Direct demonstration of complete combustion of gas-suspended powder metal fuel combustion using bomb calorimetry

Off-the-shelf calorimeters are typically used for hydrocarbon-based fuels and not designed for simulating metal powder oxidation in gaseous environments. We have developed a method allowing a typical bomb calorimeter to accurately measure heat released during combustion and achieve nearly 100% of the reference heat of combustion from powder fuels such as aluminum. The modification uses a combustible organic dispersant to suspend the fuel particles and promote more complete combustion. The dispersant is a highly porous organic starch-based material (i.e., packing peanut) and allows the powder to burn as discrete particles thereby simulating dust-type combustion environments. The demonstrated closeness of measured Al heat of combustion to its reference value is evidence of complete metal combustion achieved in our experiment. Beyond calorific output under conditions simulating real reactive systems, we demonstrate that the calorimeter also allows characterization of the temporal heat release from the reacting material and this data can be extracted from the instrument. The rate of heat release is an important additional parameter characterizing the combustion process. The experimental approach described will impact future measurements of heat released during combustion from solid fuel powders and enable scientists to quantify the energetic performance of metal fuel more accurately as well as the transient thermal behavior from combusting metal powders.

Optical and thermodynamic investigations of a methane and hydrogen blend fueled large bore engine

The following paper presents thermodynamic and optical investigations of the natural flame and OH radical chemiluminescence of a hydrogen enriched methane combustion compared to natural gas combustion. The engine under investigation is a port-fueled unscavenged prechamber 4.8 L single cylinder large bore engine. The blends under consideration are 2%V, 5%V,10%V, and 40%V of hydrogen expected to be blended within existing natural gas grids in a short and mid-term timeline in order to store green energy from solar and wind. These fuel blends could be used for stabilization of the energy supply by reconverting the renewable fuel CH4/H2 in combined heat and power plants. As expected, admixture of hydrogen extends the ignition limits of the fuel mixture toward lean ranges up to an air-fuel equivalence ratio of almost 2. No negative effect on combustion is observed up to an admixture of 40%V hydrogen. At 40%V hydrogen, abnormal combustion like backfire occurs at an air-fuel equivalence ratio of 1.5. The higher mixtures exhibit increased nitrogen oxide emissions due to higher combustion chamber temperatures, while methane slip and CO emissions are reduced due to more complete combustion. The optical investigation of the natural flame and OH radical chemiluminescence are in good agreement with the thermodynamic results verifying the more intense combustion of the fuel blends by means of the chemiluminescence intensity. Further, lube oil combustion and a continuing luminescence after the thermodynamic end of combustion are observed.

Outstanding flame retardancy for poly(vinyl alcohol) achieved using a resveratrol/tannic acid complex

The rigid molecular structure of biobased resveratrol/tannic acid (RETA) complex increases the residual amount of RETA-poly(vinyl alcohol) after complete combustion.

THE INFLUENCE OF HYDROPHOBIC COATING ON THE EFFICIENCY OF FIRE PROTECTION OF TEXTILE MATERIALS

The analysis of fire-retardant materials for fabrics is carried out and it is established that the paucity of data for explanation and description of the process of fire protection, neglect of elastic coatings, leads to ignition of fabric structures under the action of flame. The development of reliable methods for studying the conditions of fire protection of fabrics leads to the creation of new types of fire protective materials. Therefore, it becomes necessary to determine the conditions for the formation of a barrier both for high temperatures and for leaching in the presence of precipitation and to establish a mechanism for inhibition of these processes. In this regard, full-scale tests were carried out and it was found out that when the flame is applied to untreated model samples of tent elements made of canvas fabric, the surface ignites and spreads the flame, which leads to their complete combustion within 105...120 s, instead, the model The fire-resistant sample of tent elements did not catch fire when ignited with a gasoline-based substance, and the flame did not spread. In this case, the final combustion was recorded for 3 c and the swelling of the protective coating reached 3...5 mm, and the surface was charred on an area of about 80% from the inside. When tested for fire retardant efficiency for a fire-resistant sample treated with a water repellent (5 % solution of GDJ-94), a decrease in efficiency and carbonization of the material was recorded, which amounted to 100%, and for a fire-resistant sample treated with a water repellent (5 % solution), a decrease in efficiency was recorded due to the combustion of paraffin and local burnout of the material, and carbonization was 100 %. Obviously, such a mechanism of influence of the fire-retardant coating is the factor regulating the process, which preserves the integrity of the object. Thus, there is reason to argue about the possibility of targeted regulation of the processes of fire protection of the fabric by applying coatings capable of forming a protective layer on the surface of the material, which inhibits the rate of heat penetration.

