Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju


1 - 10 / 116
Na začetekNa prejšnjo stran12345678910Na naslednjo stranNa konec
Exergy analysis of a Brayton cycle with variable physical properties and variable composition of working substance
Marija Živić, Antun Galović, Jurij Avsec, Mario Holik, 2016, izvirni znanstveni članek

Opis: The exergy analysis of a Brayton cycle is performed in the paper. The four input variables: the ratio of the compressor exit and inlet pressures, the ratio of inlet temperature of gases in turbine and inlet temperature of air in compressor and the isentropic efficiencies of the compressor and turbine are analysed. The temperature ratio is varied in a way that the compressor inlet temperature of air is maintained constant, while the turbine inlet temperature of flue gases is varied from 900 to 1200°C. In the combustion chamber methane is completely combusted with excess air ratio which is determined by the temperature of flue gases at the turbine inlet. The analysis further includes variability of the molar heat capacities of air and flue gases with temperature and variability of their heat capacity ratios. The exergy destruction in turbine, compressor and combustion chamber and also total exergy efficiency of the cycle are considered in the analysis.
Ključne besede: Brayton cycle, variable physical properties, variable composition of working substance, maximum work output, maximum thermal efficiency
Objavljeno: 12.07.2017; Ogledov: 54; Prenosov: 1
.pdf Polno besedilo (789,62 KB)

The calculation of specific heats for some important solid components in hydrogen production process based on CuCl cycle
Jurij Avsec, 2014, izvirni znanstveni članek

Opis: Hydrogen is one of the most promising energy sources of the future enabling direct production of power and heat in fuel cells, hydrogen engines or furnaces with hydrogen burners. One of the last remainder problems in hydrogen technology is how to produce a sufficient amount of cheap hydrogen. One of the best options is large scale thermochemical production of hydrogen in combination with nuclear power plant. copper-chlorine (CuCl) cycle is the most promissible thermochemical cycle to produce cheap hydrogen.This paper focuses on a CuCl cycle, and the describes the models how to calculate thermodynamic properties. Unfortunately, for many components in CuCl cycle the thermochemical functions of state have never been measured. This is the reason that we have tried to calculate some very important thermophysical properties. This paper discusses the mathematical model for computing the thermodynamic properties for pure substances and their mixtures such as CuCl, HCl, Cu2OCl2 important in CuCl hydrogen production in their fluid and solid phase with an aid of statistical thermodynamics. For the solid phase, we have developed the mathematical model for the calculation of thermodynamic properties for polyatomic crystals. In this way, we have used Debye functions and Einstein function for acoustical modes and optical modes of vibrations to take into account vibration of atoms. The influence of intermolecular energy we have solved on the basis of Murnaghan equation of state and statistical thermodynamics.
Ključne besede: thermodynamics, molecular crystals, mathematical models, statistical thermodynamics
Objavljeno: 07.07.2017; Ogledov: 80; Prenosov: 6
.pdf Polno besedilo (266,80 KB)

Optimalno sledenje sončnih modulov Soncu ob upoštevanju izgub pogonskega sklopa
Sebastijan Seme, Jože Voršič, Gorazd Štumberger, 2013, izvirni znanstveni članek

Opis: V delu je obravnavan dvo-osni sledilni sistem za sledenje sončnih modulov trajektoriji Sonca. Pri tem je predstavljena nova metoda za optimalno sledenje trajektoriji Sonca, ki upošteva tudi izgube pogonskega sklopa dvo-osnega sledilnega sistema. Cilj optimalnega sledenja je maksimalna pretvorba energije sončnega sevanja v električno energijo upoštevajoč na električne izgube pogonskega sklopa. Določitev trajektorije sledilnega sistema predstavlja v optimizaciji nelinearni in omejen problem, kjer ciljna funkcija ni na voljo v eksplicitni obliki. Za optimizacijski postopek se je uporabila stohastična metoda imenovana diferenčna evolucija. Pri tem je ciljna funkcija podana z napovedjo razpoložljivega sončnega sevanja, izgubami pogonskega sklopa in izkoristkom sončne elektrarne. Omejitve problema predstavljajo konstantna hitrost premikanja in minimalna sprememba kota premika pogonskega sklopa sledilnega sistema. Podani rezultati kažejo, da je optimalna trajektorija sledilnega sistema, odvisna predvsem od razpoložljivega sončnega sevanja, izkoristka sončne elektrarne, izgub pogonskega sklopa in omejitev, ki jih upoštevamo v sami optimizaciji.
Ključne besede: sončne elektrarne, fotonapetostni sistem, optimiranje, sončno sevanje, izgube
Objavljeno: 21.12.2015; Ogledov: 713; Prenosov: 26
URL Polno besedilo (0,00 KB)

