Farklı Çalışma Parametrelerinde Hesaplamalı Akışkanlar Dinamiği Simülasyonu ile Kritik Isı Akısının Tahmini

Year 2022, , 444 - 453, 30.04.2022

Ayşe Nur Esen

https://doi.org/10.35414/akufemubid.1002711

Abstract

Çekirdekli kaynamadan ayrılma, ısı akısı değeri, kritik ısı akısı denilen sınır değere ulaştığında meydana gelir ve ısı transferinin azalması ile ısıtılan yüzeyin zarar görmesine neden olabilecek ani sıcaklık artışına neden olur. Bu çalışmada dikey bir borudaki aşırı soğutulmuş akışta kritik ısı akısının meydana geldiği çekirdekli kaynamadan ayrılma koşulları hesaplamalı akışkanlar dinamiği simülasyonu tahmin edilmiştir. Gelişmiş duvar kaynama modeli ANSYS Fluent 2019 R3 yazılımı ile uygulanmıştır. Sabit bir basınçta değişen kütle akısı ve giriş sıcaklığı koşullarında simülasyonlar gerçekleştirilmiştir. Modeli doğrulamak için mevcut literatürden deneysel veriler toplanmış ve simülasyon sonuçları ile karşılaştırılmıştır. Elde edilen HAD sonuçlarına göre kritik ısı akısı değerinin aşırı soğutma seviyesi ve kütle akısı ile arttığı belirlenmiştir. Hesaplanan kritik ısı akısı değerleri ile deneysel veriler arasındaki ortalama sapma %16’dır. Elde edilen sonuçlar uygulanan modelin kritik ısı akısını tahmin etmede başarılı olduğunu göstermiştir.

Keywords

Çekirdekli kaynamadan ayrılma, İki fazlı akış, Kritik ısı akısı, Türbülans

Supporting Institution

İstanbul Bilgi Üniversitesi

Project Number

2019.01.010

Thanks

Bu çalışma, İstanbul Bilgi Üniversitesi, Bilimsel Araştırma Projeleri birimi (BAP) tarafından 2019.01.010 numaralı proje ile maddi olarak desteklenmiştir. Doç. Dr. Elif Aslı Yetkin’e çalışmadaki katkılarından dolayı teşekkür ederim.

Estimation of Critical Heat Flux in Different Operating Parameters by Computational Fluid Dynamics Simulation

Abstract

Departure from nucleate boiling occurs when the heat flux value reaches the limit value called the critical heat flux, and it causes a sudden increase in temperature that can cause damage to the heated surface with the decrease of heat transfer. In this study, a computational fluid dynamics simulation of departure from nucleate boiling where critical heat flux occurs in a subcooled flow in a vertical pipe has been predicted. An improved wall boiling model has been applied using ANSYS Fluent 2019 R3 software. Simulations are carried out under varying mass flux and inlet temperature conditions at a constant pressure. Experimental data were collected from the literature to validate the model and the simulation results were compared with the experimental data. According to the simulation results, it was determined that the critical heat flux value increased with the subcooling level and mass flux. The average deviation between the calculated critical heat flux values and the experimental data is 16%. The results proved that applied model was qualified to predict critical heat flux accurately.

Keywords

Departure from nucleate boiling, Two phase flow, Critical heat flux, Turbulence

Project Number

2019.01.010

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