共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
3.
4.
用于故障诊断的锅炉一维温度分布模型 总被引:1,自引:0,他引:1
把三维炉膛传热计算中使用的区域法原理应用于一维炉膛模型中,建立了一个可实时求解的一维炉膛温度分布模型。该模型可以根据锅炉不同工况下的给煤量、给风量、风温、壁面灰污情况求取炉内一维温度场,从而可以确定炉内火焰中心的位置和温度,这对于燃烧故障诊断有重要意义。实际计算表明,该模型有较快的收敛速度,能够满足现场故障诊断的要求。 相似文献
5.
6.
针对锅炉炉膛热负荷很难准确预测的问题,本文提出了一种计算炉膛热负荷分布的计算模型,总结出了炉膛内热负荷分布情况,并分析验证了该模型的准确性,本计算模型可以用于工程设计指导。 相似文献
7.
流化床-煤粉复合燃烧锅炉的炉膛传热计算方法 总被引:2,自引:2,他引:0
针对流化床-煤粉复合燃烧锅炉的特点,在综合考虑流化床、火焰和受热面之间换热的基础上,推导了流化床-煤粉复合燃烧锅炉炉膛传热计算的基本方程,得到了复合燃烧锅炉炉膛传热计算的零维模型半径验法。以某75t/h树皮流化床-煤粉复合燃烧锅炉为例,进行了炉膛传热计算。图1表6参5 相似文献
8.
9.
10.
中压锅炉布置在炉膛顶部的屏式过热器,其深度占炉膛深度的比例相对于高压锅炉较大,虽然该屏靠近炉膛出口,但有些设计者也将它视为炉膛辐射受热面处理。那么,将它做为炉膛辐射受热面还是按炉膛出口半辐射屏计算,本文进行了比较,并讨论了两种计算结果。1带有屏的炉膛传热计算口1护区容积中包含有屏的炉膛顶拥示流用当炉膛容积包含有屏时,炉膛出口位子屏后,带有屏的炉膛结构如图1所示。目前在进行炉膛几何尺寸计算时,仍采用两种方法,一是将屏的面积FP和包复炉膛容积总面积民之和做为护墙总面积民,@pF一尺十几(1)炉膛总辐射受热… 相似文献
11.
以某热电厂450t/h循环流化床锅炉运行实测数据为基础,在锅炉密相区和稀相区分别建立热平衡方程式,计算循环流化床锅炉密相区、稀相区内的传热系数,并提出了稀相区内以对流为主的对流-辐射模型,新的计算方法可直接计算循环流化床锅炉稀相区辐射传热在总的传热中占的比率。图5参7 相似文献
12.
为了提高新型高效紧凑式换热器设计的功能性,并使其满足热力学性能需求,对绕管的结构参数及桥接布管方式进行设计。采用一种新型的变径变线桥接方式,在体积有限的情况下实现密集的管束布置形式;对该新型换热器设计进行全尺寸流域建模及CFD数值模拟;并将三维建模结果与一维程序计算结果对比,进行可靠性验证。计算结果表明:三维计算的各项热力学性能结果与一维计算仅有较小偏差,总传热系数相对误差仅为3.74%,总传热量相对误差仅为1.04%,验证了该三维计算模型具有较好的准确性;结合温度云图证明了换热区域基本集中在绕管段,为简化复杂换热器的计算提供了思路;该新型高效紧凑式换热器设计实现了管侧双股流可独立运行且同层间不存在无效换热区,整体换热平顺进行,壳侧流阻较小,换热能力保持较好;在工况范围内整机换热体积功率达到4.67 MW。 相似文献
13.
14.
15.
波纹管内流动与传热规律的数值计算 总被引:2,自引:1,他引:1
采用三维层流及低雷诺数湍流模型对波纹管内流动与传热性能进行了数值模拟,模拟结果与试验结果吻合良好.通过数值计算拓宽了波纹管流动与传热关联式的参数范围,发现在较大雷诺数(RP)范围内波纹管阻力系数随Re的变化趋势表现为指数规律.考察了不同波纹高度、波纹间距对流动与传热的影响,并对模型参数进行了综合性能评价,结果表明:波纹高度对波纹管内流动与传热的影响较波纹间距更显著;波纹管结构的强化传热性能只有在高Re条件下才得以体现,Re越大,波纹管综合性能因子也越高.通过数值计算得到了波纹管流动与传热的最优结构参数及最佳传热雷诺数范围. 相似文献
16.
