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Numerical modelling of heat transfer and dissipation in power electronics applications
No full textOvaj se diplomski rad bavi analizom prijenosa i disipacije topline unutar sklopa elektroničkih energetskih modula koji su montirani na hladnjak, koristeći numeričke simulacije u softverskom paketu AVL FIRE M. Diplomski rad je napravljen u suradnji s tvrtkom AVL. U radu je validiran numerički model putem već napravljenih eksperimentalnih mjerenja temperature čipova. Mjerenja su napravljena u Grazu, u laboratoriju tvrtke AVL. Nakon toga napravljen je niz parametarskih analiza s ciljem analize utjecaja radnih parametara na hlađenje čipova te, posljedično, temperature sklopa. Rezultati usporedbe eksperimentalnih mjerenja i numeričkih simulacija pokazuju najveću grešku odstupanja maksimalnih temperatura u iznosu od 5.2 °C. Parametarskim analizama je pokazano da je za povećanje prijenosa topline i smanjenje pada tlaka najučinkovitije promjeniti volumni udio etilen glikola u smjesi etilen glikol-voda, koja služi kao rashladni medij u hladnjaku. Rezultati dobiveni ovim parametarskim analizama služit će za dizajniranje učinkovitijih sustava hlađenja sklopova energetske elektronike.This Master’s Thesis focuses on analyzing heat transfer and dissipation in electronic power module assemblies mounted on coolers. The analysis is conducted using numerical simulations with the AVL FIRE M software package. This Thesis was conducted in collaboration with AVL, a leading company in the field. The Thesis problem starts with validating the numerical model by comparing it with experimental chip temperature measurements. The measurements were conducted at AVL’s laboratory in Graz. Subsequently, a series of parametric analyses were performed to investigate the impact of operating parameters on chip cooling and temperatures of the assembly’s components. The comparison between experimental measurements and numerical simulations revealed a maximum deviation error of 5.2 °C. The parametric analyses highlighted that the most effective approach to enhance heat transfer and reduce pressure drop is by adjusting the volume fraction of ethylene glycol in the ethylene glycol-water mixture used as the cooling medium, passing through the heatsink. These findings will contribute to the development of more efficient cooling systems for power electronics assemblies
Improvement of assembly of floor convectors for large spaces
No full textRadom se analizira proizvodnja podnih konvektora, posebno sa stanovišta montaže, pri čemu se istražuje mogućnost robotske montaže. Na osnovi rezultata provedenih analiza metodom DFA, ustanovljeno je da, unatoč značajnom skraćenju vremena montaže, robotska montaža ipak nije trenutačno primjenjiva, zbog premalenih proizvodnih količina i visokih troškova povezanih s i investicijama. Predloženo je idejno rješenje s robotom FANUC R-2000iC/125L koji zadovoljava tehničke zahtjeve za nosivost i radni doseg, a za izvođenje dijela montaže podnog konvektora.The paper analyzes the production of floor convectors, particularly from the assembly perspective, with a focus on exploring the possibility of robotic assembly. Based on the results of analyses conducted using the DFA method, it has been determined that, despite a significant reduction in assembly time, robotic assembly is not currently feasible due to low production quantities and high costs associated with investments. A conceptual solution has been proposed with the FANUC R-2000iC/125L robot, which meets the technical requirements for load capacity and reach, specifically for carrying out a portion of the floor convector assembly
Influence of high pressure die casting technology on shrinkage porosity of the casting
