非饱和带柴油入渗实验研究及HSSM模拟

通过土柱模拟实验研究了柴油在不同含水率、不同粒径砂土中的入渗及残留特征,并采用HSSM(Hydrocarbon Spill Screening Model)模拟了柴油在含水率为6%中砂介质中的入渗过程.结果表明:随着介质含水率增加,柴油在介质中湿润锋推进速度先增大后减小,最快速度对应含水率处于相应介质最大残余含水率40%~50%范围内,残余柴油量随介质含水率增大而减小.在细砂、中砂和粗砂3种介质,柴油入渗平均湿润锋推进速度分别为0.42,0.52,0.73cm/min;平均残余柴油量分别为98.10,68.70,48.79mL. 湿润锋推进速度及残余柴油量均与介质粒径呈负相关.HSSM拟合柴油在含水率为6%中砂介质中的湿润锋推进速度为0.5832cm/min,与实验值0.5689cm/min相比,相对误差为2.51%.HSSM能较好的模拟柴油在非饱和带入渗过程,对于土壤及地下水污染预报具有重要意义.     

FBC-DPF在柴油机颗粒物控制中的应用研究

目前针对加装FBC-DPF(燃油添加剂-柴油机颗粒捕集器)后的柴油机放特性研究较少,并且缺乏FBC-DPF对颗粒物中PAHs排放量的影响效果研究. 为全面评估加装FBC-DPF后柴油机颗粒物排放特性和FBC-DPF对柴油机尾气中的颗粒物排放污染控制效果,在发动机台架上对装有FBC-DPF的重型柴油机进行了颗粒物排放特性试验. 利用电子低压撞击仪(ELPI)测量加装FBC-DPF前、后柴油机颗粒物的数浓度与粒径分布,用玻璃纤维滤膜采集加装FBC-DPF前、后尾气中的固相PAHs,利用色谱质谱联用仪对加装FBC-DPF前、后尾气中的固相PAHs进行定量分析. 结果表明:①加装FBC-DPF后柴油机排放的颗粒物数浓度大幅降低,FBC-DPF对尾气中颗粒物的捕集效率平均值在95%左右;②加装FBC-DPF后柴油机固相PAHs总比排放量有所降低,在大负荷区域降幅在25.0%~88.0%之间;③加装FBC-DPF前的颗粒物中位直径为30~89nm,而加装FBC-DPF后的颗粒物中位直径为41~98nm,平均增幅为38.2%. 对于国Ⅳ及未来国Ⅴ柴油机排放法规,FBC-DPF是解决柴油机颗粒物排放的有效手段;此外,FBC-DPF可以大幅降低柴油机尾气中的有毒成分,并且能够适应高含硫量的燃油环境.      

Mutagenicity of diesel engine exhaust in the Ames / Salmonella assay using a direct exposure method

The aim of this study was to investigate the potential mutagenic activity of diesel engine exhaust in the Ames/Salmonella assay using a direct aerosol exposure system. So, TA 98 and TA 100 strains, with or without added S9 mix, were exposed to diesel emissions after varying degrees of filtration. Variants of these two strains, deficient in nitroreductase (TA 98NR and TA 100NR) or over-expressing O-Acetyl Transferase (YG 1024 and YG 1029), were also exposed to total (unfiltered) diesel exhaust to highlight the putative mutagenicity of any nitro-PAHs present in these emissions. Mutagenic activity of the diesel exhaust was demonstrated on Salmonella typhimurium, strains TA 100 and variants TA 100 NR and YG1029. The use of a particle filter did not modify the genotoxicity of the diesel emissions, indicating a major contribution of the gas phase to the mutagenicity of these diesel emissions. The prominent role of the particulate-associated nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) claimed by some authors working on diesel exhaust organic extracts was not confirmed by our results with native diesel exhaust exposure. Our results show that the gas phase is potentially more mutagenic than the particles alone.     