Black Carbon - A Silent Contributor to Climate Change

Black carbon is a potent climate-warming component of particulate matter formed by the incomplete combustion of fossil-fuels, wood and other fuels. Complete combustion would turn all the carbon in the fuel into carbon dioxide, but combustion is never complete, and CO2, CO, volatile organic compounds, organic compounds, and black carbon particles are formed in the process. It contributes to warming by converting incoming solar radiation to heat. When deposited on ice and snow, BC and co-emitted particles reduce surface albedo thereby melting the glaciers. The complex mixture of particulate matter resulting from incomplete combustion is referred as soot. When suspended in the atmosphere, black carbon contributes to warming by converting incoming solar radiations to heat. It also influences cloud formation and impacts regional circulation and rainfall pattern. The Artic and the glaciated regions such as Himalayas are particularly vulnerable to melting as a result. The present paper aims to review the work done on black carbon and its mitigation measure.

CFD MODELING OF VORTEX AFTERBURNING OF BIOMASS GASIFICATION PRODUCTS IN A FLUIDIZED BED FURNACE

CFD modeling of the afterburning of biomass gasification products in a fluidized bed furnace with a vortex supply of secondary air has been carried out. The effect of secondary air heating on the ecological characteristics of flue gases has been determined. Modeling has shown that gasification products swirl in the primary chamber with the formation of a central vortex, which obeys the law of solid-body rotation. An increase in the temperature of the secondary air leads to an increase in its tangential velocity and, as a consequence, to an increase in centrifugal mass forces. Calculations have shown that with an increase in the secondary air temperature, the maximum of the kinetic energy of turbulence shifts to the periphery and increases in absolute value. This results in more efficient mixing of the central (producer gas) and peripheral (secondary air) streams. As a result, this leads to a more complete combustion. The influence of secondary air heating on the ecological characteristics of the furnace has been determined. As a result of air heating from 30° C to 300° C, the concentration of carbon monoxide decreases by more than 1.5 times. The concentration of nitrogen oxides practically does not change and amounts to 3.5 mg /nm3.

Assesment of the possibility of using nanomaterials as fuel additives in combustion engines

Nanomaterials are a new group that has quickly found a wide range of applications in medicine, cosmetology, the food, weapons or automotive industry. They are also used as a fuel additive. This paper reviews the literature and assesses the current state of knowledge regarding the use of nanoparticles in automotive engine fuels. The results obtained so far are presented and further research directions in this field are identified Conclusion: The results of the review showed a discrepancy, selected groups favor the reduction of harmful gas emissions, while others do not and even increase emissions, e.g. the use of carbon nanotubes contributes to the increase in the emission of environmentally harmful nitrogen oxides, while the presence of graphene oxide reduces it. An interesting observation is also the fact that groups such as titanium and graphene oxide reduce the emission of harmful carbon monoxide by improving fuel combustion from semi-combustion to complete combustion, but at the same time increase CO2 emissions, which in turn is a greenhouse gas The whole group of nanomaterials contributes to the reduction of hydrocarbon emissions Nanomaterials improve the quality of fuel combustion The review shows tests only on diesel and a mixture with biodiesel in the review there were no studies for gasoline

Application of Technology for Combustion of Depleted Ionized Gas Fuel in an Electric Field

