中低温相变储热技术在供暖领域的研究应用

Research on the Application of Low-to-medium Temperature Phase Change Thermal Energy Storage Technology in Heating Field

电能替代已成为国内城市供暖的主要方向,储热技术可以将谷电以热的形式储存起来并实现热能的稳定输出,从根本上解决电采暖成本过高的问题。中低温相变储热以其储热密度高、储释热过程温度恒定等优势成为研究热点。中低温相变储热材料的研究主要集中于有机石蜡类及无机水合盐类,目前已有应用案例中主要为水合盐类材料,但其仍存在循环稳定性差、导热性差、腐蚀性等问题。在对相变储热装置的实验室研究中,通过设计并联螺旋盘管、填充筛网、壳管式结构等方式可以有效改善相变材料的传热性能,但在实际工程应用中,相变储热装置内以圆管换热器及带翅片的换热器为主。目前已有案例的中低温相变储热供热系统有两种,一种是电锅炉＋相变储热装置,另一种是将电加热、储热装置放置在一个结构中,两者各有优劣。相对其他几种储热技术,中低温相变储热技术具有初始投资中等、运行成本较低、限制条件较少等优点,但也存在诸多问题有待解决。研发综合性能优异的高储热密度、长循环寿命、高导热、低腐蚀、低成本的相变储热材料,优化换热器及储热装置的内部结构设计,实现强化换热仍是未来相变储热供暖领域的研究方向,实现智能调节控制、降低系统投资成本是储热供暖系统的发展方向。

Electric energy substitution has become the main direction of urban heating in China.Thermal en-ergy storage technology can store the valley electricity in the form of heat and realize the stable output of thermal energy,thus fundamentally solving the problem of high heating cost.The low-to-medium temperature phase change thermal energy storage has become a research hotspot with its advantages of high thermal ener-gy storage density and constant temperature during thermal storage and release.The study on low-to-medium temperature phase change thermal energy storage materials mainly focuses on organic paraffin and inorganic hydrated salt.Inorganic hydrated salt is mainly used in the application cases,but it still has problems such as poor circulation stability,poor thermal conductivity and corrosion.In the laboratory study on phase change ther-mal energy storage device,the heat transfer performance can be effectively improved by designing parallel he-lical coil,filling sieve,shell and tube structure,etc.However,in practical applications,round tube heat exchanger and heat exchanger with fins are mainly used.Two kinds of thermal energy storage system are used in the application cases,one is electric boiler plus phase change thermal energy storage device,and the other is electric heater built into phase change thermal energy storage device,both have their own advantages and disadvantages.Compared with other thermal energy storage technologies,low-to-medium temperature phase change thermal energy storage technology has the advantages of moderate initial investment,low operating cost and less restrictive conditions,but there are still many problems to be solved.Developing phase change thermal energy storage materials with excellent comprehensive performances such as high thermal energy storage density,long cycle life,high thermal conductivity,low corrosion and low cost,and intensifying heat exchange by optimizing the internal structure design of heat exchanger and thermal energy storage device are the re-search direction of future phase change thermal energy storage.Realizing intelligent control and reducing sys-tem cost are the development direction of thermal energy storage heating system.