No full textU ovom radu opisana je tehnologija tlačnog lijevanja. Nakon toga opisani su parametri procesa kojima se direktno utijeće na proces lijevanja, te svojstva odljevka. Uz to je opisan postupak određivanja parametara. Dalje su opisani kalupi za tlačni lijev, klasifikacija kalupa, njihovi osnovni dijelovi te materijali od kojih se izrađuju. Nakon toga slijedi odlomak o najčešćim legurama aluminija koje se koriste kod procesa tlačnog lijevanja, posebno legura AlSi9Cu3 koja je korištena za izradu odljevka na kojem su se vršila ispitivanja. Nakon legura dan je opis peći za taljenje materijala, točnije plinske koritaste plamene peći za taljenje aluminijskih legura, koja je ujedeno i korištena za dobivanje taline u promatranom procesu koji se opisuje naknadno u eksperimentalnom dijelu. Također je opisana i poroznost kao jedan od najčešćih problema koji se pojavljuju u odljevcima tlačnog lijeva. U eksperimentalnom dijelu, prije simulacije konstruiran je uljevni sustav s sustavom preljeva. Nakon toga slijedi konstruiranje kalupa koji će se koristiti za simulaciju. Slijedi, provedba simulacije u programskom paketu MAGMAsoft za odabrane parametre procesa lijevanja modela poklopca od AlSi9Cu3 legure. Nakon izvršene simulacije, prikazani su i opisani rezultati simulacija. Točnije, dan je opis i prikaz rezultata punjenja kalupne šupljine, zarobljenog zraka u kalupnoj šupljini, zračne poroznosti i poroznosti skupljanja, te ukupne poroznosti u odljevku. Naposljetku je napravljena analiza i usporedba poroznosti iz rezultata dobivenih simulacijom sa stvarnim stanjem poroznosti odljevaka sa snimki rendgena te nakon strojne obrade obrade odljevka.This paper describes the technology of high pressure die casting (HPDC). After that, the process parameters that directly affect on the casting process and the properties of the casting are described. In addition, the procedure for obtaining the parameters is described. Molds for HPDC, the classification of molds, their basic parts and the materials from which they are made are described. This is followed by a section on the most common aluminum alloys used in HPDC process, especially the AlSi9Cu3 alloy that was used to make the casting on which the test were performed. A description is given of the melting furnace, more precisely the gas furnace for melting aluminum alloys, which was used to produce the melt in the observed process, which is described subsequently in the experimental part. Porosity is also described as one of the most common problems that appear in die castings. In the experimental part, before the simulation, an gating system with an overflow system was designed. This is followed by the design of the mould that will be used for the simulation. The following is the implementation of the simulation in the MAGMAsoft software package for the selected parameters of the HPDC process of the AlSi9Cu3 alloy cover model. After the simulation, results are presented and described. More specifically, a description and presentation of the results of filling the mold cavity, trapped air in the mold cavity, air porosity and shrinkage porosity, and total porosity on the casting is given. Finally, an analysis and comparison of porosity was made from the results obtained by simulation with the real state of the porosity of the castings from the X-ray images and after machining of the casting
Analysis of the optimal product variant using the DMADV method
No full textDMADV metoda je jedna od komponenti 6-sigma metodologije te jedna od češće korištenih metoda u procesu razvoja novih proizvoda. Upotreba DMADV metode u razvoju novih proizvoda može doprinijeti stvaranju proizvoda i usluga koji zadovoljavaju potrebe kupaca, smanjuje vrijeme i troškove razvoja proizvoda, usklađuje proizvod ili uslugu sa strateškim ciljevima organizacije, te povećava konkurentnost isporučujući visokokvalitetne i jedinstvene proizvode. Metoda se sastoji od pet faza, svaka s određenim ciljevima i alatima. Početak čini faza definiranja, koja se usredotočuje na identifikaciju zahtjeva kupaca, odnosno obuhvat projekta i poslovne ciljeve. U fazi mjerenja se potom prikupljaju i analiziraju podatci o trenutnom tržištu, potrebama kupaca i potencijalnim rizicima. Nakon toga, u fazi analize generiraju se i vrednuju alternativna rješenja putem tehnika poput "brainstorminga", "benchmarkinga" i sl. Zatim u fazi dizajniranja odabire se najbolje rješenje i stvara se detaljan plan dizajna za testiranje i validaciju. Na kraju, u faza verifikacije testira se i validira dizajn s pomoću metoda poput simulacija ili FMEA analize.
