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.

Possibilities for Using Waste Hemp Straw for Solid Biofuel Production

Hemp biomass is useful in many branches of the economy. Hemp cultivation to obtain seeds has been gaining importance recently. In this process, shredded straw is a waste biomass which can be used for energy purposes. The possibilities for using waste hemp straw for solid biofuel production are described in this extended abstract, using the example of the Henola variety. The analyzed biomass was characterized by a high content of cellulose (over 40%) and hemicellulose (almost 30%), as well as a high calorific value (18,300 kJ·kg−1) and heat of combustion (17,100 kJ·kg−1).

Fabrication of Energetic Composites with 91% Solid Content by 3D Direct Writing

Direct writing is a rapidly developing manufacturing technology that is convenient, adaptable and automated. It has been used in energetic composites to manufacture complex structures, improve product safety, and reduce waste. This work is aimed at probing the formability properties and combustion performances of aluminum/ammonium perchlorate with a high solid content for direct writing fabrication. Four kinds of samples with different solid content were successfully printed by adjusting printing parameters and inks formulas with excellent rheological behavior and combustion properties. A high solid content of 91% was manufactured and facile processed into complex structures. Micromorphology, rheology, density, burning rate, heat of combustion and combustion performance were evaluated to characterized four kinds of samples. As the solid content increases, the density, burning rate and heat of combustion are greatly enhanced. Based on 3D direct writing technology, complex energetic 3D structures with 91% solid content are shaped easier and more flexibly than in traditional manufacturing process, which provides a novel way for the manufacture of complicated structures of energetic components.

A review of thermal properties of timber and char at elevated temperatures

Timber is one of the most frequently adopted combustible materials in the built environment. The thermal properties are the determining factors for assessing the fire risk in a building. The main thermal properties of timber and their char are reviewed, especially those temperature-dependent and moisture-dependent properties, including kinetic properties, ignition properties, thermal conductivity, specific heat capacity, effective heat of combustion and thermal diffusivity. The study has collected and summarized various thermal properties data and empirical models of hardwood and softwood with different mass percentages in cellulose, hemicellulose and lignin, as temperature increases. The average ignition temperature and effective heat of combustion of softwood are about 12.9% and 9.5% higher than those of hardwood, respectively. From most of the previous models, the thermal conductivity of timber char increases as temperature rises. Cellulose with a high density shows a higher thermal conductivity, but its impacts on the specific heat capacity are limited. Models to predict the main thermal properties of the hardwood, softwood and char are recommended. The collected data, together with those empirical models, can provide useful data resources and tools for the related fire risk assessments.

Problems of Hydrogen Doping in the Methane Fermentation Process and of Energetic Use of the Gas Mixture

This article discusses the technology for doping hydrogen into the fermenter to increase methane production and the amount of energy in the mixture. Hydrogen doping is anticipated to enable more carbon to be applied to produce methane. Hydrogen is proposed to be produced by using excess electricity from, for example, off-peak electricity hours at night. The possibilities of using a mixture of hydrogen and biogas for combustion in boilers and internal combustion engines have been determined. It has been proven that the volumetric addition of hydrogen reduces the heat of combustion of the mixture. Problems arising from hydrogen doping during the methane fermentation process have been identified.

Investigation of the Properties of Large and Small Fractions of Municipal Solid Waste

The results of field and laboratory studies of the component and fractional composition of solid municipal waste (MSW), humidity and ash content of MSW components, which made it possible to evaluate the properties of individual fractions and waste in general, are presented. The fractional composition of MSW was determined by the method of separating waste into five fractions of different sizes: more than 250 mm, 100-250 mm, 50–100 mm, 15–50 mm and less than 15 mm. An assessment of the energy and biological potentials of MSW of various sizes has been carried out. In each fraction, the main biogenic components have been identified, which form the biological potential. The calculation of thermal properties (moisture content, ash, combustible substances, as well as the heat of combustion) for the fractions under consideration has been performed. The dependence of the heat of combustion of MSW on the particle size has been established.