Dynamics of liquid and solids flow in oscillatory flow reactors and application to biochemical reaction with immobilized enzymes

Disertacija obuhvata eksperimentalno i teorijsko istraţivanje osnovnih fluido – dinamiĉkih karakteristika kontinualnih jednofaznih i višefaznih reaktora sa oscilatornim tokom fluida (ROT). Pored ispitivanja dinamike strujanja teĉnosti i ĉestica, u okviru ove teze ispitivana je i mogućnost primene ROT na reakciju sinteze galaktooligosaharida (GOS) pomoću slobodnih i imobilisanih enzima. U prvom poglavlju dat je detaljan pregled dosadašnjih istraţivanja koja se odnose na reaktore sa oscilatornim tokom fluida. Prikazane su karakteristike, prednosti i nedostaci ROT predstavljeni u literaturi. Posebno su prikazani i rezultati istraţivanja potencijalne industrijske primene ovog tipa ureĊaja. U drugom poglavlju „Dinamika strujanja teĉnosti u ROT“ prikazani su rezultati eksperimentalnog ispitivanja strujanja, tj. raspodele starosti teĉnosti na izlazu, u dva geometrijski sliĉna reaktora sa oscilatornim tokom fluida duţine 2 m i unutrašnjeg preĉnika 44 i 26 mm. Primenjena je metoda praćenja odziva sistema na impulsnu promenu obeleţene supstance ĉija koncentracija je merena u vremenu pomoću spektrofotometra. Na osnovu eksperimentalnih rezultata utvrĊen je uticaj operativnih parametara (frekvencija, amplituda i protok peristaltiĉke pumpe) na raspodelu starosti teĉnosti na izlazu iz ispitivanih reaktora sa oscilatornim tokom fluida. Primenom modela klipnog strujanja sa aksijalnom disperzijom, a na osnovu eksperimentalnih rezultata razvijena je matematiĉka korelacija koja povezuje bezdimenzioni Pekleov broj sa bezdimenzionim brojevima koji opisuju oscilatorni tok teĉnosti u reaktorima: oscilatorni Rejnoldsov broj, Strauhalov broj i odnos oscilatornog i Rejnoldsovog broja neto protoka. Razvijena korelacija je pored eksperimentalnih vrednosti ove disertacije verifikovana i uz pomoć eksperimentalnih rezultata dostupnih u literaturi. U trećem poglavlju „Dinamika strujanja ĉestica“ prikazani su rezultati eksperimentalnog i teorijskog istraţivanja naĉina proticanja ĉestica u kontinualnom reaktoru sa oscilatornim tokom fluida (unutrašnjeg preĉnika 26 mm) u koji se ĉestice uvode kontinualno. Primenom metode praćenja odziva sistema na stepenastu promenu obeleţenih ĉestica utvrĊen je uticaj operativnih parametara – frekvencije, amplitude ikoncentracije ĉestica na ulazu u reaktor, na kumulativnu krivu vremena zadrţavanja ĉestica u reaktoru. Kako bi se odredila koncentracija obeleţenih (obojenih) ĉestica, fotografije uzoraka su analizirane u programskom paketu ImageJ. Pored toga, ispitan je i kvantifikovan uticaj operativnih parametara na naĉin proticanja ĉestica i stešnjeno taloţenje, srednje vreme zadrţavanja kao i na udeo (zadrţanih) ĉestica u reaktoru. Teorijski i eksperimentalno su utvrĊeni kriterijumi za odreĊivanje 4 reţima proticanja ĉestica: puzajući reţim strujanja ĉestica, zgušnjeno strujanje ĉestica, razblaţeni tok ĉestica i odnošenje ĉestica...The dissertation presents experimental and theoretical investigation of the main fluid dynamic characteristics of continuous single – phase and multiphase fluid flow in continuous oscillatory flow reactors (COFR). In addition, the possibility of COFR application to reaction of galactooligosaccharides (GOS) synthesis with free – flow and immobilized enzymes was studied within this thesis. The first chapter provides a detailed overview of the research related to oscillatory flow reactors (OFR). Further, the characteristics, advantages and disadvantages of OFR presented in the literature are discussed. In addition, the possibilities of industrial application for this type of device are presented. In the second chapter "Dynamics of fluid flow in the OFR", the results of experimental investigation of the liquid residence time distribution (RTD) in two geometrically similar reactors with oscillatory flow of liquid are presented.. Reactors were 2 m in length and with internal diameter of 44 and 26 mm. The impulse response method with a tracer was applied. The concentration of the tracer in the samples was determined by measuring the absorbance using a spectrophotometer. The influence of operating parameters (frequency, amplitude and flow rate of the peristaltic pump) on the RTD in the reactors was determined. Using a plug flow with axial dispersion model and experimental results, an empirical correlation was derived. Developed correlation relates the dimensionless Peclet number to dimensionless numbers describing the oscillatory fluid flow in the reactors: oscillatory Reynolds number, Strauhal number and ratio of oscillatory and net Reynolds number. In addition to the experimental results of this dissertation, the correlation was verified using experimental results from the literature. The third chapter "Dynamics of solids flow in the OFR" presents the results of experimental and theoretical investigation of the liquid – solids flow in continuous oscillatory flow reactor (internal diameter of 26 mm) into which the solids are introduced continuously. The influence of operating parameters – frequency, amplitude and concentration of solids at the inlet of the reactor, on solids cumulative residencetime curve (F) in the reactor was determined using the step response method with a tracer (solids of a different color). In order to determine concentration of tracer, the photos of samples were analysed using the ImageJ software. In addition, the influence of operating parameters on the solids flow regime, hindered particle settling, mean residence time as well as solids holdup in the reactor was examined and quantified. Four solids flow regimes were identified theoretically and experimentally: creeping solids flow, dense solids flow, dilute solids flow and solids washout..