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Polymer-bonded magnets are a class of composite material that combines the magnetic properties of metal particles and the molding possibility of a polymeric matrix. This class of materials has shown huge potential for various applications in industry and engineering. Traditional research in this field has so far mainly focused on mechanical, electrical or magnetic properties of the composite, or on particle size and distribution. This examination of synthesized Nd-Fe-B-epoxy composite materials includes the mutual comparison of impact toughness, fatigue, and the structural, thermal, dynamic-mechanical, and magnetic behavior of materials with different content of magnetic Nd-Fe-B particles, in a wide range from 5 to 95 wt.%. This paper tests the influence of the Nd-Fe-B content on impacting the toughness of the composite material, as this relationship has not been tested before. The results show that impact toughness decreases, while magnetic properties increase, along with increasing content of Nd-Fe-B. Based on the observed trends, selected samples have been analyzed in terms of crack growth rate behavior. Analysis of the fracture surface morphology reveals the formation of a stable and homogeneous composite material. The synthesis route, the applied methods of characterization and analysis, and the comparison of the obtained results can provide a composite material with optimum properties for a specific purpose.

This paper presents a new transport model for reverse osmosis (RO) systems, which combines irreversible thermodynamics, together with solution-diffusion theory. The simplifications adopted by the classical theory for solution-diffusion mechanisms have been found to be quite lacking when it comes to predicting the separation of multicomponent mixtures. The presented model accounts for multicomponent computations through the application of thermodynamic property models, as a means to predict the various interactions amongst the species that are present in solution. The developed transport model is relatively easy to implement, and can be utilized alongside existing equipment and thermodynamic property models. The applicability of the model presented in this paper has been tested on three different case studies, including a case that investigates single component behavior and a case that investigates multicomponent behavior The proposed model shows very good agreement with experimental results.

In order to reduce negative influence of fossil fuels on environment, use of various renewable resources is highly promoted. Terpenes, naturally occurring in plants, can be added to petroleum fuel as its substitute up to a certain share. Thermodynamic properties of a fuel under high pressure and moderate temperature conditions are of significant importance for engine efficiency. This work reports density measurements of pure p-cymene, α-pinene, limonene and citral at temperatures (293.15–413.15) K and pressures (0.1–60) MPa, applying an Anton Paar DMA HP measuring cell. Density data were fitted by modified Tammann-Tait equation where the absolute average percentage deviation between measured and calculated densities was about 0.010%. The obtained parameters were used to estimate the isothermal compressibility, the isobaric thermal expansion coefficient, the internal pressure, and the difference between specific heat capacity at constant pressure and at constant volume. For examined compounds, all thermodynamic properties, except the internal pressure, decrease with pressure rise along an isotherm and increase as temperature increases at a constant pressure. The intersection point of isotherms for the isobaric thermal expansion coefficient for pure citral was registered at pressure 47 MPa, while for other analyzed terpenes the intersection point is above 60 MPa, outside the measurements pressure range.

SAFT equations of state have been widely used for the determination of different thermo-physical and phase equilibria properties. In order to use these equations as predictive models it is necessary to calculate the model parameters. In this work CK-SAFT and PC-SAFT equations of state were applied for the correlation of pure compounds densities in the wide ranges of temperature and pressure (288.15-413.15 K and 0.1-60 MPa, respectively). The calculations of densities for n-hexane, n-heptane, n-octane, toluene, dichloromethane and ethanol, under high pressure conditions, were performed with the new sets of parameters determined in this paper by CK-SAFT and PC-SAFT. Very good agreement between experimental and calculated density values was achieved, having absolute average percentage deviations lower than 0.5 %.

