S.I. engine fuelled with gasoline,methane and methane/hydrogen blends: Heat release and loss analysis

Experiments were carried out to investigate the performance of different fuels used in a internal combustion engine: gasoline, methane and fuel blends containing methane with 5%, 10% and 15% hydrogen by volume, respectively. A two-litre naturally aspirated bi-fuel engine with port fuel injection was used. The engine was operated stoichiometrically. For each fuel the spark advance for best efficiency was determined. Experiments were conducted at 2000 rpm and 2 bar brake mean effective pressure. A heat release analysis and a loss analysis were performed for all fuels. The main findings are that increasing the hydrogen fraction of the methane hydrogen fuel blend decreases the overall burn duration. This decrease is predominantly achieved by a shortened duration of the fist stage of combustion (ignition to 5% mass fraction burned). The faster combustion comes along with an increase in fuel conversion efficiency. The different losses for gasoline and pure methane operation interact such that equal fuel conversion efficiencies result. However, care has to be taken when comparing fuel conversion efficiencies among the different fuels as the relative error in fuel conversion efficiency for the gaseous fuels is 0.2% at most, whereas it is about 1% for gasoline.     

Study of performance,combustion, and NOx emission behavior of an SI engine fuelled with ammonia/hydrogen blends at various compression ratio

In the present paper, an experimental investigation has been performed under variable CR and 1400&1800RPM speed at a fixed spark timing of 24ºCA BTDC under wide-open throttle conditions. The hydrogen blending is performed based on energy fractions from 5% to 21% of the total fuel energy. With increasing compression ratio (CR), the flame development gets faster, and the flame propagation speed improves, leading to a short combustion period. Similarly, increasing hydrogen fraction improves combustion, resulting in a rapid rise in pressure and temperature. Despite a 13.64% decrease in volumetric efficiency from 5% to 21% hydrogen fraction at 1400 and 1800 RPM, BP and BTE increased by 16.89% and 33%, respectively. The slow-burning properties of NH₃ extend the combustion period, resulting in a long-delayed burning period. As a result, the temperature of the low-hydrogen fraction of the exhaust gas is higher. As the hydrogen fraction and CR increase, this effect decreases, resulting in lower EGT. The hydrogen addition increases the peak temperature; therefore, NO_x increases continuously with increasing hydrogen despite reducing ammonia. Ammonia is a key element used to reduce NO_x from vehicles. A practical solution for controlling the NO_x due to the ammonia/hydrogen blend is selective catalytic reduction (SCR).     

Life cycle assessment of various cropping systems utilized for producing biofuels: Bioethanol and biodiesel

A life cycle assessment of different cropping systems emphasizing corn and soybean production was performed, assuming that biomass from the cropping systems is utilized for producing biofuels (i.e., ethanol and biodiesel). The functional unit is defined as 1 ha of arable land producing biomass for biofuels to compare the environmental performance of the different cropping systems. The external functions are allocated by introducing alternative product systems (the system expansion allocation approach). Nonrenewable energy consumption, global warming impact, acidification and eutrophication are considered as potential environmental impacts and estimated by characterization factors given by the United States Environmental Protection Agency (EPA-TRACI). The benefits of corn stover removal are (1) lower nitrogen related environmental burdens from the soil, (2) higher ethanol production rate per unit arable land, and (3) energy recovery from lignin-rich fermentation residues, while the disadvantages of corn stover removal are a lower accumulation rate of soil organic carbon and higher fuel consumption in harvesting corn stover. Planting winter cover crops can compensate for some disadvantages (i.e., soil organic carbon levels and soil erosion) of removing corn stover. Cover crops also permit more corn stover to be harvested. Thus, utilization of corn stover and winter cover crops can improve the eco-efficiency of the cropping systems. When biomass from the cropping systems is utilized for biofuel production, all the cropping systems studied here offer environmental benefits in terms of nonrenewable energy consumption and global warming impact. Therefore utilizing biomass for biofuels would save nonrenewable energy, and reduce greenhouse gases. However, unless additional measures such as planting cover crops were taken, utilization of biomass for biofuels would also tend to increase acidification and eutrophication, primarily because large nitrogen (and phosphorus)-related environmental burdens are released from the soil during cultivation.     

