Design of emergency ventilation system for an underground storage facility

Fires have always been a major problem for underground spaces. As the demand for development of new underground structures increases, safety against fire incidents becomes even more important. This paper examines the design of an emergency ventilation system, which will provide the necessary control of smoke and heated gases within an underground warehouse facility, in case a fire occurs. Due to the pattern of the underground area and the variety of products stored, numerous fire scenarios should be examined in order to secure escape routes in every case, which significantly complicates the problem. For this reason, a different approach has been adopted, matching recent developments in fire safety from tunneling projects and ventilation practices from the mining industry. The ventilation design is based on the “critical velocity” theory; however, alternative configurations of the underground space are simulated by means of mine ventilation software. These alternatives affect the direction and velocity of the airflow and, consequently, the air quantity and the fan power required, in order to secure escape routes during fire emergency. The analysis not only determines the ventilation system characteristics, but also indicates the most appropriate design of the facility, in order to come up with a solution that is both secure and economically acceptable.     

关于高层建筑地下车库通风与防排烟设计的看法

本文简要介绍了地下车库设置排风系统的必要性、防火分区和防烟分区的划分原则,对防排烟系统的排风量和排烟量计算、对排风系统与排烟系统合用的可行性及应注意的问题进行了详细的论述,并通过工程实例分析,阐述了高层建筑地下车库平时通风与火灾时排烟合用系统的设计要点。     

Window and roof configurations for comfort ventilation

This paper assesses the applicability of some architectural design elements to provide comfort ventilation in humid tropical regions: size and location of windows, building eaves and roof shapes for a single unit house. Most window and roof configurations are sufficent to produce only a slightly more comfortable level although they can certainly increase the indoor air velocity. The improvement of indoor air velocity can minimize the physiological effect of the high humidity. Among the tested models, the room with a high gable roof combining with eaves improves significantly the indoor air velocity. Cet expose evalue l'applicabilite de certains elements de configuration visant a assurer une ventilation de confort daus les regions tropicales humides: dimensions et emplacement des fenetres, formes d'avant-toit et de toiture pour une maison individuelle. La plupart des configurations de fenetre et de toiture suffisent seulement a fournir un minime supplement de confort, bien qu'elles puissent effectivement ameliorer la circulation interieure de l'air. Une amelioration de circulation interieure de l'air peut attenuer les effets physiologiques d'une forte humidite. Parmi les modeles essayes, le local comportant une toiture a pignon eleve associee a des avant-toits offre une nette amelioration de circulation interieure de l'air.     

CFD analysis of ventilation effectiveness in a public transport interchange

A study was conducted into the ventilation effectiveness of a ventilation system within a public transport interchange (PTI) in Hong Kong. A computational fluid dynamics (CFD), steady state computational model of the PTI was used to investigate and predict the typical pollutant emission pattern for buses. In Hong Kong, the displacement ventilation (DV) scheme is often employed for the PTI. The numerical simulation investigates the effectiveness of the DV system in removing pollutants from the occupied zone. An alternative model is proposed where the supply is located at the ceiling and the exhausts are located at the lower part of the columns. It was found that both systems could adequately ventilate the PTI; however, the ceiling based air supply system is able to provide improved thermal comfort and indoor air quality (IAQ).     

地下建筑火灾危险性和消防设施设置要点分析

地下建筑的自身特点及使用的复杂性,决定其具有较大的火灾危险性,一旦发生火灾,其造成的损失远远高于地面建筑。为解决地下建筑提高火灾防御能力问题提供参考,本文从分析地下建筑的特点和火灾危险性入手,根据地下建筑火灾扑救的主要方法和依靠的消防设施,提出地下建筑设置消防设施应注意的八个要点,起到优化消防设施设置,有效提升建筑防火能力的作用。     

Model-based analysis and simulation of airflow control systems of ventilation units in building environments

Model-based analysis and simulation of the airflow control system of ventilation units is of primary importance for the design and maintenance of the entire HVAC system in building environments. In this paper, we develop a mathematical model to simulate such airflow control systems. The model is implemented and a systematic analysis of the system is carried out, including its dynamic simulations in SIMULINK. The simulation results are compared with data obtained from analytical predictions as well as with experimental results available for a lab-scale ventilation unit. Finally, based on the combination of temperature and airflow regulations with conventional PI controllers, we provide the results of simulations of the entire ventilation unit control system for two different types of loading conditions.     

基于数值模拟的北京地区地下道路立交隧道围岩变形分析

城市地下道路立交隧道施工过程中围岩变形分析是工程建设中的核心问题。依托北京城市地下道路工程,采用城区地质条件分层概化方法、三维数值模拟方法分析了临时仰拱台阶法（台阶法）、中隔壁法（CD法）、交叉中隔壁法（CRD法）和双侧壁导坑法（双侧壁法）施工影响下的立交隧道地表沉降、洞周变形和塑性区分布特征,明确了立交区域上下层隧道施工的影响规律。研究发现,立交区域同时受到了上下层隧道施工的影响,在地表形成椭球形的沉降盆,在洞周出现了较大的差异沉降|在地表地层和洞周拱脚、拱肩截面的“X”形区域出现了较为集中的破坏区|CRD法和双侧壁法在控制立交隧道地层变形和破坏方面具有明显优势。研究成果可为北京城市地下道路立交隧道设计、施工决策制定提供参考。     

A CFD-based test method for control of indoor environment and space ventilation

System dynamic simulation has been adopted to test and evaluate the local and supervisory control of air-conditioning systems for over twenty years, while the modeling of the space ventilation was usually simulated using perfect mixing models. However, the complete-mixing air model fails to consider the impact of non-uniform air temperature stratifications. This paper presents a CFD-based virtual test method for control and optimization of indoor environment by combining a ventilated room with a ventilation control system. The ventilated room and its dynamic ventilation control system are represented by a computational fluid dynamics (CFD) model and models of the temperature sensor, PID controller and actuator and VAV damper model respectively. The ventilation and its control system are programmed using the user defined function program and interfaced with the CFD model. A space temperature offset model is developed to improve the accuracy of temperature measurement and control at the occupied zone as a virtual sensor. Case studies show that the ventilation control models can interoperate with the CFD simulation of the space online which presents a new application approach of CFD simulation for testing and developing control and optimal control strategy before a system is constructed practically. The use of the virtual sensor can effectively compensate the effect of non-uniform stratification on the temperature control and improve system control reliability in a mechanical ventilated room.     

A study of an optimal smoke control strategy for an Urban Traffic Link Tunnel fire

An Urban Traffic Link Tunnel (UTLT) is a novel type of underground transportation system consisting of a main tunnel in a loop shape and several linked tunnels. It has a higher level of fire risk compared to other common road tunnels. In this study, numerical study was conducted to investigate the smoke control strategies for a designed fire scenario in the Beijing Center Business District (CBD) UTLT. An optimal smoke control strategy was developed and evaluated using three criteria: critical velocity, minimal smoke spreading area and available safe evacuation time. In developing the optimal smoke control strategy, six different smoke control strategies for the UTLT were evaluated initially by the criterion of critical velocity, and one of those control strategies was chosen as the primary strategy by steady simulation. This strategy was then modified according to the dynamic simulated results of smoke movements to satisfy the other two criteria. Consequently, the optimal smoke control strategy for the UTLT based on the primary strategy was obtained. The transient distributions of the smoke spread, smoke temperature and CO₂ concentration, were analyzed.     

Evaluating emergency ventilation strategies under different contaminant source locations and evacuation modes by efficiency factor of contaminant source (EFCS)

Emergency ventilation plays an important role in protecting occupants when a hazardous contaminant is released indoors. A number of studies have been conducted to better understand how to protect indoor occupants with effective ventilation strategies. However, little attention has been paid to the impact of the non-uniform and time-dependent distribution of occupants during evacuation. A new concept, Efficiency Factor of Contaminant Source (EFCS), has recently been proposed to evaluate the performance of emergency ventilation by comprehensively considering the spatial and temporal distributions of both the contaminant and occupants. This paper aims to: (1) propose and demonstrate a procedure for determining an optimal ventilation strategy by using EFCS; (2) examine the effects of source locations, ventilation modes, and evacuation modes on the performance of emergency ventilation. One hundred cases with ten ventilation modes, two evacuation modes, and five source locations were investigated numerically. The results show that the EFCS concept can provide a reasonable way to evaluate the performance of emergency ventilation. The threats of different source locations may vary over a large range, and certain measures should be taken to monitor and prevent the releases at high threat locations. A system equipped with multiple ventilation modes is necessary since no universal ventilation mode can successfully mitigate all hazardous situations. The effects of an evacuation mode may be more significant than that of a ventilation mode under certain situations.     

通风降温建筑室内热环境模拟及热舒适研究

将热舒适评价标准ＰＭＶ／ＰＰＤ模型与建筑动态热模拟及计算流体动力学（ＣＦＤ）模拟相结合，分别对重庆地区自然通风房间和埋管送风通风房间进行了室内气候及热舒适性模拟与分析，结果表明，埋管系统通风降温可以改善炎热地区的室内热舒适性。     

CFD simulation and optimization of the ventilation for subway side-platform

To obtain the velocity and temperature field of subway station and the optimized ventilation mode of subway side-platform station, this paper takes the evaluation and optimization of the ventilation for subway side-platform station as main line, builds three dimensional models of original and optimization design of the existed and rebuilt station. And using the two-equation turbulence model as its physics model, the thesis makes computational fluid dynamics (CFD) simulation to subway side-platform station with the boundary conditions collected for simulation computation through field measurement. It is found that the two-equation turbulence model can be used to predict velocity field and temperature field at the station under some reasonable presumptions in the investigation and study. At last, an optimization ventilation mode of subway side-platform station was put forward.     

基于CFD及《绿色校园评价标准》优化景观要素格局——以“2013全国大学生绿色校园概念设计大赛”一等奖作品为例

随着对教学环境重要性认识的不断增强,校园室外环境的优化与建设改造问题已引起教育工作者和建筑设计人员的广泛关注.基于《绿色校园评价标准》并利用CFD动态模拟技术对实有校园——沈阳建筑大学进行考察,通过对其景观要素格局的优化设计,强调从各种景观要素的生态效应角度出发,推进校园绿色生态化发展的必要性和建设发展绿色校园的重要意义.     

Analysis and improvement of the representativeness of EN ISO 15927-4 reference years for building energy simulation

Representativeness of weather inputs is crucial to limit the global uncertainty of building energy simulation results. The length of the multi-year weather data series and the methodology used for the typical month selection largely influence the results of the reference year development process. In this work, we investigate two possible modifications to the EN ISO 15927-4:2005 procedure aimed at improving the representativeness of reference year heating and cooling needs. The first modification maintains the reference years independent of their final use while the second one leads to the development of specific weather files for heating or cooling analyses by introducing weighting coefficients for the different weather parameters. The study is performed for five North Italy localities with 10 or less years in the data-set and for a sample of 48 simplified buildings. Both proposed modifications brought improvements to the representativeness of the reference year results.     

Pedestrian wind comfort around a large football stadium in an urban environment: CFD simulation, validation and application of the new Dutch wind nuisance standard

Three-dimensional steady Reynolds-averaged Navier–Stokes (RANS) Computational Fluid Dynamics (CFD) simulations are used in combination with the new Dutch wind nuisance standard to assess pedestrian wind comfort around a large football stadium in Amsterdam, before and after the addition of new high-rise buildings. The focus of the study is on the elevated circulation deck and the surrounding streets and squares. CFD validation is performed by comparison of the simulated mean wind speed at the deck with full-scale measurements. The important effect of local ground roughness specification on the simulated wind speed values is indicated. Application of the Dutch wind nuisance standard shows that wind comfort at the elevated circulation deck is only slightly influenced by the new buildings. Wind comfort at the surrounding streets and squares however significantly deteriorates. Finally, the results obtained by the Dutch wind nuisance standard are compared to those obtained by a more simplified procedure for the transformation of wind statistics to the building site, as used in earlier studies. The more sophisticated transformation procedure in the Dutch standard was successfully validated based on full-scale measurements in earlier research. Comparison of the Dutch standard results in this study with those of the simplified procedure shows that the latter provides overestimations by up to 25% for the highest discomfort probabilities. This type of large discrepancies can significantly change the outcome of wind comfort studies.     

TACO,an automated toolchain for model predictive control of building systems: implementation and verification

This paper presents TACO (Toolchain for Automated Control and Optimization), which is a Modelica-based automated toolchain for model predictive control (MPC) of building systems. Its goal is to significantly reduce the engineering expertise and the time investment required for applying MPC to buildings. TACO is based on JModelica. Modifications compared to JModelica are discussed and the implementation of our custom MPC problem formulation is presented. The implementation is verified using two example models and is benchmarked with respect to accuracy and computation time. These results show that the computation time can be reduced significantly using the toolchain options, while only slightly reducing the controller optimality.     

热水及电采暖系统动态响应的分析和比较

针对标准房间建立热水和电采暖系统动态模型,模拟和分析这两种系统动态响应。对热水采暖系统采用三通阀调节散热器循环水量,对电采暖系统采用启停控制模式来调节,并分别进行动态仿真和比较。总结出这两种采暖系统各自特性。     

浅埋偏压隧道洞口段初期支护变形分析与控制

以某在建山岭隧道为工程背景,分析了洞口段初期支护产生过大变形的原因,采用有限元软件对其开挖施工过程进行了仿真分析,结合现场监测结果,得到了浅埋偏压隧道洞口段初期支护的受力及变形状况,并提出了变形控制措施。分析结果表明:洞口偏压段初期支护呈现明显的不对称弯曲变形;最大拉应力出现在深埋侧拱腰内边缘,最大压应力出现在深埋侧的拱脚外边缘和浅埋侧的拱腰内边缘;通过有序减压卸载、增设临时斜撑、洞内注浆、及时成环等措施可有效控制变形发展。研究结果可为类似地质地形条件下隧道洞口段初期支护的设计与施工提供参考。