Continuous catalytic reforming (CCR) is known to convert refinery naphtha to a high-octane liquid product, also known as the reformate. In this paper, a First Principle Reaction Section Model for a CCR process is presented. Even though CCR is a well-established technology, the application of advanced, real-time optimization techniques that are able to quickly respond to any imposed changes onto the process, are necessary in the refinery business. This becomes particularly important as a result of changes in profit margin, changes in operating cost, and the introduction of new environmental legislations. Hence, we present a kinetic model for the CCR process using the so-called "lumped" concept. The reactors have been modeled using a quasi-steady-state approach. The unknown model parameters have been estimated by bench marking the First Principle Reaction Section results with a commercial CCR process owned by the Hungarian Oil and Gas Public Limited Company (INA-MOL). The proposed model has been tested and compared to data obtained from an existing CCR plant. The predictions of the model were found to be in good agreement with the experimental data. The relative absolute errors between the measured and model estimated variables have been found to be lower than 2%. The relative absolute error associated with the required fired heater duties were less than 1.0%. Simulating the reaction section of the CCR process requires less than 0.1 s of CPU time, which clearly indicates that this model can be very suitable for performing optimization studies. Moreover, this study shows that, although there is fluctuation in the composition of feedstock, the lumped kinetic approach was capable to predict the behavior of the CCR process well.

The Nd-Fe-B-barium ferrite hybrid composite materials with epoxy matrix presented in this paper cover maximum energy product from 1 to 13 MGOe. Mixture of magnetic particles is responsible for high magnetic quality, while the thermosetting resin plays a role in mechanical properties. Samples with various ratio of Nd-Fe-B to barium ferrite in constant weight of epoxy resin are examined by tensile strength measurements. Magnetic measurements carried out by using vibrating sample magnetometer (VSM) show typical hysteresis loop. A structural analysis of composite surface is conducted by scanning electron microscope (SEM). Uniform particle distribution of plate shape Nd-Fe-B particles and spherical barium ferrite agglomerates is essential for both, mechanical and magnetic properties of composite materials. Fine particles are incorporated in-between larger particles in epoxy bulk which lead to improving the properties., U ovom radu proučavani su hibridni Nd-Fe-B-barijum ferit kompozitni materijali sa epoksi matricom čiji se maksimani energetski proizvod kreće od 1 do 13 MGOe. Odlična magnetna svojstva kompozita potiču od smeše magnetnih čestica, dok termoočvršćavajući polimer ima uticaj na mehanička svojstva. Uzorci sa različitim odnosom udela Nd-Fe-B i barijum ferita u konstantnoj masi epoksi veziva su ispitivani na zateznu čvrstoću. Magnetna merenja vršena pomoću vibracionog magnetometra (VSM) pokazuju karakteristučnu histerezisnu petlju. Strukturnu analizu na površini kompozita sprovedena pomoću skenirajuće elektronske mikroskopije (SEM). Uniformna raspodela pločastih Nd-Fe-B čestica i sferičnih aglomerata barijum ferita je veoma značajna i za mehanička i za magnetna svojstva kompozitnih materijala. Sitne čestice su inkorporirane između velikih čestica u masi epoksida što dovodi do poboljšanja svojstava.

In order to reduce the usage of fossil fuels in industrial sectors by meeting the requirements of production processes, new heat integration and heat recovery approaches are developed. The goal of this study is to develop an approach to increase energy efficiency of an industrial zone by recovering and reusing waste heat via indirect heat integration. Industrial zones usually consist of multiple independent plants, where each plant is supplied by an independent utility system, as a decentralized system. In this study, a new approach is developed to target minimum energy requirements where an industrial zone would be supplied by a centralized utility system instead of decentralized utility system. The approach assumes that all process plants in an industrial zone are linked through the central utility system. This method is formulated as a linear programming problem (LP). Moreover, the proposed method may be used for decision making related to energy integration strategy of an industrial zone. In addition, the proposed method was applied on a case study. The results revealed that saving of fossil fuel could be achieved.

