Flow patterns in granulating systems

Particle flow patterns were investigated for wet granulation and dry powder mixing in ploughshare mixers using Positron Emission Particle Tracking (PEPT). In a 4-l mixer, calcium carbonate with mean size 45 μm was granulated using a 50 wt.% solution of glycerol and water as binding fluid, and particle movement was followed using a 600-μm calcium hydroxy-phosphate tracer particle. In a 20-l mixer, dry powder flow was studied using a 600-μm resin bead tracer particle to simulate the bulk polypropylene powder with mean size 600 μm. Important differences were seen between particle flow patterns for wet and dry systems. Particle speed relative to blade speed was lower in the wet system than in the dry system, with the ratios of average particle speed to blade tip speed for all experiments in the range 0.01–0.25. In the axial plane, the same particle motion was observed around each blade; this provides a significant advance for modelling flow in ploughshare mixers. For the future, a detailed understanding of the local velocity, acceleration and density variations around a plough blade will reveal the effects of flow patterns in granulating systems on the resultant distribution of granular product attributes such as size, density and strength.     

A fundamental study on the control of the HCCI combustion and emissions by fuel design concept combined with controllable EGR. Part 1. The basic characteristics of HCCI combustion

This article investigates the basic combustion parameters including start of the ignition timing, burn duration, cycle-to-cycle variation, and carbon monoxide (CO), unburned hydrocarbon (UHC), and nitric oxide (NO_x) emissions of homogeneous charge compression ignition (HCCI) engines fueled with primary reference fuels (PRFs) and their mixtures. Two primary reference fuels, n-heptane and iso-octane, and their blends with RON25, RON50, RON75, and RON90 were evaluated. The experimental results show that, in the first-stage combustion, the start of ignition retards, the maximum heat release rate decreases, and the pressure rising and the temperature rising during the first-stage combustion decrease with the increase of the research octane number (RON). Furthermore, the cumulative heat release in the first-stage combustion is strongly dependent on the concentration of n-heptane in the mixture. The start of ignition of the second-stage combustion is linear with the start of ignition of the first-stage. The combustion duration of the second-stage combustion decreases with the increase of the equivalence ration and the decrease of the octane number. The cycle-to-cycle variation improved with the decrease of the octane number.     

Advancements in the design and validation of an air pollution integrated assessment model for Spain

This paper describes the design and application of the Atmospheric Evaluation and Research Integrated model for Spain (AERIS). Currently, AERIS can provide concentration profiles of NO₂, O₃, SO₂, NH₃, PM, as a response to emission variations of relevant sectors in Spain. Results are calculated using transfer matrices based on an air quality modelling system (AQMS) composed by the WRF (meteorology), SMOKE (emissions) and CMAQ (atmospheric-chemical processes) models. The AERIS outputs were statistically tested against the conventional AQMS and observations, revealing a good agreement in both cases. At the moment, integrated assessment in AERIS focuses only on the link between emissions and concentrations. The quantification of deposition, impacts (health, ecosystems) and costs will be introduced in the future. In conclusion, the main asset of AERIS is its accuracy in predicting air quality outcomes for different scenarios through a simple yet robust modelling framework, avoiding complex programming and long computing times.     

我国节能减排的现状、问题与解决路径-一个文献综述

我国的节能减排问题日趋突出。本文从文献梳理角度对我国节能减排的现状、存在的问题以及解决路径进行了述评。研究显示,我国节能减排潜力巨大,节能减排效率低下。直接原因是由于我国产业结构、外贸结构、FDI 结构以及技术结构不合理造成的,但其背后更深层次的原因主要体现在：（1）GDP锦标赛下政治晋升制度的不合理导致了环境的负外部性;（2）激励与约束机制不完善导致政府缺乏节能减排的动力;（3）分税制的不完善导致了我国产业结构的不合理。为此,我们需要从优化产业结构、调整外贸结构、弱化 FDI的“污染避难所”效应以及增强技术进步效应入手,通过改革 GDP 锦标赛下政治晋升制度、完善激励与约束机制、调整财税体制等途径解决我国节能减排问题。     

Impact of sulfur-in-gasoline on motor vehicle emissions in the metropolitan area of Mexico City

Light duty gasoline vehicles account for most of CO, hydrocarbons and NO_x emissions to the urban environment in Mexico City. From the beginning of year 2001, vehicles comply with Tier 1 emissions standards. Two types of Regular gasoline are available in the country. In those ozone non-attainment areas Regular oxygenated gasoline with an average of 450 ppm S is available, while on the rest of the country, a gasoline of 750 ppm S, is sold. It is anticipated then that many or all Tier 1 vehicles in ozone non-attainment zones would be occasionally or regularly fueled with high sulfur gasoline. In this work we evaluate the impact of sulfur on new, and in-use vehicles model years 1993-2001 with gasoline ranging from 90 to 815 ppm S. It is interesting to note that for Tier 0 vehicles, CO emissions are above the standard limits at all sulfur levels, while Tier 1 vehicles are very close to the limits for NO_x emissions.     

Comparative wear performance of titanium based coatings for automotive applications using exhaust gas recirculation

This paper reports tribological characterization of titanium based coatings ion bonded on steel balls for automotive applications using exhaust gas recirculation (EGR). It is well known that lubricating oil drawn from EGR operated engine is contaminated with soot and higher amounts of wear debris compared to non-EGR operated engine. In this study, steel balls coated with TiN, TiAlN and TiCN are investigated in both fresh lubricating oil and EGR stressed oil for a comparative assessment of their wear characteristics in two mediums. Normal load was applied on the samples, tested against a rotating cast iron disk, simulating ring-liner interaction. In each experiment, about one quarter of disk was dipped in the oil (a) to ensure the presence of a thin oil film on the disk-ball interface during the experiment, and (b) to avoid exposure of the worn surface to atmospheric air. The results reveal that the wear rates of the coatings based on the change in the scar diameters of the samples, tested in EGR oil was 2-4 times higher than that of fresh lubricating oil. It was found that despite lowest hardness, TiN coated samples showed smaller scar diameters than TiAlN and TiCN coated samples in both lubricating oil environments. A simple geometric model was used to calculate the thickness of the coating removed as a function of the test duration. Results show that TiN coatings last for 120 min in fresh oil as compared to 30 min in the EGR oil under normal loading, whereas TiAlN and TiCN coating last for 60 and 30 min respectively in fresh oil and wear out in 15 min in EGR oil.     

浅谈电解铝厂规模电解槽容量与环境保护

本文对国内现行电解铝工业污染物排放标准提出了修改意见；阐述了电解铝厂生产规模、电解槽容量、污染物生成量。以及电解烟气净化回收与环境保护之间的关系；电解槽集气效率的计算方法；提高槽集气效率的措施以及强化环境保护。加强管理等若干问题。     

150柴油机排气摇臂成形工艺的研究

对150系列大功率高速柴油机排气摇臂的成形工艺进行了工艺分析，着重介绍了可确保排气摇臂成形、质量和合格品率提高的模锻工艺，锻模设计及其热处理工艺的研究，说明了排气摇臂成形工艺的可行性、实用性和效益性。     

采用消失模铸造工艺生产蠕铁排气出口管

介绍了消失模法生产蠕铁排气出口管的工艺过程.试验发现,采用反直浇道结合侧注的模组形式为佳,每组8件、管口朝下;涂料直接影响铸件表面积碳及皱皮倾向;并采用消失模法批量生产了蠕铁排气出口管,材料性能及金相组织达到要求,铸件壁厚均匀,表面光滑,已用于红旗轿车的部分车型.