Steam Turbine for Biomass Power Plant

Diplomová práce se zabývá návrhem kondenzační parní turbíny s jedním regulovaným odběrem s možností provozu 0 až 10 t/h. V první části je navrženo tepelné schéma. Turbína má také dva neregulované odběry pro nízkotlakou regeneraci a výstupní pára je chlazena vodním kondenzátorem. Stěžejní částí práce je návrh průtočného kanálu turbíny s jedním regulačním stupněm v provedení A-kolo a s 26 stupni s přetlakovým typem lopatkování. Turbína má otáčky 8500 min-1, kterým pevnostně vyhovují i kritická místa. Následující kapitoly popisují návrh vyrovnávacího pístu a ložisek. V poslední kapitole je uvedena provozní charakteristika. Součástí práce je i výkres řezu turbínou. Výsledná turbína má svorkový výkon 9259,7 kW a termodynamickou účinnost 85,5 %.Diploma thesis deals with the design of a condensing steam turbine with one controlled steam extraction. Its working range is 0 to 10 t/h. The first part contains the design of the heat balance scheme. The turbine has two unregulated steam extractions for low-pressure feedwater heater and outlet steam is cooled by water condenser. The main part is the design of the turbine flow channel with one regulative stage using impulse blading and 26 regular stages using reaction blading. The turbine rotating speed is 8500 rpm, which is strength suitable even in critical points. The following chapters are describing the design of the compensation piston and bearings. The consumption characteristic of the steam turbine is shown in the last chapter. Drawing of the turbine section is attached to this thesis. Final turbine power is 9259,7 kW and thermodynamic efficiency 85,5 %.

Comparison of tractor slip at three different driving wheels on grass

ArticleThe 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

Special tractor driving wheels with two modification of spikes inclination angle

ArticleThe paper presents a research on an improvement of tractor drawbar properties using special driving wheels. Two modifications of the special driving wheels were designed and tested under field conditions. The results were compared with standard tyres. The special driving wheels consists of the tyres with a modified tyre-tread pattern and equips with the spike segments. The special driving wheels allow to activate or deactivate the spike segments to improve a drawbar pull at worse adhesive conditions of the ground or transport on roads with standard tyres. The first modification activates all 8 spike segments at spike inclination angle 90° and the second one 4 at angle 90°and 4 at 30°. The measurements were realised in October 2017 in an area of the Slovak Agricultural Museum in Nitra. The drawbar properties of the special driving wheels were evaluated based on drawbar pull of the test tractor Mini 070 type connected with a load tractor MT8-065 type. Using the test tractor in 1st and 2nd gear, the measurements were realized at 100% wheels slip and repeated 4 times. The results show the statistically significant differences in the drawbar pull of the test tractor with different driving wheels on a grass plot. The highest increase in drawbar pull reached the value 25.56% (2nd gear) and 19.98% (1st gear) in case of the special driving wheels with 4 spike segments at 90° and 4 at 30°. In case of the special driving wheels with 8 spike segments at 90°, increase in the drawbar pull reached the value 10.09% (1st gear) and 15.21% (2nd gear) in comparation with the standard tyres

Comparison of consumption of tractor at three different driving wheels on grass surface

ArticleThe paper deals with possibility of reduction of tractor fuel consumption when working on grass surface, and compares use of two versions of spike devices embedded to the original tyre body. The device was designed at Department Transport and Handling (Slovak University of Agriculture in Nitra). Older as well as newer system proposed in 2017 comprises spikes and it is assembled to common tractor tyre tread pattern with auxiliary grooves cut in. Same device can be set to two positions, allowing to work as 8 - spikes and 16 - spikes system. The spikes are tilted in grooves when moving on paved road. The spikes are ejected out to reduce wh eels slip when operated in field. Remaining eight spikes are tilted in case of 8 - spikes system. Measurements were realised on grass surface. Tractor Mini 070 type was loaded with heavier tractor MT8 - 065 type in tests with 3 different driving wheels, balanc ing the actual weight in all cases. Drawbar pull and fuel consumption were measured in tests, allowing to compute specific drawbar consumption and fuel consumption per hour for three different loads. The results pointed out a fact the tyre slip loss and en ergy consumption of tractor movement increase at the soil humidity 19.45%. It follows from results achieved that use of both 8 - and 16 - spikes wheel device versions reduced fuel consumption when cultivating higher humidity soil, preferable for tillage. Eigh t spikes system with semi - tilted remaining spikes is the most efficient method

Microfluidics

Bakalářská práce se zabývá problematikou proudění plynů a kapalin v zařízeních s mikro rozměry. První část práce je zaměřena na problematiku Reynoldsova čísla a laminárního proudění v mikrokanálku. V druhé části jsou popsány konkrétní zařízení pro pumpování pracovní látky v mikroměřítku – mikropumpy, mikroventily, mikrojehly, mikromíchadla.The bachelor's thesis deals with phenomenon of gas and fluid flow in equipment with micro scale. The first part is dedicated to describe Reynolds number and laminar flow in micro channel. The second part is dedicated to describe specific equipment for pumping a working material – micropumps, microvalves, microneedels, micromixers.

