Gaseous Fuel Research Papers - Academia.edu (original) (raw)

Baseret på simulationer af inhalerings eksponering, er det konkluderet at udskiftning af luft i forholdet 2.2. vil medføre en markant reduktion i inhalerings eksponering. Vigtigheden af disse emissioner af helbredsmaessige hensyn... more

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- Mechanical Engineering, Chemical Engineering, Combustion, Natural Gas

The initiation of turbulent non-premixed combustion of gaseous fuels through autoignition and through spark ignition is reviewed, motivated by the increasing relevance of these phenomena for new combustion technologies. The fundamentals of the associated turbulent-chemistry interactions are emphasized. Background information from corresponding laminar flow problems, relevant turbulent combustion modelling approaches, and the ignition of turbulent sprays are included. For both autoignition and spark ignition, examination of the reaction zones in mixture fraction space is revealing. We review experimental and numerical data on the stochastic nature of the emergence of autoignition kernels and of the creation of kernels and subsequent flame establishment following spark ignition, aiming to reveal the particular facet of the turbulence causing the stochasticity. In contrast to fullyfledged turbulent combustion where the effects of turbulence on the reaction are reasonably wellestablished, at least qualitatively, here the turbulence can cause trends that are not straightforward. Autoignition occurs usually away from stoichiometry at a ''most reactive mixture fraction'', which can be approximately determined from homogeneous or laminar flow autoignition calculations, and at locations in the turbulent flow with low scalar dissipation. Such locations may be the cores of vortices. Once autoignition has occurred at a time that is mostly affected by the history of the conditional scalar dissipation, the relative magnitudes of convection, diffusion and reaction can affect the stabilisation height of flames in sprays or jets. Modelling efforts based on the Conditional Moment Closure, advanced flamelet approaches, and the transported PDF method seem suitable for capturing many, but not yet all, of the trends observed in DNS or experiment. Further experiments and DNS of realistic fuels and at conditions demonstrating chemical complexities must be performed to examine more fully the effects of scalar dissipation and its fluctuations on pre-ignition reaction zones. The statistics of the first appearance of autoignition in transient problems and its connection with the mixing field must also be studied. Ignition from a localised spark has a stochastic character that depends on the mixture fraction sampled at the spark location and duration and the local scalar dissipation. The success or not of the subsequent flame depends on the development of turbulent edge or stratified flames. Only preliminary data exist on the propagation speed of such flames and on their quenching. A lot remains to be done on turbulent edge flame propagation in unreacted and partially-reacted mixtures with inhomogeneities, turbulent flame propagation in non-uniformly dispersed droplet mists, and the transient stabilisation process of recirculating flames. The nature of the flame generation process at very short timescales, i.e. before any appreciable propagation, by sparking in inhomogeneous mixtures needs also to be examined. The development of high repetition rate diagnostics, for single-and two-phase flows, and the development of modelling approaches capturing both premixed and non-premixed reaction zones in gaseous and spray combustion are necessary.

- by Epaminondas Mastorakos
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- Mechanical Engineering, Chemical Engineering, Convection, Turbulence

Fossil fuels are exhausting day by day at a very faster rate due to excessive demand for energy.
Diesel engines are important prime movers used in different industries. When liquid petroleum fuels are
burnt in diesel engines they emit harmful exhaust emissions which pollute the environment and may
cause severe chronic diseases. Hence to mitigate over-dependency of crude oil and to protect the
environment from harmful emissions, different engine experts and scientists have proposed dual fuel
combustion technology to utilize low emissions renewable gaseous fuels without compromising its
performance. Most of the work in the literature concentrate on utilizing gaseous fuels such as CNG, LPG,
biogas, and hydrogen whereas very little quantum of work has been done to utilize acetylene in the IC
engine. The higher flame velocity, high auto-ignition temperature, and high calorific value are the
important combustion properties of acetylene which makes it more advantageous in CI engine than the
available feedstock. The acetylene can be easily produced from calcium carbonate and water. Hence, the
author has considered acetylene as a primary fuel in the present study and diesel as a pilot fuel in the
modified CI engine. In this experimental investigation, the author has optimized the flow rate of acetylene
by analyzing the performance and emission characteristics of the acetylene fuelled diesel engine at
different loads and finally, the obtained results were compared with the neat diesel. The acetylene was
inducted at a different gas flow rate of 2 LPM, 3 LPM, and 5 LPM. The results show that when acetylene
induction takes place at 2 LPM, the brake thermal efficiency (BTE) increases by 1.4 % at full load during
dual fuel mode compared to neat diesel. Brake specific energy consumption (BSEC) increases during
acetylene induction whereas carbon monoxide, hydrocarbon, and smoke decrease particularly at medium
to high engine loads this may be due to homogenous charge mixture formation, leading to stable
combustion. However, there is a slight increase in oxides of nitrogen emissions, which may be due to
higher flame speed causing uncontrolled combustion at peak loads relative to baseline diesel.

