集热板在大空间场所作用效果的讨论

通过实体火灾实验,对自动喷水灭火系统中的集热挡水板在大空间场所的作用机理及效果进行研究.针对不同尺寸集热挡水板安装在不同高度及不同火源情况下进行了实验,并按照正常情况安装喷头进行了对比实验.     

基于FDS的自动喷水灭火系统集热板不同设置有效性研究

通过对格栅型吊顶空间设置集热板情况下自动喷水灭火系统喷头动作的FDS模拟分析,得出不同集热板形式和设置在不同封闭率吊顶情况下的有效性,对集热板的合理使用提出建议。     

集热挡水板在停车库自动喷水灭火系统中的应用研究

通过实体燃烧试验,研究了面积不同大小的集热挡水板在车库自动喷水灭火使用时对系统喷头动作的作用效果问题,得出了相应结论.     

自动喷水灭火系统水力计算方法

为克服目前自动喷水灭火系统水力计算方法存在的缺陷，根据水力学原理分析了自动喷水灭火系统配水支管上各喷头流量之间的比例关系和水压平衡方程，提出了适于管路及喷头“不规则布置”的自动喷水灭火系统的水力计算方法，可精确计算自动喷水灭火系统的设计流量。     

关于自动喷水灭火系统若干问题的讨论

对自动喷水灭火系统应用范围与组成形式、供水泵自动启动控制信号的选择、消防水箱和集热挡水板的设置以及供水泵出口压力的控制措施等问题进行了分析 ,并结合现行规范和工程实际提出了相应的改进措施     

浅谈高层建筑给排水中的消防设计

基于自动喷水灭火系统,为克服目前自动喷水灭火系统水力计算方法存在的缺陷,根据水力学原理分析了自动喷水灭火系统配水支管上各喷头流量之间的比例关系和水压平衡方程,提出了适于管路及喷头“不规则布置”的自动喷水灭火系统的水力计算方法,可精确计算自动喷水灭火系统的设计流量。     

自动喷水灭火系统设计中几个问题的探讨

对自动喷水灭火系统防火设计审核中遇到的四个问题展开探讨,即最不利点的最小压力能否作为系统选泵和确定喷头间距的依据;自动喷水灭火系统管网如何布置比较科学;加密喷头闭式喷水系统作用时间和系统设置方式的选择;自动喷水灭火系统中末端试水装置设置的合理性.     

自动喷水灭火系统喷头梁间优化布置探讨

自动喷水灭火系统喷头布置正确与否直接影响灭火效果。无吊顶时洒水喷头布置方式受结构型式和构件高度影响,工程中可根据不同结构型式、柱网跨度及板下梁高净尺寸等参数,选择不同的喷头布置方式。阐述了结构梁间喷头布置的原则、步骤,总结并绘制出不同结构型式下梁间喷头布置方式及适用范围。在一个防火分区内十字梁结构型式下,比较了标准洒水喷头、扩大覆盖面积洒水喷头不同布置形式的技术及经济差异,便于设计人员通过简图与表格快速选用,减少设计人员的给排水设计工作量,同时指导施工安装。通过适度优化自动喷水灭火系统管道及喷头布置,可降低自动喷水灭火系统的工程造价。     

关于在自动喷水灭火系统闭式喷头上安装集热板的思考

《自动喷水灭火系统设计规范》第 4 .2 .3条规定 :在高架仓库的“分层板上如有空洞、缝隙 ,应在该处喷头上方设置集热板”,第 4 .1.2条规定“喷头溅水盘距吊顶、楼板、屋面板的距离 ,不宜小于 7.5cm,并不宜大于 15cm,……”。设置集热板的目的是为了解决喷头距顶板过高的问题。我们知道 ,发生火灾时向上的热气流在顶板下部聚集 ,喷头的开启就是靠聚集在顶板下部的高温烟气层使玻璃球爆裂而出水灭火。如果喷头安装距顶板距离过大 ,将大大延缓喷头开启的时间 ,这对灭火是非常不利的。虽然规范中只规定了在高架仓库内设置集热板 ,但在实际工…     

