2017, Vol. 15, No. 4

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/5358

Sirvi

Nüüd näidatakse 1 - 20 34

The assessment of hazelnut mechanical harvesting productivity
(2017) Bernardi, B.; Tous, J.; Benalia, S.; Abenavoli, L.M.; Zimbalatti, G.; Stillitano, T.; De Luca, A.I.
Hazelnut cultivation represents a new opportunity for Calabrian mountainous and sloping areas (Southern Italy), where no alternative fruit crops, except forestry, could be settled. In this Region, hazelnut production doubled during the last fifty years, inciting the farmers to introduce mechanization in cropping practices such as harvesting in order to increase productivity and decrease production costs. Indeed, harvesting is currently one of the most expensive processes of the productive cycle, moreover to be time consuming if carried out manually. Mechanization degree depends significantly on the terrain topography: in sloping areas, rakes are often associated to aspirating machines to harvest the fallen fruit, while the employment of harvesting machines from the ground prevails in flat areas. In this context, the present paper aims to assess technical and economic aspects of harvesting operation, using a harvester from the ground model ‘Jolly 2800’ (GF s.r.l., Italy). Particularly, for technical purposes data about operational working time as well as working productivity were collected according to CIOSTA requirements, in two harvesting sites, whereas, for mechanical harvesting economic evaluation, an estimation model was applied to calculate machinery cost per hour. Moreover, the cost per kg of hazelnut in shell and the average cost per hectare were estimated also. The obtained results show a working productivity of 0.065 ha h-1 op-1 in the first harvesting site, while it was equal to 0.022 ha h -1 op-1 in the second one. Concerning the average cost per hectare, the second harvesting site showed the worst economic performances, with 550.76 € ha-1 against 182.54 € ha-1 obtained in the first one.
Comparison of mechanical and electric drive of mulcher
(2017) Pexa, M.; Čedík, J.; Kumhála, F.; Pražan, R.
The contribution is focused on comparison of mechanical and electric drive of mulcher with vertical axis of rotation by means of mathematical model. The mulcher has working width of 6 m and it is usually aggregated with tractor of minimal power of 150 kW. On the test plot the torque and power transferred trough the tractor PTO, fuel consumption and the production of gaseous emissions components were monitored. This field measurement served as a basis for modelling as well as measured complete characteristics of the combustion engine of the tractor John Deere 7930. As a main base for the modelling the record of real operation of the tractor with mulcher was used. Then, in the software product MathCad the operation of the tractor with mechanical and electrical drive of the mulcher was modelled. In the case of the electrical drive of the mulcher the tractor with internal combustion engine, connected to generator was taken into consideration. Due to overall lower efficiency of the electrical drive with generator, worse values of the fuel consumption and emissions production in comparison with mechanical drive were reached in case of electric drive. At hypothetical use of batteries (100% electro-powered tractor) and when the energy mix at Czech Republic is taken into consideration, it is possible to reach the quarter values of emissions production in comparison with combustion engine.
Comparison of selected remote sensing sensors for crop yield variability estimation
(2017) Křížová, K.; Kumhálová, J.
