초임계 조건 내 CO₂-CH₄와 CO₂-N₂ 혼합물의 관 내측 열전달 계수의 수치적 해석

Abstract

In this study, the effect of mixture mole fraction, mass flux, and operational pressure on the heat transfer coefficient in supercritical conditions was investigated using commercial CFD program of FLUENT for CCS (Carbon Capture & Storage) transporting process. Simulations were carried out with mole fractions of the impurities of CH₄ and N₂ at 1, 3, and 5%, the pressure at 80, 90, and 100 bar, and the mass flux at 200, 400, and 600 kg/m². The range of inlet temperatures were set to 10 K at 5 K interval based on the point where the maximum heat transfer coefficient was observed. For CO₂, the maximum heat transfer coefficient was found at 308 K, the value was 5,270 W/m²․K. When the mole fraction of CH₄ was 3%, it was 4,400 W/m²․K at 304.5 K. When mole fraction of N2 was 3%, it was 4,000 W/m²․K at 303 K. It was observed that as the mole fraction increases, the maximum heat transfer coefficient decrease, and the temperature at which it is maximum increases. It was confirmed that the type of impurities affect the heat transfer of the mixture. As the mass flux of mixture increase, the average heat transfer coefficient increases too.