Fakulteta za energetiko, najmlajša članica Univerze v Mariboru
2009, intervju

Ključne besede: Fakulteta za energetiko, fluidna tehnika, intervju
Objavljeno: 10.07.2015; Ogledov: 355; Prenosov: 8
URL Polno besedilo (0,00 KB)

Experimental analysis of the impact of particles on the cavitating flow
Boštjan Gregorc, Andrej Predin, Drago Fabijan, Roman Klasinc, 2012, izvirni znanstveni članek

Opis: The purpose of this paper is to present an analysis of the impact of solid particles on the development of cavitating flow conditions around a hydrofoil. Experimental studies have been conducted in a cavitation tunnel with three different mixtures of particles and water. We used a particle-like properties, such as are found in river water, and with increasing mass concentration. We performed measurements of torque and the relative noise in the hydrofoil. The point in the formation of vapour phase on the hydrofoil and the pronounced frequency effect were determined by measuring the relative noise. Based on the analysis the results show that the particles increase the intensity and extent of cavitation.
Ključne besede: particles, cavitation, noise, measurements
Objavljeno: 10.07.2015; Ogledov: 499; Prenosov: 3
URL Polno besedilo (0,00 KB)

Energy renovation of an older house
Zdravko Praunseis, Simon Marčič, Renato Strojko, Jurij Avsec, 2013, izvirni znanstveni članek

Ključne besede: energy performance certificate, renovation, renewable souces
Objavljeno: 10.07.2015; Ogledov: 393; Prenosov: 14
URL Polno besedilo (0,00 KB)

Design of synchronous reluctance generator with dual stator windings and anisotropic rotor with flux barriers
Dalibor Igrec, Amor Chowdhury, Bojan Štumberger, Miralem Hadžiselimović, 2012, izvirni znanstveni članek

Opis: Appropriate design of synchronous reluctance machine with dual stator winding and anisotropic rotor with flux barriers in generator operation mode is investigated. Finite element analysis is employed in order to determine the machine performance. Two different designs for synchronous reluctance generator with dual stator windings and the same anisotropic rotor with flux barrier are presented.
Ključne besede: synchronous machine, reluctance generator, dual stator windings
Objavljeno: 10.07.2015; Ogledov: 455; Prenosov: 47
URL Polno besedilo (0,00 KB)

Graphʼs theory approach for searching the shortest routing path in RIP protocol
Saša Klampfer, Amor Chowdhury, Jože Mohorko, Žarko Čučej, 2012, izvirni znanstveni članek

Opis: Routing is a problem domain with an infinite number of final-solutions. One of the possible approaches to solving such problems is using graph theory. This paper presents mathematical analysis methodologies based on circular graphs for solving a shortest path routing problem. The problem is focused on searching for the shortest path within a circular graph. Such a search coincides with the network routing problem domain. In this paper, we introduce in the detail all necessary parts needed to understand such an approach. This includes: definition of the routing problem domain, introduction to circular graphs and their usage, circular graphʼs properties, definition of walks through a circular graph, searching and determining the shortest path within a circular graph, etc. The state of the art routing methods, implemented in contemporary highly sophisticated routers, includes well-known weight-based algorithms and distance-vectors-based algorithms. The proposed solution can be placed between the two abovementioned methods. Each of these known methods strives for optimal results, but each of them also has its own deficiencies, which should be rectified with the proposed new method. This theoretically presented method is argued by a practical example and compared with the RIP (Routing Information Protocol) technique, where we look for the shortest path and possible walks through a specified circular graph.
Ključne besede: circular graphs, shortest path, graph diameter, walk through, CIGRP, connectivity matrix, network topology, symmetry, fully connected graph
Objavljeno: 10.07.2015; Ogledov: 464; Prenosov: 14
URL Polno besedilo (0,00 KB)


Objavljeno: 10.07.2015; Ogledov: 271; Prenosov: 2
URL Polno besedilo (0,00 KB)

Induction machine
Bojan Štumberger, Miralem Hadžiselimović, Ivan Zagradišnik, 2013, izvirni znanstveni članek

Opis: The aim of this paper is to present the difference of induction machine electromechanical characteristics in motor and generator operating modes. Firstly, the paper presents analytically derived equations, which are based on equivalent circuit and are used for calculation of induction machine breakdown torque. Secondly, a comparison of calculated and measured characteristics in motor and generator operating modes is presented. Results of torque characteristics measurements, temperature rise tests and load tests are also provided. Finally the difference between the calculated and the measured results is commented on and explained in detail.
Ključne besede: indukcijski motorji, motorji, generator, meritve
Objavljeno: 10.07.2015; Ogledov: 405; Prenosov: 7
URL Polno besedilo (0,00 KB)

Iskanje izvedeno v 0.14 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici