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选择4种典型的胶合板作为研究对象,即三厘板、五厘板、九厘板和十二厘板,在ISO 9705标准的全尺寸燃烧间(3.6m×2.4m×2.4m)内对其进行全尺寸火灾实验模拟,从热释放速率方面研究了胶合板的火灾行为并获得了室内轰燃发生的时间,分析比较了材料厚度对于胶合板室内火灾过程的影响.同时将顺流(Wind-Aided)火蔓延的理论引入到室内墙角火蔓延中,对胶合板的表面火蔓延进行模拟,得到了胶合板室内火灾的热释放速率和轰燃发生时间.通过比较发现,五厘板、九厘板和十二厘板的计算结果与实验测量结果吻合得比较好,三厘板的计算结果与实验测量结果吻合得比较差些. 相似文献
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细水雾熄灭K类火灾的全尺寸模拟实验 总被引:1,自引:2,他引:1
利用ISO 9705全尺寸多功能热释放速率测试仪在开放空间研究了细水雾作用下K类火灾的发展过程,实验中对细水雾作用下食用油火的温度、热释放速率及烟气的主要特性参数变化规律进行了测量与研究,分析了预燃时间对灭火有效性的影响,系统地阐述了细水雾作用下K类火灾关键特性参数的变化规律.实验发现,细水雾可以有效地抑制K类火灾的发展,在其作用下火焰温度及热释放速率快速降低,并可以有效地冲刷烟气,降低一氧化碳及二氧化碳的浓度,提高氧气的浓度及火场能见度.同时利用稳定火源热释放速率模型计算了K类火灾发展阶段的热释放速率,与实验测量结果比较发现,模型可准确地预测K类火灾发展阶段的热释放速率的变化规律. 相似文献
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利用红外热像技术,对受限空间内热塑性材料熔融燃烧过程中初始发展阶段的固体样品表面的二维火蔓延速率进行了实验研究,分析样品与其下部油盆的间距对样品表面火蔓延速率的影响.在ISO 9705燃烧室内,针对6,mm厚聚丙烯板,考虑了0,cm、5,cm、10,cm、15,cm、25,cm和35,cm共6种不同间距,开展了6组全尺寸火灾实验,记录了样品表面的温度场数据,得到了样品表面火蔓延速率的变化规律.结果表明,由于液体油池火的影响,固体表面二维火蔓延速率随时间呈指数增长关系,且其增长速率随间距的增加而降低. 相似文献
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固体可燃物火蔓延速率对于火灾的蔓延有重要的影响。以此为背景,采用热电偶瞬态测温技术,测量了牛皮纸、硬纸板的火蔓延速率。探讨了对流环境下风速的大小对薄片可燃物火蔓延速率的影响,并建立了经验公式。在实验研究基础上建立了薄片可燃物火蔓延速率的简化模型,理论计算与实验结果较为吻合。 相似文献
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A computational fluid dynamics (CFD) model was developed for the simulation of a phase change thermal energy storage process in a 100 l cylindrical tank, horizontally placed. The model is validated with experimental data obtained for the same configuration. The cold storage unit was charged using water as the heat transfer medium, flowing inside a horizontal tube bundle, and the selected phase change material (PCM) was microencapsulated slurry in 45% w/w concentration. The mathematical model is based on the three-dimensional transient Navier–Stokes equations with nonlinear temperature dependent thermo-physical properties of the PCM during the phase change range. These properties were experimentally determined using analytical methods. The governing equations were solved using the ANSYS/FLUENT commercial software package. The mathematical model is validated with experimental data for three different flow rates of the heat transfer fluid during the charging process. Bulk temperature, heat transfer rate and amount of energy stored were used as performance indicators. It was found that the PCM bulk temperatures were predicted within 5% of the experimental data. The results have also shown that the total accumulated energy was within 10% of the observed value, and thus it can be concluded that the model predicts the heat transfer inside the storage system with good accuracy. 相似文献
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Heat transfer behaviour of thermal energy storage components using composite phase change materials 下载免费PDF全文
对基于复合相变材料储热单元的储热性能进行了研究。建立了复合材料和储热单元体内部的二维传热模型,考察了复合材料物性和结构尺寸及传热流体操作条件(流体流速)对单元体储热性能的影响,对比了两种不同结构单元体的储热性能,并搭建实验平台进行了实验对比研究。对比结果表明,模型结果与实验结果趋于一致,验证了模型的准确性。复合材料物性和结构尺寸及传热流体操作条件对单元体储热性能有较大的影响。相比较单管储热单元体,同心管储热单元体有着更优的储热特性,在相同的操作条件下,同心管储热单元体的储热、放热时间较单管储热单元体分别减少10%和15%。 相似文献
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An analytical mathematical model for determining the total heat transfer coefficient of a cylindrically shaped canned food subjected to sterilization was developed. There is a need to determine these coefficients in a simple and accurate form for process heat transfer analysis and energy optimization. In the mathematical modelling, a new technique for heat sterilization conduction problem was used by considering the boundary condition of the third kind in transient heat conduction. The temperature data at the centres of the cylindrically shaped cans were obtained in the experimental investigation at the medium temperatures of 115 and 121°C and were used to determine the total heat transfer coefficients of the individual canned products. The total heat transfer coefficient for an individual canned product increased with increasing medium temperature. The results of this study shows that the present analytical model is a simple tool for determining the total heat transfer coefficients for the individual canned products. 相似文献
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Mathematical Model and Its Application of Radial Effective Thermal Conductivity for Coil Heat Transfer in HPH Furnace 总被引:3,自引:0,他引:3
Wenfei Wu Fan Yu Xinxin Zhang Yi ZuoDepartment of Thermal Engineering School of Mechanical Engineering University of Science Technology Beijing Beijing P.R. China E-mail: xxzhang@me.ustb.edu.cn 《热科学学报(英文版)》2002,11(2):134-137
