【作者】 李志永；

【导师】 陈超；

【作者基本信息】 北京工业大学 ， 土木工程， 2011， 博士

【摘要】 北京地区地属寒冷地区,冬季供暖期长,供暖能耗占冬季建筑能耗的主要部分。但北京地区有着丰富的太阳能资源,属太阳能资源较富带。如果能充分利用太阳能作为冬季建筑供暖补充能源,则即可以减少化石能源的消耗,又可提高太阳能在建筑供暖能源中的利用率。然而太阳能固有的不稳定性和间歇性,给太阳能的热利用带来了较大的难度。本研究基于课题组多年关于相变蓄热技术的研究成果,充分利用相变蓄热材料相变潜热量大、可以在温度近似恒定的条件下蓄集大量热量的特点,提出将太阳能集热技术与相变蓄热技术结合,构筑太阳能—相变蓄热—新风供暖系统。利用太阳能为冬季新风供暖系统提供补充能源的学术思想,在太阳辐射强度大的情况下,可将多余的太阳热能蓄存在相变蓄热装置内,待夜晚或太阳辐射强度不足时,将预先蓄存在相变蓄热装置的太阳热能向新风供暖系统补充热能,实现了太阳能时间及地点的转移,提高了太阳能在建筑供能中的利用率。基于上述学术思想,本研究依据传热学、流体力学、相变贮能等理论,重点在以下几方面开展了研究工作:(1)建立了应用于闭式循环系统的全玻璃真空管集热器的传热数学模型。基于全玻璃真空管集热器在闭式循环系统中的应用条件,将其传热过程简化为在联集管内的强制流动与在一系列真空管内自然对流过程的耦合。并通过分析集热器的整体的能量转化过程与单根真空管的自然对流过程,推导出了集热器的数学模型。根据此模型,可以分析在室外太阳辐射强度、供水温度、集热器几何尺寸等参数变化条件下,集热器组件出水温度的变化规律。(2)在课题组前期的研究基础上,对已有的相变蓄热装置传热模型进行了完善。并构建了太阳能集热系统与相变蓄热系统的耦合传热模型。利用该模型,可以为太阳能时间和地点的转移,提供定量分析和指导。(3)基于上述研究结果,建立了太阳能—相变蓄热—新风供暖系统的仿真模型。依据该仿真模型,根据北京地区冬季太阳辐射变化规律,对集热系统流量、以及相变材料质量与集热器面积比等参数进行优化设计,并制定了在确保房间供给新风温度相对稳定条件下的系统运行控制策略及其控制条件。更多还原

【Abstract】 Because of located in cold area and a long winter heating period in Beijing, building heating energy consumption accounts for a major part of building energy consumption in the Beijing area.Considering there is a lot of solar energy in Beijing, if make full use of solar energy as a supplement building heating in winter, it can not only reduce fossil energy consumption, but also raise solar energy utilization rate in the building heating. But because of inherent instability and intermittent of solar energy, it is difficult to directly take solar energy to the heating end with steady demand. Based on the previous research on phase change thermal storage technology,taking advantage of the PCM’s characteristic with large latent heat and nearly keep constant melt temperature in charge and discharge period, the solar energy - phase change thermal storage - fresh air heating system is proposed. In this system, when solar radiation intensity is high at noon, it can store excess solar energy to the phase change thermal storage. And when solar radiation intensity is low at night or in the morning, the heat energy stored in PCM is used to heat fresh air. So it is achived the transfer of solar energy in time and place by this system. Considering the above academic thought, based on theory of heat transfer, fluid dynamics and phase change energy storage, some researches are carried out in the following:(1) The heat transfer model for all - glass vacuum tube collector to be used in a forced - circulation solar water heating system is established. In this model, the simplified heat transfer of the collector consists of natural convection within a single glass tube and a forced flow in a manifold header. From this, the heat balance equation of collector and the heat balance and flow equation of the single tube can be established. When known the solar radiation intensity, outdoor air temperature, as well as the inlet temperature of heat transfer fluid, outlet temperature of collector can be calculated according to the model.(2) Based on previous research, the improved phase change storage heat transfer model was published. By coupled solar collector and phase change thermal storage model, the heat transfer problem between solar collectors and phase change thermal storage is studied.(3) Based on the above research, the heat transfer model on solar energy - phase change - fresh air heating system is built. According to the system model and solar radiation in winter in Beijing, the optical collector system flowrate, the optical ratio between phase change material quality and collector area are analyzed. And operating strategy and operating conditions research to ensure the supply fresh air temperature stable is researched too.更多还原