Natural ventilation performance of a double-skin façade with a solar chimney

Double-skin façade is getting more and more attention as it provides many possibilities for energy conservation and at the same time creates good indoor environment. In this paper, natural ventilation performance of a double-skin façade is highlighted. A prototype building is proposed, which is thought to be an eight-storey office building with an atrium space in the north side. The south façade of the building is a double-skin façade and a thermal storage space called solar chimney is considered above the double-skin space. Actually, the double-skin space is connected with the chimney channel. Reduced scale model experiments and computational fluid dynamics (CFD) analysis are carried out in this research to evaluate the natural ventilation performance of the prototype building.     

中庭模型火灾烟气填充实验研究

文章介绍采用弗诺德模型律，建立1／8中庭模型试验台，开展中庭火灾烟流填充过程模型实验。研究表明：烟气填充过程中明显可见烟气分层现象，存在过渡层，上层热烟气层与下层冷空气层没有明显的分界面；烟气层沉降速度快，应设置排烟系统。模型实验与原型实验结果吻合，说明采用缩小比例的相似模型研究中庭火灾初期轰燃前烟气流动规律是合理、可行的。     

防烟空气幕二维数学模型

通过分析高层建筑火灾时引起烟气流动的因素 ,建立了烟气流动的二维流场数学模型 ,运用流函数的叠加原理 ,在实验研究的基础上 ,推导了高层建筑火灾时防烟空气幕流量、吹风口宽度和吹风口的射流速度的计算模型     

中庭烟层界面预测的探讨

该文综述了高层建筑中庭烟气层的形成,中庭烟层界面预测的方法,以及基于烟层界面预测的烟气控制系统设计的一般步骤。     

耦合电梯门狭缝流动的高层竖井火灾烟气模拟

利用FDS 建立17 层高层办公楼数值模型,考虑狭缝的小开口流动,耦合了基于开口流动理论的HVAC 模型,研究高层建筑内烟气通过电梯竖井的蔓延过程,得到了高层建筑内烟囱效应诱导的火灾烟气蔓延规律。高层建筑内较低层发生的火灾会显著加热电梯竖井中的气体,形成烟囱效应,高层建筑内部会形成中性面。通过将HVAC 模型与基于标准流量系数的模型进行比较,可以发现这两种方法计算的质量流量相差约1.5 倍。这是由于采用的HVAC 模型并没有考虑狭缝处的开口流动损失。通过进一步修正,取开口损失系数K 值为3.56 能得到较好的模拟结果。     

中庭建筑防排烟设计问题探讨

本文阐述了各种类型的中庭建筑的防排烟系统设计,提出了要解决中庭的火灾蔓延和人员疏散,应采用有效的排烟系统。     

On the use of time constants for specifying the smoke filling process in atrium halls

The time constant proposed to specify the smoke filling time in an atrium hall for design purposes is further evaluated in this paper using the plume expression fitted by dimensional analysis. The zone model FIRST developed at the Building and Fire Research Laboratory, NIST, U.S.A. is used to simulate the smoke filling time. Predicted results of the zone modelling simulation supported the fact that the time required to fill 80% of the atrium space with smoke is related to its time constant. Full-scale experimental results on smoke filling processes in atria available in the literature are used to justify this parameter. Use of this quantity to specify the smoke filling time for an atrium space is recommended with a selected design fire.     

重庆市发展长江水源热泵的水源概况分析

为了解重庆段长江水作为热泵冷热源的概况,对重庆段长江水温的横断面变化和时间变化进行了实测分析,并对江水的水质和水位变化进行了分析,得到长江水温在整个横断面基本恒定,而江水的夏季月平均温度在22~25℃,冬季月平均温度在11~16℃,水温日变化幅度不超过0.5℃。是一种具有良好品质的稳定的冷热源。而长江水作为水源热泵的冷热源,主要解决的水质问题是泥沙和悬浮物,在三峡库区形成后水位变化可达到30 m,因此取水方式可考虑采用浮船取水方式。     

含吹拔空间的高层建筑火灾烟气流动数值模拟

研究设有吹拔空间的高层建筑烟气流动及火灾蔓延特征,分析其对防火分区和安全疏散的影响。采用性能化消防设计的方法对某设有74.65 m、55.95 m双吹拔空间的一类高层建筑建立火灾发展模型、设计火灾场景、用CFD火灾模拟软件进行数值模拟。结果表明该建筑利用吹拔空间自然排烟时各火灾场景均能满足各层人员疏散的性能指标,在吹拔空间四周环廊上设置挡烟垂壁影响烟气的顺畅排出,缩短了危险来临时间,增大了火灾的危害性。提出吹拔空间式建筑宜利用烟囱效应优先采用自然排烟方式,烟气控制宜疏堵结合,以疏导为主的设计理念。     

采光中庭隔热措施优化的试验研究

由于自然采光,温室效应和烟囱效应的生态属性在节能方面有较强优势,采光中庭已在公共建筑中得到广泛应用,但若设计不合理会大大增加建筑能耗。通过采光中庭的现场测试和模型试验研究,并根据夏热冬冷地区的气候特征,提出适合夏热冬冷地区采光中庭隔热措施优化选择的建议。     

