【作者】 李萍；

【导师】 阳东；

【作者基本信息】 重庆大学 ， 供热、供燃气、通风及空调工程， 2016， 硕士

【摘要】 在现代社会中,建筑的大型化使竖向结构较为常见,例如,中庭、楼梯以及烟囱等,这些结构会驱动空气流动以及烟气蔓延。竖向结构通过热压的积累可以提高建筑自身的通风能力,进而改善建筑室内空气质量,同时竖向结构的内部热压也提高了建筑火灾时的排烟能力。所以,竖向结构用于多层建筑通风与火灾排烟凭借其节能、经济、系统简单并具有一定兼容性的优点引起国内外学者的重视。目前国内外学者对竖向结构用于建筑通风做了大量研究,但大多是关于利用竖井纯热压通风模式或者是仅针对单层建筑的竖井热压通风模式。而在竖向结构用于多层建筑通风方面的研究较少,尤其是在多层建筑中,当竖井高度有限时,若所有楼层纯粹利用热压通风,上部楼层可能会出现被下部楼层污风回灌的现象,针对此现象的理论分析方法还不完善。除此之外,当高大建筑中发生火灾时,室内外温差较大,竖向结构内部可以形成烟囱效应。所以若将竖向结构用于建筑通风模式兼顾火灾排烟模式可以实现风机与竖井积累热压构成的复合动力排烟,提高建筑自身的排烟能力并减小风机所需静压力,而且不需要额外的动力设备,可以利用通风风机替代排烟风机。所以复合动力排烟相比于传统机械排烟模式更经济、简单、易操作。因此,本文基于能量守恒、质量守恒基本原理,对竖向结构用于多层建筑复合通风以及火灾排烟无量纲模型进行了深入研究。首先对多层建筑利用竖向结构复合通风无量纲模型进行理论分析,提出无量纲参数—需求通风性能指标 λ₀,然后基于通风基本理论,得到各层房间的开口大小、中性层高度、自然通风层数三个重要设计参数。同理,提出竖向结构用于多层建筑复合排烟无量纲模型的排烟性能指标 λ₀,并分析得到复合动力排烟模式下的理论设计参数。其次,基于需求通风性能指标 λ₀,分析得出本文所提复合通风模式、其他两种低能耗通风模式（置换通风和利用竖井纯热压通风）以及机械通风模式的适用范围,为目标建筑选择合理的通风模式提供了依据。在火灾工况下,同样基于建筑排烟性能指标 λ₀,提出室内高差形成的热压排烟、利用竖井纯热压排烟、复合动力排烟以及纯机械排烟模式的适用范围。分析得到的各通风模式与排烟模式适用范围,为多层建筑综合选定最优的建筑通风与排烟模式奠定了理论基础。最后,通过对全机械通风与复合通风的能耗比（COP）分析,将本文提出的通风方案的能耗节省率进行量化,从而找到建筑结构参数最优化设计方法。在火灾工况下,对竖向结构用于多层建筑复合动力排烟模式与传统机械排烟模式的所需风机功率进行了对比分析,发现复合动力排烟模式提高了建筑自身排烟能力,减小了风机所需静压力,从而可能节省排烟风机的初投资。本文中采用CFD软件,以及三种不同的湍流模型,模拟验证目标建筑计算域内的流场分布,并将竖井中垂线温度分布、房间出风口质量流量、竖井中垂线压力分布的模拟监测结果与理论模型分析值进行对比,得出本文所提复合通风模式具有较高的准确性与可靠性。最后在相似理论分析基础上,利用小尺寸的盐水实验验证本文所提出的复合通风与排烟工况下的流场分布,从而进一步验证理论分析的正确性以及本文所提模型的合理性。更多还原

【Abstract】 In modern society, large-scale building makes the vertical structure be relatively common, for example, the atrium, stair, chimney and so on, and these structures drive the flow of air and smoke. Vertical structure through the accumulation of heat can improve ventilation capacity of the building and thus improve the indoor air quality, while the vertical structure of the internal heat also increases the smoke exhaust capacity of the building. Therefore, the vertical structures used for ventilation and smoke exhaust in the multi-story buildings with its advantages of energy saving, economy, simple and the certain compatibility, aroused the attention of scholars both at home and abroad.At present, domestic and foreign scholars to vertical structures used for ventilation in buildings have done a lot of researches, but most of them were about the use of stack based pure thermal pressure ventilation mode or only for single-story passive ventilation mode. However the studies of stack based ventilation for multi-story buildings were less, especially in multi-story buildings, when the shaft height is limited, if all floors use pure thermal pressure ventilation, the upper floors may be contaminated by the lower floors, but theoretical analysis method for this phenomenon is not perfect. In addition, when there is a fire in the tall building, large temperature difference between indoor and outdoor, the inside of the vertical structure can form the chimney effect. So the combination of stack based ventilation for multi-story buildings mode and the fire smoke exhaust mode can achieve composite power smoke exhaust mode, which improves the smoke exhaust capacity of the building and reduce the static pressure of the fan. Meanwhile the composite power smoke exhaust mode does not require additional power equipment, and can use exhaust fan to replace ventilation fan. So the composite power exhaust mode compared to the traditional mechanical smoke exhaust mode is more economical, simple and easy to operate. Therefore, based on the principle of conservation of energy and mass, this paper had a further study for the dimensionless models for stack-based hybrid ventilation and smoke exhaust in multi-story buildings.Firstly, this paper had carried on the dimensionless analysis for stack based hybrid ventilation and fire smoke exhaust system, and put forward the dimensionless parameter- ventilation performance indicator λ₀. Then based on the analysis of the basic theory of ventilation, got the three important design parameters-opening size of each room, neutral layer height, and the number of natural ventilation floor. As same to the ventilation theory, put forward the dimensionless parameter-exhaust performance indicator λ₀, and through the analysis of composite power smoke exhaust mode got the theoretical parameters. Secondly, based on the required ventilation performance indicator λ₀, analyzed the applicable scope of the proposed hybrid ventilation mode, other two kinds of low energy ventilation modes（displacement ventilation and stack based pure thermal pressure ventilation） and the mechanical ventilation mode, which provided a basis choose for the reasonable ventilation mode in target building. Similarly, in fire condition, based on the exhaust performance indicator λ₀, put forward the applicable scope of the smoke exhaust mode based on the indoor elevation difference, the pure thermal pressure formed by shaft smoke exhaust mode, hybrid power exhaust mode, and the purely mechanical smoke exhaust mode. The analysis of the scope for ventilation mode and smoke exhaust mode laid a foundation for the building to selected optimal ventilation and smoke exhaust mode. Finally, through the analysis of energy consumption ratio（COP） between the mechanical ventilation and hybrid ventilation mode, this article quantified the energy saving rate of the proposed ventilation scheme to find the optimization design method to the building structural parameters. And in fire condition, made the comparison between hybrid power exhaust mode and the traditional mechanical exhaust mode to the fan power needed and found that the hybrid power exhaust mode could improve smoke exhaust ability of the building and reduce the static pressure required for fan, which could save the initial investment of exhaust fan.This paper using the CFD software and three different turbulence models, verified flow field distribution of the computational domain in the target building, and made comparison between simulation and theoretical model analysis results for temperature distribution of shaft mid perpendicular, room outlet mass flow, and pressure distribution of shaft mid perpendicular. Then it proved that the proposed hybrid ventilation mode has higher accuracy and reliability.Finally, on the basis of the similarity theory, using the small size of the brine experiment, verified the flow field distribution of the proposed hybrid ventilation and the smoke exhaust scheme, thereby further verified the correctness of theoretical analysis and the rationality of the model proposed in this paper.更多还原