基于受热面负荷特性的超临界锅炉炉膛对流与辐射耦合传热计算

对流和辐射换热在电站锅炉炉膛蒸发受热面中呈现不同的负荷特性,忽略对流换热可能会引起炉膛全负荷热力特性偏离设计状态.建立了超临界直流锅炉炉膛对流和辐射耦合传热模型,该模型基于试验数据,采用多维函数最小化技术,从炉膛变负荷运行特性中提取对流和辐射热的组成信息,对5台超临界锅炉32个负荷状态的对流和辐射换热进行计算.结果表明,炉膛实际换热量和预测值吻合较好,辐射和对流耦合传热模型能够准确描述炉膛受热面负荷变化特性,当锅炉运行条件发生变化时,可用于修正热工调节参数,指导超临界锅炉燃烧和汽温控制.     

生物质热风炉的设计与应用

给出了一种基于洁净型生物质燃烧技术的新型生物质热风炉,主要设计参数的计算公式以及计算示例。工业应用实测结果表明,设计参数与测试数据比较接近,可以应用于工程设计。     

热辐射下常用木材热解的动力学与燃烧特性

在热重分析仪上进行了空气气氛、不同升温速率下几种木材的热解动力学过程的研究.对不同升温速率以及木材种类对失重过程的DTG曲线的影响进行了深入分析,在热重实验的基础上建立了"双组分两阶段反应"模型来描述空气气氛下木材的热解动力学过程,并利用C-R方法求得了对应失重阶段的动力学参数.在火灾早期特性实验台上进行了4种木材在空气气氛、不同辐射热流下的热解与燃烧过程的特性研究,通过对高、低热流下几种木材表面温度变化、失重率以及着火时间等参数的对比,发现在较高热流下,固定碳含量相似的几种木材的反应机理及其表观热行为趋于一致.     

掺混生物质焦和煤焦共气化的热重分析

采用热重分析法对煤焦和几种生物质焦及其混合物的气化过程及动力学规律进行了分析,分析结果表明煤焦的失重与生物质焦相比差别明显,混合物中的生物质焦所占比重越大、发生失重的温度越低。进一步采用Coats—Redfern方法对样品气化过程进行了动力学分析,得到了生物质焦、煤焦及其混合物表观活化能。     

工业炉内辐射换热模型研究进展

对工业炉内辐射换热模型的研究进行了综合评述,其中涉及区域法、热通量法、概率模拟法或称蒙特卡洛法、球形谐波法、离散传递法以及离散坐标法、有限体积法等几个方面,对全面了解辐射换热模型的研究现状及前景提出了看法。     

Modeling and Experiments for Heat Transfer Process in Pulverized Coal-Firing Furnace With Two-Dimensional Radiation Characteristics

A dimension-reducing method for calculating the radiant heat transfer with two-dimensional characteristics is introduced in this article. Using this dimension-reducing method, the two-dimensional discrete transfer method (DTM) was applied to a cylindrical enclosure where the medium was absorptive and emissive. The two-dimensional DTM was proved to produce equivalent prediction results as the three-dimensional radiation computation. Then the two-dimensional DTM was incorporated into a general pulverized coal combustion model to estimate radiant heat transfer. The temperature distribution and the net heat flux distribution of an axisymmetric pilot furnace, in which three kinds of lignite were burned, respectively, were calculated using the comprehensive model. The prediction using this model has been found to have a high agreement with the measured data, that the temperature errors was at ± 5% and the net heat flux error was at about ± 15%. The results have demonstrated the feasibility and potential of using the two-dimensional DTM for radiation modeling in pulverized coal flame, and confirmed that the dimension-reducing method and the overall model will be simple and convenient for engineers to use.     

