Istraživanje kinetike sušenja u sušioniku s pliticama

master's thesis

• Title (english): Investigation of the drying kinetics in a tray dryer
• Author: Ana Baković
• Mentor: Aleksandra Sander (mentor)
• Committee member: Aleksandra Sander (predsjednik povjerenstva)
• Committee member: Jasna Prlić Kardum (član povjerenstva)
• Committee member: Vesna Tomašić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2021-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Sušenje je složena toplinska operacija kojom se smanjuje sadržaj vlage u proizvodu namijenjenom za različite svrhe. Predstavlja proces koji se često koristi u prehrambenoj i kemijskoj industriji. U ovom radu je istraživana kinetika sušenja tikvica u šaržnom sušioniku s pliticama. Tikvice su povrće koje sadrži visok udio vlage zbog čega su osjetljive na propadanje tijekom vremena. Cilj rada je istražiti utjecaj temperature, brzine strujanja zraka i geometrije materijala (debljine ploške) na kinetiku sušenja tikvica. Dobivene eksperimentalne krivulje sušenja aproksimirane su Lewisovim, Pageovim, Henderson – Pabis, Weibull i Midilli et al modelom, a njihovi su parametri dovedeni u vezu s uvjetima provedbe procesa. Za ocjenu uspješnosti aproksimacije eksperimentalnih podataka sušenja korišten je indeks korelacije, R^2. Na temelju dobivenih podataka zaključeno je da je proces sušenja brži, a vrijeme trajanja procesa kraće pri višim temperaturama, većim brzinama strujanja zraka i pri manjim debljinama materijala. Određen je efektivni difuzijski koeficijent za period padajuće brzine sušenja koji objedinjuje sve mehanizme, kao i difuzijski koeficijent za vodu za cijeli tijek sušenja primjenom normiranog Weibullovog modela. Ispitan je utjecaj uvjeta provedbe procesa na efektivni difuzijski koeficijent. Iz dobivenih podataka se očituje da vrijednost efektivnog difuzijskog koeficijenta raste sa porastom temperature, brzine strujanja zraka i debljine materijala. Prije i poslije sušenja izmjeren je promjer uzoraka, na temelju čega je zaključeno da se materijal skuplja u većoj mjeri pri višim temperaturama i brzinama strujanja zraka, te pri manjim debljinama uzoraka.

Abstract (english)

Drying is a complex thermal operation that reduces the moisture content in a product intended for various purposes. It is a process often used in the food and chemical industries. This work investigated the drying kinetics of zucchini in a tray dryer. Zucchini is a vegetable that contains a high percentage of moisture, which is why they are susceptible to decay over time. This study aimed to investigate the influence of temperature, air flow rate, and material geometry (plate thickness) on the drying kinetics of zucchini. Drying kinetic curves obtained from the experimental data were approximated with Lewis, Page, Henderson - Pabis, Weibull and Midilli et al. models, and their parameters were correlated with the process conditions. The correlation index, R^2, was used to evaluate the success of the approximation of the experimental drying data. Based on the obtained data, it was concluded that the drying process is faster, and the duration of the process is shorter at higher temperatures, higher air flow rates and lower material thicknesses. The effective diffusion coefficient for the period of decreasing drying speed, which combines all mechanisms, was determined, as well as the diffusion coefficient of water for the entire drying course using the standardized Weibull model. The influence of process conditions on the effective diffusion coefficient was examined. From the obtained data, it is evident that the value of the effective diffusion coefficient increases with increasing temperature, air flow rate and material thickness. Before and after drying, the diameter of the samples was measured. Therefore, it is concluded that the material shrinks to a greater extent at higher temperatures and air flow rates and in the case of smaller sample thicknesses.

• Keywords: sušenje; tikvice; kinetika sušenja; matematički model; efektivni difuzijski koeficijent; skupljanje materijala
• Keywords (english): drying; zucchini; drying kinetics; mathematical model; effective diffusion coefficient; material shrinkage
• Language: croatian
• URN:NBN: urn:nbn:hr:149:499304
• Study programme: Title: Chemical Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-04-20 13:57:33