镁在水蒸气中高温氧化的动力学特性

对镁在水蒸气中着火前的高温氧化特性和机理进行了研究.发现水蒸气中镁的高温氧化反应可以分为3个阶段:在400℃前基本不发生反应;高于400℃后为高温氧化阶段,属于表面反应;在大约500℃后可能出现气相反应,继续加热可能出现着火和燃烧.通过实验和理论分析研究了内、外扩散速率和化学反应速率量级,明确了化学反应速率是该过程的速率控制步骤.在对镁高温氧化模型进行分析的基础上,计算了镁在水蒸气中高温氧化阶段的动力学参数.     

二甲醚水蒸气重整制氢的模型和数值模拟

为研究二甲醚的水蒸气重整制氢过程,设计了一种带有隔热套、瓦片式加热通道和催化反应床的重整反应器.建立了反应器的数学模型,并利用COMSOL软件对其仿真.试验研究了反应气体温度、水蒸气与二甲醚的物质的量比和反应器结构参数对二甲醚转化率、氢产率的影响.模拟结果显示了二甲醚水蒸气重整制氢过程中的各组分质量分布及不同温度、不同...     

高压壬酸乙酯比定压热容的实验测量与关联

壬酸乙酯是生物柴油的主要组分之一,其热物理性质是生物柴油制备及应用过程设计的基础数据。利用流动型量热法高压流体比定压热容实验测量系统对壬酸乙酯在温度为303.00～393.00 K、压力为0.10～25.00 MPa时的比定压热容进行了测量,该系统比定压热容的测量不确定度为0.98%。通过实验数据研究了壬酸乙酯比定压热容的变化规律,并对壬酸乙酯比定压热容的实验数据进行了关联,其计算值与实验值之间的最大偏差为0.54%。     

某型增压柴油机排气系统的仿真研究

排气系统设计是否合理对柴油机的性能有着重要影响,为了探求某型增压柴油机采用不同排气系统的优越性,本文以内燃机性能仿真软件GT-Power为平台,建立了工作过程仿真模型,利用试验数据验证了模型的可靠性.柴油机采用脉冲增压系统,针对定压增压系统和MPC增压系统对原机的排气系统进行了重新设计,建立了定压增压系统和MPC增压系统的柴油机模型,并分别对其进行了稳态工作过程计算,着重分析研究了采用不同排气系统对该柴油机性能的影响,为该柴油机排气系统的改进提供了参考依据.     

中空纤维膜管内LiBr溶液除湿过程的数值研究

为研究中空纤维膜和吸湿溶液结合进行制冷预除湿过程的传质机理,建立了膜管外的水蒸气通过膜孔最后被溴化锂溶液吸收传质过程的数值模型,研究了液体进口流速、进口浓度和进口温度对管内溶液的温度分布、质量分数分布和膜孔内水蒸气质量分数分布的影响,并比较了这三种因素对传质的影响程度。在一般预除湿用疏水性膜组件的内部溶液压力条件下(小于10kpa),溶液与水蒸气的接触面在疏水性膜内壁表面。溶液流速的增大,溶液进口质量分数的增大以及溶液进口温度的降低均有利于传质进行,其中,提高溶液进口质量分数对加强传质最为有效。     

常压热水锅炉供暖系统及其调试特点

介绍了常压热水锅炉供热系统的单点定压及双点定压两种系统的调试方法,同时指出在设计时,应注意供暖系统的定压问题、有关管路的负压问题以及锅炉氧腐蚀等问题,以使整个系统在安全经济的状态下运行.     

调峰型气化炉内换热区换热行为模拟研究

基于两相流的欧拉壁膜模型和组分输运模型耦合的方法,针对1种调峰型的气化炉壳侧内部进行建模,研究了烟气垂直向上流动时,螺旋盘管管壁外表面的相变行为及液膜的形成过程和分布情况.计算结果表明:当烟气通过管道外壁面时,烟气中水蒸气在管道外壁发生相变.首先在底部盘管壁面发生凝结形成液膜,随着时间的推进,凝结过程持续进行.底部盘管...     

发动机废气能量的利用

本文主要介绍了废气中的可用能量及其在定压系统中的利用.阐述了为有效利用废气能量,在实践设计中排气系统的要求及充分利用废气在定压系统中推动涡轮作功的分析方法,以求提高涡轮的实际使用效率.     