A technology is proposed to improve the efficiency of heat devices operating on gas fuel. The technology is based on the use of a method of burning depleted ionized gas fuel in an electric field. Application of the method allows to reduce the formation of soot deposits and provides a more complete combustion of the gas. Increasing the efficiency of heating devices is achieved due to the formation of an electric field by including an ionizing radiation device in the structure of the gas stove. The energy of the ionizing radiation of the gas fuel provides the formation of Coulomb forces. Combustion intensifies, and convective heat exchange increases due to electroconvection. The design of the ionizing radiation device includes electrodes located at a distance from each other. Power is supplied from a voltage source. The electrodes are fixed using porcelain ring insulators. The proposed design solutions provide not only a decrease in gas fuel consumption, but also an increase in the flame temperature and the power of thermal radiation not only in the visible, infrared and ultraviolet ranges. Additional electrolysis of the fuel mixture, and the acceleration of its combustion rate is achieved due to ionization. The results of experimental studies to determine the parameters of the combustion processes of gas fuel (isobutane (CH3-CH(CH3)-CH3) – 72 %, butane (CH3-CH2– CH2-CH3) – 22 %, propane (C3H8) – 6 %) are presented. It was found that with a variable electric field strength for gas ionization, an increase in the temperature of the frying bed by 39%, heat transfer by 2 times, a decrease in carbon oxides by 31–36%, and a decrease in gas fuel consumption by 26% are achieved.

Increasing fire and the decline of fire adapted black spruce in the boreal forest

Intensifying wildfire activity and climate change can drive rapid forest compositional shifts. In boreal North America, black spruce shapes forest flammability and depends on fire for regeneration. This relationship has helped black spruce maintain its dominance through much of the Holocene. However, with climate change and more frequent and severe fires, shifts away from black spruce dominance to broadleaf or pine species are emerging, with implications for ecosystem functions including carbon sequestration, water and energy fluxes, and wildlife habitat. Here, we predict that such reductions in black spruce after fire may already be widespread given current trends in climate and fire. To test this, we synthesize data from 1,538 field sites across boreal North America to evaluate compositional changes in tree species following 58 recent fires (1989 to 2014). While black spruce was resilient following most fires (62%), loss of resilience was common, and spruce regeneration failed completely in 18% of 1,140 black spruce sites. In contrast, postfire regeneration never failed in forests dominated by jack pine, which also possesses an aerial seed bank, or broad-leaved trees. More complete combustion of the soil organic layer, which often occurs in better-drained landscape positions and in dryer duff, promoted compositional changes throughout boreal North America. Forests in western North America, however, were more vulnerable to change due to greater long-term climate moisture deficits. While we find considerable remaining resilience in black spruce forests, predicted increases in climate moisture deficits and fire activity will erode this resilience, pushing the system toward a tipping point that has not been crossed in several thousand years.

An Experimental Study on a Dual-Fuel Generator Fueled With Diesel and Simulated Biogas

Diesel fueled generators are widely used for power generation in remote and/or off-grid communities. In such communities, local organic waste streams can be used to generate biogas which can be used to replace diesel used by diesel generators to lower fuel cost and reduce greenhouse gas (GHG) emissions. Diesel powered generators can be easily retrofitted with a biogas dosing line in the engine intake to introduce biogas, but appropriate optimization would be of great help to further improve generator performance and reduce GHG emissions. The objective of this research is to demonstrate simplified optimization methods that can reduce GHG emissions (carbon dioxide and methane) from such retrofitted dual-fuel engines under various biogas compositions. The study was conducted on a modern 30 kilowatt (kW) generator using an electronically controlled, four-stroke, four-cylinder, direct injection, turbo-charged diesel engine. The engine was operated with the factory electronic control unit (ECU) and a programmable ECU which allowed for control of the fuel injections and exhaust gas recirculation (EGR) valve. Biogas was simulated by using natural gas (with more than 95% methane by volume) which was diluted with either carbon dioxide or nitrogen. This study consisted of two areas. The first one was the comparison of the engine performance when operating with biogas using the factory ECU and the programmable ECU with user optimized fuel injection. The second one was the influence of volume fraction of carbon dioxide or nitrogen in the biogas. The test results reinforced the importance of optimizing the diesel injections when the engine was operated in the biogas-diesel dual-fuel mode to ensure complete combustion and achieve a reduction in GHG emissions. Increasing nitrogen fraction had a minimal effect on the emissions, but increasing carbon dioxide fraction caused the NOx and methane emissions to decrease, and the indicated thermal efficiency to increase.