新型地下跨季节复合储热系统热量损失机理研究

Study on the Heat Loss Mechanism of a New Composite Seasonal Underground Thermal Storage System

可再生能源受天气、地域、季节限制,具有间歇性和不稳定性等属性,从而导致供需不匹配。跨季节储热是解决上述问题的有效方法。然而,传统地下跨季节储热具有储热方式单一、热量损失大等缺点。该文将水箱储热(hot water energystorage,HWES)和地埋管储热(boreholethermal energy storage,BTES)方式相结合,建立跨季节复合储热系统,研究该复合储热系统的储释热温度和储释热量变化规律,揭示系统热量损失机理。结果表明:复合储热模式的储热量和释热量均大于水箱储热模式和地埋管储热模式,其储热量随着运行年限的增长而逐渐降低,释热量则随着运行年限的增长而逐渐增加;对比3种不同储热模式的土壤平均温度,得出地埋管储热模式最高,水箱储热模式最低,复合储热模式居于两者中间;此外,研究发现,复合储热模式的热量损失主要来自上边界,系统运行至第五年上边界的热量损失占比高达42.2%,因此需要对复合储热模式上边界进行有效保温,降低热量损失,提高复合储热系统效率。

Renewable energy is ch aracterized b y intermittency and instability due to weather, region and season, which leads to mismatch between supply and demand. Seasonal thermal storage is an effective method to solve the above problems. However, the traditional seasonal underground thermal storage has the disadvantages of single storage mode and serious heat loss. The underground hot water energy storage(HWES) mode and the borehole thermal energy storage(BTES) mode were combined to establish the composite seasonal thermal storage system. The change law of the storage temperature and heat storage/release of the composite thermal storage system was studied, and the heat loss mechanism of the system was revealed. Results showed that the heat store and release capacity of the composite thermal storage mode were better than that of the HWES mode and BTES mode, and the heat store capacity gradually decreases with the growth of the operation years, while the heat release gradually increases with the growth of the operation years. For the average soil temperature of the three different thermal storage modes, BTES mode was the highest, the HWES mode was the lowest, and the composite mode was in the middle of the two. In addition, the heat loss of the composite mode mainly came from the upper boundary, which accounted for 42.2% in the fifth year. Therefore, it is necessary to effectively insulate the upper boundary of the composite mode to reduce the heat loss and improve the efficiency of the composite thermal storage system.