Search

U ovom radu provedena je karakterizacija dvofaznog strujanja kapljevina − kapljevina u milireaktorima izrađenim aditivnom proizvodnjom. Kao modelne kapljevine, koje predstavljaju nemješljive fluide u petrokemijskoj, farmaceutskoj i drugim industrijama, odabrane su redestilirana voda i dodekan. Određen je utjecaj promjera cijevi reaktora, vrste milimiješala, brzine protoka kapljevina te omjer protoka faza na vrstu strujanja. Provedeno je ukupno 84 pokusa u tri vrste milireaktora s različitim vrstama milimiješala (T i Y) i promjera cijevi (2,5 mm i 1,5 mm). Ispitane su vrste strujanja te bezdimenzijske značajke (Reynoldsov, kapilarni, Webbberov i Bondov broj). Na temelju rezultata moguće je zaključiti sljedeće: oblik milimiješala nema značajan utjecaj na uspostavljanje režima strujanja kao kod mikroreaktora. Izračunom Bondove značajke za milireaktore s promjerom cijevi od 2,5 mm, uočen je utjecaj gravitacijske sile; dok kod promjera cijevi od 1,5 mm dominiraju sile međupovršinske napetosti i viskoznosti. Geometrija i prisustvo zavoja utječu na stabilnost i režim strujanja u milireaktorima. Aditivna proizvodnja rastaljenim filamentom pokazala se kao brza, jednostavna i jeftina metoda izrade milireaktora. Dobiveni rezultati predstavljaju doprinos upotrebi milireaktora za sustave nemješljvih kapljevina te na temelju kojih je moguće predvidjeti vrstu strujanja te optimirati kemijske procese (sinteza, ekstrakcija, separacija). In this work, the characterization of the two-phase flow of liquid−liquid in millireactors made by additive manufacturing was carried out. Redistilled water and dodecane, which represent immiscible fluids in the petrochemical, pharmaceutical and other industries, were chosen as model liquids. The influence of reactor channel diameter, type of millimixer, liquid flow rate and phase flow ratio on the flow type was determined. A total of 84 experiments were conducted in three types of millireactors with different millimixers (T and Y) and channel diameters (2,5 mm and 1,5 mm). Flow types and dimensionless features were examined. Based on the results, it is possible to conclude the following: the shape of the millimixers does not have a significant influence on the establishment of the flow regime as it is in the case of microreactors. Flow types and dimensionless features (Reynolds, capillary, Webber and Bond numbers) were examined. By calculating the Bond number feature for millireactors with a tube diameter of 2.5 mm, the influence of the gravitational force was observed; while with a pipe diameter of 1.5 mm the forces of interfacial tension and viscosity dominate. Geometry and the presence of bends influence the stability and flow regime in millireactors. Fused filament fabrication, FFF, has proven to be a fast, simple and inexpensive method of manufacturing millireactors. The obtained results represent a contribution to the use of millireactors for systems of immiscible liquids , on the basis of which it is possible to predict the type of flow and optimize chemical processes (synthesis, extraction, separation).

Biodizel je ekološki prihvatljiva i održiva zamjena za petrokemijski dizel. Prema kemijskom sastavu biodizel obuhvaća monoalkilne estere masnih kiselina i jednostavnih alkohola. Sirovine za proizvodnju biodizela čine razna biljna i otpadna ulja poput suncokretovog, repičinog ulja te ulja kikirikija i soje, dok su od alkohola za sada najzastupljeniji metanol i etanol. U posljednje vrijeme istražuje se mogućnost korištenja i drugih alkohola poput butanola, izobutanoal i pentanola kao sirovina za proizvodnju biodizela. Biodizel se proizvodi reakcijom transesterifikacije ulja s alkoholom. U ovom radu obrađen je utjecaj četiri reakcijska parametra na bazno kataliziranu transesterifikaciju suncokretova ulja s izobutanolom uz kalijev hidroksid kao katalizator. Parametri čiji utjecaj je određivan su: vrijeme reakcije (1 - 3 h) , temperatura (40 - 80 °C), molarni omjer alkohola i ulja (6:1 - 12:1) te maseni udio katalizatora (1 - 3 %). Pomoću programskog paketa Desin-Expert 11 napravljen je Box-Behnkenov plan 28 pokusa. Rezultat svakog pokusa je iskorištenje reakcije. Iskorištenje je određeno pomoću 1H NMR analize reakcijske smjese. Na temelju eksperimentalnih rezultata napravljen je model ovisnosti iskorištenja o reakcijskim parametrima. Dobivenim modelom napravljena su tri slučaja optimizacije. Optimalni uvjeti za jedan od slučajeva su: vrijeme reakcije od 1 sat pri temperaturi od 71,98 uz omjer izobutnola i ulja 10,17:1 sa 1,72 % KOH katalizatora. Previđeno iskorištenje iznosi 99,69 %. Biodiesel is ecologically acceptable a sustainable substitute for petrochemical diesel. By its chemical composition biodiesel is a mixture of monoalkyl esters of fatty acid and simple alcohols. Biodiesel is produced from different waste and cooking oils such as sunflower, castor, peanut and soybean oils. Nowadays, most used alcohols are methanol and ethanol. In recent times, other alcohols, such as butanol, isobutanol and pentanol, are being investigated for biodiesel production. Biodiesel is produced by the reaction of transesterifiction of oil with alcohol. In this paper, the influence of four reaction parameters on base catalysed transesterificaton of sunflower oil with isobutanol was studied. Potassium hydroxide was used as catalyst. Reaction parameters were: reaction time (1 - 3 h), temperature (40 - 80 °C), molar ratio of alcohol and oil (6:1 - 12:1) and mass percentage of catalyst (1 - 3 %). Using Desin-Experst software a Box-Behnken plan with 28 experiments was made. Result of every experiment was the biodiesel yield which was determined by 1H NMR spectroscopic analysis. Based on the experimental results, a model of the dependence that takes into account the yield on the reaction parameters was made. Using the model three optimisation cases were made. Optimal reaction parameters for one of those cases were: 1 h of reaction time at 71.98 °C using 10,17:1 ratio of isobutanol and oil and 1.72 % of KOH catalyst. The estimated yield was 99.69%.