Currently, spectral indices are very common tool how to describe various characteristics of vegetation. In fact, these are mathematical operations which are calculated using specific bands of electromagnetic spectrum. Nevertheless, remote sensing sensors can differ due to the variations in bandwidth of the particular spectral channels. Therefore, the main aim of this study is to compare selected sensors in terms of their capability to predict crop yield by NDVI utilization. The experiment was performed at two locations (Prague-Ruzyně and Vendolí) in the year 2015 for both locations and in 2007 for Prague-Ruzyně only, when winter barley or spring barley grew on the plots. The cloud-free satellite images were chosen and normalised difference vegetation indices (NDVI) were calculated for each image. Landsat satellite images with moderate spatial resolution (30 m per pixel) were chosen during the crop growth for selected years. The other data sources were commercial satellite images with very high spatial resolution – QuickBird (QB) (0.6 m per pixel) in 2007 and WorldView-2 (WV-2) (2 m per pixel) in 2015 for Prague-Ruzyně location; and SPOT-7 (6 m per pixel) satellite image in 2015 for Vendolí location. GreenSeeker handheld crop sensor (GS) was used for collecting NDVI data for both locations in 2015 only. NDVI calculated at each of images was compared with the yield data. The data sources were compared with each other at the same term of crop growth stage. The results showed that correlation between GS and yield was relatively weak at Ruzyně. Conversely, significant relation was found at Vendolí location. The satellite images showed stronger relation with yield than GS. Landsat satellite images had higher values of correlation coefficient (in 30 m spatial resolution) at Ruzyně in both selected years. However, at Vendolí location, SPOT-7 satellite image has significantly better results compared to Landsat image. It is necessary to do more research to define which sensor measurements are most useful for selected applications in agriculture management.
Comparison of tillage systems in terms of water infiltration into the soil during the autumn season
(2017) Kovář, S.; Mašek, J.; Novák, P.
The soil belongs to the most valuable parts of the planet Earth. It is, endangered by water erosion, which causes huge destruction every year, or damage to farmland. More than half of the agricultural land in the Czech Republic is threatened by water erosion. The measurement was performed in the location Nesperská Lhota. The trial has been established on loamy sand Cambisol. In the field experiment, there were created 6 different variants which wad differed by soil tillage and crop. In the individual variants maize and oats were located. The field trial has been existing for a long time, as it was founded in 2009. Two measuring methods of water infiltration were used for the measurements: a mini disk infiltrometer and a single ring. The measurement was performed in the period of September 2016 before the harvest of maize. The soil aggregates were already stabilized at that time after all tillage operations. The measurement result showed the difference between the methods of soil tillage. The greatest ability of infiltration had a variant of maize with inter-row oats. Surprisingly, it was followed by maize, which was processed by ploughing technology. The lowest infiltration capacity was showed by oats reduced by soil tillage. A variant without vegetation had the second lowest infiltration. Our results obtained at rate of water infiltration into the soil affirm the need to control measures in the late vegetative stages. It is important for most of the rainfall to be quickly infiltrated so that it prevents the formation of massive surface runoff.
Comparison of tractor slip at three different driving wheels on grass
(2017) Abrahám, R.; Majdan, R.; Drlička, R.
The paper deals with a possibility of tractor slip reduction on a grass and evaluates an use of two versions of special wheels. Both prototypes were developed at the Department of Transport and Handling of the Slovak University of Agriculture in Nitra. The first system was designed in 2010 year as blades wheels. The second system (spikes device) consists of spikes which are mounted onto standard tractor tyres with special cuts, was designed in 2014 year. The spikes are settled in these cuts while moving on road surface. The second one is placed near the drive wheels and uses the blades. The spikes and blades are ejected to reduce wheels slip when tractor operates on grass or soil. The base position allows tractor transport on road with standard tyres. The goal of experiments realized on grass surface was to compare mutually slip behaviour achieved. The measurements were realized with standard tyres without any modification, too. A tractor with three types of drive wheels were loaded by heavier tractor. Drawbar pull and wheel rotation speed for slip calculation were measured in tests. The results show a fact that a loss of energy due to the wheels slip increases, while a penetrometric resistance in the surface layers of a soil decreases, at soil humidity 33.2%. An application of both prototypes is very advantageous because they reduce the wheels slip, increase tractor operation efficiency and so protect the soil.
