Techno-economic study of hydrogen production using CSP technology

There are different processes for hydrogen production and different sources of energy could be used to drive these processes. However, a hydrogen production technique won't insure market penetration unless it succeeds in securing the economic competitiveness.In the present work, techno-economic study of the solar-electrolysis based hydrogen production techniques is carried out. The present study is limited to the case of hydrogen production using a hybrid solar parabolic trough-gas power plant-electrolysis system. The effect on hydrogen production cost of different factors, such the direct normal irradiance and the solar fraction are investigated.This technique of hydrogen production is considered for the case of Algeria. In order to determine the effect of the climatic conditions on the cost of hydrogen production, two different sites have been chosen: one in Northern Algeria and the other one in Southern Algeria.The results indicate that the cost of hydrogen production is dominated by the cost of hydrogen related to the cost of energy production. This cost is highly dependent on solar fraction and solar insolation. The results show also that solar CSP based hydrogen production technique is more competitive than the conventional PV based hydrogen production technique but as competitive or less competitive than CPV based hydrogen production technique.     

A novel route to synthesis of glycerol dimethyl ether from epichlorohydrin with high selectivity

The effective utilization of glycerol, a by-product in the production of biodiesel, into useful chemicals is desirable from the viewpoint of green chemistry. With this in mind, a novel and highly selective route to synthesizing glycerol dimethyl ether (2,3-dimethoxy-1-propanol), a potential fuel additive, from glycerol was proposed. This route uses both glycerol and methanol as starting materials, takes epichlorohydrin as an intermediate product, and utilizes HCl as a recycling agent. Hereinto, the key step of this route is the reaction between epichlorohydrin and methanol to produce 2,3-dimethoxy-1-propanol which is identified by GC–MS, ESI-MS, IR and NMR. The thermodynamics of this reaction was analyzed and the result showed that the thermodynamics of a reaction was favorable and a high product yield was expected. The effect of various parameters such as kind of acid catalyst, molar ratio of epichlorohydrin to methanol, reaction temperature and reaction time was studied. Among various acid catalysts investigated, the acidic ionic liquid [HSO₃-b-N(CH₃)₃]HSO₄ exhibited the highest activity and selectivity: conversion of epichlorohydrin of 100% and selectivity of 2,3-dimethoxy-1-propanol of 99% at 393 K, 10 h, an initial pressure of 0.1 MPa and a molar ratio of catalyst:ECH:CH₃OH of 0.01:1:5. After the reaction, [HSO₃-b-N(CH₃)₃]HSO₄ was separated by vacuum distillation and then reused for the next cycle directly. The results showed that the product selectivity remained at about 94% but the conversion of epichlorohydrin dropped to 75% after being used five times. Subsequently, a reaction mechanism for the synthesis of 2,3-dimethoxy-1-propanol from epichlorohydrin and methanol was proposed.     

淋滤条件下水泥固化铅污染高岭土的强度及 微观特性的研究

通过半动态淋滤试验,研究淋滤液初始pH=2,4,7时水泥固化铅污染土的强度、微观和钙溶出特性。无侧限抗压强度试验及钙溶出率（CFR_Ca）结果表明：半动态淋滤试验使试样无侧限抗压强度（q_u）较标准养护39 d试样降低了1%～42%；淋滤液初始pH=2时,CFR_Ca为pH=4或7时的2～7倍,而pH=4与7时q_u及CFR_Ca差别均不明显；水泥掺量由12%提高到18%时,q_u增大了35%～98%,CFR_Ca降低了40%～58%；固化铅污染土较固化未污染土,其q_u小50%～68%,而CFR_Ca大29%～175%。试样无侧限抗压强度比q_r（淋滤后试样q_u/标准养护39 d试样q_u）与CFR_Ca在双对数坐标下呈现良好线性关系：随CFR_Ca增大,q_r减小,说明钙的溶出是控制固化污染土/未污染土强度的主要因素之一。X射线衍射、扫描电镜及压汞试验结果表明,高浓度铅抑制水泥水化/火山灰反应,固化铅污染土与固化未污染土孔隙分布分别呈单峰和双峰特征,固化铅污染土中铅形成Si-O-Pb结合体、PbAl₂O₄、CaPbO₃等沉淀是铅固化稳定化的主要机理之一。     

