Analysis of elliptical diesel nozzle spray dynamics using a one-way coupled spray model

The elliptical nozzle has the potential ability to increase the air-fuel mixture quality. A one-way coupled spray model and Homogenous Relaxation Model (HRM) was adopted to investigate the spray behaviors and the air-fuel mixture progress in real diesel combustion chamber with the application of elliptical and circular diesel nozzle. The results indicated that the spray cone angle and the air entrainment mass of elliptical nozzle were larger than that of the circular nozzle, while the spray penetration of the elliptical nozzle which the aspect ratio is 1.5 and 2 was shortened by 11% and 8.3% as compared to circular spray respectively. Also, the air entrainment mass of the elliptical spray with a ratio of 1.5 and 2 increased by 60% and 35% as compared with circular spray respectively. Furthermore, the partial equivalent ratio and the high concentration area in the cylinder is reduced for elliptical nozzle, and the air-fuel mixture is more uniform. The fuel evaporation rate of elliptical spray is always higher than that of the circular spray.

Spatial and Temporal Distribution Characteristics and Source Apportionment of VOCs in Lianyungang City in 2018

From April to September 2018, five sampling sites were selected in Lianyungang City for volatile organic compounds (VOCs) analysis, including two sampling sites in the urban area (Lianyungang City Environmental Monitoring Supersite and Mine Design Institute), one sampling site in the industrial area (Deyuan Pharmaceutical Factory), and two sampling sites from the suburb (Hugou Management Office and YuehaiLou). The results showed that the mean VOCs concentration followed this pattern: industrial area (36.06 ± 12.2 µg m−3) > urban area (33.47 ± 13.0 µg m−3) > suburban area (27.68 ± 9.8 µg m−3). The seasonal variation of the VOCs trend in the urban and suburban areas was relatively consistent, which was different from that in industrial areas. The concentration levels of VOCs components in urban and industrial areas were relatively close, which were significantly higher than that in suburban areas. The possible sources and relative importance of VOCs in Lianyungang City atmosphere were measured by the characteristic ratio of toluene/benzene (T/B), ethane/acetylene (E/E) and isopentane/TVOCs. The contribution of traffic sources to the VOCs in Lianyungang City was significant (T/B ~ 2), and there were obvious aging phenomena in the five sampling sites (E/E > 4). The ratio of isopentane/TVOCs in the contribution of gasoline volatilization sources in urban and suburban areas was significantly bigger than that in industrial areas. According to the maximum incremental reactivity (MIR) method, aromatics (40.32–58.09%) contributed the most to ozone formation potential (OFP) at the five sampling sites. The top 10 OFP species showed that controlling n-hexane and aromatics, such as benzene, toluene, xylene, and trimethylbenzene in Lianyungang City can effectively control ozone generation. Nineteen typical VOCs components were selected and the sources of VOCs from five sampling points were analyzed by the principal component analysis (PCA) model. The sources of VOCs in different areas in Lianyungang were relatively consistent. Five sources were analyzed at the two sampling sites in the urban area: industrial emission + plants, vehicle exhaust, fuel evaporation, combustion and industrial raw materials. Four sources were analyzed in the industrial area: industrial emission + plants, vehicle exhaust, fuel evaporation and combustion. Five sources were analyzed at the two sampling sites in the suburban area: industrial emission + plants, vehicle exhaust, fuel evaporation, combustion and solvent usage.

Efficiency enhancement of the vehicle fuel tank ventilation system by improving its architecture and design

Hydrocarbon emissions from fuel evaporation contribute significantly to the total emissions of harmful substances from vehicles with forced spark ignition. To meet the legally established standards for limiting hydrocarbon emissions from evaporation, all current vehicles use fuel vapor control systems. The design of the system can vary and depends on the sales market of a particular vehicle. This article describes the development of this system for the market of the Russian Federation, as well as optimization for promising sales markets with more stringent environmental requirements.