Fokus rada je na testiranju različitih koncepata, odnosno varijanti proizvoda koji se očituje u različitim arhitekturama pogonskog sklopa električnog vozila. Rezultate dobivene simulacijskim modelima potrebno je usporediti primjenom adekvatnih metoda, te konačno dati prijedlog optimalnog proizvoda uzimajući u obzir kriterije kako eksploatacijskih performansi tako i troškova proizvodnje odabrane varijante.The DMADV method is one of the components of the 6-sigma methodology and one of the more frequently used methods in the process of developing new products. The use of the DMADV method in the development of new products can contribute to the creation of products and services that meet the needs of customers, reduce the time and costs of product development, align the product or service with the strategic goals of the organization, and increase competitiveness by delivering high quality and unique products. The method consists of five phases, each with specific goals and tools. The beginning is the definition phase, which focuses on the identification of customer requirements, that is, the scope of the project and business goals. In the measurement phase, data on the current market, customer needs and potential risks are collected and analyzed. After that, in the analysis phase, valuable alternative solutions are generated using techniques such as "brainstorming", "benchmarking", etc. Then, in the design phase, the best solution is selected and a detailed design plan is created for testing and validation. Namely, in the verification phase, the design is tested and validated using methods such as simulation or FMEA analysis.
The focus of the work is on testing different concepts, i.e., product variants, which are manifested in different architectures of the powertrain of an electric vehicle. It is necessary to compare the results obtained by simulation models using adequate methods, and finally give a proposal for the optimal product, taking into account both the exploitation performance and the production costs of the selected variant
Design of a refrigeration system in supermarket with CO2 as refrigerant
No full textU ovom radu napravljen je cjelokupan projekt izvedbe rashladnog sustava supermarketa s ugljik
dioksidom kao radnom tvari. U uvodu je opisan ugljik dioksid kao radna tvar te vrste rashladnih
procesa sa ugljik dioksidom. Izračunat je potreban toplinski kapacitet za hlađenje prehrambenih
proizvoda u komorama i u vitrinama na primjeru supermarketa na području sjeverozapadne
Hrvatske. Na temelju izračunatog potrebnog toplinskog kapaciteta, dimenzionirane su
komponente rashladnog sustava – isparivača, kompresora i hladnjaka plina. Određen je rashladnih
proces sa dva seta kompresora, jedan set za plus režim te jedan za minus režim. Dimenzioniran je
cjevovod cijelog rashladnog sustava. Odabrane su potrebne komponente sustava – isparivači,
rashladne vitrine, setovi kompresora i hladnjak plina. Cjelokupni rashladni proces je opisan, te su
određene točke procesa. Opisan je rad automatske regulacije. Također je opisana izvedba projekta
po fazama, od početka do kraja te su navedeni sigurnosni zahtjevi radi korištenja ugljik dioksida
kao radne tvari.This thesis presents a thorough project that implements a supermarket cooling system with carbon
dioxide as a refrigerant. Introduction describes carbon dioxide as a refrigerant and types of cooling
processes with carbon dioxide. Cooling capacity needed for cooling food in cold rooms and
refrigerated cabinets is calculated on an example of a supermarket in northwest Croatia. Based on
this calculation, components of a cooling system are dimensioned - evaporator, compressor, and
gas cooler. Cooling process with two sets of compressors is specified, one set of compressors for
the plus regime, one for the minus regime. Pipeline of the whole cooling system is dimensioned.
Necessary system components are chosen - evaporators, refrigerated cabinets, compressor sets,
and gas cooler. Complete cooling process is described and points of the cooling process are
determined. Automatic regulation is described. Likewise, project implementation is described in
phases, from beginning to end, and safety requirements are listed, due to using carbon dioxide as
a refrigerant
Synthesis of bioadditives based on gallic acid for improvement of application properties of diesel fuel
No full textU ovom radu opisana je sinteza i metoda pročišćavanja četiri bioaditiva reakcijom esterifikacije između galne kiseline i odgovarajućega alkohola. Alkoholi koji su korišteni za reakcije su etanol, propanol, butanol i pentanol, a kao katalizator korišten je p-toluen sulfonska kiselina. Sintetizirani produkti pročišćeni su ispiranjem s vodom. Struktura i čistoća priređenih spojeva analizirana je spektroskopskim metodama infracrvene spektroskopije s Fourierovom transformacijom i protonskom nuklearnom magnetskom rezonancijom.