- by ROSHAN RAMAN
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- Diesel engines, Acetylene, Dual Fuel Engine, Gaseous Fuel

Grass is an excellent energy crop due to long persistence of high yields accompanied by low energy inputs. Approximately 91% of Irish agricultural land is under grass. The national herd has decreased and will continue to do so. Cross compliance does not encourage the conversion of permanent pastureland to arable land; thus we have and will continue to have increased quantities of excess grassland. Therefore, grass must be considered a significant source of biomass. Current grass species and cultivation practices are favourable for anaerobic digestion (AD), which is a mature technology. Upgrading biogas to biomethane, injecting into the gas grid, leads to an effective bioenergy system complete with distribution to all major cities and 620,000 houses. The Renewable Energy Directive allows a double credit for biofuels derived from residues and lignocellulosic material (such as grass). It is shown that 100,000 ha of grass (2.3% of agricultural land) will allow compliance with the 10% renewable energy in transport target for 2010. Alternatively, this would substitute for 35% of residential gas consumption. Reactor design must take account of the specific feedstock or combinations of feedstock; the reactor must be suited to the feedstock. This is not technically difficult. Of significant concern in the sustainability of the biofuel produced is the parasitic energy demand of the process and the vehicle efficiency. Emission reductions are optimised by the use of green electricity and the use of biomass for thermal energy input. On a field-to-wheel basis, it is essential that the vehicle operating on biomethane has an equivalent efficiency (expressed as MJ/km) as the displaced fossil fuel. The Renewable Energy Directive requires an emission savings of 60% compared with the displaced fuel for new facilities constructed after 2017. This is readily achieved for grass biomethane through optimisation of the system. Allowing for carbon (C) sequestration in grassland of 0.6 t C ha/year will lead to emissions savings of 89%. This would suggest that grass biomethane is one of the most sustainable indigenous, non-residue-based transport biofuels. The economics of biomethane are shown to be difficult. There is a requirement for innovative policy and marketing of the industry. A compressed natural gas transport fuel market is an essential prerequisite to using biomethane as a transport fuel. Mandating a certain percentage of biomethane in natural gas sales is of benefit to biomethane as both a transport and a thermal biofuel. Government policy is required to support a biomethane industry. Further research is required in the following areas:
Bioresource mapping: This includes the creation of a Geographical Information System to highlight sources of the organic fraction of municipal solid waste (OFMSW), slurry, slaughter waste and areas of high-yielding silage production. The system would include distribution systems (natural gas grid, electricity grid) and demand nodes (e.g. transport fleets, district heating, new towns) to propose areas with significant potential for biomethane production.
Assessment of biomethane facilities: This includes full life-cycle analysis of different biomethane facilities, including co-digestion of slurries and grass silage, mono-digestion of OFMSW, and mono-digestion of slaughter wastes. The research should allow assessment of the cost of the produced biomethane.
Digester design: This basic research should assess optimal digester systems for different feedstocks.
Agricultural impact of AD: This research includes monitoring carbon sequestration in grasslands where silage is cut and digestate is applied. This should be compared with carbon sequestration on grazed pastures. The fertiliser value of different digestates needs to be assessed along with the emissions associated with application of digestate. The research should also assess the effect on biodiversity.

- by Dr. Abdul-Sattar Nizami and +1
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- Renewable Energy, Energy, Bioenergy, Biogas

The oxy-fuel process is one of three carbon capture technologies which supply CO 2 ready for sequestration e the others being post-combustion capture and IGCC with carbon capture. As yet no technology has emerged as a clear winner in the race to commercial deployment. The oxy-fuel process relies on recycled flue gas as the main heat carrier through the boiler and results in significantly different flue gas compositions. Sulphur has been shown in the study to have impacts in the furnace, during ash collection, CO 2 compression and transport as well as storage, with many options for its removal or impact control. In particular, the effect of sulphur containing species can pose a risk for corrosion throughout the plant and transport pipelines. This paper presents a technical review of all laboratory and pilot work to identify impacts of sulphur impurities from throughout the oxy-fuel process, from combustion, gas cleaning, compression to sequestration with removal and remedial options. An economic assessment of the optimum removal is not considered. Recent oxy-fuel pilot trials performed in support of the Callide Oxyfuel Project and other pilot scale data are interpreted and combined with thermodynamic simulations to develop a greater fundamental understanding of the changes incurred by recycling the flue gas. The simulations include a sensitivity analysis of process variables and comparisons between air fired and oxy-fuel fired conditions -such as combustion products, SO 3 conversion and limestone addition.

- by Rohan Stanger
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- Mechanical Engineering, Chemical Engineering, Thermodynamics, Recycling