The aim of this study was to construct a polymer-based mixed matrix membrane that could be used for waste gases treatment. Therefore, high permeability for the carbon dioxide and low permeability for other gases commonly present in the industrial combustion waste gases (nitrogen, oxygen, hydrogen and methane) are essential. These membranes belong to the group of dense composite membranes, whose separation is based on the solution diffusion mechanism. In this paper, feasibility of the application of poly(ethylene oxide)-copoly(phtalamide) was tested. In order to enhance the permeability of carbon dioxide, three different zeolites with two-dimensional pores (IHW, NSI and TER) were incorporated, and in order to improve compatibility between the inorganic particles and polymer chains, n-tetradecyldimethylamonium bromide (NTAB) was added. The best results in carbon dioxide/hydrogen selectivity were obtained with the membrane constructed with PEBAX 1657 and surface treated zeolites, while better results concerning selectivity were gained with membranes based on Polyactive., Cilj ovog rada je bio da se konstruiše neporozna kompozitna membrana bazirana na polimernom matriksu koja može da bude upotrebljena za tretman otpadnih gasova. Za ovu svrhu, neophodno je da membrana ima visoku permeabilnost za ugljen-dioksid i nisku permeabilnost za druge gasove koji ne najčešće sreću u produktima sagorevanja (azot, kiseonik, vodonik, metan). Ove membrane pripadaju grupi neporoznih membrana i mehanizam separacije gasova je baziran na rastvorljivosti i difuziji. U ovom radu, testirana je mogućnost primene poli(etilenoksida)-kopoli(ftalamida). Da bi se povećala permeabilnost ugljen-dioksida, dodavana su tri različita zeolitna praha, a da bi se poboljšala kompatibilnost neorganskih čestica i polimernih lanaca, dodat je n-tetradeciltrimetilamonijum-bromid (NTAB). Ispitivani zeoliti pripadaju grupi sa dvodimenzionalnim porama (IHW, NSI i TER). Najbolji rezultati u separaciji ugljen-dioksida i vodonika su postignuti kod membrana baziranim na polimeru PEBAX 1657 i zeolitima uz dodatak aditiva. Sa druge strane, bolja selektivnost je postignuta kod membrana baziranih na Polyactive polimeru.

The main task of the work is to construct the polymeric membrane that could be used for the waste gases treatment. For this purpose, membrane must have high permeability for the carbon dioxide and low permeability of the other gases commonly present in waste gases (hydrogen, oxygen, nitrogen and methane). The constructed membranes were of a dense type, based on a solubility/diffusivity mechanism. In order to enchase the permeability of carbon dioxide, four different zeolytes were added, and in order to improve mechanical stability two different additives were tested. Three zeolytes were with the 3-dimensional pores (ZSM5; Faujasite Linde type A) and one was with the 1-dimensional pores (Linde type L). As an additive, n-tetradecyldimethylamonium bromide - n-C14TMABr was tested. The aim of an additive was to provide good wetting of a highly electrically charged zeolyte particle by the hydrophobic polymer chains. The other examined additive was dimethylaminopyridine (DMAP) which should improve the solubility of carbon dioxide due to its alkali properties. The best results in carbon dioxide/hydrogen selectivity and permeability were obtained with the membrane constructed with PEBAX 1657 and surface treated zeolyte. The obtained permeability of carbon dioxide was 128 Barrer, and the carbon dioxide/hydrogen selectivity was 9.7., Cilj istraživanja prikazanih u ovom radu je izrada polimerne membrane koja bi imala primenu u prečišćavanju otpadnih gasova. Membrana konstruisana za ovu primenu bi morala da ima visoku permeabilnost za ugljen-dioksid i nisku permeabilnost za druge gasove koji su standardno prisutni u otpadnim gasovima (vodonik, kiseonik, azot i metan). Dobijene membrane pripadaju tipu neporoznih membrana čija se permeabilnost bazira na mehanizmu rastvaranja i difuzije. U ovom radu, ispitivana je mogućnost primene poli(etilenoksida) - kopoli(ftalamida) za ovu svrhu. Da bi se povećala permeabilnost ugljen-dioksida, dodate su četiri različite vrste zeolitnih prahova, a u cilju poboljšanja mehaničkih svojstava, ispitivana su dva aditiva. Tri zeolitna praha korišćena u eksperimentu imaju trodimenzionalne pore (ZSM5, Faujasit i Linde zeolit tip A), a jedan prah je sa jednodimenzionalnim porama (Linde zeolit tip L). Kao aditiv je testiran n-tetradeciltrimetilamonijum bromid. Cilj dodavanja ovog aditiva je da omogući dobar kontakt između dugih, hidrofobnih polimernih lanaca i naelektrisanih čestica zeolita. Drugi ispitivani aditiv je dimetilaminopiridin, čija bi bazna svojstva trebalo da poboljšaju rastvorljovost ugljen dioksida. Najbolji rezultati su postignuti korišćenjem membrane konstruisane sa PEBAX 1657 polimerom i zeolitom u prisustvu aditiva.

