Numerical Analysis of Unsteady Heat Transfer for Location Selection of CPVC Piping

Myoung-Young, Choi; Hyoung-Gwon, Choi

doi:2015.29.6.33

Int J Fire Sci Eng > Volume 29(6); 2015 > Article

Fire Science and Engineering 2015;29(6):33-39.
DOI: https://doi.org/10.7731/KIFSE.2015.29.6.033 Published online December 31, 2015.

CPVC 배관 동파방지용 열선의 위치 선정을 위한 비정상 열전달 수치해석

최명영, 최형권

¹한국화재보험협회 방재시험연구원
²서울과학기술대학교 기계자동차공학과

Numerical Analysis of Unsteady Heat Transfer for Location Selection of CPVC Piping

Choi Myoung-Young, Choi Hyoung-Gwon

¹Fire Insurers Laboratories of Korea
²Dept. of Mechanical & Automotive Engineering, Seoul National Univ. of Science & Technology

요약

본 논문에서는 동절기 소방용 CPVC 배관의 동파방지를 위하여 최적의 열선위치를 에너지방정식과 비정상 비압축성 Navier-stokes 방정식을 사용하여 수치해석을 수행하였다. CPVC 배관은 탄소강관과 열용량 등 주요 물성에 큰 차이가 있어 배관 내 물의 유동에 큰 차이를 보이는 것을 확인할 수 있었다. 물의 자연대류와 CPVC 배관의 열전도가 결합된 복합열전달을 해석하였다. 상용코드(Fluent)를 사용하여 혼합 열전달 배관 내 물의 비정상적인 유동과 온도분포를 확인하였다. 소방용 CPVC 배관 단면의 하부에 열선을 설치하는 것이 다른 위치에 설치하는 것보다 시간에 따른 물의 최저 온도가 가장 높아서 동파방지에 보다 효과적인 것을 확인하였다.

Abstract

In this paper, a numerical experiment was conducted to find out the optimal location of electrical heat trace for anti-freeze of water inside the CPVC pipe for fire protection. The unsteady incompressible Navier-Stokes equations coupled with energy equation were solved. Since the conduction equation of pipe was coupled with the natural convection of water, the analysis of conjugate heat transfer was conducted. A commercial code (ANSYS-FLUENT) based on SIMPLE-type algorithm was used for investigating the unsteady flows and temperature distributions in water region. From the present numerical experiment, it has been found that the vector field of water inside the PVC pipe is opposite to the case of steel because of the huge difference of material properties of the two pipes. Furthermore, it was found that the lowest part of the pipe was an optimal position for electrical heat trace since the minimum water temperature of the case was higher than those of the other cases.

Key Words: Heat tracing, CPVC, CFD, Natural convection, Conjugate heat transfer