Recent Advances of Photocatalytic Hydrogenation of CO2 to Methanol

Constantly increasing hydrocarbon fuel combustion along with high levels of carbon dioxide emissions has given rise to a global energy crisis and environmental alterations. Photocatalysis is an effective technique for addressing this energy and environmental crisis. Clean and renewable solar energy is a very favourable path for photocatalytic CO2 reduction to value-added products to tackle problems of energy and the environment. The synthesis of various products such as CH4, CH3OH, CO, EtOH, etc., has been expanded through the photocatalytic reduction of CO2. Among these products, methanol is one of the most important and highly versatile chemicals widely used in industry and in day-to-day life. This review emphasizes the recent progress of photocatalytic CO2 hydrogenation to CH3OH. In particular, Metal organic frameworks (MOFs), mixed-metal oxide, carbon, TiO2 and plasmonic-based nanomaterials are discussed for the photocatalytic reduction of CO2 to methanol. Finally, a summary and perspectives on this emerging field are provided.

Laser synthesis of nanocomposite hydrocarbon fuel and CARS diagnostics of its combustion flame

We report an analysis of diffusive combustion in oxygen of a composite fuel formed by the addition of aluminium nanoparticles (NPs) to isopropanol. The process of obtaining Al NPs consisted in laser fragmentation of initially large industrial NPs using radiation of a pulsed nanosecond neodymium laser. The size distribution of Al NPs was determined using a measuring disk centrifuge. The average nanoparticle size was 20 nm, which is confirmed by transmission electron microscopy data. A diagnostic system based on coherent anti-Stokes Raman scattering (CARS) was used to experimentally study the diffusive combustion of composite fuel. The temperature distributions were measured in two mutually orthogonal directions (along the flame and in the transverse direction) in pure isopropanol and in isopropanol with the addition of 0.15 wt % of Al nanoparticles.

The Effect of Inert Fuel Compounds on Flame Characteristics

To describe the effects of inert compounds in gaseous fuel, experiments on three different process burners (staged fuel burner, staged air burner, and low-calorific burner) were carried out. The tested burners are commercially available, but they were specially designed for experimental usage. Tests were carried out in the semi-industrial burner testing facility to investigate the influence of inert gases on the flame characteristics, emissions, and heat flux to the combustion chamber wall. Natural gas was used as a reference fuel, and, during all tests, thermal power of 500 kW was maintained. To simulate the combustion of alternative fuels with lower LHV, N2 and CO2 were used as diluents. The inert gas in the hydrocarbon fuel at certain conditions can lower NOx emissions (up to 80%) and increase heat flux (up to 5%). Once incombustible compounds are present in the fuel, the higher amount of fuel flowing through nozzles affects the flow in the combustion chamber by increasing the Reynolds number. This can change the flame pattern and temperature field, and it can be both positive and negative, depending on actual conditions.

Effect of Dimple Depth-Diameter Ratio on the Flow and Heat Transfer Characteristics of Supercritical Hydrocarbon Fuel in Regenerative Cooling Channel

In order to extend the cooling capacity of thermal protection in various advanced propulsion systems, dimple as an effective heat transfer enhancement device with low-pressure loss has been proposed in regenerative cooling channels of a scramjet. In this paper, numerical simulation is conducted to investigate the effect of the dimple depth-diameter ratio on the flow and heat transfer characteristics of supercritical hydrocarbon fuel inside the cooling channel. The thermal performance factor is adopted to evaluate the local synthetically heat transfer. The results show that increasing the dimple depth-diameter ratio h / d p can significantly reduce wall temperature and enhance the heat transfer inside the cooling channel but simultaneously increase pressure loss. The reason is that when h / d p is rising, the recirculation zones inside dimples would be enlarged and the reattachment point is moving downstream, which enlarge both the high Nu area at rear edge of dimple and the low Nu area in dimple front. In addition, when fluid temperature is nearer the fluid pseudocritical temperature, local acceleration caused by dramatic fluid property change would reduce the increment of heat transfer and also reduce pressure loss. In this study, the optimal depth-diameter ratio of dimple in regenerative cooling channel of hydrocarbon fueled is 0.2.

Two Stages Thermal and Catalytic Cracking of Polyethylene Terephthalate to Fuel Production

PET (polyethylene terephthalate) is made up of polymerized repeating units of the ethylene terephthalate monomer (C10H8O4). PET is a recyclable plastic with the number 1 as its identification code. PET, which has a molecular weight of 192 gm/mole and contains 62.5 percent carbon, 33.3 percent oxygen, and 4.2 percent hydrogen, is utilized as synthetic fiber, polyester, plastic packaging, and soft drink containers all over the world. The main purpose of this study is to convert PET waste into liquid hydrocarbon fuel. Because PET use has risen significantly over the world, and the bulk of garbage is thrown into the soil rather than recycled, posing an environmental risk. During the heat breakdown phase, PET decomposes. It creates very strong and solid non-biodegradable terephthalic acid and benzoic acid complexes. To obtain liquid hydrocarbon fuel from PET, at 250-300℃, calcium hydroxide Ca(OH)2 is used as a catalyst in this study.

