【作者】 冀海燕；

【导师】 王恩宇；

【作者基本信息】 河北工业大学 ， 供热、供燃气、通风及空调工程， 2011， 硕士

【摘要】 土壤高温储热作为太阳能跨季节储热技术的一种高效、实用的方式,逐渐得到了广泛的关注。在高温储热过程中,通过研究土壤的热湿迁移现象对其储热性能的影响,不仅完善了土壤热湿迁移的理论还可以指导优化太阳能土壤储热系统的设计,也是太阳能跨季节储热技术能否广泛应用的关键。本文主要采用数值模拟与试验相结合的方法,对土壤的热湿迁移进行了研究。在实验室的二维轴对称高温储热试验台上,以非饱和含湿土壤为研究对象,对于不同的储热温度和不同初始含水率的土壤,进行了59℃、79℃高温储热和8℃取热试验研究。重点分析了排热温度和初始含水率对土壤储热速率和取热速率的影响。试验结果表明,排热温度和土壤初始含水率对土壤储热有较大影响。排热温度对储热速率的影响还与土壤初始含水率有关。初始含水率低的土壤,高储热温度会使储热速率增大,而当土壤初始含水率达到一定数值时排热温度的高低对于土壤的储热影响很小。取热速率却总是受排热温度的影响明显。在相同排热温度,高初始含水率的土壤有利于传递热量,表现出更高的储热速率和取热速率。本文还以质量和能量守恒为基础,建立了二维非稳态的热湿迁移模型,并与实验数据比较验证模型,同时开展了部分数值模拟。模拟结果表明:与纯导热相比,考虑土壤的热湿迁移过程,使土壤整体温度降低,更加接近实验值;验证了在不同初始含水率和不同排热温度对土壤储热的影响的规律;相对于低温储热,土壤的热湿迁移过程对土壤高温储热影响较大。更多还原

【Abstract】 Thermal energy storage in soil is an efficient and practical way for solar seasonal thermal storage, and has got the attention widely. Through the study of the phenomenon that coupled heat and moisture transfer on the thermal performance of soil under high temperature ground storage, not only perfected heat and moisture migration theory in the soil also guide the optimization of the design of solar seasonal thermal storage system. It is also a key that favor solar seasonal thermal storage system be widely applied. Theoretical and experimental methods were used to research the heat and moisture transfer in the soil.The experiments of charging heat (79℃or 59℃) and discharging heat (8℃) in unsaturated soil storage with different initial water content were done in a two-dimensional experimental setup. The effects of charging temperature and initial moisture content on the heat and moisture behaviors in unsaturated soil were analyzed. The temperature and moisture variation and the heat rejection or extraction abilities in various cases of heat source temperature and/or initial volumetric moisture content were analyzed.The results show that the charging and discharging behaviors in watery soil are drastically affected by temperature and initial moisture content. For soil with lower initial moisture content, the ability of thermal storage in the soil increases with the rejection temperature. On the other hand, the rejection temperature has nearly no influence on the soil storage ability when the initial moisture content is large enough. However, the rejection temperature always has influence on the heat extraction ability. Under the same rejection temperature, higher initial moisture content of the soil can result in higher heat rejection and extraction ability.A two-dimensional unsteady heat and moisture transfer numerical was built, which based on the mass and energy conservation. The numerical model was validated by comparing the results with experimental data, while some of the numerical simulations were carried out. Simulated results show that compared with the case of the thermal conductivity only, the heat and moisture transfer during high-temperature thermal storage has reduced the soil temperature, and the simulated results closer to the experimental value. And the results also prove the conclusion for the charging behaviors in watery soil are drastically affected by temperature and initial moisture content. Compared with the low-temperature thermal storage, the heat and moisture transfer has greater influence for the high-temperature thermal storage.更多还原