Contribution of pumped hydro energy storage for more RES utilization on autonomous power systems
(2017) Katsiagiannis, Y.; Annuk, Andres; Karapidakis, E.S.; Estonian University of Life Sciences. Institute of Technology. Department of Energy Engineering
This paper addresses the performance issues of autonomous power systems under high renewable energy sources (RES) penetration. Renewable energy sources could be the main option for isolated power generation at remote locations in case that energy storage introduced. At the moment, pumped hydro storage (PHS) units and batteries storage systems (BSS) represent the most mature technologies for large scale energy storage. The basic criteria for this kind of energy storage unit installations include, (a) the existence of an autonomous power system with local power stations, (b) the high electricity production cost, (c) the potential of renewable energy sources (mainly wind and solar), and (d) the non-flat terrain morphology (for PHS). Greek islands represent ideal cases for large scale energy storage installations, as they fulfil all the above criteria. This paper shows the effect of the installation of a planned PHS unit in Crete island. The calculations are based on real data provided by the Cretan power system operator, whereas the results show the effect of energy storage units operation on the energy mix, as well as the economic viability of the project, which is combined with significant environmental benefits.
Critical velocity of solid mineral fertilizers in a vertical upward airstream and repose angle
(2017) Hůla, J.; Kroulík, M.; Honzík, I.
Critical velocity of mineral fertilizers in airstream is important not only at the application of fertilizers by spreaders but also at combine of fertilizing and sowing. The knowledge of angles of repose is important to design hoppers on spreaders for solid mineral fertilizers. Critical velocities for six solid mineral fertilizers were measured in the vertical aspiration duct of a laboratory sorting machine. Variation curves were constructed for particular fertilizers and the mean critical velocity of fertilizers (velocity of uplift) was computed. The mean critical velocity of fertilizers was between 8.53 and 12.43 m s -1 . The lowest critical velocity was found out in the fertilizer UREA 46%, the highest in the fertilizer LAV. Statistical significance of differences in the critical velocity of fertilizers was assessed. Angles of repose of eight solid mineral fertilizers were also measured and statistical significance of differences was evaluated. The highest values of repose angle were determined for potassium salt and ammonium sulfate (35.9° respectively 34.9°), the lowest values for UREA and LAV (28.7° respectively 29.6°). The obtained results extend information applicable to an assessment of parameters of the operation quality of spreaders during mineral fertilizer application.
Dry matter accumulation and nitrogen concentration in forage and grain maize in dryland areas under different soil amendments
(2017) Lamptey, S.; Yeboah, S.; Li, L.; Zhang, R.
Soil amendment plays significant role in improving soil fertility and increasing crop productivity in rain–fed agriculture. Understanding the grain yield associated with dry matter and N concentration is essential for improving maize production. A 3– year field study was conducted to determine dry matter accumulation, nitrogen concentration and grain yield of forage and grain maize under different soil amendments in the Western Loess Plateau of China. The experiment was conducted using a randomized complete block design with four treatments and three replicates per treatment. Results showed that dry matter accumulation and nitrogen concentration in the swine manure in combination with chemical fertilized (SC) crops was significantly higher (by ≈ 60% and 39%) than no amendment (NA) which therefore translated into increased grain yield ≈ 74%. The SC treatment also improved leaf area index and chlorophyll content (P < 0.05) by approximately 34% to 32% compared to NA, which supported the above results. The nitrogen concentration in the leaf was higher at jointing and lower at maturity. Grain yield positively correlated with dry matter accumulation and nitrogen concentration at jointing, flowering and milk stage. Dry matter accumulation and grain yield also increased in the sole swine manure (SM) and maize stover (MS) treatments, but to lesser extent than SC. Based on the improvement of dry matter accumulation, nitrogen concentration and grain yield, swine manure in combination with chemical fertilizer appears to be a better fertilization option under dryland cropping systems.
Effect of controlled traffic farming on weed occurrence
(2017) Barát, M.; Rataj, V.; Týr, Š.; Macák, M.; Galambošová, J.
Soil compaction caused by field traffic is one of the most important yield limiting factors. Moreover, published results report that soil over-compaction inhibits the uptake of plant nutrients and decreases their ability to compete with weeds. Controlled Traffic Farming (CTF) is technology which prevents excessive soil compaction and minimizes compacted area to the least possible area of permanent traffic lines. A long-term experiment was established at University farm in Kolinany (Slovakia) in 2010 with 6 m OutTrack CTF system. Random Traffic Farming (RTF) is simulated by 1 annual machinery pass crossing the permanent traffic lines. Aim of presented study was to assess the effect of CTF on weed infection pressure. To achieve this, weed occurrence at different traffic treatments was determined. Emerged weeds per square meter were counted, identified and recorded at 14 monitoring points. Results showed that higher weed infection was found at the area with one machinery pass compared to the non-compacted area. Following weeds were identified: Bromus secalinus L., Stellaria media (L.) VILL., Veronica persica POIR. in LAMK., Poa annua L., Polygonum aviculare L., Convolvulus arvensis L. Occurrence of these weeds could be used as soil compaction indicator. Based on these results it can be concluded, that CTF technology has potential to decrease weed infestation in comparison to RTF system due to ration of non-compacted to compacted area. Moreover, with exact localization of weeds in traffic lines together with exact identification of weed species, it is possible to target the application of herbicides.
Effect of drill machine operating speed on quality of sowing and biomass yield
(2017) Maga, J.; Krištof, K.
The paper is focused on the study and evaluation of quality of the seeding of seeds and its effect on the biomass yield. The aim was to evaluate the space arrangement of the seeds by using of polygon method on one field with the repetition for different forward speeds of the drill machine. For the evaluation there were used digital photographs, which were taken during repeated measurements of the each value of the forward speed after sprouting of crop. These images have been used in order to determine the shape and size of the surface area belonging to the plant. Own software TfPolyM was used for the image analysis. The shape of the polygons belonging to the individual plants was expressed by values of the shape factor Tf. This factor characterises the suitability the shape of polygon surface related to the individual plant. By comparing of the values of the shape factors for different forward speeds of the drill machine we can determine the optimal value of the forward speed from the point of seed placement uniformity in horizontal level. During harvest of the crop there was analysed the variability of the biomass yield in relation to values of the forward speed used during seeding. The most suitable values of shape factor Tf (0.8519) was recorded for speed of drill machine set on 12 km h -1 . For other tested speeds 8, 10, 15 km h -1 were recorded lower values of shape factor 0.7994, 0.8173 and 0.8449, respectively. In determination of biomass production for drill machine speed 12 km h -1 the greatest yield from 1 m2 was observed. Subsequently, for speeds 8 and 10 km h -1 was lower about 4.26% and 1.83%, respectively. For tested speeds of drill machinery 15 km h -1 and above was observed only a small descent of yields about 0.6%. Fluctuation in yields affected by working speed then demonstrates fluctuation in sowing rate. It was also observed that the working speed of sowing machinery also affect the amount of yield directly. However, in case of lowest yield of straw recorded it was observed even 20% decrease in yield of grains.
Effect of rake angle and cutting speed on energy demands of mulcher with vertical axis of rotation
(2017) Čedík, J.; Pexa, M.; Pražan, R.
The contribution deals with the reduction of agriculture energy demands. For maintenance and treatment of permanent grassland areas, areas left fallow and put to rest the mulching in combination with other workflows (mowing, grazing) is advantageous procedure. As conventional impact grass cutting and chopping is energy demanding procedure, it is proper to reduce the energy demands of such device. In the paper the effect of shape of cutting tool, particularly the rake angle, on energy demands of mulcher with vertical axis of rotation is studied. The effect of cutting speed on energy demands is also verified. The measurement was performed using mulcher MZ 6000 made by Bednar FMT Ltd. with working width of 6 m and three rotors. During the measurement the test rides using the cutting tools with different rake angle and cutting speeds of 105m s-1 , 89 m s-1 and 79 m s-1 were performed. The rake angle of cutting tools were chosen 0°, 15° and 25°. The test area was pasture with permanent grassland. During the measurement the torque and power, transferred through PTO to the machine, fuel consumption and GPS coordinates were measured. From each test ride the samples of grass matter were taken in order to determine the yield and moisture content. It was found that increase of the rake angle up to 25° and decrease of the cutting speed resulted in decrease of the power requirement of the mulcher.