KSA is the world's third largest per capita water user country. 1.17 (domestic), 0.38 (industrial) billion m 3 /year wastewater is generated in KSA. 612, 767 MW electricity can be produced for years 2025, 2035 from wastewater by MEC. Net 508, 637 MW electricity for years 2025 and 2035 can be added to national grid. MEC technology can achieve 25.6% of KSA 3G W electricity from waste target by 2035. Keywords: Microbial electrolysis cell (MEC) Hydrogen (H 2) energy Urban wastewater Waste-to-energy (WTE) Wastewater treatment plant a b s t r a c t This paper reviews the status of microbial electrolysis cells (MEC) as a mean for hydrogen (H 2) production and urban wastewater treatment method. A case study of the Kingdom of Saudi Arabia (KSA) under MEC concept was developed. KSA is the world's third largest per capita water user country with no lakes and rivers. Every year, around 1.17 and 0.38 billion m 3 of domestic and industrial wastewater is generated respectively. The KSA government is seeking sustainable solutions for wastewater treatment and waste-to-energy (WTE) production to bridge the ever increasing water and energy demand-supply gap. However, there is no WTE facility exists to convert the wastewater into energy. Moreover, the potential of wastewater is not examined as an energy recovery substrate. This study, for the first time, estimated that a total electricity of 434 MWe can be produced in 2015 from the KSA's wastewater if MEC technology is employed. Similarly, an estimated total electricity of 612 and 767 MWe can be produced for the years 2025 and 2035 from the domestic and industrial wastewater by using MEC technology. A surplus electricity of 508 and 637 MWe for the years 2025 and 2035 respectively can be added to the national grid after fulfilling the energy requirement of MEC wastewater treatment plants. Collectively, MEC will contribute 20.4% and 25.6% share of the KSA government's WTE target of 3 GW in 2025 and 2035 respectively. A number of challenges in MEC such as ohmic and concentration losses, saturation kinetics and competing reactions that lower the H 2 production are discussed with their potential solutions including, the improvements in MEC design and the use of appropriate electrolytes, antibiotics and air or oxygen.

- by Dr. Abdul-Sattar Nizami and +1
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- Renewable Energy, Energy, Water and wastewater treatment, Municipal Solid Waste Management

In this paper, a numerical study to simulate and analyze the combustion process occurred in a compressed natural gas direct injection (CNG-DI) engine by using a multi-dimensional computational fluid dynamics (CFD) code was presented. The investigation was performed on a single cylinder of the 1.6-liter engine running at wide open throttle at a fixed speed of 2000 rpm. The mesh generation was established via an embedded algorithm for moving meshes and boundaries for providing a more accurate transient condition of the operating engine. The combustion process was characterized with the eddy-break-up model of Magnussen for unpremixed or diffusion reaction. The modeling of gaseous fuel injection was described to define the start and end of injection timing. The utilized ignition strategy into the computational mesh was also explained to obtain the real spark ignition timing. The natural gas employed is considered to be 100% methane (CH 4 ) with three global step reaction scheme. The CFD simulation was started from the intake valves opening until the time before exhaust valves opening. The results of CFD simulation were then compared with the data obtained from the single-cylinder engine experiment and showed a close agreement. For verification purpose, comparison between numerical and experimental work are in the form of average in-cylinder pressure, engine power as well as emission level of CO and NO.

The use of biomass to provide energy has been fundamental to the development of civilisation. In recent times pressures on the global environment have led to calls for an increased use of renewable energy sources, in lieu of fossil fuels. Biomass is one potential source of renewable energy and the conversion of plant material into a suitable form of energy, usually electricity or as a fuel for an internal combustion engine, can be achieved using a number of different routes, each with specific pros and cons. A brief review of the main conversion processes is presented, with specific regard to the production of a fuel suitable for spark ignition gas engines. Ó

- by Peter McKendry
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- Renewable Energy, Biotechnology, Biomass, Bioenergy

We studied the hydrolytic pretreatment at thermophilic temperature of grass silage. Different organic loading rates and hydraulic retention times were carried out. A two-phase system for anaerobic digestion improved methane production by 30%. A maximum of 368 L N CH 4 kg À1 VS was obtained in the mesophilic phase. a b s t r a c t Thermophilic hydrolysis of grass silage (GS) at 55 °C with organic loading rates (OLRs) of 6.5, 5, 2.5 and 1.0 kg VS m À3 days À1 and hydraulic retention times (HRT) of 10, 6, 4 and 2 days were evaluated in 12 glass bioreactors side by side. The hydrolytic process was measured by variation in pH, volatile solids (VS), VS destruction, soluble chemical oxygen demand (sCOD), hydrolysis and acidification yields. Biological methane potential (BMP) assays were carried out to measure the upper limit for methane production of grass silage with different hydrolytic pretreatments at mesophilic temperature (37 °C). The optimum methane yield of 368 L N CH 4 kg À1 VS was obtained at an OLR of 1 kg VS m À3 days À1 and a HRT of 4 days, showing an increase of 30% in the methane potential in comparison to non-hydrolysed GS.

- by Dr. Abdul-Sattar Nizami
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- Renewable Energy, Bioenergy, Waste-to-Energy, Optimization techniques

This paper addresses the impact of fuel composition on the operability of lean premixed gas turbine combustors. This is an issue of current importance due to variability in the composition of natural gas fuel supplies and interest in the use of syngas fuels. This paper reviews available results and current understanding of the effects of fuel composition on combustor blowout, flashback, dynamic stability, and autoignition. It summarizes the underlying processes that must be considered when evaluating how a given combustor's operability will be affected as fuel composition is varied. Fig. 15 Comparison of flow reactor data with kinetic modeling using different detailed mechanisms †35,40,56-59 ‡