Weighted Sum of Gray Gas Modeling for Nongray Radiation in Combusting Environment Using the Hybrid Solution Methodology

A hybrid solution approach is proposed to solve the radiation transfer equation (RTE) in combusting environment using the weighted sum of gray gases model for modeling the absorption coefficient. The hybrid approach uses a selective combination of the finite-volume method (FVM) and P1 approximation to solve the RTE for different gray gases. A comprehensive study with a wide range of test cases with homogenous and nonhomogenous media is carried out to study the accuracy, speed, and convergence rate of the hybrid solution approach. The differences between hybrid and FVM results are described, and the sources of errors are discussed.     

强化传热生物质燃料热风炉研究

在我国,粮食及其它农副产品的安全储存是一个重要问题.安全储存的一个技术关键就是要将其水分降至安全水分,采用热风炉间接加热空气的干燥方法应用最为广泛.但是,目前使用的各种不同形式的热风炉普遍存在污染环境和热效率低的缺点.为此,在理论及实验指导下,研制出用于粮食及其它农副产品干燥的新型热风炉.此炉型采用生物质燃料洁净燃烧技术及高强化传热技术,具有低污染、高效率、长寿命等优点.     

燃烧室内三维温度场的辐射反问题

本文提出了一种在介质辐射特性已知的条件下,由壁面入射辐射热流的测量值反演燃烧室内三维温度场的方法。该方法是在辐射传递方程离散坐标近似的基础上,用求目标函数极小值的共轭梯度法进行反演计算。通过对吸收系数、散射不对称因子、反照率、壁面黑度和燃烧室大小尺寸等参数对反演精度影响的分析,结果表明,即使存在随机测量误差,这些参数对温度场反演精度的影响也不大,本文所提出的方法可较精确地反演燃烧室内三维温度场。     

特大型热油炉的设计

介绍特大型热油炉的炉型结构,炉排型式以及对流室和辐射室的热负荷分配。     

Optimum Arrangement of Tube Coil in Radiation Type of Tubular Furnace

Tube coil arrangement dominantly influences the thermal-hydraulics characteristics of furnace and its economy. The presented method is based on standard long-used design methods (Lobo-Evans method, Belokon method). It is shown how these standard global design methods can be (for common-operating conditions) suitably generalized and simplified. It allows (for the purpose of optimum design of coil arrangement) to arrange the basic heat transfer equation for radiant chamber. In connection with investment cost relations for individual furnace subsystems (tube coil, burners, lining, etc.) and operating cost relations (fuel consumption, fluid pumping cost), the final objective function of total cost can be obtained. This objective function then allows finding the optimum coil arrangement from minimum total cost point of view. Moreover, the obtained results allow one to formulate some general recommendations suitable for furnace designers. The developed method can be used for the individual solution of a radiation-type of tubular furnaces and also for the first (preliminary) design stage usually connected with a proposal for the customer when only basic process and furnace design data are known. The developed method can be also used for the effective solution of the integration of radiation furnaces into processes. The application of the developed method is demonstrated through a case study—the optimum arrangement of coil in a gas plant regeneration furnace.     

炉膛中二维温度场与辐射参数的同时重建

辐射逆问题研究受到了广泛的关注。以炉膛为研究对象,开展了二维温度场与辐射参数同时重建的研究。用CCD接收边界辐射强度图像和辐射温度图像,提出用正则化方法从辐射温度图像中重建介质温度场,从辐射强度图像中更新辐射参数,两者交替迭代,直到收敛。模拟计算表明,在测量数据中加入标准方差为0.02,0.05的正态分布的误差后,仍可以较好地重建出介质温度场与辐射参数。图4表4参13     

生物燃料圆形熔铝炉加热室优化设计及分析

在510 kg生物燃料圆形熔铝炉加热室内壁设置螺旋导火道(在加热室炉壁与锅钳之间设置螺旋状挡火层),利用挡火层对火焰的滞留作用增强热交换,迟滞加热室室温的散失,在保持锅钳内铝合金熔融温度的同时,降低加热室内压,增强气流通畅性,从而达到提高熔融速度、储能保温、降低燃料消耗、降低熔铝成本的效果。燃料成本节约率约为11.24%。     