Trimetallic amorphous catalyst with low amount of platinum: Comparative study for ethanol,bioethanol and CO electrooxidation

The use of ethanol and bioethanol demonstrates the viability of alternative fuels to gasoline with optimum energy purposes. The development of suitable catalysts is fundamental to improve the electrical performance in Direct Alcohol Fuel Cells (DAFCs). For that reason, a series of amorphous Ni₅₉Nb₄₀Pt_0.6Y_0.2Z_0.2 (PtYZ) alloys adding three different transition metals (Y, Z = Cu, Ru and Sn) were manufactured by Mechanical Alloying (MA) method. The low amount of Pt and bifunctional-electronic role of cocatalysts was analyzed using electrochemical techniques such as Cyclic Voltammetry (CV), chronoamperometry and CO stripping experiments. Concerning to reactivity towards alcohol electrooxidations, alloys with Cu showed the best catalytic performance. However, its use is limited by Cu dissolution in acid media. The PtYZ catalysts showed higher CO tolerance, achieving smaller rates of poisoning (δ) for PtRuSn alloy. CO stripping reveals that CO oxidation on alloys with Ru takes place at lower electrode potentials. The experimental results showed better electric performance, but higher poisoning of the catalytic surface for bioethanol electrooxidation. Acetaldehyde and formic acid were found in bioethanol by HPLC, influencing the electrochemical response.     

The dynamic modeling and the exergy assessment of hydrogen synthesize and storage system with the power-to-gas concept for various locations

In this article, the solar hydrogen storage is modeled and hourly investigated with TRNSYS software. The Photovoltaic (PV) panel is employed for green power generation that is consumed in the electrolyzer subsystem and produced hydrogen. Additionally, the required electricity at the lack of enough solar irradiation is supplied from the grid. The performance of the system is comparatively analyzed for three main cities. Results show that the maximum power generation by PV panel is about 1670 kW in June which approximately is the same for two cities. The energy and Faraday efficiency of electrolyzer changes between 0.85-0.89 and 0.89–0.92 respectively. The amount of hydrogen production reaches 1235 m³/h for one of them in May. The total amount of hydrogen production is 13,181 m³/year in Yazd, 13,143 m³/year in hot city, and 13,141 m³/year in most populated city.     

A critical review: Application of methanol as a fuel for internal combustion engines and effects of blending methanol with diesel/biodiesel/ethanol on performance,emission, and combustion characteristics of engines

This article presents a comprehensive overview of methanol as a potential oxygenated fuel for internal combustion engines. Here two approaches have been examined to evaluate the utilization of methanol, namely blending with diesel/biodiesel/methanol and premixing with intake air or fumigation. In conventional compression ignition engines, up to 95% and 25% diesel can be replaced by methanol through fumigation and blending, respectively. Higher latent heat of vaporization of alcohol led to lower peak in-cylinder pressure and NO_x; however, it negatively affects thermal efficiency and hydrocarbon and carbon monoxide emissions. Fumigation of alcohol requires modifications in the existing engine, whereas blending needed surfactants or additives to produce stable alcohol–diesel blends. High injection pressure and late direct injection, methanol–diesel blends have shown lower emissions and proved their potential as a suitable replacement for ethanol–diesel blends from the components durability perspective.     

The viscosity of diesel oil and mixtures with straight vegetable oils: Palm, cabbage palm, cotton, groundnut, copra and sunflower

The feed back experience of using straight vegetable oil (SVO) as a fuel in the existing diesel engines evidences the need for fitting several physical properties, among them the fuel viscosity. An empirical modelling is proposed in order to interpolate viscosity to any kind of diesel oil/SVO blend. This model is fitted on an experimental viscosity database on blends, varying the SVO mass proportion in the blend, the blend temperature between cloud point and 353 K, and including six vegetable oils varying the fatty acids composition. Extrusion rheology was also checked by varying the pressure drop. Measurements show that blends behave Newtonian.     

The influence of thermal barrier coating on an LHR engine fueled by soybean biodiesel blended with various additive spectrums: Performance,combustion, and emission analysis