Assessment of hydrocarbon emissions from diesel invert mud residues treated in a bioreactor

Hydrocarbon emissions from a diesel invert mud residue (DIMR) were monitored while the hydrocarbons were being biodegraded in a solid‐phase bioreactor. Five to twenty percent of the reduction in diesel hydrocarbons was attributed to evaporation depending on the treatment, i.e. homogenization, cultivation, and aeration. Most of these volatile hydrocarbons were linear C₈ — C₁₂ alkanes and one‐ring aromatics. Of the treatments aeration had the largest effect on emissions; forced air through the bottom of the bioreactor cells increased emissions by three times over that of the non‐aerated cells. Cultivation increased hydrocarbon emission concentration as much as twofold over the pre‐cultivation value, however, emissions returned to the original levels within 12 hours. Homogenization had the least effect of all treatments. Diurnally, the emission rate was 40% higher in late afternoon than at midnight; the cause of which was probably atmospheric fluctuations such as temperature and solar radiation. The effects of daily atmospheric fluctuations were empirically modeled and taken into account for determining the total volume of emissions.     

Particulate and semivolatile associated aliphatic hydrocarbon exhaust emission from heavy duty diesel vehicles

The exhaust emissions from two heavy duty diesel vehicles running on eight different fuel compositions were investigated regarding their content of high molecular weight (≥ C₁₂) aliphatic/ olefinic hydrocarbons. It was concluded that the emitted amount of semi‐volatile associated aliphatic hydrocarbons (range C₁₂‐C₂₂) depend on the fuel used in the engines and that these emissions mainly consisted of uncombusted fuel components. It was also found that uncombusted engine lubrication oil was the main constituent of the emitted particulate associated aliphatic hydrocarbons (C₁₇‐C₄₀). These constituted between 58% and 95% of the total emissions of the high molecular weight aliphatic compounds. Emission factors for the total of high molecular aliphatic hydrocarbons (C₁₂‐C₄₀) were demonstrated to be in the range of 15–100 mg/km. Some individual aliphatic hydrocarbons with cocarcinogenic effects were identified and quantified in both particulate and semi‐volatile phases of the exhaust. Multivariate data analysis was used to investigate the relationship between fuel parameters and emission of semi‐volatile aliphatic emission.     

Effects of a diesel oxidation catalyst on gaseous pollutants and fine particles from an engine operating on diesel and biodiesel

The effects of a diesel oxidation catalytic (DOC) converter on diesel engine emissions were investigated on a diesel bench at various loads for two steady-state speeds using diesel fuel and B20. The DOC was very effective in hydrocarbon (HC) and CO oxidation. Approximately 90%–95% reduction in CO and 36%–70% reduction in HC were realized using the DOC. Special attention was focused on the effects of the DOC on elemental carbon (EC) and organic carbon (OC) fractions in fine particles (PM_2.5) emitted from the diesel engine. The carbonaceous compositions of PM_2.5 were analyzed by the method of thermal/optical reflectance (TOR). The results showed that total carbon (TC), OC and EC emissions for PM_2.5 from diesel fuel were generally reduced by the DOC. For diesel fuel, TC emissions decreased 22%–32% after the DOC depending on operating modes. The decrease in TC was attributed to 35%–97% decrease in OC and 3%–65% decrease in EC emissions. At low load, a significant increase in the OC/EC ratio of PM_2.5 was observed after the DOC. The effect of the DOC on the carbonaceous compositions in PM_2.5 from B20 showed different trends compared to diesel fuel. At low load, a slight increase in EC emissions and a significant decrease in OC/EC ratio of PM_2.5 after DOC were observed for B20.     

Feasibility analysis of renewable hybrid energy supply options for Masirah Island

In this paper, the assessment and modelling of alternative renewable energy systems for Masirah Island is considered. The hybrid system that is simulated comprises various combinations of wind turbines and/or photovoltaic (PV) supplemented with diesel generators and short-term battery storage. It was found from the analysis that the PV–wind–diesel hybrid system, with battery unit, has the lowest cost values as compared to solar-only or wind–diesel hybrid systems. Furthermore, the study illustrates that for a given hybrid system the presence of battery storage will reduce diesel consumption. The decrease in carbon emission, the percentage of fuel savings, the cost of energy production and the effect of wind and PV penetration are also addressed in this paper. The PV–wind–diesel hybrid option is techno-economically viable for the electrification of the Masirah Island.     