生物质燃油燃烧特性分析

以小桐子油、小桐子生物柴油、地沟油、地沟油生物柴油、0#柴油作为研究对象,对这5种燃油的黏温特性进行了探究分析,同时在自行搭建的雾化燃烧试验平台研究燃油在炉内燃烧火焰体积、长度及火焰温度变化规律,试验结果表明燃烧温度越高,生物质燃油和0#柴油的运动黏度均减小,地沟油减少幅度最大为81.75%;试验条件相同情况下,0#柴油的火焰长度最大为288.209 mm,地沟油火焰长度的最小为207.814 mm,5种燃油燃烧温度在轴线方向先上升后下降,在径向方向波动较大;在不同工况下,随过量空气系数α或雾化压力p的增大,生物质燃油和0#柴油燃烧火焰体积及火焰长度均呈下降趋势;燃油火焰平均温度的变化趋势随过量空气系数α增大先增大后减小,随氧体积分数的增大一直上升,小桐子油增幅最大为25.90%.     

封闭漫射灰腔内辐射在加热炉中的应用

应用封闭漫射灰腔内辐射理论，直接建立起连续推钢加热炉燃耗，生产率、加热质量关系的数字模型。结果表明，模型能够真实反映加热炉的温度制度与供热制度，并且对燃耗及主变化预报灵敏     

南京地区的太阳能辐射特性

太阳能热利用系统的性能与当地太阳能辐照特性直接相关。利用南京地区全年辐射强度统计数据建立了逐时太阳能强度及其计算模型,结果可以作为太阳能热利用系统提供性能分析和方案论证的参考依据。     

Thermal Property Measurements of a Large Prismatic Lithium-ion Battery for Electric Vehicles

Because of the high cost of measuring the specific heat capacity and the difficulty in measuring the thermal conductivity of prismatic lithium-ion batteries, two devices with a sandwiched core of the sample-electric heating film-sample were designed and developed to measure the thermal properties of the batteries based on Fourier's thermal equation. Similar to electrical circuit modeling, two equivalent thermal circuits were constructed to model the heat loss of the self-made devices, one thermal-resistance steady circuit for the purpose of measuring the thermal conductivity, the other thermal-resistance-capacitance dynamic circuit for the purpose of measuring the specific heat capacity. Using the analytic method and recursive least squares, the lumped model parameters of these two thermal circuits were extracted to estimate the heat loss and correct the measured values of the self-made devices. Compared to the standard values of the reference samples of the glass and steel plates, the measured values were corrected to improve the measurement accuracies beyond 95% through steady thermal-circuit modeling. Compared to the measured value of the specific heat capacity of the battery sample at 50% state of charge using the calorimeter, the measured value using the self-made device was corrected in order to elevate the measurement accuracy by about 90% through dynamic thermal-circuit modeling. As verified through the experiments, it was reliable, convenient, and low cost for the proposed methodology to measure the thermal properties of prismatic lithium-ion batteries.     

W火焰炉炉内流动特性的试验研究

为摸清从国外引进的一台330 MW W火焰锅炉炉内流动特性,依据相似模化的准则,对该锅炉建立了1∶10冷态单相试验台,在试验台上进行了变锅炉配风(即三次风占总二次风的比例R=0％、6％、14％、20％和27％共5个工况)的冷态模化试验,得出了炉内流场特征和拱部下行气流衰减规律.当R=0～6％时炉内流场基本对称,R值加大至14％后炉内流场出现偏斜现象,继续加大R值,则流场偏斜加剧,前、后墙侧下行气流的衰减特性差异变大.     

双炉膛炉内空气动力场的数值模拟研究

本文对１０００ｔ／ｈ直流炉单炉体双炉膛的炉内空气动力场进行了数值模拟研究 。