The novelty of this research work deals with green synthesized nanoadditives (5% of graphene, carbon nanotubes, and carbon black), oxygenated additives (5% of n-butanol, n-heptane, and n-pentanol), and then the test fuels are prepared by blending of 20% of soybean biodiesel and 70%, 80%, and 100% of premium diesel. The experimental outcomes revealed that the Nickel Chromium Aluminum (NiCrAl-120 micron), partially stabilized zirconia, and titanium dioxide ceramic composites at about 400 microns achieve the thermal barrier coat of low heat rejection (LHR) engine parts by the air-plasma spray method. Compared with Blend B, green synthesized carbon black (5%), premium diesel (70%), and n-pentanol (5%) mixed soybean biodiesel (20%) fuel (Blend E) tested on the LHR engine achieved 4.90% higher brake thermal efficiency and 25.31% lower brake-specific fuel consumption at peak load owing to the presence of an oxygenated agent (n-pentanol) in the fuel blend, which minimizes carbon deposition. The carbon monoxide, hydrocarbon, NO_x, and smoke emissions were reduced by 25.58%, 29.41%, 5.06%, and 7.75% when compared to Blend B at peak load. Then, the in-cylinder pressure and heat release rate were found to be 4.52% and 8.87% higher for Blend E at peak load compared to Blend B. This was because the mix of oxygenated additive and carbon black bio-based nanofuels made the combustion process go faster. These fuel blends were tested on LHR diesel engines at various load conditions.     

Open space for the physisorption of H2: Cointercalation of graphite with Li,Ti metal atoms and ethylene molecules

Based on first-principles plane-wave calculations, we explored the method with the ethylene molecules and Ti, Li atoms intercalated into the graphite to open space for the physisorption of hydrogen. And our simulation indicated that the interlayer distance of the graphene is close to the optimal physisorption of hydrogen with this method. From our computation, we got that the type of 3 × 3 supercell has the lowest converge energy and is energetically favorable. The energy barrier of changing the type of 2 × 2 supercell to 3 × 3 supercell is high.     

陶瓷烧成窑高效、节能、低污染燃烧技术的研究--高温预热空气互补型受控脉动燃烧技术

由成对的高性能高速燃烧器构成的使用 42 0℃预热空气的互补型燃气受控脉动燃烧技术在陶瓷烧成窑上的试用 ,表明它是一种节能、低 CO、低 NOX排放量的燃烧技术 ,并介绍了该技术的发展过程和运行机理     

The economic effect of electricity net-metering with solar PV: Consequences for network cost recovery,cross subsidies and policy objectives

Net-metering is commonly known as a practice by which owners of distributed generation (DG) units may offset their electricity consumption from the grid with local generation. The increasing number of prosumers (consumers that both produce and consume electricity) with solar photovoltaic (PV) generation combined with net-metering results in reduced incomes for many network utilities worldwide. Consequently, this pushes utilities to increase charges per kW h in order to recover costs. For non-PV owners, this could result into inequality issues due to the fact that also non-PV owners have to pay higher chargers for their electricity consumed to make up for netted costs of PV-owners. In order to provide insight in those inequality issues caused by net-metering, this study presents the effects on cross-subsidies, cost recovery and policy objectives evolving from different applied netmetering and tariff designs for a residential consumer. Eventually this paper provides recommendations regarding tariffs and metering that will result in more explicit incentives for PV, instead of the current implicit incentives which are present to PV owners due to net-metering.     

Metal (oxide) modified (M= Pd,Ag, Au and Cu) H2SrTa2O7 for photocatalytic CO2 reduction with H2O: The effect of cocatalysts on promoting activity toward CO and H2 evolution

Ag, Pd, Au, Cu₂O as cocatalysts were loaded on the layered H₂SrTa₂O₇ (HST) for photocatalytic CO₂ reduction with H₂O. The characterization revealed that cocatalysts loaded on the surface of HST can effectively promote the separation of photogenerated electrons and holes due to the formation of Schottky barrier or p-n junction, thus enhancing photocatalytic activity. Of note, Ag, Pd, Au, Cu₂O loading exhibited obviously different performance on promoting photocatalytic activity of HST toward CO evolution and H₂ evolution because of the different overpotentials of CO evolution and H₂ evolution on loaded photocatalysts. Cocatalysts with low overpotentials of CO or H₂ evolution act as active sites for CO or H₂ evolution, thus controlling the selectivity toward CO or H₂. The Au/HST exhibited high activity for only H₂ evolution (17.5 μmol g⁻¹ h⁻¹) due to relative low overpotential for H₂ evolution (0.67 V) while the Cu₂O/HST exhibited high activity only for CO evolution (0.23 μmol g⁻¹ h⁻¹) due to relative low overpotential for CO evolution (0.40 V). The Pd/HST sample exhibits high photocatalytic activity for both CO and H₂ evolution rates due to the low overpotential for CO and H₂ evolution, reaching 4.0 and 4.7 times of bare HST, respectively. This work here gives an in-depth understanding of the effect of cocatalysts on promoting photocatalytic activity and selectivity and can also give guidance to design photocatalysts with high activity and selectivity for photocatalytic CO₂ reduction with H₂O.