Effects of EGR,swirl augmentation techniques on combustion of biodiesel/ethanol and their blends in a diesel engine

The diminishing resources and continuously increasing cost of petroleum in association with their alarming pollution levels from diesel engines have caused an interest in finding alternative fuels to diesel which are renewable and sustainable. Emission control and engine efficiency are two most important parameters in current engine design. The impending introduction of emission standards such as Euro IV and Euro V is forcing the research towards developing new technologies for combating engine emissions. The classification of Euro IV and V norms is applicable to heavy-duty engines in Europe, where as Euro 5 is applicable to light-duty engines. This paper presents the effects of exhaust gas recirculation (EGR), swirl augmentation techniques and ethanol addition on the combustion of Honge oil methyl ester (HOME) and its blends with ethanol in a diesel engine. From the experimental work conducted, it is found that the combustion of HOME plus up to 15% ethanol blend in a diesel engine operated with optimised parameters of injection timing 23° Before Top Dead Centre and compression ratio 17.5 results in acceptable combustion emissions and improved brake thermal efficiency (BTE). The addition of ethanol increased BTE with reduced hydrocarbons (HCs), CO and smoke emissions. However, NO _x emissions increased dramatically. Use of appropriate EGR reduces NO _x to acceptable levels. The implementation of swirl augmentation techniques further resulted in increased BTE and considerable reduction in tail pipe emissions such as smoke, HCs, CO and NO _x . The effect of swirl by providing grooves on the piston was taken into consideration to find the overall biodiesel engine performance, which gives scope for further studies.     

Intelligent power supply management of an autonomous hybrid energy generator

ABSTRACT

This work deals with the optimization of an hybrid energy system used to supply an isolated site. The proposed system combines a wind turbine, a photovoltaic panel, a diesel generator and a battery bank to electrify atypical home. An energy cost-effectiveness approach is adopted in accordance with meteorological data, time profile of energy consumption, and the cost of different alternative systems. A variety of performances is obtained through simulations within the Homer Pro environment. The selection of an optimal combination is based on the maximum integration of renewable energy in the suggested system with a minimum of gas emission. According to the obtained results, the overall cost of the selected installation is about 72,900 €, with 0.415€ the unit cost of a kWh electric energy provided with a contribution of renewable energy of around 86%. Simulations show a technical and financial benefits of the different configurations obtained to supply the target site. To control the proposed hybrid energy system, a supervision algorithm is developed and implemented on TMS320F28027 DSP platform. The proposed energy system aims to take advantages of renewable energy sources and shift to conventional sources only when necessary in order to ensure source autonomy and service continuity.     

EGR率对农用单缸柴油机燃用生物柴油的NOx与PM排放特性影响分析

单缸柴油机作为小型农用机械不可或缺的动力源,在使用过程中会产生大量污染物.其中氮氧化合物（NO_x）和颗粒（PM）是气溶胶的主要组成部分,对大气环境造成了严重污染.为有效改善农用单缸柴油机NO_x和PM排放,本研究通过添加生物柴油对柴油进行改质以及采用机内EGR净化技术两种方案,测量了柴油机分别燃用柴油B0,生物柴油调合燃料B20、B50在不同EGR率下的NO_x和PM排放.结果表明,采用EGR技术能够明显改善柴油机的NO_x排放,但同时会引起碳烟排放的增加.通过在柴油中添加生物柴油能够在一定程度上降低碳烟排放,其中高负荷、大EGR率条件下的改善最为明显.在2000 r·min^-1、75%负荷,EGR率为30%时,燃用B50的碳烟排放与燃用B0相比降低了47.3%.总体上柴油中添加生物柴油与EGR技术共同作用能够有效降低柴油机高负荷工况时的颗粒排放总数量.