Robust oxygen fraction estimation for conventional and premixed charge compression ignition engines with variable valve actuation

In-cylinder oxygen fraction serves as a critical control input to advanced combustion strategies, but is extremely difficult to measure on production engines. Fortunately, the in-cylinder oxygen levels can be estimated based on accurate estimates or measurements of the oxygen fraction in the intake and exhaust manifolds, the in-cylinder charge mass, and the residual mass. This paper outlines such a physically based, generalizable strategy to estimate the in-cylinder oxygen fraction from only production viable measurements or estimates of exhaust oxygen fraction, fresh air flow, charge flow, fuel flow, turbine flow and EGR flow. While several of these flows are accurately measured or estimated, significant errors in the turbine and EGR flows are commonly observed and can highly degrade the accuracy of any calculations which utilize these flows. An EGR flow estimator was developed to improve the accuracy of this flow measurement over the stock engine control module (ECM) method and is detailed in this paper. Furthermore, the in-cylinder oxygen estimation algorithm is developed, and proven, to be robust to turbine flow errors. Regulation of in-cylinder oxygen levels is of interest for not only in conventional combustion modes but also in advanced combustion strategies such as premixed charge compression ignition. The proposed oxygen fraction estimator is designed such that its performance and stability is ensured in both conventional and advanced combustion modes. The model-based observer estimates the oxygen fractions to be within 0.5% O₂ and is shown to have exponential estimator error convergence with a time constant less than 0.05 s, even with turbine flow errors of up to 25%.     

Use of heavy fraction of bio-oil as fuel for hydrogen production in iron-based chemical looping process

Chemical looping hydrogen (CLH) process with renewable energy sources as fuel shows the potential of producing pure hydrogen with inherent capture of CO₂ in a low-cost and sustainable way. The heavy fraction (HF) of bio-oil, derived from the fast pyrolysis of biomass and characterized as an energy carrier with difficulty in upgrading itself to bio-fuel or chemicals, was used in this study to generate H₂. Four low-cost iron-based oxygen carriers including an ilmenite and three iron ores were initially evaluated with respect to their reducibility and the ability to minimize carbon or iron carbide (Fe₃C) formation in a thermogravimetric analyzer (TGA). The reactivity and cyclic performance of the selected best candidate was then assessed in a laboratory scale fixed-bed reactor with HF bio-oil as fuel. The screening test in TGA showed that ilmenite was superior over the three iron ores in terms of promoting CO conversion and minimizing carbon or Fe₃C formation. Ilmenite could maintain its increasing reducibility with the increase of surrounding CO concentration, in contrast with the iron ores that were deactivated seriously by the formed carbon or Fe₃C. Subsequent CLH test with ilmenite and HF bio-oil showed that the reducibility and H₂ production capacity of ilmenite were strongly dependent on the operating temperature. The steam oxidation step at 950 °C yielded H₂ concentration and hydrogen yield exceeding all of those observed at the other investigated temperatures because of the deepest reduction degree of ilmenite at 950 °C. The decrease in the reducibility and H₂ production capacity of ilmenite in the cyclic test could be ascribed to the poorer physical structure of ilmenite with cycles.     