提高自动喷水灭火系统的可靠性

完善可靠的自动喷水灭火系统是保证自动喷水灭火系统灭火效率的核心问题。本文就自动喷水灭火系统设计中的控制阀、消防水池、水流指示器等设置及喷头的布置问题提出个人看法。     

Assessing the Sprinkler Activation Predictive Capability of the BRANZFIRE Fire Model

This paper describes an investigation into the sprinkler response time predictive capability of the BRANZFIRE fire model. A set of 22 fire/sprinkler experiments are simulated where the sprinkler activation time and the heat release rate (HRR) for each individual experiment had been determined. The experiments provided data for use in validating the sprinkler activation prediction algorithms in the BRANZFIRE zone model. A set of base case values were chosen and input files constructed for the simulations. The experiments were then simulated by the fire model using both the NIST/JET ceiling jet and Alpert’s ceiling jet options (which are the two ceiling jet correlations available in the BRANZFIRE zone model). The fire model included a heat transfer calculation for the temperature of the heat sensitive sprinkler element. Different sprinkler operational parameters such as the conduction factor, response time index (RTI) and the sprinkler depth below ceiling were also varied to assess the sensitivity of their effect on the activation time. Results showed that using the NIST/JET ceiling jet algorithm gave a closer prediction of the sprinkler response time in a small room than Alpert’s correlation. This was expected, since the former includes the effect of a hot upper layer while the latter applies to unconfined ceilings. The experiments available for comparison had been conducted inside an enclosure with a developing hot upper layer. The findings also signified that changing the sprinkler operational parameters can change the predicted sprinkler activation time significantly.     

民用建筑中12~18m高大空间场所自动灭火系统设计

《自动喷水灭火系统设计规范》(GB 50084—2017)的实施,为民用建筑12~18 m高大空间场所可采用的自动灭火消防系统类型提供了又一选择,即可采用自动喷水灭火系统保护高大空间场所。结合具体项目实例,围绕此类场所中自动喷水灭火系统与大空间智能型主动喷水灭火系统的设计方案进行比选,利用消防计算软件从系统设计流量、水力计算以及设计中遇到的问题等相关角度进行分析探讨,建议在有条件设置喷淋的区域优先考虑设置自动喷水灭火系统,并单独设置高大空间区域减压装置,同时对非仓库型特殊应用喷头在现行规范认证标准还未执行情况下的使用提出了应对措施。     

辐射热启动喷头的研究

为解决传统闭式洒水喷头安装的局限性,分析了传统闭式洒水喷头的吸热方式,揭示了传统闭式洒水喷头不能有效吸收辐射热的原因。根据辐射热的基本原理,提出了提高喷头感温元件吸收辐射热的方法并设计研发了辐射热启动喷头。为验证辐射热启动喷头的启动优势,进行了辐射热源和油盘火试验,对辐射热启动喷头和传统闭式洒水喷头的启动性能进行了对比研究。结果表明,在无法与热烟气进行对流换热的情况下,辐射热启动喷头能够通过吸收辐射热而启动。分析总结了影响喷头启动速度的因素以及在实际火灾条件下,辐射热启动喷头的热交换情况。     

Model scale tunnel fire tests with automatic sprinkler

The study focuses on the performance of an automatic sprinkler system in a model scale tunnel with longitudinal ventilation. A total of 28 tests were carried out in a 1:15 model scale tunnel using an automatic sprinkler system with glass bulbs. The maximum heat release rate, energy content and failure of the automatic sprinkler system were analysed. The results show that high ventilation rates and low water flow rates result in a failure of the automatic sprinkler system in a longitudinal ventilated tunnel fire. The main reason for the failure under the tested water flow rates was the effect of the longitudinal flow on the fire development and the hot gas flow close to the sprinklers. The fire development and the activation heat release rate of the first activated bulb are intimately related to the ventilation velocity. The fire spread to the neighbouring wood crib was investigated and a presentation of tests conducted using a deluge system are given.     

