Optimal scenario balance of reduction in costs and greenhouse gas emissions for municipal solid waste management

To reduce carbon intensity, an improved management method balancing the reduction in costs and greenhouse gas(GHG)emissions is required for Tianjin's waste management system. Firstly, six objective functions, namely, cost minimization, GHG minimization, eco-efficiency minimization, cost maximization, GHG maximization and eco-efficiency maximization, are built and subjected to the same constraints with each objective function corresponding to one scenario. Secondly, GHG emissions and costs are derived from the waste flow of each scenario. Thirdly, the range of GHG emissions and costs of other potential scenarios are obtained and plotted through adjusting waste flow with infinitely possible step sizes according to the correlation among the above six scenarios. And the optimal scenario is determined based on this range. The results suggest the following conclusions. 1) The scenarios located on the border between scenario cost minimization and GHG minimization create an optimum curve, and scenario GHG minimization has the smallest eco-efficiency on the curve; 2) Simple pursuit of eco-efficiency minimization using fractional programming may be unreasonable; 3) Balancing GHG emissions from incineration and landfills benefits Tianjin's waste management system as it reduces GHG emissions and costs.

Simulation analysis of municipal solid waste pyrolysis and gasification based on Aspen plus

To predict and analyze the municipal solid waste(MSW)pyrolysis and gasification process in an updraft fixed bed more veritably and appropriately,numerical modeling based on Gibbs energy minimization was executed using the Aspen plus software.The RYield module was combined with the RGibbs module to describe the pyrolysis section,while the RGibbs module was used for the gasification section individually.The proposed model was used to forecast and analyze the target performance parameters including syngas composition,lower heating value(LHV)and carbon conversion rate under different conditions of the gasification temperatures,and ratios and types of gasifying agents.The results indicate that there is a good agreement between the experimental data and the simulated data obtained using this model.The predicted optimum gasification temperature is approximately 750°C,and the best ratio of water vapor as gasifying agent is around 0.4.The mixture of flue gas and water vapor has an economical and recycled prospect among four commonly used gasifying agents.

纳米流体在微尺度特斯拉阀中流动的数值研究（英文）

目的:微通道以其效率高、体积小等特点在许多领域有着越来越广泛的应用。特斯拉阀是一种没有运动部件的止回阀,在微流动控制领域有着明显的优势。大量研究表明,将纳米流体运用到微尺度通道中可明显提高换热效率。本文将二者结合,研究Al2O3-水纳米流体在微尺度特斯拉阀中的流动特性,为微尺度特斯拉阀以及纳米流体的进一步研究提供参考。创新点:1.将特斯拉阀应用于纳米流体的微流动控制中;2.研究不同的操作条件和不同的介质特性对纳米流体在微尺度特斯拉阀中流动特性的影响;3.研究纳米流体在微尺度特斯拉阀中不同流动方向的流体分布和压力情况,并根据特斯拉阀的压降比(反向流动压降/正向流动压降)来分析特斯拉阀对微流动的控制效果。方法:1.建立微尺度特斯拉阀的三维模型;2.通过有效性验证的数值方法,在不同操作条件和不同流动介质特性的情况下,模拟纳米流体在微尺度特斯拉阀中正反两个方向的流动;3.根据流体在流动过程中的分布以及压力的变化情况,分析温度、流体流量和纳米颗粒体积分数对纳米流体在微尺度特斯拉阀中流动特性的影响。结论:1.纳米流体在特斯拉阀中正向流动时,大部分流体进入了分叉段中的直通道;而反向流动时,大部分流体进入了分叉段中的弧形通道,并且随着流量、温度和纳米颗粒体积分数的增加,主流量的百分比增加。2.当纳米流体反向流动时,在弧形通道出口处的射流对压降的影响非常明显,这是导致反向流动压降大于正向流动的重要原因。3.特斯拉阀的压降比受流量的影响最显著;在本文的研究范围内,压降比随着流量的增加而线性增加。

生物质衍生醇类水相重整制氢研究进展(英文)

氢气作为一种清洁、高效的可持续能源,近年来得到了广泛关注。水相重整技术以生物质衍生醇类制备氢气,具有来源广泛、反应条件温和、运行成本较低等优点,相较于其他制氢方法更有优势。本文详细阐述生物质衍生醇类水相重整制氢的研究进展,同时讨论不同催化剂的反应机理。Pt系催化剂表现出较高的氢气选择性,但是醇类转化率较低。Ni系催化剂反应活性和转化率均较高,但仍存在氢气选择性和氢气产率较低等问题。