Total radiative heat loss and radiation distribution of liquid pool fire flames

The radiative characteristics of laboratory-scale pool fire flames have been studied in detail. Experiments were conducted in the ASTM E2058/ISO 12136 Fire Propagation Apparatus (FPA). Eleven liquid fuels with different sooting propensities, including alcohols and alkanes, burning in a 9.5 cm diameter quartz dish were considered. Radiative power distribution (along the flame axis) and global radiant emission were measured for all the fuels by using slit and wide-view-angle radiometers, respectively. The effects of measurement location and fuel type on the measured data were investigated. Radiation distribution profiles for a given fuel, when adequately normalized, show little sensitivity to the horizontal separation distance of the slit radiometer. Fuels with similar chemical structures exhibit similar distributions, consistent with flame image analyses. The radiative power distributions along with the wide-view-angle radiometer data were used to derive radiant fractions for the pool fires studied by applying a multiple-point source (MPS) radiation model. To examine the sensitivity of the calculated radiant fractions to the measurement location, the position of the wide-view-angle radiometer was considerably varied both vertically and horizontally. The results show that the radiant fractions derived based on the measured radiative power distribution are independent of the location of the wide-view-angle radiometer and consistent with literature values. Therefore, the approach developed in this study presents a flexible methodology apt for the accurate determination of radiation properties of diffusion flames in a laboratory setting.     

High selectivity of erythritol production from glycerol by Yarrowia lipolytica

The effect of different vitamins and nitrogen sources on the yield, productivity and selectivity of erythritol production from glycerol in batch and fed-batch cultures by Yarrowia lipolytica Wratislavia K1 strain was examined in the study.Thiamine was a vitamin necessary for efficient erythritol production and the yeast extract (YE) turned out to be its best source. The YE was additionally a very good source of nitrogen in this process. Erythritol production may be efficient in the media containing only yeast extract and crude glycerol. The application of a high substrate concentration (325 kg m⁻³) in the fed-batch system with pulsed addition of glycerol resulted in erythritol production of 201.2 kg m⁻³ after 168 h of cultivation. The mass fraction of by-products, such as other polyols and organic acids, did not exceed 10%. The study showed that by-products formation could be significantly reduced by the addition of a nitrogen source after glycerol depletion from the media. Wratislavia K1 strain does not utilize erythritol in the presence of other carbon sources and this feature was used in order to increase product selectivity up to 99.7% and protein content in yeast biomass up to 28.7%. The factors determining the use of biomass as animal feed, i.e. protein concentration and presence of metal ions, were discussed as well.     

Electricity generation and microbial community structure of air-cathode microbial fuel cells powered with the organic fraction of municipal solid waste and inoculated with different seeds

The organic fraction of municipal solid waste (OFMSW), normally exceeding 60% of the waste stream in developing countries, could constitute a valuable source of feed for microbial fuel cells (MFCs). This study tested the start-up of two sets of OFMSW-fed air-cathode MFCs inoculated with wastewater sludge or cattle manure. The maximum power density obtained was 123 ± 41 mW m⁻² in the manure-seeded MFCs and 116 ± 29 mW m⁻² in the wastewater-seeded MFCs. Coulombic efficiencies ranged between 24 ± 5% (manure-seeded MFCs) and 23 ± 2% (wastewater-seeded MFCs). Chemical oxygen demand removal was >86% in all the MFCs and carbohydrate removal >98%. Microbial community analysis using 16S rRNA gene pyrosequencing demonstrated the dominance of the phylum Firmicutes (67%) on the anode suggesting the possible role of members of this phylum in electricity generation. Principal coordinate analysis showed that the microbial community structure in replicate MFCs converged regardless of the inoculum source. This study demonstrates efficient electricity production coupled with organic treatment in OFMSW-fueled MFCs inoculated with manure or wastewater.     

New empirical correlation for estimation of vaporization enthalpy of algerian saharan blend petroleum fractions

A Real-coded Genetic Algorithm has been used to develop a new correlation to estimate the enthalpy of vaporization for pure compounds and petroleum fractions as a function of the normal boiling point and specific gravity. In developing the correlation 80% of the data was used and the remaining are used for validation. The results of the proposed correlations are compared to others in literature. The comparison indicates that the proposed model is simple to use and more accurate than the most common correlations for predicting the enthalpy of vaporization of pure compounds and petroleum fractions.