- by Vincent McDonell
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- Mechanical Engineering, Aerospace Engineering, Combustion, Stability

h i g h l i g h t s 2-Methylfuran gasoline blend and ethanol gasoline blend were compared in a SI engine. Combustion duration, thermal efficiency and regulated emissions were studied. Compared with E10, BSFC and COV of IMEP can be improved by M10 blend. M10 are similar to E10 and superior to gasoline in terms of HC and CO emissions. NO X emissions increase is found by using M10 blend fuel. a b s t r a c t Currently, 2,5-dimethylfuran (DMF) has already been extensively studied as a novel potential gasoline substitute. With its improved reaction sequences, another main molecule transformed from fructose has also aroused worldwide interest, which is known as 2-methylfuran (MF). MF has similar energy density and knock suppression ability to DMF. However, little is known about its behavior in spark-ignition (SI) engines, especially when it is used as a gasoline additive. Therefore, focus was given on the combustion and emissions characteristics of 10% volume fraction 2-methylfuran gasoline blend fuel (M10) in this work, which was investigated experimentally in a single-cylinder four-stroke SI engine at various engine speeds (800-1800 rpm in 200 rpm intervals) and wide open throttle (WOT). The in-cylinder combustion process as well as engine performance of M10 were compared with gasoline and the same proportion ethanol gasoline blend fuel (E10) under gasoline maximum brake torque (MBT) spark timing and stoichiometric air-fuel ratio. Results of engine tests show that M10 produces relatively high in-cylinder peak pressure and temperature, which is mainly attributed to its consistently shorter combustion duration. Compared with engine performance of E10, the output torque and brake power increase slightly with less brake specific fuel consumption when M10 is used. Lower regulated gas emissions of hydrocarbons (HC) and carbon monoxide (CO) can be found for both E10 and M10 blend. In addition, more nitrogen oxides (NO X ) emissions are generated from M10 due to its higher combustion temperature.

- by salah omari
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- Engineering, Mechanical Engineering, Chemical Engineering, Economics

Resumen: Se aplicó un modelo matemático desarrollado para quemadores de cocinas domésticas y para los quemadores utilizados en calentadores comerciales en la evaluación del funcionamiento de la caldera de gas utilizada para el calentamiento de agua del hotel IberoStar Taínos, en Varadero, y se obtuvo que el coeficiente de exceso de aire estaba por encima de lo recomendado.

- by Roberto Gonzalez-Castellanos and +1
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- Design, Monitoring And Evaluation, Combustion, Heat Transfer

A model for steam gasi®cation of biomass was developed by applying thermodynamic equilibrium calculations. With this model, the simulation of a decentralized combined heat and power station based on a dual¯uidized-bed steam gasi®er was carried out. Fuel composition (ultimate analysis and moisture content) and the operating parameters, temperature and amount of gasi®cation agent, were varied over a wide range. Their in¯uences on amount, composition, and heating value of product gas and process eciencies were evaluated. It was shown that the accuracy of an equilibrium model for the gas composition is sucient for thermodynamic considerations. Net electric eciency of about 20% can be expected with a rather simple process. Sensitivity analysis showed that gasi®cation temperature and fuel oxygen content were the most signi®cant parameters determining the chemical eciency of the gasi®cation.

- by Hermann Hofbauer
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- Thermodynamics, Renewable Energy, Biomass, Sensitivity Analysis

Nowadays Non-Conventional motor fuels are receiving increased attention and use. This paper shows the study of the safety of three alternative gaseous fuels plus gasoline and the advantages and disadvantages of each. The gaseous fuels are hydrogen, methane (natural gas), and propane. Qualitatively, the overall risks of the four fuels should be close. Gasoline is the most toxic. For small leaks, hydrogen has the highest ignition probability and the gaseous fuels have the highest risk of a burning jet or cloud.

- by Sumit sharma
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- Biomass to fuel conversion, Gaseous Fuel

A gas-to-liquid (GTL) fuel derived from Low Temperature Fischer-Tropsch process has been tested in an automotive diesel engine fulfilling Euro 4 emissions regulations. Both regulated and non-regulated emissions have been compared with those of a commercial diesel fuel, a commercial biodiesel fuel and a GTL-biodiesel fuel (30% and 70% v/v, respectively) in order to check blending properties, synergistic effects and compatibility between first and second generation production technologies for biofuel consumption in current diesel engines. After presenting a detailed literature review, and confirming that similar efficiencies are attained with the four tested fuels under identical road-like operating conditions (this meaning fuel consumption is inversely proportional to their heating values), significant reductions in smoke opacity, particulate matter emissions and particle number concentration were observed with both GTL and biodiesel fuels, with small changes in NO x emissions. Compared with the reductions in PM emissions derived from the use of biodiesel fuels, those derived from using GTL fuels were quite similar, despite its lower soot emissions reductions. This can be explained by the lower volatile organic fraction of the PM in the case of GTL. By adequately blending both fuels, a considerable potential to optimise the engine emissions trade-off is foreseen.