Measurement report: Summertime and wintertime VOCs in Houston: Source apportionment and spatial distribution of source origins

The seasonal variations of volatile organic compounds (VOCs) was studied in the Houston metropolitan area in the summertime and wintertime of 2018. The analysis of hourly measurements obtained from the automated gas chromatograph (auto-GC) network showed the total VOC average concentrations of 28.68 ppbC in the summertime and 33.92 ppbC in the wintertime. The largest contributions came from alkane compounds, which accounted for 61 % and 82 % of VOCs in the summer and winter, respectively. We performed principal component analysis (PCA) and Positive Matrix Factorization (PMF) and identified seven factors in the summertime and six factors in the wintertime, among which alkane species formed three factors according to their rate of reactions in both seasons: (1) the emissions of long-lived tracers from oil and natural gas (ONG long-lived species), (2) fuel evaporation, and (3) the emissions of short-lived tracers from oil and natural gas (ONG short-lived species). Two other similar factors were (4) emissions of aromatic compounds and (5) alkene tracers of ethylene and propylene. Summertime factor 6 was associated with acetylene, and one extra summertime factor 7 was influenced by the biogenic emissions. The factor 6 of wintertime was affected by vehicle exhaust. Higher nighttime and lower daytime values of the ethylene/acetylene ratios during the summertime indicated the stronger impacts of ethylene photochemical degradation. Also, the exploration of the photochemical processes of the VOCs showed that the ethylene and propylene had the highest contributions to the summertime and wintertime ozone formation as well as the emissions of the isoprene, which showed a high impact on summertime ozone. Our results acknowledged that ethylene and propylene continue to be significant emissions of VOCs, and their emissions control would help the mitigation of the ozone of Ship Channel. Based on trajectory analysis, we identified main VOC emission sources in Houston Ship Channel (HSC) local industrial areas and regions south of the HSC. Ambient VOC concentrations measured at the HSC were influenced by the emissions from the petrochemical sectors and industrial complexes, especially from the Baytown refinery and Bayport industrial district next to the HSC and Galveston Bay refineries at the south of the study area.

Sisal xylem fibre-based activated carbon fibres for fuel adsorption: effect of thermal stabilization of diammonium phosphate

Activated carbon fibres (ACFs) are considered as the next generation of activated carbon products. However, lack of structural diversity in pore structure and high prices of raw materials for ACFs has restrained the development of ACF materials. In this paper, a sisal-based activated carbon fibre (SACF) material was prepared from sisal wastes with a unique thermal stabilization treatment to maintain fibrous shapes of SACFs while dispersing in solutions, and the SACFs were prepared as raw fibre materials for fuel evaporation emissions controlling products. Experimental results of N 2 adsorption showed that SACF has a typical I-type adsorption isotherm, with specific surface area of SACF samples of approximately 1200 m 2 g −1 , and mainly microporous pore structure. Compared with commercial samples (specific surface area, 1841.29 m 2 g −1 ), the butane working capacities of SACF for advanced fuel evaporation emissions controlling product was 0.4 g/100 ml higher. Furthermore, two dynamic models, Thomas model and Clark model, were applied to adsorption breakthrough data, which showed excellent fit. And it indicated from the adsorption breakthrough curves and parameters of both models that the SACF has better performance in fuel adsorption and desorption process than the commercial samples.

ANALYSIS OF THERMODYNAMIC PROCESSES IN DIESEL ENGINES

The article analyzes the first law of thermodynamics in terms of the classical law of energy conservation for thermodynamic systems formulated by J. R. Mayer, J. P. Joule and L. Helmholtz, as applied to contemporary piston engines with compression mixture in diesels. The prevailing factor in the system functioning (diesel engine) is the internal energy of a working mixture, rather than the heat input, as it was in the classical treatment of the first thermodynamic law. That is why, the wording of the law should be usefully changed from “heat delivered to the thermodynamic system is used for changing its internal energy and doing work against external forces” to “internal energy of a thermodynamic system determines the amount of heat given off inside the system and amount of work against external forces”. The mathematical form of the law and graphical interpretation of the theoretical thermodynamic Trinkler-Sabathe cycle are modified, accordingly. It has been stated that in practice the achievement of high technical and economic indices is provided by increasing the quality of working mixture: complete fuel evaporation in hot and moving medium, air/fuel ratio in the mixture in line with adopted standards of air/fuel proportion, high level of mixture homogeneity. The initial index to ensure highly efficient operation for reciprocating internal-combustion engines will be the internal energy of the working mixture which will determine the amount of heat emitted in the cylinder during mixture combustion and the amount of completed work against external forces.