列表法计算发电厂蒸汽管道双层保温经济厚度

发电厂蒸气管道采用双层保温材料可以降低保温投资成本,改善保温结构并延长其使用寿命。双层保温材料经济厚度的计算是一个复杂过程,本文根据经济厚度原理,采用列表法计算了发电厂蒸汽管道双层保温结构的经济厚度。     

火电机组热力系统抽汽等效热降矩阵算法

在对热力系统进行局部定量分析之前首先需要确定新蒸汽的等效热降和各级抽汽的等效热降.各级抽汽等效热降的传统算法比较繁琐,通过深入研究等效热降理论,应用线性代数理论导出了一种求取火电厂热力系统抽汽等效热降的矩阵算法,利用该方法能够迅速准确计算出不同热力系统各级抽汽等效热降,具有很好的通用性.     

采用增量法的BCHP系统经济性分析

在与传统能源系统方案比较基础上,提出冷热电联供(BCHP)系统经济性的增量评价法,从而避免了热价、冷价等人为因素干扰,使 BCHP 系统经济性的评价更加客观,并针对大学的 BCHP 系统进行经济性案例分析.分析认为,最大利用小时数、运行效率、能源价格乃至系统容量等因素对冷热电联供系统经济性影响很大,进而认为体育场馆、会馆等设备利用小时数少,住宅电价低,这类用户不宜采用BCHP系统.合适的容量利于提高 BCHP 系统的经济性.     

利用火电厂锅炉排烟废热的新方法

耐酸不锈钢制造的新型低温省煤器,配有强制性机械清灰装置,能够长期工作在露点以下烟气环境中,抗腐蚀,不堵灰,可以将发电厂锅炉排烟温度从135℃~150℃降低到74℃~84℃,提高发电厂热效率2.5%~3.0%,2年之内收回节能改造投资。根据现有引风机富余全压设计新型低温省煤器阻力,可以不改造引风机。     

利用Monte Carlo方法对循环流化床锅炉炉膛传热的数值计算

作者对循环流化床锅炉炉膛传热进行数值研究,所建模型考虑轴向和径向颗粒浓度分布的影响。模型计算揭示烟气温度和热流密度在炉膛内的分布变化,计算结果表明在循环流化床锅炉炉膛传热计算中,颗粒相对流换热不能忽略。     

Analysis of Conduction and Radiation Heat Transfer in a 2-D Cylindrical Medium Using the Modified Discrete Ordinate Method and the Lattice Boltzmann Method

This article deals with the analysis of radiative transport with and without conduction in a finite concentric cylindrical enclosure containing absorbing, emitting, and scattering medium. Isothermal medium as the radiation source confined between the cold cylinders and a nonisothermal medium with the inner cylinder as the radiation source are the two nonradiative and radiative equilibrium problems. They involve only calculation of radiative information. In the third problem, a conducting-radiating medium is thermally perturbed by raising the temperature of the inner cylinder. In all problems, radiative information is computed using the modified discrete ordinate method (MDOM), and in the third problem, the lattice Boltzmann method (LBM) is used to formulate and solve the energy equation. Depending on the problems, effects of various parameters such as the extinction coefficient, the scattering albedo, the boundary emissivity, the conduction-radiation parameter, and the radius ratio are studied on temperature and heat flux distributions. The MDOM and the LBM-MDOM results are compared with those available in the literature. To further establish the accuracy of the MDOM and the LBM-MDOM results, in all problems, comparisons are made with the results obtained from the finite volume method (FVM) and the finite difference method-FVM approach, in which FVM provides the radiative information. The selection of the FDM-FVM for the third problem is also with the objective that for this problem, not much work is reported in which the FVM is used to calculate the radiative information. MDOM and LBM-MDOM results are found to compare well with those available in the literature, and in all cases they are in excellent agreement with FVM and FDM-FVM approaches.