- by Octavio Armas
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- Mechanical Engineering, Chemical Engineering, Biodiesel, Literature Review

Application of different alternatives for increasing the reaction furnace temperature of Claus sulfur recovery units (SRUs) are investigated by chemical equilibrium calculations. The Gibbs free minimization method based on Lagrangian multipliers is used for formulating the problem. The usefulness of different techniques such as fuel gas spiking, indirect air and/or acid gas preheating, oxygen enrichment, acid gas enrichment and direct air preheating for increasing the furnace temperature are determined by the proposed algorithm. In the case of lean feed acid gases, it may be necessary to use a combination of methods in order to attain the minimum furnace temperature required for flame stability and complete destruction of acid gas hydrocarbon contaminants. It is found that the acid gas enrichment is a reliable technique for providing the required reaction furnace temperature when a high flow of too lean acid gas is to be processed in a Claus unit. The predicted reaction furnace temperatures are in good agreement with the measured experimental values.

- by Bahman ZareNezhad
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- Mechanical Engineering, Stability, Algorithm, Temperature

In top-blown oxygen converter steelmaking process, a large amount of high-temperature off-gas is produced, and the off-gas is a precious valuable fuel containing high concentration of carbon monoxide (CO). Numerical model is developed for top-blown oxygen converter off-gas formation, the off-gas formation is simulated using the developed model, and the influences of the operating model of converter on the characteristics of off-gas (concentrations, temperature, flowrate and sensible heat flux) are investigated. The simulated results indicate that CO concentration varies gently, CO concentration can reach about 80% during 10-80% blowing oxygen time, the change trend of CO 2 concentration is contrary to that of CO concentration during 0-90% blowing oxygen time, and the dramatic changes of oxygen lance height result in significant fluctuations of off-gas flowrate. The operation model of oxygen-blowing pressure significantly affects off-gas sensible heat flux, and the sensible heat flux is high during 40-80% blowing oxygen time.

- by Xiaolin Wei
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- Mechanical Engineering, Chemical Engineering, Concentration, Numerical Simulation

BACKGROUND: The aim of this work is to define the chemical and mineralogical composition of the fuel gas desulphurization (FGD) gypsum produced from the Meliti thermal power plant in the region of Florina in North West Greece, in order to investigate potential uses in the cement industry. Mineralogical and microprobe analyses were carried out on FGD gypsum samples collected from the Meliti 330 MW lignite-fired power plant. RESULTS: Results show that the main component of the FGD gypsum is pure mineral gypsum (CaSO ...

- by Charalampos Vasilatos
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- Chemical Engineering, Earth Sciences, Geochemistry, Mineralogy

Pd/ZnO/Al 2 O 3 catalysts were studied for water-gas-shift (WGS), methanol steam reforming, and reverse-water-gas-shift (RWGS) reactions. WGS activity was found to be dependent on the Pd:Zn ratio with a maximum activity obtained at approximately 0.50, which was comparable to that of a commercial Pt-based catalyst. The catalyst stability was demonstrated for 100 hours time-on-stream at a temperature of 360 0 C without evidence of metal sintering. WGS reaction rates were approximately 1 st order with respect to CO concentration, and kinetic parameters were determined to be E a = 58.3 kJ mol -1 and k 0 = 6.1x10 7 min -1 . During methanol steam reforming, the CO selectivities were observed to be lower than the calculated equilibrium values over a range of temperatures and steam/carbon ratios studied while the reaction rate constants were approximately of the same magnitude for both WGS and methanol steam reforming.

- by Robert Dagle
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- Chemical Engineering, Heterogeneous Catalysis, Catalyst, Alcohol

A RF (radio frequency) plasma pyrolysis reactor was presented in this paper. Application of this reactor to the pyrolysis treatment of biomass at different operating pressures (3000-8000Pa), with various input powers (1600-2000W) was investigated. Interest was focused on the effect of the pyrolysis conditions on the yield of gas and char, the gas composition as well as the quality of the char. On average, the gas yield can reach 66 wt% of the biomass feed at the input power 1800W and operating pressure 5000Pa. The total content of CO and H 2 in the gas product reached 76 vol.% on a nitrogen-free basis. Thus the utilization efficiency is increased after the biomass is converted into gaseous fuel, which has wider applications such as city gas, burning in utility boilers, gas turbines or gas engines to generate electricity.

- by Bilal Shafique
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- Biomass, Energy Recovery Systems, Gaseous Fuel

Poland has one of the largest sulfur and nitrogen emissions in Europe. This is mainly because coal is a main fuel in industrial and nonindustrial combustion. The aim of this paper is to assess the amount of sulfur and nitrogen deposited from SNAP sector 02 (nonindustrial sources) coal combustion. To assess this issue, the Fine Resolution Atmospheric Multipollutant Exchange (FRAME) model was used. The results suggest that industrial combustion has the largest impact on deposition of oxidized sulfur, whereas the oxidized nitrogen national deposition budget is dominated by transboundary transport. The total mass of pollutants deposited in Poland, originating from nonindustrial coal combustion, is 45 Gg of sulfur and 2.5 Gg of nitrogen, which is over 18% of oxidized sulfur and nearly 2% of oxidized nitrogen deposited. SNAP 02 is responsible for up to 80% of dry-deposited sulfur and 11% of nitrogen. The contribution to wet deposition is largest in central Poland in the case of sulfur and in some areas can exceed 11%. For oxidized nitrogen, nonindustrial emissions contribute less than 1% over the whole area of Poland. The switch from coal to gas fuel in this sector will result in benefits in sulfur and nitrogen deposition reduction.

