Quantum-Chemical Calculation of Reactive Fuels as H-Acids

Abstract

The theoretical evaluation of acid strength reactive fuels, through quantum-chemical calculation by the method CNDO/2 of the charges on hydrogen atoms, which correlate with the universal index of acidity is presented. Correlations defining relationship of some parameters of combustion with the accounting parameters of acidic strength of the fuels are established to oxygen.     

Leveling the playing field of transportation fuels: Accounting for indirect emissions of natural gas

Natural gas transportation fuels are credited in prior studies with greenhouse gas emissions savings relative to petroleum-based fuels and relative to the total emissions of biofuels. These analyses, however, overlook a source of potentially large indirect emissions from natural gas transportation fuels, namely the emissions from incremental coal-fired generation caused by price-induced substitutions away from natural-gas-fired electricity generation. Because coal-fired generation emits substantially more greenhouse gases and criteria air pollutants than natural-gas-fired generation, this indirect coal-use change effect diminishes potential emissions savings from natural gas transportation fuels. Estimates from a parameterized multi-market model suggest the indirect coal-use change effect rivals in magnitude the indirect land-use change effect of biofuels and renders natural gas fuels as carbon intensive as petroleum fuels.     

Oxidative processes of desulfurization of liquid fuels

Environmental concerns have introduced a need to remove sulfur‐containing compounds from light oil. As oxidative desulfurization is conducted under very mild reaction conditions, much attention has recently been devoted to this process. In this contribution, the developments in selective removal of organosulfur compounds present in liquid fuels via oxidative desulfurization, including both chemical oxidation and biodesulfurization, are reviewed. At the end of each section, a brief account of the research directions needed in this field is also included. Copyright © 2010 Society of Chemical Industry     

CO2 valorisation based on Fe3O4/FeO thermochemical redox reactions using concentrated solar energy

The solar‐driven dissociation of CO₂ by thermochemical looping via Fe₃O₄/FeO redox reactions is considered. The process recycles and upgrades CO₂ to ultimately produce chemical synthetic fuels from high‐temperature solar heat and abundant feedstock as only inputs. The two‐step process encompasses the endothermic reduction of Fe₃O₄ to FeO and O₂ using concentrated solar energy as the high‐temperature source for reaction enthalpy and the nonsolar exothermic oxidation of FeO with CO₂ to generate CO. The resulting Fe₃O₄ is then recycled to the first step and carbon monoxide can be further processed to syngas and serve as the building block to synthesise various synfuels by catalytic processes. This study examines the thermodynamics and kinetics of the pertinent reactions. The high‐temperature thermal reduction of Fe₃O₄ is realised above the oxide melting point by using concentrated solar thermal power. The reactivity of the synthesised FeO‐rich material with CO₂ at moderate temperature is then investigated by thermogravimetry. FeO conversion higher than 90% can be achieved with reaction rates depending on temperature, particle size and CO₂ concentration. The solar‐produced nonstoichiometric FeO is more reactive with CO₂ than commercial pure FeO. Activation energies of 57 and 68 kJ/mol are derived from a kinetic analysis of the CO₂‐splitting reaction in the range of 600 °C to 800 °C with solar and commercial FeO, respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

Measurement and calculation of neutron densities in BWR high burn-up fuels

A neutron-scanning device was developed for measuring accurate neutron densities of BWR high burn-up fuels up to 65 GWd tU⁻¹. Characteristic test of this device was done with a ²⁵²Cf source and adopted to measure axial distributions of neutron densities of BWR spent fuels with various enrichments (2.0–3.4%), which had been irradiated up to 60 GWd tU⁻¹ at Fukushima Daini Nuclear Power Station Unit 2(2F-2). We found the measured neutron densities were proportional to about fourth power of the corresponding burn-up values. The neutron densities calculated by the ORIGEN2.1 code and various cross section libraries showed good agreements with the measured ones in profile and absolute value except for BWR-UE file mainly based on ENDF/B-IV. The BS240J32 library based on JENDL3.2 was the best among the investigated libraries.     