高温氦气环境中石墨的水蒸气氧化特性模拟研究

在正常运行工况下高温气冷堆内石墨材料的氧化对石墨结构材料的服役时间有重要影响.主要介绍高温气冷堆燃料元件氦气孔道内石墨材料与水蒸气发生氧化反应的模拟.该模型使用COMSOL软件进行建模,采用k-ε模型模拟冷却剂的流动,使用Langmuir-Hinshelwood方程描述石墨与水蒸气的化学反应.使用该模型计算了冷却剂管道温度分布为线性、水蒸气压力低于1 Pa的氧化情况.计算结果表明,在堆芯底部氧化主要发生在表面,石墨材料转化率高于8%的厚度约1 mm.     

绝热压缩空气储能电站储热定压系统研究

对绝热压缩空气储能电站中储热定压系统的几种方式进行对比分析、计算，剖析各定压系统的优缺点，结合工程实际应用，推荐适合的定压系统，为后续绝热压缩空气储能电站的定压设计提供指导和参考。     

水合物藏定质量流量转定井底流压开采规律研究

天然气水合物资源潜力巨大，降压法是水合物资源开采最有前景的方法。本文提出了定质量流量转定井底流压生产的降压开采模式，使用数值模拟方法研究了此模式下水合物藏的气水生产动态和物理场的变化规律。结果表明：（1）定质量流量生产阶段的产气速率约为定井底流压生产阶段的3倍；对于分解气速率，定质量流量生产阶段与定井底流压生产阶段相当，但在定井底流压生产阶段后期分解气速率上升幅度近200%；产水速率在定质量流量生产阶段和定井底流压生产阶段整体较为稳定。（2）储层的压力场、温度场和水合物饱和度场的变化有相似的规律，随时间增加，低压、低温和低水合物饱和度范围均以井筒为中心不断扩大。（3）本文降压生产模式的总体开发效果介于单一的定质量流量生产和定井底流压生产之间，具有较高的产量，且能够较好地保持地层能量。     

Measurement of apparent solid-side mass diffusivity of a water vapor-silica gel system

A measurement of the apparent solid-side mass diffusivity of water vapor adsorbed in a regular density silica gel is performed by using a constant-pressure thermal gravimetrical apparatus. The diameter of the silica gel particles is 2 mm. Six adsorption isotherms, individually correspond to 5.1, 22.2, 34.3, 49.5, 64.4 and 79.6 °C, are measured. The covered range of moisture content is from 0% to 40%. Using a previously developed model, which considers both surface (film) heat and mass transfer resistances, the measured uptake curves yield the apparent solid-side mass diffusivities. The apparent solid-side mass diffusivity is expressed as a function of temperature and moisture content. The thermal effect and importance of surface mass transfer resistance are individually discussed.     

Modelling approaches to acoustic cavitation in transmission pipelines

A general treatment of acoustic cavitation was presented, including both fluid dynamics instabilities that can occur at cavitation inception as well as non-equilibrium thermal and mechanical effects during bubble dynamics. Different approaches to cavitation modelling were considered and compared.A novel barotropic cavitation model has been developed, based on the partial differential equations governing the mass-conservation and momentum balance. The fluid has been taken as a homogenous mixture of a pure liquid, its vapor and a quantity of gas, both dissolved and undissolved. The analytical expression for the vapor source term driving cavitation has been carried out by means of the energy conservation equation and a general formula for the sound speed in homogeneous bubbly flows has been derived.A recently developed conservative, implicit, high-resolution, second-order accurate numerical scheme was applied to solve the equations governing the pipe flow. The resultant computational algorithm was assessed through comparison with experimental data referring to a system made up of a pipe connecting two constant-pressure reservoirs of water. The model predictions were examined and discussed in order to underline the most interesting fluid-dynamic phenomena, such as the dynamics of shock waves arising at cavitation collapse.The influence of the frequency-dependent friction on the simulation of the pressure wave dynamics in the presence of cavitation was also analyzed and discussed.     

