Primjena nanofluida u pločastom izmjenjivaču topline

master's thesis

• Title (english): Application of nanofluid in plate heat exchanger
• Author: Marina Samardžija
• Mentor: Jasna Prlić Kardum (mentor)
• Committee member: Jasna Prlić Kardum (predsjednik povjerenstva)
• Committee member: Aleksandra Sander (član povjerenstva)
• Committee member: Ljubica Matijašević (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2015-09-24, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Mechanical, Thermal and Separation Processes

Abstract

U smjesu fluida (voda i glicerol) dispergirane se nanočestice aluminijeva (III) oksida (Al2O3), u različitim koncentracijama sa i bez stabilizatora, sa ciljem poboljšanja toplinske vodljivosti. Nakon postizanja stabilnosti suspenzija različitih koncentracija, određeno je njihovo reološko ponašanje, izmjereni su koeficijenti toplinske vodljivosti te specifični toplinski kapacitet pripravljenih nanofluida. Uspoređeni su različiti teoretski modeli sa eksperimentalno dobivenim vrijednostima termo-fizikalnih svojstava nanofluida. Primjenom nanofluida u pločastom izmjenjivaču topline izračunat je koeficijent prijelaza i prolaza topline, te djelotvornost pločastog izmjenjivača topline pri različitim protocima. Također, mjerenja su provedena s fluidom u koji je dodan stabilizator Tween 20. Ovaj stabilizator izabran je kao najbolji između testiranih (arapska guma i Triton X100). Reometrijskim mjerenjem utvrđeno je da nanofluidi pokazuju newtonovska svojstva s neznatnim povećanjem gustoće i viskoznosti u odnosu na bazni fluid. Koeficijent prijelaza topline poboljšavaju se s poboljšanjem hidrodinamičkih uvjeta u izmjenjivaču topline. Postignuta iskorištenja u izmjenjivaču topline su visoka, a smanjuju se pri većim protocima toplog fluida te povećanjem koncentracije nanočestica. Vrijednosti eksponenata m u korelacijskim jednadžbama dobivenih korištenjem nanofluida povećana su u usporedbi s vrijednostima dobivenih za vodu pri laminarnim uvjetima strujanja.

Abstract (english)

Aluminium III oxide (Al2O3) nanoparticles have been dispersed into the mixture of a fluid (water and glycerol) in different concentrations with or without the stabilitator with the aim to improve thermal conductivity. Having achieved the stability of suspensions of different concentrations, the rheological behaviour of the prepared nanofluids has been determined, and coefficient of thermal conductivity also as the specific heat capacity have been measured. Different theoretical models have been compared with the experimentally obtained values of thermo-physical properties of nanofluids. By applying nanofluids in the plate heat exchanger the heat transfer coefficient and overall heat transfer coefficient have been calculated as well as the efficiency of the plate heat exchanger at different flows. Likewise, measurements have been carried out with the fluid which contains Tween 20 stabilitator. This stabilitator has been selected as prime among the tested samples (Arab rubber and Triton X100). Rheometrical measurement has affirmed that nanofluids indicate Newton's behaviour with slight increase in density and viscosity comparing to the base fluid. Improving of hydrodynamic conditions in the heat exchanger leads to heat transfer coefficient increasing. The achieved efficiency in the heat exchanger is high, being diminished at higher flows of hot fluid and with the increase of nanoparticles concentration. By comparison with the values obtained for water in laminar flow conditions, values of m exponents in the correlation equations obtained for nanofluids have been increased.

• Keywords: koeficijent prijelaza topline; korelacijske jednadžbe; nanofluid; pločasti izmjenjivač topline; stabilizatori
• Keywords (english): heat transfer coefficient; correlation equations; nanofluid; plate heat exchanger; stabilitators
• Language: croatian
• URN:NBN: urn:nbn:hr:149:425651
• 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: 2017-03-13 13:40:51