Produkt je detaljnije analiziran pomoću metoda diferencijalne pretražne kalorimetrije i kromatografije isključenja po veličini. Nadalje, promatrala se topljivost produkata u vodi, dimetilsulfoksidu i dizelskome gorivu. Ustanovljeno je da sintetizirani produkti nisu topljivi u dizelskokome gorivu zbog čega se antiokisdativno djelovanje bioditiva ne može odrediti. Iz svih provedenih analiza može se zaključiti da su produkti sintetizirani, ali s jako malim iskorištenjem.This paper describes the synthesis and purification method of four bioadditives through the esterification reaction between gallic acid and the corresponding alcohol. The alcohols used for the reactions were ethanol, propanol, butanol, and pentanol, with p-toluenesulfonic acid used as the catalyst. The synthesized products were purified by rinsing with water.
The structure and purity of the prepared compounds were analyzed using spectroscopic methods such as Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance. The synthesized product was further analyzed using differential scanning calorimetry and size-exclusion chromatography. Additionally, the solubility of the products in water, dimethyl sulfoxide, and diesel fuel was observed. It was established that the synthesized products were not soluble in diesel fuel, making it impossible to determine their antioxidative properties. From all conducted analyses, it can be concluded that the products were synthesized but with very low yield
Synthesis of fatty acid pentyl esters and application properties of their blends with mineral diesel
No full textPotraga za održivim izvorima energije potaknula je preispitivanje tradicionalnih goriva, potičući pojavu alternativa koje pridonose očuvanju okoliša. Za razliku od konvencionalnog dizelskog goriva koje se uglavnom dobiva iz fosilnih izvora, biodizel je privukao značajnu pažnju zbog svoje sposobnosti umanjivanja negativnih utjecaja koje na okoliš imaju emisije stakleničkih plinova i smanjenja ovisnosti o neobnovljivim resursima. Biodizel je obnovljivo gorivo dobiveno iz bioloških izvora poput biljnih ulja, životinjskih masti i otpadnih ulja za kuhanje. U ovome radu biodizel je sintetiziran iz otpadnog ulja za kuhanje dobivenog nakon prženja i alkohola 1-pentanola uz katalizator KOH procesom transesterifikacije. Sintetizirani biodizel je nakon pročišćavanja pomiješan s neaditiviranim mineralnim dizelom u različitim volumnim udjelima (2,5-20 vol. %). Uz sustav dizel-biodizel kao usporedni sustavi pripremljene su mješavine dizela i 1-pentanola te biodizela i 1-pentanola u različitim volumnim omjerima (2,5-20 vol. %). Ispitana su svojstva površinske napetosti, gustoće, viskoznosti, provedena je toplinska analiza diferencijalnom pretražnom kalorimetrijom, kao i ispitivanje niskotemperaturnih svojstava maglišta i tecišta. Izmjereni rezultati za napetost površine mješavina ne mijenjaju se s promjenom volumnih udjela komponenata FAPE i dizela. Rezultati gustoće i viskoznosti pokazuju povećanje svih vrijednosti s povećanjem volumnog udjela biodizela FAPE, no sve su vrijednosti unutar normiranih granica. Proučavanjem niskotemperaturnih svojstava rezultati maglišta i tecišta pokazuju ujednačenost i bliskost vrijednostima čistog dizela, odnosno dodatak FAPE u dizel do 20 vol.% ne utječe na pogoršanje niskotemperaturnih svojstava dizelskog goriva.The search for sustainable energy sources has spurred a reevaluation of traditional fuels, giving rise to alternatives that offer greater ecological benefits. Unlike conventional diesel fuel, primarily derived from fossil sources, biodiesel has garnered significant attention due to its ability to mitigate the negative impacts of greenhouse gas emissions and reduce dependence on non-renewable resources. Biodiesel is a renewable fuel derived from biological sources like vegetable oils, animal fats, and waste cooking oils. In this paper, biodiesel is synthesized from waste cooking oil and alcohol 1-pentanol using KOH as a catalyst via the transesterification process. The synthesized biodiesel is upon purification blended with non-additivated mineral diesel in varying volume fractions. In addition to diesel-biodiesel blends as comparative systems, mixtures of diesel and 1-pentanol, as well as biodiesel and 1-pentanol in different volume fractions, were