Temperature uniformity of steel coils in High Performance Hydrogen bell-type annealing furnace has a significant effect on their quality and production. The hot rolled coil can be considered as a periodically laminated material composed of steel layers and interface layers in radial direction. A new formula for the radial effective thermal conductivity has been proposed, which is based on surface characteristic, strip thickness and compressive stress of the rolled coil. Furthermore, it has been used to develop a heat transfer mathematical model for steel coils in the HPH furnace. The calculated annealing curves using this mathematical model are in good agreement with the experimental data. 相似文献
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Congge He Anzhu Xu Zifei Fan Lun Zhao Bing Bo 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2019,41(1):65-77
The accurate determination of reservoir heat efficiency of steam injection in heavy oil reservoirs is very important for heating radius calculation and production dynamic prediction. In conventional calculation methods of reservoir heat efficiency, the steam-injection wellbore is assumed as taking steam over the entire height. In fact, a liquid level in steam-injection wellbore is a very significant observation with respect to the steam override. Aiming at the actual situation that the steam-injection wellbore always has a liquid level, combined with the formation temperature distribution, the new mathematical model for reservoir heat efficiency with the consideration of liquid in steam-injection wellbore was established based on the Van Lookeren steam override theory and the energy conservation principle. The established mathematical model was used to calculate and analyze the reservoir heat efficiency of steam injection in heavy oil reservoirs. The results show that because the new mathematical model considers the liquid in the steam-injection wellbore, the predicted results are more reasonable, thus verifying the correctness of the new model. According to the influential factors analysis based on the new model, it is observed that although increasing the steam quality can effectively increase the steam-taking degree of the steam-injection wellbore, it has limited impact on reservoir heat efficiency. Moreover, the larger the steam-injection rate, the higher the steam-taking degree and reservoir heat efficiency. The reservoir heat efficiency decreases with the pay-zone thickness when the steam-injection wellbore has liquid. 相似文献
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《Applied Thermal Engineering》2000,20(11):1019-1037
A latent heat storage unit incorporating heat pipes embedded in phase change material (PCM) is developed and tested for a novel application in low energy cooling of buildings. A one-dimensional mathematical model of the heat transfer from air to PCM is presented to allow sizing of a test unit. Details of the construction and testing of one heat pipe/PCM unit in a controlled environment are described, and measurements of heat transfer rate and melting times are presented. When the difference between air and PCM temperature was 5°C, the heat transfer rate was approximately 40 W over a melt period of 19 h. The heat transfer rate could be improved, and the phase change time shortened, with an alternative design for finning of the heat pipe inside the PCM. 相似文献
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为了更加有效地利用玉米秸秆复合菌兼氧预处理环节所产生的生物热,探究预处理过程中反应装置内部及反应堆体的产热特性及温度场分布,利用自制秸秆类生物质兼氧预处理反应器对玉米秸秆进行了复合菌兼氧预处理。凭借微元体的能量守恒规律,结合实验中采集的温度数据以及各项参数,利用多项式拟合理论和Origin数据分析软件拟合得到内热源与时间的关联经验公式,并利用FLUENT软件在二维空间内建立其物理模型,结合实验得到的约束条件及相关的数学模型对反应装置内部及反应堆体温度场分布进行模拟分析,进而形象地模拟出复合菌预处理过程中反应器内部物料温度场的分布以及流动的相关动态及规律。实验表明,模拟的温度场实时分布及变化过程与实验测得的结果基本吻合,从而验证所建立的数学模型是准确且可靠的,为生物法复合菌预处理过程中生物热的研究与利用提供理论支撑。 相似文献
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The heat and mass transfer in an unsaturated wet cylindrical bed packed with quartz particles was investigated theoretically and experimentally for relatively low convective drying rates. The medium was dried by blowing dry air over the top of the porous bed which was insulated by impermeable, adiabatic material on the bottom and sides. Local thermodynamic equilibrium was assumed in the mathematical model describing the multi‐phase flow in the unsaturated porous medium using the energy and mass conservation equations for heat and mass transfer during the drying. The drying model included convection and capillary transport of the moisture, and convection and diffusion of the gas. The wet and dry regions were coupled with a dynamic boundary condition at the evaporation front. The numerical results indicated that the drying process could be divided into three periods: the initial temperature rise period, the constant drying rate period, and the reduced drying rate period. The numerical results agreed well with the experimental data, verifying that the mathematical model can evaluate the drying performance of porous media for low drying rates. ©2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(5): 290–312, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20205 相似文献