Carbon nanofluids flow behavior in novel composites

Nanocomposite materials have broadened significantly to encompass a large variety of systems, made of distinctly dissimilar components and mixed at the nanometer scale. This rapidly expanding field is generating many exciting new advanced composites with promising properties. However, during the fabrication of nanocomposites, many problems could arise and remain as challenging tasks. One such problem is controlling of the nanofluid flow behavior around the microfiber perform as in case of Resin Transfer Molding (RTM) process because of the high resin viscosity and the low preform permeability. In this paper, a two-dimensional simulation model based on the Eulerian multiphase approach has been performed and solved to investigate and predict the flow characteristics of a carbon nanofluid around a staggered microfiber matrix. ‘The interactions between the microfiber walls and the interfacial nanofluid layers during the flow process have been also studied. Based on the predicted results an energy “imbalance” technique has been applied between the microfiber walls and the interfacial nanofluid layers allowing them the potential to flow more smoothly around the microfiber walls to prevent any potential sticking on the microfiber walls.     

Taxation on vehicle fuels: its impacts on switching to cleaner fuels

Vehicular consumption of fossil fuel contributes over 90% of air pollution in Hong Kong. A key strategy to improve Hong Kong's air quality is to discourage dirty fuels (e.g., leaded petrol and high-sulphur diesel) and to promote the use of clean fuels (e.g., low-sulphur diesel and liquefied petroleum gas (LPG)). This paper presents the empirical evidence on the effectiveness of the Government's clean fuel programs that offer tax subsidy to lower the consumption cost of such fuels. For the cases of unleaded petrol and ultra-low-sulphur diesel, lower fuel duties were offered so that the prices of these fuels were below those of leaded petrol and conventional diesel. Conventional petrol and diesel were phased out. In order to decide on the level of fuel duty concessions required to introduce LPG for taxis and bio-diesel for other vehicles, various Government-run trial programs were introduced to obtain cost estimates of using these alternative cleaner fuels. LPG using vehicles were subsequently exempted from the fuel duty in order to attract taxi and light bus operators to switch to LPG. It is apparent that the higher the subsidy, the faster is the rate at which switching to cleaner fuels takes place.     

Chemical-Enhanced Washing for Remediation of Soils Contaminated with Marine Diesel Fuel in the Presence/Absence of Pb

The effects of the operating conditions, the initial concentrations of marine diesel fuel (MDF) and the coexisting Pb in the soil, and the ethylene diamine tetra acetic salt (EDTA) in solution on MDF removal by sodium dodecyl sulfate (SDS) washing were extensively investigated with the aim of optimizing the process parameters and determining the MDF removal efficiency by SDS under different contamination conditions. The experimental results from batch tests indicated that the majority of MDF was removed by SDS in the first 2?h, and its optimal pH was nearly neutral. Increasing the SDS concentration linearly increased the MDF removal efficiency. At a given SDS concentration, the removal efficiency was dependent on the existing forms of MDF in soils, and the free phase of MDF was found to be more easily removed than the adsorbed phase. MDF removal by SDS was significantly reduced by the coexisting Pb in soils, which likely forms a complexation with SDS and thereby enhances the partitioning of MDF in the soil by the re-adsorption of released MDF onto the hydrophobic tails of the adsorbed SDS. EDTA alone, or with SDS, could remove MDF, but the remaining MDF in the contaminated soil after EDTA washing became more difficult to be removed by SDS. Therefore, the EDTA washing followed by SDS washing is not recommended for MDF removal.     

黑龙江省汽车代用燃料的可行性研究

本文简述了国内、外汽车汽油代用燃料的现状与发展趋势。详细分析了液化石油气（LPG）、天然气（NG）、甲醇及乙醇等燃料的特点、毒性和安全性、使用经济性等。并对我省甲醇生产的情况进行了分析，探讨了甲醇汽油在使用过程中的优、缺点。开展了甲醇汽油发动机台架实验研究，在发动机负荷特性及发动机怠速工况下的排放实验中发现，甲醇汽油的某些性能优于汽油。黑龙江省首选汽车代用燃料应为甲醇汽油。