Razvoj metode rješavanja problema kondenzacije u niskotemperaturnom toplovodnom kotlu

Malinovec Puček, Marina (2009) Razvoj metode rješavanja problema kondenzacije u niskotemperaturnom toplovodnom kotlu. = Doctoral thesis , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Švaić, Srećko.

[img]
Preview
Text
MALINOVEC-Razvoj metode rjesavanja problema kondenzacije u NTK.pdf - Published Version Jezik dokumenta:Croatian

Download (15MB) | Preview

Abstract (Croatian)

Cilj prikazanog istraživanja je razviti numerički model i simulirati rad različitih konstrukcija prototipova niskotemperaturnog kotla s glavnom svrhom sprječavanja kondenzacije dimnih plinova na ogrjevnim stijenkama kotla. Rezultati provedenih numeričkih simulacija, koristeći programski kod Fluent, uspoređeni su s rezultatima mjerenja. Razvoj prototipova i eksperimentalni dio rada proveden je u Laboratoriju za toplinu i toplinske uređaje Fakulteta strojarstva i brodogradnje u Zagrebu. Istraživanje je provedeno kombinacijom znanstvenih i inženjerskih metoda, sintezom teorijskih modela i praktičnih eksperimenata. U prvom dijelu rada opisani su niskotemperaturni toplovodni kotlovi i njihove posebnosti. Dani su izrazi i postupak proračuna izmjene topline u toplovodnom kotlu. Zbog kompleksnosti modela niskotemperaturnog toplovodnog kotla najprije su provedene numeričke simulacije dimovodnih cijevi s umetnutim turbulatorima i bez njih u širokom području parametara. U simulacijama dimovodne cijevi varirani su: brzina i temperatura dimnih plinova na ulazu u dimovodnu cijev, koeficijent prijelaza topline na strani vode, duljina vanjske cijevi, debljina zračnog sloja, te koeficijent toplinske vodljivosti stijenke cijevi. Na osnovu provedenih numeričkih simulacija dobivena je geometrija dvoslojnih dimovodnih cijevi, kakve se primjenjuju u svrhu sprječavanja kondenzacije dimnih plinova. U drugom dijelu uz opis ispitne linije dan je opis provedenih mjerenja i rekonstrukcija na prototipovima niskotemperaturnog toplovodnog kotla nazivnog učina 25 kW. Treći dio obrađuje razvoj numeričkog modela niskotemperaturnog toplovodnog kotla pomoću kojeg su, u svrhu sprječavanja kondenzacije dimnih plinova na ostalim ogrjevnim stijenkama, provedene numeričke simulacije. Postavljena su dva modela; model kojim je obuhvaćena strana vode i dimni plinovi u dimovodnim cijevima i model kojim su obuhvaćeni plamenik, ložište i predkomora. Slijedeći rezultate numeričkih simulacija i prethodnih mjerenja, definiran je prototip niskotemperaturnog kotla nazivnog učina 25 kW. Razvijeni numerički model niskotemperaturnog kotla omogućava optimiranje relevantnih geometrijskih parametara u svrhu sprječavanja kondenzacije dimnih plinova, i smanjuje broj eksperimenata u fazi razvoja kotla.

Abstract

The aim of presented research is to develop a numerical model and to simulate the operation of different designs of low temperature boiler prototypes with the main purpose of preventing combustion gas condensation on the heated boiler surfaces. The results of the numerical simulation performed using the computational package Fluent are compared with the measurement results. The development of prototypes and the experimental part of research have been conducted in the Laboratory for Applied Thermodynamics at the Faculty for Mechanical Engineering and Naval Architecture of the University in Zagreb. The research methodology is based on the combination of scientific and engineering methods, as a synthesis of theoretical methods and practical experiments. In the first part of this work low temperature boilers and their features are described. Expressions and calculation procedures of the heat transfer in boilers are provided. Due to the complexity of low temperature boiler models, numerical simulations of combustion gas tubes inserted with turbulators and without them are firstly performed in a wide range of parameters. In the simulations the velocity and temperature of combustion gases at tube inlet, heat transfer coefficient on the water side, the length of outer tube, the air gap thickness and heat conductance of the tube material were varied. By means of conducted numerical simulations geometry of the double walled tubes, which are used to prevent the condensation of combustion gases, is obtained. In the second part of the work, beside the description of the experimental setup, the conducted measurements and reconstructions on the low temperature boiler prototypes of nominal heat capacity 25 kW are described. The third part of the work deals with the development of low temperature boiler numerical model for numerical simulations developed with the purpose to prevent combustion gas condensation on other heated surfaces. Two models are set up: the model that comprises the water side and combustion gases in tubes and the model that comprises the burner, combustion chamber and chamber between the combustion chamber and the tubes. Following the results of numerical simulation and former conducted measurements, the low temperature boiler prototype of nominal heat capacity 25 kW is defined. The developed numerical model of a low temperature boiler enables the optimization of relevant design parameters in order to prevent combustion gases condensation, as well as the reduction of tests needed in the designing process of the boiler.

Item Type: Thesis (Doctoral thesis)
Uncontrolled Keywords: niskotemperaturni kotao, sprječavanje kondenzacije dimnih plinova, izmjena topline u kotlu, numerička simulacija rada kotla, Fluent, turbulentno nepredmiješano izgaranje, mjerenja
Keywords (Croatian): low temperature boiler, prevention of combustion gases condensation, heat transfer in boiler, CFD simulation of boiler operation, Fluent, turbulent non-premixed combustion, measurements
Subjects: TECHNICAL SCIENCE > Mechanical Engineering
Date Deposited: 09 Dec 2015 10:07
Last Modified: 09 Dec 2015 10:07
URI: http://repozitorij.fsb.hr/id/eprint/4940

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year

Nema podataka za dohvacanje citata