The aim of this paper is to obtain microbeads of natural polymers such as alginate and chitosan. These microbeads were used as potential carriers for the active ingredients so that in this study the diffusion of various substances from them is analyzed. Alginate microbeads were obtained by electrostatic droplet method. In the resulting microbeads was performed absorption of three tracer indicators with different molecular weight (acridine orange, blue dextran, methylene blue). The goal of the experiment is to monitor indicators release kinetics from microbeads. Based on these measurements the layoffs curve should give an answer on the impact of the molecular size of the three indicators on the diffusion rate of microbeads. In order to achieve the slow release of indicators alginate microbeads were coated with chitosan. Chitosan has an impact on reducing the porosity of gel, which further led to lower release tracer indicators of microbeads. Comparative analysis of the obtained layoffs curves answers about the impact on the process of obtaining micro diffusion rate indicator., U ovom radu je prikazan proces sinteze mikročestica od prirodnih polimera, alginata i hitozana, kao i neka njihova svojstva. Osnovna primena ovih mikročestica je da se koriste kao potencijalni nosači za aktivne supstance. U tom smislu je ispitivana i difuzija različitih supstanci iz njih. Na alginatne mikročestice dobijene metodom elektrostatičke ekstruzije vršena je apsorpcija tri trejserska indikatora sa različitim molekulskim masama: akridin oranž, plavi dekstran i metilensko plavo. Praćenjem kinetike otpuštanja indikatora iz mikročestica konstruisane su krive otpuštanja koje daju informaciju o uticaju veličine molekula svakog od indikatora na brzinu difuzije iz mikročestica. Da bi se postiglo što sporije otpuštanje indikatora alginatne mikročestice su oblagane hitozanom. Hitozan ima uticaj na smanjenje poroznosti gela, što dovodi do sporijeg otpuštanja trejsersikh indikatora iz mikročestica. Uporedna analiza dobijenih krivih otpuštanja daje odgovor o uticaju postupka dobijanja mikročestica na brzinu difuzije indikatora.

Polymer bonded magnets are contemporary materials with a very large range of applications. The objective of this study is to assess how different content of Nd-Fe-B and/or barium ferrite particles affect on magnetic and morphological properties of bonded composite materials. Interactions between employed magnetic powders and interactions between magnetic powders and polymer binder are considered. For examination of the magnetic behavior Vibrating Sample Magnetometer (VSM) is used. Different shape and size of obtained hysteresis loops are used for comparison and prediction of polymer bonded materials properties., Polimerom vezani magneti predstavljaju savremene materijale sa veoma širokim spektrom primene. Cilj ovog rada je da se analizira i prikaže kako različiti udeli čestica Nd-Fe-B i/ili barijum ferita utiču na magnetna i morfološka svojstva bonded kompozitnih materijala. Razmatrane su interakcije između primenjenih magnetnih prahova različitog tipa i interakcije između magnetnih prahova i polimerne matrice. Za merenje magnetnih svojstava kompozita korišćen je vibracioni magnetometar (VSM). Različiti oblici i veličine dobijenih histerezisnih petlji su poređeni i analizirani u cilju predviđanja magnetnog ponašanja kompozita.

