Template-Type: ReDIF-Article 1.0 Author-Name: R. Majdan Author-Workplace-Name: Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: Z. Tkáč Author-Workplace-Name: Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: J. Kosiba Author-Workplace-Name: Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: R. Abrahám Author-Workplace-Name: Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: J. Jablonický Author-Workplace-Name: Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: Ľ. Hujo Author-Workplace-Name: Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: M. Mojžiš Author-Workplace-Name: Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: P. Ševčík Author-Workplace-Name: Slovnaft, a.s., member of MOL Group, Bratislava, Slovak Republic Author-Name: M. Rášo Author-Workplace-Name: Slovnaft, a.s., member of MOL Group, Bratislava, Slovak Republic Title: Evaluation of tractor biodegradable hydraulic fluids on the basis of hydraulic pump wear Abstract: Two types of biodegradable hydraulic fluids (HEES and HEPR) with the mineral oil-based hydraulic fluid (HV) were compared. The tests were performed using a test bench. During the tests with a tractor hydraulic pump, the fluids were loaded by a cyclic pressure load. The tests of fluids were evaluated on the basis of wear of the pump. Evaluation parameters were the flow characteristics of the pump and the cleanliness level of tested fluids. The temperature of the fluid under which the test was performed was measured in real operating conditions of the Zetor Forterra 11441 tractor. It is possible to state upon the test results that the mineral oil-based fluid was classified in the first place, the biodegradable fluid of the HEPR type in the second place, and the biodegradable fluid of the HEES type received the last position. Keywords: test bench, cleanliness level, flow efficiency, agricultural tractor, fluid temperature Journal: Research in Agricultural Engineering Pages: 75-82 Volume: 59 Issue: 3 Year: 2013 DOI: 10.17221/18/2012-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/18/2012-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201303-0001.txt Handle: RePEc:caa:jnlrae:v:59:y:2013:i:3:id:18-2012-RAE Template-Type: ReDIF-Article 1.0 Author-Name: J. Malaťák Author-Workplace-Name: Department of Technological Equipment of Buildings, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: L. Škarková Author-Workplace-Name: Department of Technological Equipment of Buildings, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: A. Prošková Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Title: Chemical, stoichiometric and thermal analysis of fatty acid methyl esters from processed animal fat Abstract: The paper focuses on liquid biofuel raised by transesterification of processed animal fat from rendering plant production suitable for energy use. The objective of the paper is to carry out an element analysis and stoichiometric analysis of selected samples of fuel from rendering plant production and to compare them with classic elements. The results of the analyses prove higher values of nitrogen concentration in the samples from rendering plant fat. In case of the samples of fatty acid methyl esters (FAME) from it a reduction of nitrogen was proved even if the values are still higher than at fatty acid methyl esters rape oil. Concerning the concentration of sulphur and chlorine in the samples of both rendering plant fat and FAME from it their concentration concerning the limiting values do not cause any problem. The net calorific value of the analysed samples is slightly lower. The net calorific value of the samples is particularly reduced by the higher amount of ash and by the oxygen concentration in the sample itself. Higher amount of ash in the fuel increases the amount of solid emissions. Keywords: biofuel, rendering plant fat, transesterification, net calorific value, emissions Journal: Research in Agricultural Engineering Pages: 83-90 Volume: 59 Issue: 3 Year: 2013 DOI: 10.17221/27/2010-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/27/2010-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201303-0002.txt Handle: RePEc:caa:jnlrae:v:59:y:2013:i:3:id:27-2010-RAE Template-Type: ReDIF-Article 1.0 Author-Name: M. Šeďová Author-Workplace-Name: Department of Mechanical Engineering, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: R. Adamovský Author-Workplace-Name: Department of Mechanical Engineering, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: P. Neuberger Author-Workplace-Name: Department of Mechanical Engineering, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Title: Analysis of ground massif temperatures with horizontal heat exchanger Abstract: The paper is aimed at specification of ground massif temperatures in the horizontal heat exchanger area in both the heating season and during heat exchanger stagnation. The energetic potential of the ground massif was evaluated using the difference of temperatures of the ground massif in the area of the heat exchanger at the beginning and at the end of the heating season. Specific heat rates of the ground heat exchanger were also determined, and the influence of the ground massif thermal resistance and coefficient of heat transfer between the inner wall of the heat exchanger pipe and the heat-carrying liquid were analysed. Keywords: heat pump, heat conduction, heat transfer, heat transfer fluid, thermal power Journal: Research in Agricultural Engineering Pages: 91-97 Volume: 59 Issue: 3 Year: 2013 DOI: 10.17221/30/2012-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/30/2012-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201303-0003.txt Handle: RePEc:caa:jnlrae:v:59:y:2013:i:3:id:30-2012-RAE Template-Type: ReDIF-Article 1.0 Author-Name: P. Vaculík Author-Workplace-Name: Department of Technological Equipment of Buildings, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: J. Maloun Author-Workplace-Name: Department of Technological Equipment of Buildings, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: L. Chládek Author-Workplace-Name: Department of Technological Equipment of Buildings, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: M. Přikryl Author-Workplace-Name: Department of Technological Equipment of Buildings, Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Title: Disintegration process in disc crushers Abstract: Grinding or crushing hard raw materials is usually a primary operation which precedes the follow-up technological processes in a number of industrial sectors. A great variety of machines using different principles of fragmentation are employed in the technology of pulverization. The food industry uses roller mills, in which the main process is the shear grinding. In the animal feed industry impact machines known as hammer mills are often used. In recent years, mills have been employed that use their frontal edges for grinding or crushing during the rotation of one of two adjacent discs. The modern design disc machines used for grinding grain have resulted from long development and their operation has a relatively low noise level with reduced dust. The separation process that occurs in the gap between the active edges of the discs can be described as shear grinding and is currently the subject of attention which is focused on the specific energy consumption and fractional composition of the product of grinding. Keywords: grinding process, grinding discs, trajectory of grist fragments, logarithmic spiral Journal: Research in Agricultural Engineering Pages: 98-104 Volume: 59 Issue: 3 Year: 2013 DOI: 10.17221/28/2012-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/28/2012-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201303-0004.txt Handle: RePEc:caa:jnlrae:v:59:y:2013:i:3:id:28-2012-RAE Template-Type: ReDIF-Article 1.0 Author-Name: Ľ. Kubík Author-Workplace-Name: Department of Physics, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: S. Zeman Author-Workplace-Name: Department of Production Engineering, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Title: Determination of oxygen permeability of polyethylene and polypropylene nonwoven fabric foils Abstract: The paper deals with determination of oxygen permeability of the polyethylene and polypropylene foils applied in mulching and food packaging. The construction of the equipment of measurement of gas permeability through the foils is discussed. The design and construction of the equipment was realized with applying of the Standard STN EN 77 0333. The measurement of permeability of oxygen through the polyethylene Bralen 2-63 with 9% colored concentrate Maxithen HP 533041 - violet foil, Polyten®MLB black&white foil and black polypropylene nonwoven fabric foil were realized by means of the modified method. Keywords: gas transmisivity, equipment construction, packaging, mulching Journal: Research in Agricultural Engineering Pages: 105-113 Volume: 59 Issue: 3 Year: 2013 DOI: 10.17221/31/2012-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/31/2012-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201303-0005.txt Handle: RePEc:caa:jnlrae:v:59:y:2013:i:3:id:31-2012-RAE Template-Type: ReDIF-Article 1.0 Author-Name: I. Karas Author-Workplace-Name: Department of Production Engineering, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: R. Gálik Author-Workplace-Name: Department of Production Engineering, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: Š. Pogran Author-Workplace-Name: Department of Production Engineering, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Author-Name: M. Šesták Author-Workplace-Name: Department of Production Engineering, Faculty of Engineering, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic Title: Computer simulation of the teat-cup liner stress and strain tensor Abstract: The three-notch black pressed teat-cup liners were selected into the set of the analysed teat-cup liners, and, for comparison purposes, teat-cup liners produced from silicone mixture. Wall thicknesses of the analysed teat-cup liners were adjusted by smoothing of the middle working part in length of 30 mm. The working part thickness thus changed from the original 2.37 to 0.41 mm for a teat-cup liner produced from black mixture and from the original thickness of 2.30 to 0.40 mm for a silicone teat-cup liner. A possibility of maximum closure of teat-cup liners in the pressing tact was assessed at the working suction of 50 kPa, the flow of distilled water through a measurement device reached the value of 4.4 l/min. Under laboratory conditions, with the above criteria fulfilled, the following stress relations were detected at teat tips: black teat-cup liner 30.25 kPa, silicone teat-cup liner 23.14 kPa. From the acquired results follows that the silicone teat-cup liner showed, from the aspect of suction loss, a more favourable value by 7.11 kPa. Physical-mechanical qualities of the analysed teat-cup liners were further used for the computer simulation of the teat-cup liners stress and strain tensor. Keywords: tensile test, suction, closing stopper, reduced stress Journal: Research in Agricultural Engineering Pages: 114-119 Volume: 59 Issue: 3 Year: 2013 DOI: 10.17221/23/2012-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/23/2012-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201303-0006.txt Handle: RePEc:caa:jnlrae:v:59:y:2013:i:3:id:23-2012-RAE