- by Viviane Querubim
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- Engineering, Chemistry, Carbon, Modeling

New computational procedures are proposed for experimentally evaluating air-fuel ratio and mass fractions of exhaust emissions as well as EGR rate, oxygen mass fraction and thermal capacity of the inducted charge in IC engines running with diesel oil, gasoline or any alternative liquid or gaseous fuel, such as LPG or CNG. Starting from the chemical reaction of fuel with air, from gaseous and smoke level measurements in the raw gases, the procedures calculate the volume fractions of oxygen in the combustion air and of compounds in the exhaust gases, including those that are not usually measured, such as water, nitrogen and hydrogen. The methods also take the effects of various fuel and combustion air compositions into account, as well as to the presence of water vapor, CO 2 , Ar and He in the combustion air. The algorithms are applied to four different automotive engines under wide ranges of steady-state operating conditions: three turbocharged diesel engines featuring high-pressure cooled EGR systems, and an SI naturally aspirated bi-fuel engine running on either gasoline or CNG. The computed air-fuel ratios are compared to those obtained from directly measured air and fuel mass-flow rates as well as from more conventional UEGO sensor data. The mass emissions are worked out in terms of both brake specific mass emissions and emission indexes of each pollutant species, and the results are compared to those obtained by applying SAE and ISO recommended practices. The computed oxygen mass fraction of the inducted charge was then compared to that derived from direct measurement of O 2 concentration in inlet manifold. Finally, the sensitivity of results to the main engine working parameters, the influence of environmental conditions (in particular the effect of air humidity on NO x formation) and the experimental uncertainties are determined.

- by Stefano D’Ambrosio
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- Mechanical Engineering, Chemical Engineering, High Pressure, Algorithm
- by Carlos Duque-Daza
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- Natural Gas, Bus, Compressed Natural Gas, Route

The use of Pd-based sorbents for high temperature removal of AsH 3 from gasified coal was investigated using a simulated gas feed. A sorbent consisting of 5 wt% Pd on alumina beads has been tested for AsH 3 removal from synthetic fuel gas (CO, CO 2 , H 2 ) at 204 and 288°C. Arsenic uptake was found to be essentially linear with exposure time and considerably higher than that for unpromoted alumina beads. Arsenic loadings in excess of 7 wt% were achieved, though the sorbent is unlikely to be saturated at this loading. As the arsenic loading on the sorbent increased a PdAs 2 phase was identified in the XRD pattern. The adsorption of arsine on palladium has potential implications for catalysts, electrodes, and membranes for the separation of hydrogen from fuel gas.

- by Stephen Poulston
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- Mechanical Engineering, Chemical Engineering, Carbon, Adsorption
- by Jamel Bessrour
- •
- Turbulence, Numerical Simulation, Incineration, Turbulent Flow

ABSTRACT Three perfluorinated compounds (PFCs), PP10, PP11, and PP25, manufactured by F2 Chemicals Ltd., U.K., were investigated as physical solvents for selective CO2 capture from synthesis gas or syngas streams at elevated pressures and temperatures. The equilibrium solubility, the hydrodynamic, and the mass-transfer parameters of CO2 in the solvents were measured in a 4-L ZipperClave agitated reactor under wide ranges of operating conditions: pressures (6−30 bar), temperatures (300−500 K), mixing speeds (10−20 Hz), and liquid heights (0.14−0.22 m). The CO2 solubilities in the three solvents decreased with an increasing temperature at constant pressure and followed Henry’s law. The CO2 solubilities in PP25 were greater than those in PP10 and PP11. The volumetric liquid-side mass-transfer coefficients (kLa) of CO2 in the PFCs increased with mixing speed, pressure, and temperature. Also, the gas−liquid interfacial areas of CO2 in the three PFCs appeared to control the behavior of kLa. This study proved the thermal and chemical stability and the ability of the PFCs to selectively absorb CO2 at temperatures up to 500 K and pressures as high as 30 bar. A preliminary conceptual process design using PP25 for selective CO2 capture from hot-shifted gas with pressure-swing and pressure−temperature-swing regeneration options was devised [a temperature-swing option was also examined but is not reported here because it is outside the context of the present study, which involves a physical solvent process benchmark (Selexol) for which temperature-swing regeneration is not a viable option]. The pressure−temperature-swing option led to greater PP25 solvent loss but a more favorable (more negative) net enthalpy than the pressure-swing option. However, for either regeneration option to be economically viable, the PP25 solvent must be completely recovered from the process.