prepared. Surface tension, viscosity, and density were the examined properties, while DSC thermal analysis was performed, along with an investigation of the low-temperature properties of cloud point and pour point. The results for surface tension are consistent regardless of the changing volume fractions of the FAPE and diesel components. The examined density and viscosity results show an increase in values with increasing volume fraction of biodiesel FAPE, but all values remain within the standardized limits. The study of low-temperature properties reveals that cloud point and pour point results are consistent and close in values to the pure diesel, i.e. the addition of FAPE to diesel up to 20 vol.% does not negatively affect the low-temperature properties of diesel fuel
Crystallization process control using direct nucleation control
No full textU ovom radu istraživana je primjena metode izravne kontrole nukleacije tijekom kristalizacije keratin monohidrata. Uspoređena su dva načina regulacije tijekom eksperimenta – standardna putem plašta i s vanjskim grijanjem. Metoda izravne kontrole nukleacije podrazumijeva vođenje procesa koje osigurava stalan broj kristala u sustavu, pri čemu se procesna temperatura regulira s obzirom brojnost kristala u sustavu. Cilj je skratiti trajanje procesa primjenom vanjskog grijala, kao i postići odgovarajuću raspodjelu veličine kristala, odnosno povećati udio većih kristala. Za praćenje broja kristala u sustavu primijenjen je mikroskop visoke rezolucije koji kontinuirano prati broj kristala u sustavu i analizira slike u stvarnom vremenu. Na temelju eksperimenata izravne kontrole nukleacije zaključeno je da se primjenom vanjskog grijanja, u usporedbi sa standardnim sustavom regulacije temperature putem plašta , ostvaruje bolja regulacija, što skraćuje provedbu procesa i rezultira formiranjem većeg broja većih kristala.This master thesis investigates the application of the direct nucleation control (DNC) during the crystallisation of creatine monohydrate. Two approaches of temperature control during the experiment were compared – standard jacket control and control with external heating. The direct nucleation control involves process control that ensures a constant number of crystals in the system. With this method, the process temperature is adjusted depending on the number of crystals present. The aim is to shorten the batch duration by external heating and to achieve a desirable crystal size distribution, in particular by increasing the proportion of larger crystals. To monitor the number of crystals in the system, a high-resolution microscope was used to enable continuous image analysis in real time and to track the counts of crystals. Based on the DNC experiments, it was found that the use of an external heating allows for faster temperature control compared to a standard batch system without an external heater, which shortens the overall process time and leads to the formation of a larger number of larger crystals
Commissioning of flexible robotic cell
No full textU sklopu diplomskog rada prikazana je izrada programske podrške za fleksibilnu robotsku ćeliju kakva se može vidjeti u današnjim proizvodnim postrojenjima. Ćelija sadrži tri robotske ruke proizvođača Stäubli te joj je zadatak sklapanje tri različita predmeta u sklop. Dijelovi od kojih se sastoji sklop su kućište sklopa, PTC senzor i klin. Programibilni logički kontroler (PLC) sinkronizira rad pojedinih elemenata ćelije. Zadaci pojedinih robotskih ruku prikazani su dijagramima toka i opisani su tipovi robotskih ruku. Robotski kontroler CS9 i PLC komuniciraju koristeći Profinet komunikacijski protokol. Fokus ovog rada je izrada programske podrške za tri robotske ruke koja je izrađena u programskom paketu Stäubli Robotics Suite.A flexible robotic cell that can be seen in a modern production facility is presented in this paper. The cell contains three robotic arms manufactured by Stäubli, whose task is to assemble three different objects into an assembly. The assembly is comprised of a housing, PTC sensor and a wedge. A Programmible Logical Controller (PLC) syncronises the movements of specific elements of the cell. The tasks of individual robotic arms are shown in flowcharts and the types of robotic arms are described, The CS9 controller and the PLC communicate using the Profinet communication protocol. The focus of this paper is the creation of software support for three robotic arms, which was created using Stäubli Robotics Suite software package