Multicomponent Solid Fuel Production Technology Using Waste Water

An assessment is given to the problems of urban wastewater sludge utilization in our country and abroad, with determination of formation and usage level. Global trends in the reduction of carbon dioxide emissions exacerbate the urgency of solving the designated tasks. At the same time, recently, in connection with the EU’s plans to introduce a cross-border carbon levy, it has become necessary to reduce the carbon footprint from burning traditional fuels, which is an urgent problem of modern society. One of the directions that provide a solution to this problem is the replacement of part of the hydrocarbon fuel by the consumption of multicomponent solid fuel based on the use of combustible waste that is part of the multicomponent fuel. This solid fuel can be used to meet the needs of small consumers, for example, in the autumn-summer period to generate a drying agent for the preparation of grain on the threshing-floor, in small boiler houses, in sand drying plants of locomotive depots, heat installations of hangars and workshops, as well as in other heat-generating installations operating on solid fuels. At the same time, solving the problem of reducing the carbon footprint for Belarus is closely related to another urgent task – reducing the energy component of industrial products and the environmental consequences of storing accumulated and generated waste. The paper presents the results of joint scientific research in the field of application of modern technologies and equipment using electrohydraulic treatment to reduce and minimize the level of anthropogenic and polluting substances in wastewater sludge. The described technological equipment, technology and post-treatment modes reduce the content of harmful substances in the wastewater sludge composition even with short-term treatment. An assessment of the effectiveness of the developed technology for the use of sewage sludge is given, using the method of wet multicomponent briquetting to obtain a multicomponent fuel. The presented process flow diagram of multicomponent briquetting using sewage sludge and plant-wood waste directly shows the undeniable advantages of using watered wastewater sludge as a raw material for the production of solid fuel. At the same time, the optimally selected ratio of components and moisture content of the briquetted composition solves a number of technologically difficult problems that cannot be realized using traditional briquetting technologies. The presented data of the conducted research and the developed technology make it possible to expand the area of using wastewater sludge as a secondary renewable material resource.

Assessment of the Impact of Applying a Non-Factory Dual-Fuel (Diesel/Natural Gas) Installation on the Traction Properties and Emissions of Selected Exhaust Components of a Road Semi-Trailer Truck Unit

Problems such as global warming and rising oil prices are driving the implementation of ideas to reduce liquid fuel consumption and greenhouse gas emissions. One of them is the use of natural gas as an energy source. It is a hydrocarbon fuel with properties that allow the reduction of CO2 (Carbon Dioxide) emissions during combustion. Solutions are being implemented that allow for the use of natural gas to means of transport, namely in trucks of various categories and intended use. These installations are used in new vehicles, but also in the form of conversion for used cars, usually several years old. The article presents the results of tests of an engine from a used semi-trailer truck with a mileage of approx. 800 thousand km, with the compressed natural gas supply system installed. This installation (hardware and software), depending on the engine operating conditions, enables the replacement of up to 80% of diesel (base fuel) with natural gas. The impact of changing the fuel supply method on the traction characteristics calculated with the use of external characteristics of both conventional and dual-fuel mode was assessed. The emissions of exhaust gas components were also determined under the conditions of the UNECE Regulation No. 49. The test results confirm that compared to conventional fueling, dual fueling allows for a significant reduction in CO2 emissions, even in a used vehicle with high mileage. The use of a non-factory installation did not significantly affect the traction properties of the vehicle, and engine wear is of greater importance in this case (comparison with factory data). The work is a valuable supplement to the results of the research in which the impact of the use of a non-factory CNG (Compressed Natural Gas) supply system on the performance of a semi-trailer truck unit equipped with such an installation was assessed compared to a semi-trailer truck unit powered in a classic way with diesel fuel.

Skeletal Kinetic Modeling for the Combustion of Endothermic Hydrocarbon Fuel in Hypersonic Vehicle

Chemical kinetic mechanism plays a vital role in the deep learning of reacting flow in practical combustors, which can help obtain many details of the combustion process. In this paper, a surrogate model and a skeletal mechanism for an endothermic hydrocarbon fuel were developed for further investigations of the combustion performance in hypersonic vehicles: (1) The surrogate model consists of 81.3 mol% decalin and 18.7 mol% n-dodecane, which were determined by both the composition distributions and key properties of the target endothermic hydrocarbon fuel. (2) A skeletal kinetic mechanism only containing 56 species and 283 reactions was developed by the method of “core mechanism​ sub mechanism”. This mechanism can be conveniently applied to the simulation of practical combustors for its affordable scale. (3) Accuracies of the surrogate model and the mechanism were systematically validated by the various properties of the target fuel under pressures of 1-20atm, temperatures of 400-1250K, and equivalence ratios of 0.5-1.5. The overall errors for the ignition and combustion properties are no more than 0.4 and 0.1, respectively. (4) Laminar flame speeds of the target fuel and the surrogate model fuel were also measured for the validations. Results show that both the surrogate model and the mechanism can well predict the properties of the target fuel. The mechanism developed in this work is valuable to the further design and optimization of the propulsion systems.

Identification and Quantification of Hydrocarbon Functional Groups in Gasoline Using 1H-NMR Spectroscopy for Property Prediction

Gasoline is one of the most important distillate fuels obtained from crude refining; it is mainly used as an automotive fuel to propel spark-ignited (SI) engines. It is a complex hydrocarbon fuel that is known to possess several hundred individual molecules of varying sizes and chemical classes. These large numbers of individual molecules can be assembled into a finite set of molecular moieties or functional groups that can independently represent the chemical composition. Identification and quantification of groups enables the prediction of many fuel properties that otherwise may be difficult and expensive to measure experimentally. In the present work, high resolution 1H nuclear magnetic resonance (NMR) spectroscopy, an advanced structure elucidation technique, was employed for the molecular characterization of a gasoline sample in order to analyze the functional groups. The chemical composition of the gasoline sample was then expressed using six hydrocarbon functional groups, as follows: paraffinic groups (CH, CH2 and CH3), naphthenic CH-CH2 groups and aromatic C-CH groups. The obtained functional groups were then used to predict a number of fuel properties, including research octane number (RON), motor octane number (MON), derived cetane number (DCN), threshold sooting index (TSI) and yield sooting index (YSI).