中庭内火灾烟气流动规律的研究

本文分析了中庭建筑内的火灾烟气运动特点,同时开展了一系列全尺寸对比性试验,并对实验数据与理论模型进行了比较。结果表明。中庭内烟气层的发展基本上仍可用区域模型来计算。     

中庭建筑设计及其热舒适度控制

中庭具有温室效应和烟囱效应的特点 ,因此 ,中庭的垂直温度分布梯度大 ,设计不当 ,易使环境的热舒适度变差 ,并会增加能耗。在保留中庭的精髓———空间共享的同时 ,提出对中庭与周边空间的界面进行合理选择与分区 ,使之能够分别对各区域的热舒适度加以有效地控制和分割     

某办公大楼中庭的消防安全性能化分析

提出了中庭采用自然排烟所带来的消防问题。采用计算流体力学(CFD)方法对烟气在中庭中的传播进行了模拟分析。通过对模拟结果的分析，提出了有关加强中庭消防安全措施的建议。     

中庭建筑烟气控制措施分析

介绍了中庭烟气控制的特点、控制措施及设计方法,并就常见措施—自然排烟与机械排烟作了进一步的论述。     

Experimental studies on natural smoke filling in atrium due to a shop fire

How smoke spilling out of a shop fire would fill up an atrium has been studied experimentally in this paper. Full-scale burning tests were carried out in the PolyU/USTC Atrium constructed in Hefei, China. Since balcony spill plume expressions appeared in the literature might not be applicable for a shop fire with finite width, two plume models for smoke spilling out of a shop fire inside an atrium were proposed and assessed. An equation on studying the smoke layer interface height with a two-layer approach was derived.     

Atrium buildings: Calculating smoke flows in atria for smoke-control

This paper presents methods for predicting, to an accuracy sufficient for smoke-control design purposes, smoky gas flows leaving a compartment on fire and passing into an atrium. It discusses the height of any flames that might be present in the atrium, as well as the temperatures in those flames to which building (or other) materials might be exposed. It presents methods for calculating entrainment into the thermal plume (rising against the wall or out in the open). Much of this is also applicable to the exterior of buildings in the absence of wind.It further presents methods for calculating the time for smoke to fill an atrium to close above the fire, both with and without the presence of venting. It gives formulae for calculating the required capacity of either powered or natural extract for steady-state ‘throughflow’ smoke ventilation.It is concluded that, apart from exceptional circumstances, it is not usually feasible to design successful smoke-ventilation systems to keep the base of the atrium's buoyant layer more than 8 – 16 m above the fire-room opening. In practice, this means that ‘throughflows’ smoke ventilation will rarely allow escape routes to be open to the atrium above the fourth or fifth floor.     

中庭类建筑排烟补风研究现状及进展

综述国内外在中庭类建筑排烟补风方面的研究现状,包括中庭进行机械排烟时理论补风量的确定、补风速度对烟气沉降的影响、补风口位置对烟气沉降的影响、自然补风口面积对烟气层高度的影响及补风对排烟效率的影响等,总结中庭类建筑火灾时补风的理论研究成果及相关规定,指出不足之处,并对下一步研究方向提出建议。     

性能化设计方法在烟气控制安全评估中的应用

根据已建立的烟控模型结合某工程实例 ,按照建筑防火性能化设计的步骤和要求进行了一次性能化设计的二级评估。通过实践 ,验证了烟控模型在建筑防火性能化设计中可发挥的重要作用 ,并提出了中庭防火设计在规格式规范设计方案之外的又一方案     

Low cost passive cooling system for social housing in dry hot climate

The low energy approach should be the key concept in any long-term strategy aiming to build sustainability. For Madrid climate, action should be taken to reduce energy demand for heating and cooling in residential buildings.The performance of a passive cooling system was developed as a part of design work for the project of a low cost residential building. The passive cooling systems incorporate a solar chimney and precool the air by using the sanitary area of the building. The natural ventilation is enhanced with the help of the solar chimney and fresh air is cooled down by circulation within the sanitary area. The application of this system to the living rooms of a low cost residential building was evaluated and implemented. This cooling system incorporated to a residential building is the third prototype developed since 1991 by the designers. A model was developed to allow to predict the temperature of the air in the living room. The performance of the passive cooling system was evaluated based on the energy balance for a typical summer day.To reduce the energy demand in winter, a new design and window orientation has been developed and evaluated using DOE-2 simulation tool. The building has been constructed and monitored during 2006-2007.     

Physical and numerical modelling of a solar chimney-based ventilation system for buildings

This paper describes an experimental and numerical study to analyse the thermal performance of a bio-climatic building prototype in Nigeria. The roof performs as a solar chimney, generating an air flow through the living space of the building to provide cooling. Experimental tests on a 1:12 small-scale model of the prototype are outlined, and the results, bith qualitative and quatitative, are used to validate a two-dimensional flow simulation model, in which the steady state conservation equations of mass, momentum and thermal energy are solved using a finite volume formulation.

The experimental and numerical results, expressed in terms of temperature and velocity fields, for two different window geometries are critically evaluated and compared with good agreement.