2020.
[18] 苏庆宗,段建国,许立鹏,等.有机相变储能材料及强化传热研究进展[J].化工新型材料,2021,49(4):21-25,30.
[19] 栾丹明.添加纳米颗粒的相变流体制备及特性研究[D].北京:北京建筑大学,2018.
[20] 邹得球,肖睿,何世辉,等.基于纳米粒子/相变石蜡乳状液的研究[J].材料导报,2009,23(15):103-107.
[21] Wang F,Zhang C,Liu J,et al.Highly stable graphite nanoparticle-dispersed phase change emulsions with little supercooling and high thermal conductivity for cold energy storage[J].Applied Energy,2017,188:97-106.
