Potential of Biochar Derived from Agricultural Residues for Sustainable Management

A horizontal drum kiln is a traditional method widely used in Southeast Asian countries for producing biochar. An understanding of temperature conditions in the kiln and its influence on biochar properties is crucial for identifying suitable biochar applications. In this study, four agricultural residues (corncob, coconut husk, coconut shell, and rice straw) were used for drum kiln biochar production. The agricultural residues were turned into biochar within 100–200 min, depending on their structures. The suitability of biochar for briquette fuels was analyzed using proximate, ultimate, and elemental analysis. The biochar’s physical and chemical properties were characterized via bulk density, iodine number, pHpzc, SEM, and FTIR measurements. All biochars had low O/C and H/C ratios and negative charge from both carbonyl and hydroxyl groups. Coconut husk and shell biochar had desirable properties such as high heating value and a high amount of surface functional groups which can interact with nutrients in soil. These biochars are thus suitable for use for a variety of purposes including as biofuels, adsorbents, and as soil amendments.

Mixing of Particles in a Rotating Drum with Inclined Axis of Rotation

Various experimental and numerical studies have been carried out to study the mixing processes inside rotating drums with a horizontal axis of rotation in the past, but little effort has been made to investigate the rotating drums with an inclined axis of rotation, though such inclined drums exist in industrial waste management, food processing, power and pharmaceutical industries. To fill this gap, in this work, the discrete element method was used to study the mixing phenomena of a rotating drum for different angles of inclination from 0° to 15°. It was found that for inclined rotating drums, the whole bed Lacey mixing index is higher than that for the horizontal drum by 7.2% when the angle of inclination is 10°. The mixing index is related to the area ratio of the active region to the whole bed and volumetric fill. Increase in volumetric fill would lead to the decrease of the mixing index. The mixing index and area ratio exhibit similar patterns along the length of the drum for different angles of inclination.

Mixing of Bi-Dispersed Milli-Beads in a Rotary Drum. Mechanical Segregation Analyzed by Lab-Scale Experiments and DEM Simulation

Mechanical flow and segregation phenomena within a bed composed of milli-metric size spherical beads rotated in a horizontal drum were investigated. The beads population was bi-dispersed, with two kinds of binary (half by half) compositions: a bi-size bed with two different sizes and a bi-density bed with two different densities. The distributions of the beads were observed optically on the front side of the bed by means of a lab-scale drum prototype. Different numbers and lengths of peripheral straight baffles were tested as well as different drum filling ratios. The photographical data were processed to obtain the front layer mechanical segregation index. This experimental index was compared to the simulated one, obtained by means of commercial discrete element software EDEM. The simulations were corroborated by the experiments provided that the friction coefficients of the discrete elements method (DEM) model were correctly adjusted. The global segregation index was also calculated from simulation data for all considered cases and its values were lower and less sensitive to baffles’ configurations than those for the front layer.

STUDY OF EFFICIENCY OF DRUM DRYERS OF METALLURGICAL PRODUCTIONS USING PERFORATED PIPES WITH LOCALIZATION OF HEAT FLOWS

The article presents the design of a drum furnace, providing for the provision of differentiated heat flows through the use of an internal perforated pipe. The design of the presented horizontal drum dryer with a perforated tube having openings is designed to eliminate such technological risk factors as the ignition of the oil component of the processed material, and the metal dispersed material itself having pyrophoric properties. As a result of the numerical simulation using the LS–DYNA program, the temperature and heat fluxes in the quasi-boiling zone of the drained oil-containing dispersed material were determined. The calculations made it possible to establish the dependence of the temperature in the quasi-boiling zone on the number of holes of the perforated pipe. Analysis of the obtained graphs allows us to conclude that the gradient of temperature (heat) flows in fixed sections of the furnace of the quasi-boiling zone.

Overview of Gc Tests Used to Evaluate Composite–Composite Adhesive Joints

The quality of composite–composite bonded joints is a very important issue for industries, especially for the aerospace sector. A deficient joint may stop the manufacturing process and its repairing may include very high costs. Nowadays, the quality of the joint is obtained by means of interlaminar fracture toughness tests, estimating the [Formula: see text] value (Energy Release Rate used to produce crack propagation) over coupons with (theoretically) the same conditions as those included in an actual part. Usually, [Formula: see text] is obtained by means of a Double Cantilever Beam (DCB) test. Although DCB is the reference test, it may present some drawbacks when a non-symmetrical coupon is used and when the adherents stiffness is low. An alternative to DCB is the Climbing Drum Peel (CDP) test which is able to address some of the DCB drawbacks. Nevertheless, both tests need the use of a universal testing machine, then they cannot be done in situ. In the present investigation, DCB and CDP main characteristics are analyzed and a new device, called Horizontal Drum Peel (HDP), which includes the advantages of previous tests and the possibility to perform the test over an actual part is presented.

Mechanical and thermal segregation of milli-beads during contact heating in a rotary drum. DEM modeling and simulation.

The flow mechanics and heat transfer phenomena within a bed of milli-metric size spherical beads rotated and heated by contact in a horizontal drum were simulated by means of commercial discrete element software EDEM. Mono-dispersed and bi-dispersed beds (two particle sizes or two particle densities) were considered. The mechanical segregation index (standard deviation of local bed compositions) and the thermal segregation index (standard deviation of beads temperatures) were calculated for the different types of bed and same operating conditions. The thermal segregation was found to be enhanced by mechanical segregation and was much stronger for bi-dispersed beds than for monodispersed one. Keywords: rotating drum; particulate solid; segregation; contact heat transfer; DEM simulation.