关键词: 储能系统, 相变储热, 电加热, 动态储热过程

Abstract:

This study presents an electric-thermal phase change energy storage system using Na₂CO₃-K₂CO₃/MgO as the heat storage medium with a heating power of 100 kW, implemented through a modular integration concept. This research involves the development of composite thermal storage materials using physical methods. Characterization analysis techniques, including scanning electron microscopy and differential scanning calorimetry, are employed to examine the composition distribution and thermal storage properties of the composite materials. By analyzing the time-temperature test curve of the heat storage and release process, we introduce the heat storage or release progress function. Investigating the changing trend of the progress function curves in different positions of the system elucidates the dynamic-heat-storage/-release process. Our findings reveal that heat transfer of hot air accumulates from the center of the heat storage module to the top, gradually diffusing to the periphery during the heat storage process. During heat release, cold air absorbs heat successively from the center of the front module, the front module surface, the middle module surface, and the rear module surface along the wind path direction. Heat in the middle and rear thermal storage modules transfers from the center to the bottom, sides, and top surface areas, thereby diffusing to the surrounding areas. A comparative analysis of the progress functions of the heat storage system based on composite phase change material and magnesium iron oxide indicates that the system experiences faster heat storage and release processes when composite phase change material is employed as the heat storage medium. Setting the heating water temperature at 70—80 ℃, the stable heating time of the composite phase change heat storage system is determined to be 1100 min, representing a 37.5% increase compared to the magnesium iron oxide heat storage system. Therefore, this study helps promote the application of phase change thermal storage technology in heating systems and serves as a reference for studying the dynamic heat exchange process in electric heating phase change energy storage systems.

Key words: energy storage system, phase change storage, electric heating, dynamic thermal storage