【作者】 周军莉；

【导师】 张国强；

【作者基本信息】 湖南大学 ， 供热、供燃气、通风及空调工程， 2009， 博士

【摘要】 随着可持续发展战略的提出,建筑自然通风技术逐渐受到人们的重视。合理利用自然通风可改善建筑热环境、减少空调能耗。自然通风应用效果与建筑蓄热密切相关,不同的建筑蓄热能力将导致不同的室内温度。本文力求探讨建筑蓄热与自然通风的耦合关系,揭示建筑蓄热对自然通风室内温度波动的影响规律,其研究成果将为建筑材料的选取、自然通风系统的设计与控制策略的确定打下理论基础。建筑蓄热体可分为建筑外蓄热体和内蓄热体。外蓄热体即为建筑外围护结构,建筑外围护结构是室内环境与室外环境的联系纽带,人们对建筑外围护结构的研究着重在其对空调环境下负荷的影响,而自然通风环境下的围护结构作用则鲜有研究;建筑内蓄热体包括建筑内墙、内部家具等物体,一般情况下,可以认为内部蓄热体温度与室内空气相等,但当内部蓄热体不满足集总参数法时,则不能这样简化计算;此外,自然通风主要驱动力为热压和风压,当风压驱动时,我们可认为自然通风量为已知值,而当热压驱动时,室内温度、自然通风量呈非线性耦合关系,室内温度计算更为复杂。针对上述问题,本文主要开展了以下工作:(1)提出了自然通风建筑热压等效流量概念及计算方法。无论是热压驱动还是定风压驱动的自然通风,建筑室内温度均呈周期性变化,本文分析得到了等效流量计算公式。通过数值计算验证,利用该值可在一定误差范围内将热压驱动自然通风视作定流量自然通风处理,即可将自然通风量、室内温度非线性耦合问题线性处理,从而简化问题,缩短计算时间。(2)系统分析探讨了内外蓄热体导热系数、体积热容、面积等参数对自然通风房间室内温度的影响。将内外蓄热体视作有限板层,联合一维非稳态热传递方程与自然通风房间热平衡方程,通过数值计算方法对内外蓄热体以及流量、热源等对自然通风建筑室内温度的影响进行了计算分析。该分析结果有助于指导自然通风建筑设计。(3)提出了综合考虑建筑内外蓄热能力与自然通风的室内温度计算方法。引入谐波反应法,得到外墙内壁温度分布,并结合室内热平衡方程,计算得到了室内温度平均温度、衰减系数及延迟时间与内外蓄热体的关系式,其中描述内外蓄热体的参数分别为无量纲换热数λ和时间常数τ。利用该方法可较为简便地对内外蓄热体作用进行分析,计算自然通风房间室内温度、设计室内蓄热体。该方法还可扩展计算间歇供冷/制热房间响应时间,以及在考虑建筑蓄热情况时比较不同城市自然通风潜力。(4)提出了应用虚拟球法计算分析室内蓄热体作用的方法。对自然通风建筑室内温度计算模型进行改进,引入虚拟球法来计算内部蓄热体蓄热作用,联合外墙内壁温度分布及室内热平衡方程,最终得到了以虚拟球法模拟室内蓄热作用的自然通风建筑室内温度计算方法。该方法在综合考虑室内多种外形、多种材质、以及内部温度非均匀分布蓄热体的蓄热作用时相比其他方法更为准确。(5)提出了综合考虑建筑内外蓄热能力的夜间通风室内温度计算方法。在前述自然通风室内温度计算模型基础上,将夜间通风视为阶段性通风,提出了室内温度计算方法,并通过了实验验证。利用该方法系统分析了夜间通风时间、室内热源、夜间通风换气次数、外围护结构、室内蓄热质、昼夜温差对夜间通风效果的影响,并计算提出了夏季典型建筑应用夜间通风的得热极限及夜间通风最佳换气次数。该分析结果有助于指导夜间通风设计和应用。更多还原

【Abstract】 With the direction of sustainable development, nowadays people in increasing numbers begin to notice the importance of natural ventilation. Applying the technology of natural ventilation can improve indoor thermal comfort, and reduce air-conditioning consumption. The role of natural ventilation is related close with thermal mass. The main focus of this paper is to study theoretically and numerically the coupling between ventilation and thermal mass in naturally ventilated building. The content is help to choosing building’s material and designing or controlling natural ventilation.Thermal mass can be classified as external thermal mass and internal thermal mass. The external envelopes such as external walls and roofs belong to this category. They connect the outdoor environment and the indoor environment. Most of previous researchers focused on the impact of building envelopes on the heating/cooling loads of buildings assuming the indoor air temperature is constant, but few focused on the impact of it on natural ventilated building. Furniture, and internal wall are internal thermal mass. Usually, the temperature distribution of the internal thermal mass is assumed to be uniform and equal to the indoor air temperature, but the problem would be complicated if the elements are not meet the condition of lumped method. Moreover, natural ventilation can be induced by wind or stack force. When the buildings are ventilated by wind, the ventilation flow rate can be treated as given value. But when the buildings are ventilated by stack force, the ventilation flow rate has nonlinear relation with indoor air temperature. In view of these problems, following work are carried out in the paper.(1) Stack equivalent flow rate and its calculating method are presented. Temperature variation of indoor air in natural ventilated building is periodic whatever the power induced is constant wind pressure or stack effect pressure, so the problem of natural ventilation with stack effect pressure may be treated as ventilation with constant wind pressure. Indoor air temperature of natural ventilated building with stack effect can be calculated out easily by using stack equivalent flow rate.(2) By using numerical simulation method, the effects of external and internal thermal mass on decrement factor and time lag of indoor air temperature are analyzed, including thermal conductivity, volume heat capacity, area and depth etc. In the model, the heat transfer of all thermal mass are treated as one dimension unsteady heat transfer problem. The conclusions are help for natural ventilation’s design.(3) On the base of harmonic response method and the temperature shift of interior side of external thermal mass, the indoor air temperature of natural ventilated building coupling with thermal mass is calculated. Heat transfer number and time constant represent the effect of external and internal thermal mass individually. By using the model, the effects of external and internal thermal mass on indoor air temperature are analyzed. Moreover, the response time of building with intermittent cooling/heating, and natural ventilation potential of different city can be calculated and analyzed by the model.(4) On the basis of previous model, virtual sphere is introduced in analyzing and calculating the effect of internal thermal mass in natural ventilated building. The method can receive more accurate results in considering the effect of internal thermal mass with various shapes, various materials, and uneven temperature.(5) Night ventilation is analyzed by the model as phase ventilation and the calculation method about indoor air temperature is presented. This method is validated by night ventilation experiment. The effect of ventilation time, internal heat gains, flow rate of night ventilation, thermal mass, and diurnal temperature range on efficiency of night ventilation are analyzed. The limit for heat gains in building with night ventilation and the optimal flow rate are pointed out. The conclusions are help for night ventilation’s design and application.更多还原