目前,燃煤锅炉三维CFD数值模拟中对炉膛水冷壁传热分布的预测大都基于给定的壁面温度边界条件。然而,此方法无法体现锅炉运行状态对壁面传热与壁温分布的影响。提出了一种基于锅炉烟气侧放热与汽水侧吸热间热平衡关系的壁面传热计算方法,并重点讨论了壁面传热系数的物理意义及取值方法。研究发现,壁面传热系数基本由壁面结渣状态决定,因此可根据壁面渣层的传热系数确定。本文方法将影响壁面传热的关键因素合理地体现在计算过程中,同时在模型复杂性与工程适用性之间保持了合理的平衡。采用此方法对一台320 MW锅炉的燃烧与传热分布进行了数值模拟,水冷壁吸热量的预测结果与锅炉运行数据吻合良好。 相似文献
17.
Existing complicated and complex calculation procedures for the design of process tubular furnaces create the main reason why the connection of targeting and detail design stage of furnaces (i.e., the continuous design and/or retrofit approach) is a serious problem in design practice. A complex, newly developed approach of furnace design and/or retrofit is presented in this paper. This comprehensive approach involves the application of heat transfer (radiation and convection) in equipment design, thermodynamic analysis for process design from the point of view of furnace integration, and the latest approach consisting in involving process fluid flow and hydrodynamic analysis to avoid potential problems in operation. This new methodology bridges existing gaps between modern targeting methods based on pinch analysis (providing optimized parameters such as the temperature of preheated air, stack temperature, and excess air) and the detailed design of furnaces. It is partly interactive and based on three stages of design: targeting, synthesis, and detailed design. It can be applied for both grassroots and retrofits problems. 相似文献
18.
19.
Thermal energy storage (TES) is a technology that stocks thermal energy by heating or cooling a storage medium so that the stored energy can be used later for heating and cooling applications and for power generation. TES has recently attracted increasing interest to thermal applications such as space and water heating, waste heat utilisation, cooling, and air conditioning. Phase change materials (PCMs) used for the storage of thermal energy as latent heat are special types of advanced materials that substantially contribute to the efficient use and conservation of waste heat and solar energy. This paper provides a comprehensive review on the development of latent heat storage (LHS) systems focused on heat transfer and enhancement techniques employed in PCMs to effectively charge and discharge latent heat energy, and the formulation of the phase change problem. The main categories of PCMs are classified and briefly described, and heat transfer enhancement technologies, namely dispersion of low‐density materials, use of porous materials, metal matrices and encapsulation, incorporation of extended surfaces and fins, utilisation of heat pipes, cascaded storage, and direct heat transfer techniques, are also discussed in detail. Additionally, a two‐dimensional heat transfer simulation model of an LHS system is developed using the control volume technique to solve the phase change problem. Furthermore, a three‐dimensional numerical simulation model of an LHS is built to investigate the quasi‐steady state and transient heat transfer in PCMs. Finally, several future research directions are provided. 相似文献
20.
A mathematical model for three‐dimensional heat and mass transfer in metal–hydrogen reactor is presented. The model considers three‐dimensional complex heat, and mass transfer and chemical reaction in the reactor. The main parameter in hydriding processes is found to be the equilibrium pressure, which strongly depends on temperature. Hydride formation enhanced at regions with lower equilibrium pressure. Hydriding processes are shown to be two dimensional for the system considered in this study. Effects of heat transfer rate and R/H (radius to height) ratio on hydride formation are investigated. Hydride formation increases significantly with larger heat transfer rate from the boundary walls, however after a certain heat transfer rate, the increase in formation rate is found to be not significant, due to the low thermal conductivity of the metal‐hydride systems. The estimated results agree satisfactorily with the experimental data in the literature. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献