以碳纳米管(CNTs)/石蜡纳米复合材料作为相变蓄热介质,将纳米复合材料应用于热泵热水器中,探讨了相变蓄热式热泵热水器的传热性能。研究表明,在石蜡中添加CNTs填料后,纳米复合材料的蓄、放热速率显著提高,相变蓄热式热泵热水器系统在运行过程中具有很好的稳定性。相变蓄热系统中温度场的分布存在一些差异,尤其是放热阶段的差异特别明显,甚至靠近水介质出口的拐角处出现“滞积”热量的现象,因此在确定相变蓄热材料用量时,有必要适当增加材料的用量。与传统带水箱的蓄热式热泵热水器相比,纳米复合材料的添加使得相变蓄热式热泵热水器蓄热箱体积减少约1/2,热效率明显提到,可达86%,说明CNTs/石蜡纳米复合材料可以作为热泵热水器的蓄热材料。较高的环境温度下,CNTs/石蜡纳米复合材料的温度上升速度较快,热传递时间较短,显然环境温度对热泵系统的性能有显著的影响。
To explore the feasibility of applying carbon nanotubes (CNTs)/paraffin composites to heat pump water heater system as phase change heat storage media,the heat transfer characteristics of phase change thermal storage heat pump water heater were analyzed and discussed.It was shown that the heating and cooling rates of nanocomposite phase change materials were significantly improved upon the addition of CNTs nanoparticles,and the heat pump heat water with thermal storage had good stability in heat storage and release process.There were some differences in the distribution of temperature field in phase change heat storage system,especially in the exothermic stage.Thermal “stagnation” occurred near the corner of the outlet of water medium,so it was necessary to increase the amount of materials appropriately.Compared with traditional regenerative heat pump water heater with water tank,the volume of regenerator of heat pump water heater was reduced by about 1/2 with the addition of nanocomposites,and the thermal efficiency can reach 86%.The running experimental results of the heat pump water heater suggested the reliability of designment of the thermal energy storage and the feasibility of CNTs/paraffin using in the heat pump water heater.The temperature of CNTs/paraffin composites rised faster and the heat transfer time was shorter at higher ambient temperature.Obviously,ambient temperature had a significant impact on the performance of heat pump system.
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基金资助
广东省科技计划项目(2016A010104002);广东省普通高校特色创新类项目(2017GKTSCX075)
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