Ispitivanje dinamike miješanja pri različitim brojevima okretaja miješalice

master's thesis

• Title (english): Examination of dinamic of mixing at different rotation numbers of mixer
• Author: Sanja Vlastelica
• Mentor: Ingrid Bauman (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Process Engineering); (Laboratory for Measurement, Regulation and Automatisation); Zagreb
• Defense date and country: 2005-07-14, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Miješanje je tehnološka operacija kojom se dobivaju homogene smjese dva ili više sastojaka u uređajima za miješanje. Homogenost mješavine ocjenjuje se stupnjem izmiješanosti. Složeni mehanizam miješanja rezultat je kompleksnosti hidrodinamičkih uvjeta, složenosti reoloških svojstava, utjecaja sile teže i centrifugalne sile, te kemijskih i fizikalnih interakcija među česticama. Cilj ovog rada bio je ispitati stupanj izmiješanosti dvokomponentne smjese zrnatog i praškastog materijala u laboratorijskoj bubnjastoj miješalici "Turbula" pri različitim brojevima okretaja kada su komponente u smjesi zastupljene u različitim volumnim omjerima, odnosno kada je jedna od komponenata u znatnom suvišku. Mješavine čija je homogenost ispitivana služe za pripremu specijalnih vrsta kruha s povećanom nutritivnom vrijednošću. Zbog svojih prehrambenih karakteristika, kao zrnati materijal je odabrana sojina šunka, a kao praškasti materijal uzeto je pšenično i kukuruzno brašno. Udio krupnije komponente u smjesi odredio se uzorkovanjem i granulometrijskom analizom. Pokusi su rađeni pri odabranim brzinama miješalice, optimalnoj ispunjenosti cilindra i pri različitim vremenskim intervalima. Uzorkovanjem smjese praćena je dinamika miješanja, a statističkim metodama određivan je stupanj izmiješanosti. Na temelju eksperimentalno dobivenih podataka za standardne devijacije izrađena je matematička analiza procesa miješanja, a rezultati su prikazani grafički. Uočeno je da se dobra homogenost postiže kod nižih brojeva okretaja miješalice dok je homogenost postignuta u svim korištenim omjerima što je bitno za proizvodnju kod koje je udio pojedine komponente određen recepturom.

Abstract (english)

Mixing is technological process which gives homogeneuos mixtures of two or more components by mixing equipment (mixers). Homogenity of mixture is estimated by the level of blended mixture. Complex mechanism of mixing is a result of complexity of hydrodynamical conditions, reological conditions, together with influence of gravity and centrifugal force, chemical and physical interactions between particles. The purpose of this work was to examine level of blended component mixtures of granular and powdered materials in a laboratory drum mixer type "Turbula" at different rotation number when components in mixture were representative in different proportions, i.e. when one of components was in surpluse. Mixtures which homogenity was examined are for preparation of special bread type with enlarged nutritive value. Because of its dietary characteristics, soy hum was chosen. Portion of larger component in the mixture was determined by sampling granulometric analisys. Tests were done at chosen mixer speed, optimal filling of cylinder and at different time intervals. Dynamic of mixing was defined by sampling of mixture. The level of blending was determined by statistical tests. Based on experimental data for standard deviations, mathematical analysis of mixing process was done, and results are presented graphically. Good homogenity was achieved at lower revolution number of mixer. Homogenious mixtures were achieved at all used proportions which is important for special bread type production in which share of each component is determined by recipe.

• Keywords: miješanje; prahovi; "Turbula" miješalica
• Keywords (english): mixing; powders; "Turbula" mixer
• Language: croatian
• URN:NBN: urn:nbn:hr:159:002072
• Study programme: Title: Food Technology; specializations in: Food Engineering; Course: Food Engineering; Study programme type: university; Study level: graduate; Academic / professional title: diplomirani inženjer prehrambene tehnologije; smjer prehrambeno inženjerstvo (diplomirani inženjer prehrambene tehnologije; smjer prehrambeno inženjerstvo)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-09-13 11:43:41