Synthesis of isobutyl and isopentyl fatty acid esters and investigation of the application properties of mixtures with mineral diesel
No full textZbog sve manje zalihe fosilnih goriva, a istovremeno sve veće potrebe za energijom radi neprestanog tehnološkog razvitka javila se potreba za alternativom iz obnovljivih izvora. Od ranih početaka izuma motora s unutarnjim izgaranjem pa sve do današnjice, kao gorivo za pogon vozila najintenzivnije se koristilo gorivo iz neobnovljivih izvora. Tokom izgaranja takvog goriva dolazi do emisije štetnih plinova što posljedično jednim dijelom uzrokuje pojavu globalnog zatopljenja. Kako bi ljudska populacija osigurala što kvalitetniju budućnost, niz znanstvenika istražuje goriva iz održivih izvora. Kao jedno od boljih rješenja spomenutog problema pokazao se biodizel. Većina komercijalnih biodizela sintetizirana je reakcijom transesterifikacije iz nižih i ravnolančanih alkohola, metanola ili etanola. U novije doba pojavio se interes za sintezom biodizela iz viših i razgranatih alkohola zbog bolje mješljivosti s mineralnim dizelom, višeg cetanskog broja, veće toplinske vrijednosti, kao i spoznaje da prisutnost strukturalnog grananja dovodi do potencijalnog poboljšanja niskotemperaturnih svojstava biogoriva. U ovom radu sintetizirani su izobutilni esteri masnih kiselina iz otpadnog jestivog ulja, uz kalijev hidroksid (KOH) kao katalizator te izopentilni esteri masnih kiselina također iz otpadnog jestivog ulja, ali uz kiseli katalizator tj. sumpornu kiselinu (H2SO4). Mješavinama biodizela, alkohola i dizela izmjerena su primjenska svojstva koristeći normirane metode te je provedena karakterizacija mješavina pomoću diferencijalne pretražne kalorimetrije (DSC) i goniometra. Svojstva koja su ispitana su kinematička viskoznost, gustoća, napetost površine, temperatura kristalizacije i entalpija kristalizacije. Viskoznost, gustoća i napetost površine smjesa povećavaju se s povećanjem udjela biodizela, a smanjuju se dodatkom alkohola. Kod mjerenja niskotemperaturnih svojstava DSC metodom dokazana je hipoteza o sniženju temperature početka i maksimuma kristalizacije upotrebljavajući za sintezu biodizela razgranate alkohole.Due to the decrease in fossil fuel reserves and the simultaneous increase in energy demand caused by continuous technological development, the demand for an alternative from renewable sources has risen. From the beginnings of the invention of the internal combustion engine to the present day, fuel from non-renewable sources has been used most intensively to power vehicles. The combustion of such fuels releases harmful gasses, which consequently and partly contribute to global warming. To ensure the best possible future for the human population, numerous scientists are researching fuels from sustainable sources. Biodiesel has proven to be one of the better solutions to this problem. Most commercial biodiesel is synthesized from lower alcohols, methanol or ethanol. Recently, there has been increased interest in synthesizing biodiesel from higher alcohols due to better miscibility with mineral diesel, higher cetane number, and higher heating value. In this work, fatty acid isobutyl esters were synthesized from waste cooking oil using potassium hydroxide (KOH) as catalyst and fatty acid isopentyl esters were also synthesized from waste cooking oil but with an acid catalyst, i.e., sulfuric acid (H2SO4). The application properties of the biodiesel, alcohol and diesel mixtures were measured using standardized methods, and their characterization was performed using differential scanning calorimetry (DSC) and a goniometer. The properties tested are kinematic viscosity, density, surface tension, crystallization temperature and enthalpy of crystallization. The viscosity, density and surface tension of the mixtures increase with increasing biodiesel content, while they decrease with the addition of alcohol. When the low-temperature properties were measured by the DSC method, the hypothesis of lowering the crystallization onset and peak temperatures by branched alcohols in the synthesis of biodiesel was confirmed