Modeling and comparative thermal performance of ground air collector and earth air heat exchanger for heating of greenhouse

The potential of using the stored thermal energy of ground for space heating has been investigated with the help of two buried pipe systems, i.e., ground air collector and earth air heat exchanger, integrated with the greenhouse located in the premises of Indian Institute of Technology, Delhi, India. The total length of the buried pipes in both the arrangements was kept same for making a comparative study. A complete numerical model has been developed to predict and compare their thermal performance for choosing a suitable heating method in the composite climate of India. Experiments were conducted extensively during winter period from November 2002 to March 2003, but the model was validated against the clear and sunny days. Performance of these two arrangements was compared in terms of thermal load leveling and total heating potential. Temperatures of greenhouse air with ground air collector were observed to be 2–3 °C higher than those with earth air heat exchanger. The temperature fluctuations of greenhouse air were also less when operated with ground air collector as compared to earth air heat exchanger. Predicted and computed values of greenhouse air temperatures in both the systems exhibited fair agreement. Finally ground air collector was chosen as a suitable option for heating of greenhouse in the above climate.     

A mathematical simulation of a solar assisted heat pump system using the ground for energy storage

A residential heating system utilizing a combination of a solar collector, a heat pump and an energy storage in the ground is described and some simulation results are presented.It is concluded that for ground heat-pump systems without a solar collector the best positioning of the heat absorbing tubes are horizontal, whereas the vertical tube configuration seems to be superior when a solar collector is included in the system.Finally it is observed that the use of a heat storage consisting of vertical tubes buried under the house appears to be a rather attractive solution.     

Numerical simulation of the performance of an air heating solar collector

The effects of the thermal and hydrodynamics entry length for both laminar and turbulent flow regimes within an air-heating solar collector have been studied using a numerical procedure. Two internal arrangements were considered: (1) air passing on both sides of the absorber (parallel flow), and (2) use of finned and other augmented surfaces.

Results of the analysis showed that the temperatures of the cover plates for the parallel flow collector were lower than if the air had passed on only one side of the absorber plate (single flow). Consequently, the heat losses were reduced and the efficiency of the parallel flow collector was increased. Also the pumping power per unit energy gained by the collector for parallel flow mode was less than that for the single flow mode. By using a finned surface, the temperatures of the cover plates were lower than for single and parallel flow and consequently the heat losses were reduced and the efficiency of the finned surface collector was increased. But in this case, the pumping power per unit energy gained by the collector and operating costs also increased.     

太阳能平板集热器关键参数对其热性能的影响

为了提升太阳能在建筑能源供给体系中的比重,形式多样的太阳能集热设备及其系统在建筑领域得到了广泛应用。基于机理分析法,建立了具有单层玻璃盖板的管板式太阳能平板集热器的稳态传热模型。并且针对集热管间距、集热管内径、工质入口温度和工质质量流量等关键参数对集热器集热效率的影响特性进行了数值模拟与分析。结果表明,建立的该稳态传热模型是可行的;此外,在其余参数值保持不变的情况下,减小集热管间距或增加集热管内径均可使集热器瞬时效率增大;增大工质入口温度会导致集热器瞬时效率下降;而增大工质质量流量会提升集热器瞬时效率。这些结论对于太阳能平板集热器在太阳能建筑一体化的实际应用中,具有一定的参考作用。     

历史文化街区保护性开发过程中的防火间距问题

为了解决历史文化街区保护性开发建设过程中建筑新建或修缮改造所面临的防火间距设置要求问题,选择某历史文化街区内3类典型建筑形式,利用FDS对防火间距分别为2.0、2.5、4.0、6.0 m条件下相邻建筑外墙所受的最大热辐射强度进行模拟计算。结果表明,间距为4.0 m时,辐射热流密度可达到或接近易燃家具的引燃辐射热流密度值;间距为6.0 m时,辐射热流密度小于可燃物的引燃辐射热流密度值。在此基础上,结合相关规范条文分析和实际项目改造要求,分别考虑外墙上不开口、开口错开,设置防火门窗和（或）设置喷淋系统等不同技术措施,提出历史文化街区内新建建筑之间、新建建筑与改造建筑、既有建筑间的防火间距的设置要求。