- by Badie I. Morsi
- •
- Engineering, Mass Transfer, Mixing, Process Design

Poly-generation systems for combined production of manifold energy vectors such as electricity, heat at different enthalpy levels (for instance, in the form of hot water and steam), and cooling power from a unique source of primary energy (typically natural gas) are increasingly spreading, above all on a small-scale basis (below 1 MW e), owing to their enhanced energy, environmental and economic characteristics. Availability of suitable tools for assessing the performance of such systems is therefore fundamental. In this paper, a unified general model is proposed for assessing the energy and CO 2 emission performance of any type of poly-generation system with natural gas as the energy input. In particular, the classical energy saving model for cogeneration systems is extended to include in the analysis further energy vectors by defining the novel PPES (Poly-generation Primary Energy Saving) indicator. In addition, equivalent efficiencies for CO 2 emission assessment are defined and used in the formulation of the new PCO2ER (Poly-generation CO 2 Emission Reduction) indicator, specifically introduced for environmental analysis. The formal analogy between the PPES and the PCO2ER indicators is highlighted. Numerical applications are provided to show the effectiveness of the proposed models and to quantify the typical benefits that poly-generation systems can bring. In particular, the new indicators are of relevant interest for both energy planners and policy makers, above all in the outlook of formulating financial incentive strategies, as it already occurs for cogeneration systems, or of participating to specific energy-related markets such as the ones for trading white certificates or emission allowances.

- by Gianfranco Chicco
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- Performance, Electricity, Natural Gas, Models

This paper is to experimentally and numerically investigate the cell performance and the localized characteristics associated with a high-temperature proton exchange membrane fuel cell (PEMFC). Three experiments are carried out in order to study the performance of the PEMFC with different operating conditions and to validate the numerical simulation model. The model proposed herein is a three-dimensional (3-D) computational fluid dynamics (CFD) non-isothermal model that essentially consists of thermal-hydraulic equations and electrochemical model. The performance curves of the PEMFC predicted by the present model agree with the experimental measured data. In addition, both the experiments and the predictions precisely demonstrate the enhanced effects of inlet gas temperature and system pressure on the PEMFC performance. Based on the simulation results, the localized characteristics within a PEMFC can be reasonably captured. These parameters include the fuel gas distribution, liquid water saturation distribution, membrane conductivity distribution, temperature variation, and current density distribution etc. As the PEMFC is operated at the higher current density, the fuel gas would be insufficiently supplied to the catalyst layer, consequently causing the decline in the generation of power density. This phenomenon is so called mass transfer limitation, which can be precisely simulated by the present CFD model.

- by Yuh-ming Ferng
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- Mechanical Engineering, Mass Transfer, Computational Fluid Dynamics, Modeling

This research report is about the effect of non-thermal plasma (NTP) on particulate matter (PM) and on the physical and chemical characteristics of rice bran biodiesel (RBD) fuel engines. First, the RBD fuel was successfully prepared by the transesterification method. The main components of the RBD fuel were detected by gas chromatography-mass spectrometry. Other properties, such as the density, the water content, and the calorific value of the fuel, were examined. Second, the bench test was carried out with NTP technology, and the results showed a marked decrease in smoke conversion after NTP treatment. In the third step, scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS) were used to detect the physical and chemical characteristics of the PM sample. The amount of carbon atoms in the PM sample was significantly reduced, while other metal components were almost the same after NTP treatment.

- by Olivier Alard
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- Engineering, Analytical Chemistry, Mass Spectrometry, Scanning Electron Microscopy

Acoustic effects accompany the combustion of gaseous fuels in bubbling fluidized beds of inert materials. In an exploratory study of this effect, using a laboratory-size fluidized bed in which a mixture of propane and butane was burned, the bed's temperature was monitored continuously and the acoustic effects were recorded. The temperature ranges over which combustion was "noisy" and "quiet" were identified; the acoustic signals were shown to fall into a number of characteristic patterns, which can yield information about the character of the combustion process, in relation to "mini-explosions" in bubbles of the combustible mixture rising through the bed, their intensity and frequency. The results could be used to develop a new method of controlling the operation of fluidized beds burning a gaseous fuel.

- by Witold Żukowski
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- Mechanical Engineering, Chemical Engineering, Combustion, Fluidized Bed Systems

- by Roberto Gonzalez-Castellanos
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- Design, Monitoring And Evaluation, Combustion, Heat Transfer

An experimental study on co-firing used engine lubrication oil (UELBO) with a gaseous fuel such as LPG in a small furnace is conducted. A wide range of fuel and air admission conditions is considered. It is found that when even a small amount of UELBO is co-fired with the gaseous fuel it significantly enhances thermal radiation capabilities of the gaseous fuel flame. For example, radiation capability of LPG flames can be enhanced by about 80% when UELBO at a rate of about 0.5 g/s is co-fired with 1 g/s LPG. UELBO-based results are also compared with ones obtained when a diesel fuel is co-fired with LPG in the same furnace, under operating conditions similar to those of UELBO/LPG tests. The comparisons confirm once more the significant role played by UELBO in enhancing radiation heat transfer from gaseous fuels flames. They also highlight UELBO as a renewable energy source with an attractive potential.

