电热水器内部结构优化及储能特性研究

Research on internal structure optimization and energy storage characteristics of electric water heater

将相变储能技术应用于电热水器,并通过添加石墨纳米颗粒改善相变材料的导热特性,对其储能过程进行调节,可以起到"移峰填谷"的作用。建立了四种不同结构的电热水器三维模型,模拟了电热水器内部速度场与温度场分布特性。考察了进出口水管结构、电加热管布置方式、保温层结构等因素对热水器内部流场及传热特性的影响,研究了不同储能层厚度对电热水器储能的影响。结果表明,水平加热管与垂直加热管相比,加热过程中加热效率提高了2.2%;进水管管径增大1.5倍,热水输出率提升了17.9%;加入相变材料可在相同保温时间内(36 h)使水温最大提高10.6%。

The energy consumption of electric water heater in China has a large proportion of total energy consumption. Therefore, it is of great significance to optimize the energy consumption process of electric water heater. The phase change materials(PCM) have the characteristics of high energy storage density and approximately constant temperature in the process of phase transition. In addition, the thermal conductivity of phase change materials can be enhanced by adding nanometer materials such as graphite. Therefore, it has obvious advantages in heat energy storage and utilization of phase change materials. So, the phase change energy storage technology can be applied to electric water heater to adjust the energy storage process and the goal of "peak shifting" also can be achieved. In this work, the energy storage characteristic of energy storage water heater with phase change material were researched employing numerical simulation method. Four different structural models were established and the influent of inlet and outlet piping construction, electric heating tube arrangement, insulation structure on flow and heat transfer characteristics of water in water heater were discussed. And the influence of energy storage layer thickness on energy storage of electric water heater were researched. The results showed that, compared with the vertical heating tube, the water temperature distribution of horizontal heating tube was more uniform during heating process, and the heating efficiency was improved by about 2.2%. When the inlet tube diameter increased to 1.5 times, the output status of hot water can be excellent improved, and the hot water output efficiency can be increased17.9%. The addition of phase change materials can increase the water temperature by 10.6% under the condition of same heat preservation time(36 h). The results of this study can provide data support for structural optimization of electric water heater and application of phase change energy storage technology.