Contamination of transmission and hydraulic oils in agricultural tractors and proposal of by-pass filtration system

ArticleTractors use various types of lubricating oils in transmission and hydraulic system. Oils are contaminated by different ways depending on the work of the lubricated system. There are general requirements on the cleanliness level of the oil in the tractor transmission and hydraulic system according to the standard DIN 51524. According to all that, this paper presents research conducted by two tractors. The tractor John Deere 8100 used only its own implements (ploughs, trailers etc.) and it was operated in compliance with user manual. In this tractor, the oil cleanliness level met the standard DIN 51524 because reached the stage 7 (NAS 1638). The tractor Zetor Forterra 124 41 contained extremely contaminated oil, it reached stage > 12 (NAS 1638), due to the non-standard operation which was opposite to the user manual. Both ways of tractor operation are typical for farmers activity in the Slovak Republic, depending on the tractor type and style of agricultural production at most. The second part of this paper is aimed at the proposal of by-pass filtration system to eliminate the oil contamination. The by-pass filtration system is the second stage of the oil filtration in the tractor, whereas the first one means standard tractor filter. Function of the system was tested according to the decrease of chemical elements concentration characterising the oil contamination and visual method based on filter and its change after operating of tested tractor. There was evaluated the decrease of concentration of Fe (41.6%), Cu (28.7%) and Si (20.5%) after by-pass filtration system was running under operational conditions. It can be concluded that the by-pass filtration system was proposed correctly and it is suitable for tractors operation

Presentations Web Editor

Cieľom tejto práce je implementácia webovej aplikácie s tlstým klientom pre spravovanie prezentácií s obsahom typu Markdown, ktorý sa následne prezentuje pomocou prezentačného rámca(framework) Reveal.js. Frontend aplikácie je vytvorený pomocou Vue.js s nadstavbou Nuxt.js, backend pomocou Express.js a ako úložisko dát je zvolená NoSQL dokumentová databáza MongoDB. Frontend a backend časti aplikácie komunikujú medzi sebou cez technológiu REST. Výsledná aplikácia umožňuje užívateľom zobrazovať, upravovať a vytvárať viacero verzií danej prezentácie.  Práca naďalej obsahuje popis, porovnanie súčasných technológií a zdôvodnenie ich výberu.The aim of this thesis is to implement a web application to manage presentations with Markdown content, which are then presented through slideshow framework Reveal.js. Frontend of the application is created with Vue.js and Nuxt.js, backend with Express.js and for data storage I have chosen MongoDB, a NoSQL document database. Frontend and backend parts of the application communicate with each other through REST technology. The application allows users to view, edit and create more versions of the same presentation. This thesis furthermore contains description, comparison of current technologies and substantiation of their selection.

Design of microfluidic mixer

Mikrofluidická zařízení jsou stále častěji používána v oblasti medicíny, jelikož využívají pouze malých množství pracovních vzorků jako např. krve či reagenčních chemikálií. Pro práci s danými látkami mnohdy vyžadujeme efektivního smísení a zde nastává hlavní problém v mikrofluidických systémech. Z důvodu malých rozměrů je zde proudění pouze laminární a na mísení se tedy nepodílejí turbulentní víry, ale jen molekulární difuzivita.Microfluidic devices are more frequently being used in medicine as they operate with small amounts of test samples, such as blood or reagent chemicals. To work with such substances, effective mixing of the solution is usually required, which emerged as the most challenging problem in microfluidic systems. Due to the minor dimensions of the devices only laminar flow occurs, thus the turbulent eddies do not contribute to the mixing, but only the molecular diffusivity.

Evaluación de la pérdida del suelo mediante el modelo Rusle en la microcuenca del río Jucusbamba, Provincia de Luya, Región Amazonas (Perú)

La erosión del suelo es un problema importante a nivel mundial, el cual deriva de las malas prácticas agrícolas y actividades antrópicas. Este problema afecta a la calidad física y química de la tierra y del agua. En este trabajo de investigación se evaluó la pérdida del suelo mediante la Ecuación de Pérdida de Suelo Universal Revisada (RUSLE) con el uso de herramientas de Sistemas de Información Geográfica (SIG) y teledetección en la microcuenca del río Jucusbamba (Perú). Los factores de la ecuación se estimaron a partir de información base como datos de precipitación (Factor R), mapa de suelos de la FAO (Factor K), modelo de elevación digital de terreno (Factor LS), mapa de cobertura y uso actual del suelo (Factor C) y mapa de pendiente (Factor P). Los resultados indican que el 93,34 % (0 a 5 tn/ha.año) del área total existe una pérdida leve, en el 3,94% (5 a 10 tn/ha.año) existe una pérdida moderada, en el 1,82% (10 - 20 tn/ha.año) ocurre una pérdida alta, en el 0,61% (20 - 40 tn/ha.año) la pérdida de suelo es muy alta, y solo en el 0,29% (> 40 tn/ha.año) la pérdida de suelo es severa. Se concluye que las zonas con alta, muy alta y severa erosión del suelo se localizan en la parte media y baja de la microcuenca.Tesi