- by Salah Omari
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- Radiation, Renewable Energy, Combustion, Heat Transfer
- by Humberto Acevedo
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- Natural Gas, Bus, Compressed Natural Gas, Route

A method for both combustion irreversibility and working medium availability computations in a high-speed, naturally-aspirated, four-stroke, internal combustion engine cylinder is presented. The results of the second-law analysis of... more

- by Dimitrios Kyritsis
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- Mechanical Engineering, Energy, Combustion, Internal Combustion Engine

- by Gianfranco Chicco
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- Performance, Electricity, Natural Gas, Models

- by Harvey E Jeffries
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- Engineering, Carbon, Modeling, Combustion

- by Juan Jose Hernandez
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- Mechanical Engineering, Chemical Engineering, Biodiesel, Literature Review

The paper analyses the dynamic aspects of the temperature field in a fluidised bed of solids particles (e.g., sand) in which a gaseous fuel is being burned. Such a hot bed emits electromagnetic radiation within the visible range and this can be recorded using a digital video camera. This fact has been used to develop a method for measuring the bed's temperature in the line of sight, through the quartz sides of the reactor. A solid probe is only used for calibration.

- by Jerzy Baron
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- Mechanical Engineering, Chemical Engineering, Combustion, Heat Transfer

Gas hydrates from CO2/N2CO2/N2 and CO2/H2CO2/H2 gas mixtures were formed in a semi-batch stirred vessel at constant pressure and temperature of 273.7 K. These mixtures are of interest to CO2CO2 separation and recovery from flue gas and fuel gas, respectively. During hydrate formation the gas uptake was determined and the composition changes in the gas phase were obtained by gas chromatography. The rate of hydrate growth from CO2/H2CO2/H2 mixtures was found to be the fastest. In both mixtures CO2CO2 was found to be preferentially incorporated into the hydrate phase. The observed fractionation effect is desirable and provides the basis for CO2CO2 capture from flue gas or fuel gas mixtures. The separation from fuel gas is also a source of H2H2. The impact of tetrahydrofuran (THF) on hydrate formation from the CO2/N2CO2/N2 mixture was also observed. THF is known to substantially reduce the equilibrium formation conditions enabling hydrate formation at much lower pressures. THF was found to reduce the induction time and the rate of hydrate growth.

- by Praveen Linga
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- Mechanical Engineering, Chemical Engineering, Speciation, Carbon Dioxide

... These boilers have very simple water-circulation system, which often brings about flow instabilities followed ... When the tube wall is thin, CHF is mainly controlled by the two-phase flow ... Chemical Engineering Research and Design... more

- by mamoru ozawa
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- Chemical Engineering, Chemistry, Design, Modeling

A three-dimensional combustion model which couples turbulent flow statistics with chemical reactions and radiative heat transfer is used to evaluate the effect of soot and turbulence-radiation coupling on radiative transfer in an industrial-scale furnace. Radiation and soot formation models are presented which include the nonlinear dependencies between fluid turbulence effects, soot formation and radiative absorption and emission in the participating

- by Brad Adams
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- Mechanical Engineering, Chemical Engineering, Materials Science, Combustion

A cold flow model was built and operated in order to study the fluid dynamics of a 120-kW chemical looping pilot rig for gaseous fuels. The system consists of two interconnected circulating fluidized bed reactors with globally circulating bed material (dual circulating fluidized bed-DCFB). Gas mixing between the two reactors is prevented by moderately fluidized loop seals. In the cold model, both reactors are fluidized with air at two stages to control the solids circulation. The data presented focus on the solids circulation rates and on pressure profiles of both reactors, depending on selected operating parameters like fluidization gas flow rate, level of gas introduction, loop seal fluidization, and solids inventory. The results show high solids circulations in the global loop between the two reactors for the scaled base case operation conditions already at low bed inventories.

- by Hermann Hofbauer
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- Mechanical Engineering, Chemical Engineering, Modeling, Chemical

The increasing diffusion of small-scale energy systems within the distributed generation (DG) paradigm is raising the need for studying the environmental impact due to the different DG solutions in order to assess their sustainability. Addressing the environmental impact calls for building specific models for studying both local and global emissions. In this framework, the adoption of natural gas-fueled DG cogeneration technologies may provide, as a consequence of cogeneration enhanced overall energy efficiency and of natural gas relatively low carbon content, a significant reduction of global impact in terms of CO 2 emissions with respect to the separate production of electricity and heat. However, a comprehensive evaluation of the DG alternatives should take into account as well the impact due to the presence of plants spread over the territory that could increase the local pollution, in particular due to CO and NO x , and thus could worsen the local air quality. This paper provides an overview on the characterization of the emissions from small-scale natural gasfueled cogeneration systems, with specific reference to the DG technologies nowadays most available in the market, namely, microturbines and internal combustion engines. The corresponding local and global environmental impacts are evaluated by using the emission balance approach. A numerical case study with two representative machines highlights their different emission characteristics, also considering the partial-load emission performance.

- by Gianfranco Chicco
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- Air Quality, Performance, Energy Conversion, Internal Combustion Engine

In this study, an oil shale sample from the Ellujjun deposit, in the central part of Jordan, was gasi®ed in relation to the bed temperature and type of¯uidising gas using a continuous feed¯uidised bed reactor. The composition, quantity and calori®c value of the generated gas were determined. There was a nearly linear increase in the amount of fuel gas produced as a function of temperature, reaching H350 kg (i.e. 318 m 3) per tonne of dry raw shale, and the gross calori®c value ranged from 15 to 23 MJ kg À1 with carbon monoxide and hydrogen being the major constituents.

- by Jamal Jaber
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- Oil Shale, Electrical And Electronic Engineering, Gaseous Fuel