Proračun lokalnih termohidrauličkih uvjeta za potrebe kvalificiranja električne opreme sigurnosne klase

scientific master's theses

• Title (english): Calculation of local thermal-hydraulic conditions for qualification of safety class electrical equipment
• Author: Boris Sučić
• Mentor: Nikola Čavlina (mentor)
• Committee member: Željko Bogdan (predsjednik povjerenstva)
• Committee member: Nikola Čavlina (član povjerenstva)
• Committee member: Davor Grgić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Energy and Power Systems); Zagreb
• Defense date and country: 2004-07-08, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Power Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering ; 004 - Computer science and technology. Computing. Data processing

Abstract

U ovom radu napravljen je trodimenzionalni model IB prostorija na elevaciji 100.3 metara nuklearne elektrane Krško koje su pod utjecajem loma u sustavu za čišćenje parogeneratora. Od vitalnog je značaja za sigurnost elektrane osiguranje točno propisanih uvjeta u prostorijama s akumulatorskim baterijama i punjačima koje se nalaze na ovoj elevaciji u IB zgradi jer se na taj način osigurava i napajanje kompletne nuklearne instrumentacije. Za propisani maseni protok ispuštenog fluida i za različite scenarije otvaranja komunikacije prema turbinskoj zgradi i okolišu, te izolacije mjesta loma, uz pomoć CFD programa FLUENT određena je trodimenzionalna raspodjela temperature i identificirane su povoljne lokacije za ugradnju temperaturnih senzora. U prvoj fazi rada su se zbog što je moguće bolje komparacije s programom GOTHIC ali i zbog upoznavanja mogućnosti programa FLUENT napravili proračuni u relativno jednostavnoj geometriji. Upravo su iskustva stečena na ovim tzv. jednostavnijim modelima predstavljala značajan doprinos kasnijem, kvalitetnijem, modeliranju te proračunu strujanja u složenoj geometriji IB prostora. U uvodim poglavljima ovog rada napravljen je pregled osnovnih značajki analize (Grgić, 2001) koja je trasirala put i postavila temelje analizi napravljenoj u ovom radu. Također, predstavljene su osnove jednadžbe dinamike i mogućnosti CFD programa FLUENT. Kroz analizu dobivenih rezultata na modelu IB prostorija, neovisno o analiziranom scenariju, pokazalo se je da je najpovoljnija lokacija za ugradnju temperaturnih senzora prostorija IB010 i to njezini zidovi prema zgradi kontejmenta i prema prostoriji IB007. Kao zaključak može se reći da je i uz sva nužno uvedena pojednostavljenja uvođenje CFD programa FLUENT u rješavanje ove klase problema sigurno opravdalo svoju svrhu. Naime, po prvi su se put vidjele lokalne raspodjele temperature i brzine strujanja koje su jako nedostajale proračunima s modelima s distribuiranim volumenima. Također, i sama nestacionarnost i trodimenzionalnost problema zahtijevala je softverski paket koji je najučinkovitiji upravo u tom dijelu. Korištenjem CFD programa FLUENT se po prvi put kroz rezultate uspjela potvrditi činjenica da prilikom uspostavljanja dominantnog strujanja prema turbinskoj zgradi na vratima IB010-IB001 dolazi do reverziranja smjera strujanja. Međutim, nikako se ne smije zanemariti i jako velika kompleksnost modeliranja dvofaznih strujanja kroz program FLUENT, te čak i uz dosta pojednostavljenja jako dugo vrijeme izračuna. Upravo u zadnje navedenim činjenicama leži najveća prednost programa GOTHIC u odnosu na program FLUENT, brže vrijeme izračuna i jednostavnije modeliranje dvofaznih strujanja. Kombiniranjem ova sva programska paketa dobrim dijelom su se anulirale mane svakog od njih te dobiveni rezultati čine jednu, kompaktnu, cjelinu. Budući rad u ovom području upravo je determiniran kombiniranim korištenjem CFD programa i programa s distribuiranim volumenima koji bi bili alat za validaciju rezultata dobivenih CFD analizom.

Abstract (english)

In this master thesis three dimensional model of Nuclear power plant Krsko IB rooms on the elevation of 100.3 meters which could be under influence of the break in the blowdown processing system was built. It is essential for the safety operation of the nuclear power plant to preserve very strictly defined environmental condition in rooms with DC batteries and their chargers. If the batteries and chargers are preserved in good operating condition we have the strongest guarantee for the safety of nuclear instrumentation power supply. For the defined mass flow of discharged fluid and for the different scenarios of break point isolation and communication with environment, via turbine building or via IB001 room, with the CFD code FLUENT three dimensional contours of temperature were calculated. Also based on the results of this analysis optimal locations for temperature sensors were defined. In the first phase of the master thesis work with the aim to get a better comparison with results obtained with GOTHIC code first calculations with FLUENT were made on a simple geometry models. Results and experience obtained on this simple geometry models were essential for the quality of the calculation in quite complicated model of IB rooms. In the first chapters of this paper basic overview of the past analysis (Grgić, 2001) were made. This past analysis (Grgic, 2001) was the base and input for the analysis that was made in this paper. Also in the first, so called introducing chapters key set of fluid dynamics equations and basic capabilities of the CFD code FLUENT were presented. Through the analysis of the results obtained on the model of IB room optimal location for the temperature sensors were defined. Based on all scenarios, wall between room IB010 and containment building and wall between IB010 and IB007 which are in the room IB010 were declared to be optimal location for the sensors. As global conclusion after these analysis we may say that even regarding all simplifications of the model that were necessary to make introduction of the CFD code FLUENT in this class of problem was very valuable. Results of analysis preformed with FLUENT clearly present local distribution of temperature and velocity vectors. Also unsteadiness and three dimensionality of the resolving problem was ideal place for the implementation of CFD code FLUENT. Results of the analysis confirmed for the first time that in the moment when communication via turbine building would be opened, on the door between rooms IB001 and IB010 would occur a reverse flow. Also we can not neglect the fact that modelling multi-phase phenomena with FLUENT is a very complex problem. Very good advantage of GOTHIC code is defined in this last sentence that describes disadvantage of FLUENT. GOTHIC code has very good capabilities for the multi-phase phenomena modelling but limited three dimensional capabilities. Combination of these codes provides the best results when applied to the analysis of this class of problems. Perspectives for the future work in this field are underlined with the combined usage of CFD codes and codes with distributed volumes for the validation of the results obtained with CFD codes.

• Keywords: Računalna dinamika fluida; FLUENT; termohidraulički uvjeti; električna oprema sigurnosne klase
• Keywords (english): Computational fluid dynamics; FLUENT; thermal-hydraulic conditions; safety class electrical equipment
• Language: croatian
• URN:NBN: urn:nbn:hr:168:164663
• Study programme: Title: Postgraduate master programme in electrical engineering; Study programme type: university; Study level: postgraduate; Academic / professional title: Magistar znanosti elektrotehnike (Magistar znanosti elektrotehnike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2019-06-06 11:54:07