Effectiveness of simulation models on technical skills among surgeons. A critical review
(2017) Raimla, Riin; Merisalu, Eda; Estonian University of Life Sciences. Institute of Technology. Husbandry Engineering and Ergonomics
Based on simulation models the surgeons can train technical skills and improve their functional status of musculoskeletal state. Work in good ergonomic position could reduce and prevent musculoskeletal disorders. The aim of this review is to carry out critical analysis of research on simulation techniques analysing the effectiveness of simulators on technical skills among the surgeons. The search of the articles based on the databases EBSCO, Science Direct and Web of Science. The articles published in 2011–2016 years and not the literature reviews of simulator models in surgery were the selection criteria. Most often the simulator models have used for training of laparoscopic operations, choosing new instruments or introducing new methodologies. Some articles have paid more attention to ergonomic equipment layout in practice to prevent musculoskeletal disorders. It is important to use simulators in the university hospitals, where the young surgeons and medical students are practicing.
Energy balance of sunflower production
(2017) Akdemir, S.; Cavalaris, C.; Gemtos, T.
The aim of the present study was to make an energy analysis of sunflower crop in the Trakya Region of Turkey, to evaluate the potential for using it as bioenergy source. Actual data for the common cropping practices applied in the region were collected with questionnaires given to the farmers. Literature data were used to obtain necessary energy indices. The collected information was used to establish energy budgets. Two alternative scenarios were examined: 1st - Using only the seed for biofuel production and 2nd -using the seed for biofuel and the stalks as biomass for bioenergy. The results showed that sunflower presented positive energy balance for both cases. Net energy was 35,334 MJ ha-1 when only the seed was taken into account and 87,308 MJ ha-1 for both seed and stalks. Energy efficiency was 3.67 and 7.34 respectively. Fertilization was the most energy intensive input (6,594 MJ ha-1 ) accounting for 48–50% of the total inputs. Tillage was the second most energy intensive input (3,595 MJ ha-1 ) accounting for 26–27% of total inputs. There were 6 different tillage operations such as ploughing, 4 machinery passages for seedbed preparation and hoeing in the sunflower production. All these operations increased energy inputs of the tillage. The total energy inputs were relatively low because it was possible to achieve high yields without irrigation.
Evaluation of nutritional and physical values of pellets based on pea and lupine with added yeast in chickens fattening
(2017) Chladek, L.; Plachy, V.; Vaculik, P.; Brany, P.
The article is focused on the development of the new type of broiler chicken feed, based on pea (Pisum sativum L.) and blue lupine (Lupinus angustifolius L), enriched with used dried brewer´s yeast. This composition eliminates use of soybean meal (PES) that was yet a traditional component in chicken feed. The main reason for its elimination was the using of genetically modified varieties of soybean and its relatively high price around 0.5 €uro kg-1 in Czech Republic. For milling of pea or blue lupine was used vertical (hammer) mill type Taurus, supplied by company TAURUS, for drying of used brewer´s yeast had been used drier Memmert UFE 800, final dry matter of the yeast was 88%. For pellets production were used two devices, press type JGE 120-6110 and Testmer. For the determination of physical properties of manufactured pellets (the weight of 1,000 pieces, bulk density, abrasiveness and pellet durability index PDI) were used following laboratory devices, Pellet Tester Holmen NHP and Testmer 200. Experimental activities had shown that the best results were reached using pellets manufactured on base blue lupine enriched by dried brewer´s yeast (6%).
Experimental analysis of hydrotreated vegetable oil (HVO) and commercial diesel fuel blend characteristics using modified CFR engine
(2017) Gailis, M.; Rudzitis, J.; Kreicbergs, J.; Zalcmanis, G.
