M. Brožek

Evaluation of selected properties of briquettes from recovered paper and board.

Brožek M. (2015): Evaluation of selected properties of briquettes from recovered paper and board. Res. Agr. Eng., 61: 66–71. Worldwide increasing energy demand is today permanently covered by a majority of non-renewable energy sources, namely by coal, crude oil and natural gas. This causes the rapid decline of their reserves and the time gets near when they will be run out. Therefore in the last years the exploitation of renewable energy sources has been permanently preferred. One of alternative fuel forms is fuel on the basis of paper waste. In this paper the results of tests are published, which were carried out using six sorts of recovered paper and board (group and grade 1.05, 1.06, 2.02, 2.05, 2.07 and 2.08 according to CSN EN 643:2002), pressed into the form of briquettes. During the tests following briquettes parameters were watched: moisture content, ash amount, gross calorific value, length and diameter, weight, density, rupture force and mechanical durability. It was proved that briquettes made from recovered paper and board compared with briquettes from wood waste are of high density, high mechanical durability and for their rupture, relatively high force is necessary. But at the same time they have high ash amount and low gross calorific value.

Energy Balance of Briquette Production from Various Waste Biomass

Abstract Production of briquette bio-fuel is related to several aspects of densification process. The present paper deals with the relation between briquette volume density ρ (kg·m−3) and required deformation energy Ed (J). Wood, energy crop and cardboard feedstocks were compressed by a laboratory briquetting press of two diameters (40 and 65 mm); in this way six kinds of briquette samples (W40, W65, E40, E65, C40, C65) were produced. The values of compressing force F (N) and briquette volume density ρ were measured directly during feedstock densification; the deformation energy Ed was calculated subsequently. The amount of deformation energy Ed consumed within the achievement of specific briquette volume density ρ levels differed in case of all samples, the same as the maximum achieved briquette volume density ρ levels. Best results, i.e. efficiency of briquette production (the highest ρ, the lowest Ed), were achieved by cardboard samples, followed by wood and finally by energy crop samples. An overall evaluation indicated a higher production efficiency of briquette samples 40 mm in diameter and the disadvantage of the production of briquette samples with briquette volume density ρ > 1000 kg·m−3; above such level, the amount of consumed deformation energy Ed increased disproportionately sharply.

Microparticle composites on the basis of scrap utilizable in the field of agricultural production

Valasek P., Brožek M. (2015): Microparticle composites on the basis of scrap utilizable in the field of agricul tural production . Res. Agr. Eng., 61: 92–97. For renovation of functional surfaces of machines and devices for agricultural production it is possible to use, in addition to conventionally used methods, polymers with fillers – composites. The presence of microparticles in the polymeric matrix improves substantially the abrasive wear resistance and hardness. This contribution describes tribological properties of epoxy resin filled with chips of ferrous metals – the change of volume losses increase in dependence on the pressure increase (load) having effect on the worn surface. From the carried out experiments the considerable de crease of filled resin losses is evident compared with the resin without filler. At the same time the exponential increase of volume losses with the increased load was quantified in the course of tribological tests.

Bonding of plywood

Brožek M. (2016): Bonding of plywood. Res. Agr. Eng., 62: 198–204. The contribution contains results of bonded joints strength tests. The tests were carried out according to the modified standard ČSN EN 1465 (66 8510):2009. The spruce three-ply wood of 4 mm thickness was used for bonding according to ČSN EN 636 (49 2419):2013. The test samples of 100 × 25 mm size were cut out from a semi-product of 2,440 × 1,220 mm size in the direction of its longer side (angle 0°), in the oblique direction (angle 45°) and in the direction of its shorter side (crosswise – angle 90°). The bonding was carried out using eight different domestic as well as foreign adhesives according to the technology prescribed by the producer. All used adhesives were designated for wood bonding. At the bonding the consumption of the adhesive was determined. After curing, the bonded assemblies were loaded using a universal tensile-strength testing machine up to the rupture. The rupture force and the rupture type were registered. Finally, the technical-economical evaluation of the experiments was carried out.

Bonding of wood.

Brožek M. (2015): Bonding of wood. Res. Agr. Eng., 61: 134–139. The paper presents the results of strength tests of joints made using six different adhesives destined by their producers for bonding wood. Bonded samples were made from seven sorts of wood commonly growing in the Czech Republic, namely ash, beach, cherry, maple, pine, spruce and walnut. From semi-products (boards, planks, squared timber logs) the test samples of dimensions 25 × 100 mm and 4 mm thickness were cut out in the direction of year rings. Always two samples were bonded together so that their overlap was of 12.5 mm. All these assemblies were loaded using the universal testing machine up to their rupture. The rupture force and the rupture type (rupture in the joint, in the bonded material) were registered. The aim of the tests was to assess the influence of the used adhesive on the bonded joint strength at different woods, to assess the variability of the adhesive consumption at the manual adhesive application by different workers and to determine costs for bonding of different woods using different adhesives. From the results it follows that between six tested adhesives used for bonding of seven sorts of wood, considerable differences exist not only as regards their price, but also their quality. From the results it also follows that the manual adhesive application is very unequal, because it depends on the dexterity and care of the worker. Next, the costs for bonding of different woods using different adhesives were determined.

Influence of Storage on Briquettes Mechanical Properties

Abstract The effects of the storage place, placing manner, and storage time on mechanical properties of briquettes made from birch chips were laboratorily tested. A unique methodology developed by the present author enabling a relatively easy assessment of mechanical properties of the briquettes is described. The briquettes properties were evaluated by their density and rupture force determination. From the test results it follows that if the briquettes are stored in a well closed plastic bag, neither the place nor the storage time influence significantly their life time. When stored in a net plastic bag, the briquettes get seriously damaged, namely depending on their storage place and storage time.