Karakterizacija emulzija teškog loživog ulja i vode

undergraduate thesis

• Title (english): Characterization of water in heavy fuel oil emulsions
• Author: Kristina Miškić
• Mentor: Ante Jukić (mentor)
• Committee member: Ante Jukić (predsjednik povjerenstva)
• Committee member: Fabio Faraguna (član povjerenstva)
• Committee member: Vesna Ocelić Bulatović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2018-09-12, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Chemical Engineering in Material Development

Abstract

U radu su istraženi stabilnost i reološka svojstva emulzija vode u loživom ulju. S obzirom na široku upotrebu loživog ulja i mogućnost povećanja njegove energetske učinkovitosti miješanjem s vodom, važno je znati kako se emulzije ponašaju u različitim uvjetima. Ispitivani materijali bili su čisto loživo ulje, emulzija s 10 mas. % vode i emulzija s 20 mas. % vode. Emulzije su pripravljene kavitacijskim namješavanjem, bez dodanih površinski aktivnih tvari. Od uzoraka s navedenim udjelima vode, u svrhu utvrđivanja stabilnosti i svojstava kroz vrijeme stajanja, uzorkovanje se je provodilo u četiri različita termina, u razmaku od sedam dana. Nadalje, zbog pretpostavke da se sastav emulzija razlikuje pri vrhu i dnu, kao posljedica veće gustoće vode od gustoće loživog ulja, uzorci su uzimani s oba dijela posude. Udjel vode i stabilnost emulzija mjereni su termogravimetrijom pri čemu je praćen gubitak mase vode. Velika razlika u količini vode između uzoraka vrha i dna ukazuje na nestabilnu emulziju. Od reoloških svojstava mjerena je viskoznost i njena promjena s povećanjem smične brzine i temperature. Dodatkom vode u loživo ulje očekuje se povećanje viskoznosti. Mjerenja su provedena u rasponu smičnih brzina od 1 s^-1 do 100 s^-1, a temperaturno područje mjerenja bilo je od 25 °C do 50 °C i od 25 °C do 100 °C. Ustanovljeno je da se viskoznost emulzija vode u loživom ulju smanjuje s povećanjem temperature i smične brzine, a povećava s povećanjem udjela vode. Također, stabilnost emulzija se smanjuje s povećanjem sadržaja vode.

Abstract (english)

This thesis studies the stability and rheological characteristics of water / fuel oil emulsions. The knowledge of an emulsions' behavior under different conditions is important when it comes to the wide usage of fuel oil and the possibility of achieving higher energy efficiency when mixing fuel oil with water. The analyzed materials were pure fuel oil, an emulsion with 10 wt. % of water and an emulsion with 20 wt. % of water. The emulsions were obtained by cavitation mixing, without using surface active components. In order to determine the change of the emulsions' characteristics during time, samples were taken four times in periods of seven days. Moreover, because of the assumption of different water content in the emulsions at the top and at the bottom of the vessel, as a result of the water's higher density compared to fuel oil, the samples were taken from the top as well as from the bottom of the vessel. The water content and the emulsions' stability were measured by thermogravimetry, where the loss of water was followed. A high difference between the top and the bottom water content suggests an emulsion of weak stability. From the rheological characteristics, the viscosity and its change with the increase of the shear rate and temperature was measured. The shear rate was in the range from 1 s^-1 to 100 s^-1, and the temperature increased in the first set of experiments from 25 °C to 50 °C, and afterwards from 25 °C to 100 °C. It was determined that the viscosity of water / fuel oil emulsions decreases with an increase of temperature and shear rate, and increases with an increase of the water content. Also, the viscosity results indicate that the stability of emulsions decreases with an increase of water content.

• Keywords: loživo ulje; voda; emulzija; reologija; termogravimetrija; viskoznost; stabilnost
• Keywords (english): fuel oil; water; emulsion; rheology; thermogravimetry; viscosity; stability
• Language: croatian
• URN:NBN: urn:nbn:hr:149:629131
• Study programme: Title: Applied Chemistry - Undergraduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Environmental chemistry and green technologies; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-11-22 12:28:24