Performance parameters of different commercial diesel fuels is a subject of interest for fuel consumers. Fuel retailer Neste recently introduced a new brand of WWFC 5th grade diesel fuel in Baltic market, consisting of diesel fuel and hydrotreated vegetable oil (HVO) blend. Fuel samples have been recently tested on chassis dynamometer, measuring wheel power and torque and in road conditions, measuring fuel consumption. Evaluation of fuel consumption and performance parameters in road or laboratory conditions may yield uncertain results due to complexity of modern automobile engine management and emission reduction systems. To better evaluate the combustion, fuel samples have been tested in modified CFR engine at various intake air pressure, temperature and compression ratio settings. Engine indicated performance parameters and combustion phasing of regular diesel fuel and diesel fuel-HVO blend are presented. Comparing to regular diesel fuel, fuel blend with HVO showed reduced apparent heat release rate (AHRR) during premixed combustion phase at low inlet air temperature and low compression ratio conditions, comparing to regular diesel fuel. Premixed combustion phase AHRR of diesel-HVO blend increased above AHRR of regular diesel fuel at higher inlet air temperature and higher compression ratio conditions. Diffusion controlled combustion phase AHRR of diesel-HVO blend increased above AHRR of regular diesel fuel at higher inlet air temperature, higher compression ratio conditions and supercharged air supply.
Fair Trade and social responsibility – whose duty? Estonian consumers’ attitudes and beliefs
(2017) Riivits-Arkonsuo, Iivi; Ojasoo, Merle; Leppiman, Anu; Mänd, Kristina
This article investigates how the Estonian consumers endorse the idea of Fair Trade (FT) and understand the principles of social responsibility. The article is based on a study on Fair Trade and social responsibility conducted in 2014. The study examined the consumers’ attitudes and beliefs associated with FT and local Estonian agricultural production. The article aims to compare if there are any difference in the beliefs and attitudes among the Estonian consumers towards supporting local farmers and producers versus supporting the FT ideas which benefit the farmers and producers from the Global South. The authors fully recognise that there is no competition among these two groups per se, but the perception exists in the minds of the consumers. The respondents of the nation-wide representative sample (n = 1,007) evaluated the responsibility of different economic agents such as public sector, retailers, suppliers, producers, and consumers. Most of the respondents regarded the principle of social responsibility as giving the priority to local Estonian agricultural production. The Estonian consumers tend to be sceptical about the benefits of FT or the workers and farmers from the developing countries. The awareness and knowledge about FT ideas is not high.
Fodder galega (Galega orientalis Lam) grass potential as a forage and bioenergy crop
(2017) Meripõld, Heli; Tamm, Uno; Tamm, Sirje; Võsa, Taavi; Edesi, Liina
Fodder galega (Galega orientalis Lam.) is a forage legume that has been grown in Estonia for almost forty five years. Pure galega is known to be persistent, high-yielding crop and rich in nutrients, in particular crude protein (CP), neutral detergent fibre (NDF) and acid detergent fibre (ADF). Galega is usually grown in a mixture with grass in order to optimize its nutrient concentration, increase dry matter (DM) yield and improve fermentation properties. The trial plots were established on a typical soddy-calcareous soil. There are certain grass species suitable for the mixture. In this study galega mixtures with reed canary grass cv. ‘Marathon’, timothy cv. ‘Tika’, red fescue cv. ‘Kauni’ and festulolium cv. ‘Hykor’ were under investigation in three successive years (2013–2015). In order to increase competitiveness of grasses and the yield of the first cut, two N fertilization levels were used: N0 and N50 kg ha-1 . Two cuts were carried out during the growing season in all three years. The total dry matter yield varied from 9.1 to 12.8 t ha-1 . The NDF concentration in the DM varied from 495−559 g kg-1 . Both DM-yield and NDF were dependent on the year, mixture, cutting time and fertilization. Nitrogen fertilization (N50 kg ha-1 ) favoured grass growth and reduced the role of galega in the sward.
