应用石蜡/GO复合相变材料的太阳能PV/T系统性能

Performance of a solar PV/T system applying a paraffin/graphene oxide composite phase change material

为了提高太阳能PV/T系统能效,采用超声搅拌法制备了GO(氧化石墨烯)质量分数为0.01%、0.02%和0.03%的石蜡/GO复合相变材料,并对其潜热、导热性和流动性进行测试分析。其中,GO质量分数为0.02%的复合相变材料相比于制备的其他复合相变材料具有最佳的综合性能,其相变温度为35℃,相变潜热为42.93 J/g,热导率最高为0.505 W/(m·K),黏温拟合程度为0.91。为了分析石蜡/GO复合相变材料对太阳能PV/T系统热电性能的影响,搭建了两套完全相同的平板热管式太阳能PV/T系统,并将GO质量分数为0.02%的石蜡/GO复合相变材料和水作为两系统的传热介质运行。采用热效率和电效率对太阳能PV/T系统的热电性能进行表征。研究结果表明,在相同工况下,运行(石蜡质量分数为30%以及GO质量分数为0.02%)石蜡/GO复合相变材料的平板热管式太阳能PV/T系统的热电性能均比运行水的系统性能有所提升,其中系统热效率提高92.28%,电效率提高8.87%,换热水箱集热量提高15.80%。该研究为复合相变材料(流体)在太阳能储存领域的应用提供了借鉴。

Paraffin/GO(graphene oxide)composite phase change materials are prepared and characterized for latent heat,thermal conductivity,and fluidity to increase the energy efficiency of solar PV/T(photovoltaic/thermal)systems.With a phase change temperature of 35℃,a latent heat of phase change of 42.93 J/g,a maximum thermal conductivity of 0.505 W/(m·K),and a viscosity-temperature fit of 0.91,the composite phase change material with a GO mass fraction of 0.02%has the best overall performance when compared to other known composite phase change materials.Two identical flat-plate heat pipe solar PV/T systems are built,and paraffin/GO composite phase change materials(a GO mass fraction of 0.02%and water)are operated as the heat transfer medium for both systems to analyze the effect of the paraffin/GO composite phase change material on the thermoelectric performance of a solar PV/T system.Herein,characterization of the thermoelectric performance of the solar PV/T system using thermal and electrical efficiencies was performed.Results show that under the same operating conditions,the thermoelectric performance of the flat-plate heat pipe solar PV/T system running(paraffin wax mass fraction of 30%and GO mass fraction of 0.02%)with a paraffin/GO composite phase change material is improved compared to that running with water,with an increase in system thermal efficiency of 92.28%,electrical efficiency of 8.87%,and heat collection in the heat exchanger tank of 15.80%.This study provides value for applying composite phase change materials(fluids)in solar energy storage.