关于常压热水锅炉的系统设置和节能

常压热水锅炉在国内已有广泛的应用,但常压热水锅炉房目前尚无权威的设计布置方法,而导致安全事故常有发生。在这种锅炉的布置中必须有通大气管和锅炉热水箱。循环热水泵应设于锅炉的出口。在循环热水泵选型时,其压头应为热用户与锅炉房的高程差及管网阻力之和,回水管路上必须设启闭网和阻力调节阀。常压锅炉的节能特性应视热水管网的构成情况具体分析。这种锅炉大体上用在低层、低参数、小容量的场合较为合适。     

Dynamic process of hydrogen and heat generation from reaction of Al–Li alloy powders and water vapor at moderate temperatures

As one of the alternative clean fuels, aluminum is suitable for generating hydrogen and power via metal hydrolysis. The reaction process characteristics were studied in a cylindrical reactor with 5 g of Al–Li alloy powder as fuel at moderate temperatures. The test performed good results with 1,130 mL/g alloy of H₂ yield, 86% of the reaction efficiency, and 54.5% of usable heat ratio. The dynamic change of temperature distribution was measured by 12 thermocouples in the reactor, and the maximum was not beyond 892°C. On the basis of the temperature characteristics, the reaction propagation speed was calculated and in the range of 0.57–0.95 mm/s. Moreover, the micromorphology and ingredients presented obvious differences between top product and bottom product, which was resulted from water vapor diffusion. The reaction of Al–Li alloy and steam was determined by both water vapor diffusion and heat transfer, which led to the distinct temperature trends near the vapor inlet, away from the vapor inlet, on the top and at the bottom. On the basis of the results, a mild and controllable hydrogen generation can be achieved at moderate temperatures by optimizing vapor inlet arrangement.     

8E15OZ_LC型增压柴油机的研制

本文论述了8E150ZLC型二冲程回流扫气增压柴油机的研制。该机在原E150C型产品的基础上对主要件进行了较大改进，采用等压增压使柴油机的动力性、经济性达到了国内同类柴油机较好水平。     

Numerical analysis of the influence of two-phase flow mass and heat transfer on n-heptane autoignition

This paper investigates the influence of liquid fuel presence on the autoignition of n-heptane/air mixtures over a wide range of conditions encountered in internal combustion engines. To this end, evaporating droplet physics and skeletal chemistry mechanisms are simultaneously solved considering a homogeneous constant-pressure reactor. A skeletal mechanism is introduced to account for specific kinetics behavior in the Negative Temperature Coefficient (NTC) region. The impact of mass and heat source terms during evaporation is emphasized by comparing a two-phase flow scenario with a purely gaseous case. The competition between fuel vapor availability and the evaporation-induced gas temperature decrease is specific to two-phase flow autoignition. On the one hand, droplet evaporation delay restricts the gaseous local fuel/air equivalence ratio and consequently the kinetics runaway. On the other hand, temperature reduction due to evaporation may either reduce or enhance chemical reactivity, depending on the local thermodynamic conditions lying either inside or outside the NTC region. By simultaneously accounting for evaporation source terms and skeletal chemistry, we can reproduce the already experimentally observed transformation of the NTC region into a Zero Temperature Coefficient (ZTC) region depending on thermodynamic conditions and droplet size. The ZTC phenomenon appears when combustion heat-release starts before complete droplet evaporation. Since the ZTC behavior can be captured using the point source approach, in which droplets are considered only as zero-dimensional source terms of mass and energy, the present results pave the way for future exploration of NTC chemistry in sprays with a direct numerical simulation of discrete particles considering detailed chemistry and turbulent flows.     

小型锅炉酸洗除垢的方法

根据小型锅炉多为常压,低压锅炉的特点,通过我们多年的实践,提出了“长时间、低浓度、分次加酸、分部位酸洗”的除垢方法,解决了酸洗法对锅炉损伤大的问题,取得了减小锅炉损伤、除尽水垢的效果。     

Theoretical and experimental investigation of a constant-pressure adsorption process

This paper presents a theoretical and experimental analysis of a constant pressure adsorption process. The governing heat and mass transfer equations derived from local thermodynamic equilibrium and energy balance are solved numerically. The model is validated by comparison with experimental results. It is then used to analyze the effect of some operating and design parameters on a constant-pressure sorption process. The adsorbent thickness and heat transfer coefficient between the adsorbent and the heating/cooling fluid have the strongest influence on sorption kinetics and on the cooling capacity of adsorption systems.     

综合自动化管理系统在某机场二次供水泵站的应用

某机场目前二次供水设备存在设备老化严重、设备运行工况无法实时监控、设备自动化程度低等问题,为此通过技术改造,安装1套综合自动化管理系统,对反映设备运行工况的各项参数进行远程监控,实现对多台水泵轮换运行的自动控制、变频调速、恒压供水,对消毒液及进水进行自动控制,采用高精度数字化仪器仪表对水压、水位、流量、加药量等参数进行精确测量,极大地提高了工作效率和自动化程度。