Improving job satisfaction with different intervention methods among the school personnel in Estonia and Latvia
(2017) Hrenov, G.; Vilcane, I.; Urbane, V.; Tint, Piia
This investigation was carried out in two high schools: one in Estonia (EST1) and one in Latvia (LAT1). The offices EST2 and LAT2 were chosen from the countryside of the both countries. Office EST1 is situated in an atrium-type building for educational and research needs. The second building is mainly for education (auditoriums) and the offices LAT1 are situated on the ground floor. The third and the fourth offices were taken for comparison. Office EST2 is situated in a countryside in an old wooden building; the fourth office LAT2 is located in a new building in Latvian countryside. All together 181 office-workers were involved. At first, the work environment conditions were measured. The ergonomics of workplaces was assessed with ARTtool and Kiva-questionnaire was used to study psychosocial conditions and job satisfaction at computer-equipped workplaces. Occupational hazards were measured to clarify, do the work environment influence on the behaviour and the job motivation and satisfaction of the worker at workplace? After the first questioning of workers using Kiva-questionnaire, the Metal Age programme was implemented and after the intervention, the Kiva-questionnaire was carried out again. The results showed that if the preventive measures for solving the problems at workplace are implemented, and the employers and the employees are trained and consulted using the appropriate programmes, the stress situations could be avoided. The workers in all offices were confident that the discussion about the problems is very important as the work with computers is intensive and there is a very short time to communicate with each other. The educational work is also stressful.
Influence of raw material properties on the quality of solid biofuel and energy consumption in briquetting process
(2017) Muntean, A.; Ivanova, T.; Hutla, P.; Havrland, B.
The present paper is related to a pressing process research of raw materials with different density in order to investigate impact of biomass density on a formation of monolithic structure and the briquette’s strength. Another focus of the study is an influence of raw materials particles’ size on agglomeration process and quality of final product. Different biomass materials like two varieties of miscanthus, industrial hemp and apple wood were selected for experimental purposes of this research. Mechanical durability which represents one the main indicator of briquettes’ mechanical quality (strength) was determined. The research was conducted using hydraulic piston briquetting press. For assessment of briquetting efficiency during the whole process energy consumption was measured. One of the most important factors that can affect briquetting process is the temperature of pressing chamber which was registered as well. The main goal of the research was practical study of possibilities for increasing production efficiency and quality of briquettes on hydraulic piston briquetting press with respect to optimization of particles’ size of raw materials and use of raw materials the most appropriate density.
Influence of shape of cutting tool on pressure conditions in workspace of mulcher with vertical axis of rotation
(2017) Čedík, J.; Chyba, J.; Pexa, M.; Petrásek, S.
Nowadays there is laid great insistence on work efficiency improvement. This effort also affects the construction of mowers such as mulchers. Mulching with a vertical axis of rotation is very energy demanding work operation mainly, due to high energy losses. These energy losses, but also the quality of work, are influenced by the airflow and associated conditions of pressure inside the workspace of mulcher. Airflow in the workspace ensures repetitious contact of the truncated forage crops with the cutting edge tool and thus ensures crushing of aboveground parts of plants. The paper deals with the influence of the cutting tool shape on the mulcher’s inside workspace pressure conditions with the vertical axis of rotation. The influence of the trailing edge angle and rake angle on the pressure profile in the mulcher’s workspace with dependence on the rotor speed was examined. Measurements were performed on a laboratory single rotor mulcher model. It was found that in the mulcher’s workspace the vacuum is formed by virtue of the rotary movement of the cutting tools wherein the vacuum increases with rotor speed. The maximum measured vacuum was about 2.4 kPa and from the centre of the rotor towards its circumference almost linearly decreases. Furthermore, it was found that with decreasing trailing edge angle and with increasing rake angle the maximum vacuum decreases. When reducing the angle of the trailing edge from 45° to 25° led to reduction of vacuum of about 0.3 kPa (12.6%).

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