Various types and contents of magnetic powder and polymer matrix induce different mechanical, magnetic, electrical and optical properties of final composite material. The strong influence of relatively small amounts of filler particles on the dynamic mechanical properties of polymers has significantly contributed to increased use of polymer materials in many commercial applications. The higher content of magnetic filler has direct influence on magnetic properties of composites, but also may change the rheology of polymer melt during process and, subsequently, impact the mechanical strength of bonded magnets. For better insight into viscoelastic behaviour of composites, beside experiments, a theory that explicitly takes the shape factor, particle distribution, particle-particle interactions as well as particle-polymer matrix interactions into account is required. The mathematical prediction of storage modulus behaviour is examined. The several proposed analytical models are tested versus experimental results. Some of applied models agree very well with experimental data, whilst others deviate significantly., Različite vrste primenjenih magnetnih prahova i polimerne matrice, kao i njihovi udeli, utiču na mehanička, magnetna, električna i optička svojstva finalnog kompozitnog materijala. Veliki uticaj relativno malih udela čestica punioca na dinamičko mehanička svojstva polimera značajno doprinosi većoj komercijalnoj upotrebi kompozitnih materijala. Veliki udeli magnetnog praha u mnogome utiču na magnetna svojstva kompozita, ali takođe mogu dovesti do reoloških promena u polimeru tokom procesa topljenja, što ima direktan uticaj na mehanička svojstva polimerom vezanih (bonded) magneta. Radi boljeg uvida u visokoelastična svojstva kompozita, osim eksperimenata, neophodno je uzeti u obzir i teorijska razmatranja koja eksplicitno objašnjavaju uticaj faktora oblika, raspodelu čestica, interakcije između čestica, kao i interakcije između čestica i polimera. U tom smislu vršeno je i matematičko predviđanje ponašanja modula uskladištene energije (E') kompozita. Nekoliko predloženih analitičkih modela su testirani i upoređeni sa eksperimentalnim rezultatima. Neki od primenjenih modela se veoma dobro slažu sa dobijenim eksperimentalnim rezultatima, dok neki značajno odstupaju.

Environmental regulations imposed on transport fuels, especially specifications on sulfur and nitrogen content, generally boost hydrogen requirements in refining industries. The catalytic naphtha reformer (CNR) process is one of the major sources of hydrogen in naphtha refinery, thus improving its hydrogen production would be of great importance for refining industries. Close examination of the reaction kinetics of CNR processes has identified temperature, hydrogen concentration and catalyst activity as key variables affecting the process's performance. In this paper, a new reactor concept is developed that better exploits these process variables. The proposed membrane moving-bed reactor promises to significantly outperform the conventional continuous catalyst regenerative (CCR) design. A case study identifies improvements of 23.6 mol% in hydrogen production, 18.8 mol% in aromatics production. Moreover, the reformate yield was found to increase by 10.6 wt%, while the production of light gases decreases to a value of 18.6 wt%. Copyright

Lately, there has been great attention paid to the research of bonded hybrid composites with improved dynamic mechanical capacities capable of replacing bonded Nd-Fe-B magnetic materials, by using cheaper (ferrite) materials instead of the Nd-Fe-B powder while retaining the satisfying values of the maximum magnetic energy. The objective of this study is to assess how different contents of Nd-Fe-B and/or barium ferrite particles can affect morphological, dynamic mechanical and magnetic properties of bonded composite materials. The interactions between employed magnetic powders and the interactions between magnetic powders and polymer binder are considered. For the examination of the magnetic behaviour, a vibrating sample magnetometer (VSM) is used. Different shapes and sizes of the obtained hysteresis loops are used for comparison and prediction of the polymer bonded materials properties. The homogeneous distribution of the magnetic particles in the polymer matrix is validated using scanning electron microscopy (SEM). The elastic and damping behavior examined by dynamic mechanical analysis (DMA) show improved properties for hybrid composite materials., Istraživački trend u oblasti polimerom vezanih (bonded) Nd-Fe-B magnetnih materijala se reflektuje kroz razvoj bonded hibridnih kompozita sa poboljšanim dinamičko-mehaničkim svojstvima i primetno nižoj ceni zbog zamene skupe Nd- Fe-B legure jeftinijim magnetnim materijalima (ferit) uz postizanje zadovoljavajućih vrednosti maksimalne magnetne energije. Cilj ovog rada je da ukaže i predvidi uticaj različitog sadržaja Nd-Fe-B i/ili barijum feritnih čestica na morfološka, dinamičko mehanička i magnetna svojstava bonded magneta. Posmatrane su i analizirane interakcije između magnetnih prahova, kao i interakcije između magnetnih prahova i polimernog veziva i njihov uticaj na finalna svojstva bonded magneta. Za ispitivanje magnetnog ponašanja korišćen je vibraconi magnetometar (VSM). Različite veličine i oblici dobijenih histerezisnih krivih su poređeni i korišćeni za predviđanje svojstava ispitivanih kompozitnih materijala. Homogena raspodela magnetnih čestica u polimernoj matrici je potvrđena korišćenjem skenirajućeg elektronskog mikroskopa (SEM). Elastična svojstva i svojstvo prigušenja oscilacija ispitivano je korišćenjem dinamičko mehaničke analize (DMA) koja ukazuje na poboljšana svojstva kod hibridnih kompozita.

Proces katalitičkog reforminga benzina je jedan od glavnih procesa u industrijskojpreradi nafte, koristi se za proizvodnju visoko-oktanskih motornih benzina, kao i zaproizvodnju sirovina za procese u petrohemijskoj industriji.U doktorskoj disertaciji razmatrani su tehnologija, matematičko modelovanje procesa,strategija energetske optimizacije i pravci budućeg razvoja procesa katalitičkog reformingabenzina.Za modelovanje procesa katalitičkog reforminga benzina uspostavljen jetermodinamički model i razvijen je semi-empirijski pseudo-kinetički model. U cilju primeneodgovarajućeg termodinamičkog modela ravnoteže para-tečnost testirano je nekoliko modela:Redlich-Kwong, Soave-Redlich-Kwong, Benedict-Webb-Rubin-Starling i Chao-Seader. Nabazi dobijenih rezultata utvrđeno je da je Soave-Redlich-Kwong-ov model najadekvatniji zamodelovanje procesa katalitičkog reforminga benzina. U razvijenom kinetičkom modelustrategija grupisanja komponenti bazirana je na „PIONA” analizi. Grupisanje energijaaktivacija je uvedeno, kako bi se različite vrednosti energija aktivacije u okviru specifičnereakcione klase uzeli u razmatranje. Parametri modela određeni su usaglašavanjem vrednostidobijenih pomoću uspostavljenog modela sa podacima dobijenim iz industrijskogeksperimenta. Postignuto je veoma dobro slaganje vrednosti parametara procesa dobijenihupotrebom modela i parametara procesa sa postrojenja. Prednost pomenutog modela daveoma dobro predviđa koncentracije vodonika i lakih gasova u odnosu na postojeće modele,predstavlja značajan rezultat.S obzirom na to da je model formulisan na osnovnim principima procesa katalitičkogreforminga benzina, razvijeni kinetički model, uz određene modifikacije, može se primenitina bilo koji katalitički reformer.U radu je predložen i novi pristup za simulaciju i optimizaciju kontinualnoregenerativnogkatalitičkog reformera. Tipični kontinualno-regenerativni proces sastoji se odtri ili četiri reaktora sa reciklom. Reakciona šema i reaktori su matematički opisan, Catalytic naphtha reforming is one of the primary processes of naphtha refining. Thisprocess is used for the production of the primary component of high-octane motor fuels andalso for the production of feedstock for petrochemical industry.This thesis study the technology, process mathematical modeling, strategy for energyoptimization, and the direction for future developments of catalytic reformer process.A thermodynamic model has been set up and a semi-empirical pseudo-kinetic modelfor catalytic reforming has been developed with intention to provide correct processmodeling. In order to set up a proper thermodynamic model several models have been tested:Redlich-Kwong, Soave-Redlich-Kwong, Benedict-Webb-Rubin-Starling i Chao-Seader.Based on obtained results, it has been found that the Soave-Redlich-Kwong is the mostappropriate model for modeling catalytic naphtha reforming process. In the developed kineticmodel, the component “lumping” strategy is based on “PIONA” analysis. “Activation energylumps” were introduced to take into consideration different values of activation energieswithin the specific reaction classes. The parameters of the model have been estimated bybench marking with industrial data. Simulation results have been found to be in very goodagreement with plant data. Also, one of the significant advantages of the present kineticmodel is that it predicts the concentration of hydrogen and light gases very well, comparing tothe existing models.Since it was formulated from basic principles, this kinetic model with somemodification can be applied to any catalytic reformer.In addition, in the thesis the new approach for simulation and optimization of acontinuous catalytic regenerative reformer process was proposed. Typical continuous catalyticregenerative reformer process consists of three to four reactors with recycle. The reactionpatterns and reactors are typically modeled using system of partial differential equations.Furthermore, due to the fact that the nu