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Language: korean

Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received October 31, 2013
Accepted December 29, 2013

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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일정한 응고속도를 갖는 2성분 응고에서 조성 대류의 특성 및 안정성

Characteristics and Stability of Compositional Convection in Binary Solidification with a Constant Solidification Velocity

황인국^†

In Gook Hwang^†

수원대학교 공과대학 화학공학과, 445-743 경기도 화성시 봉담읍 와우안길 17

Department of Chemical Engineering, The University of Suwon, 17 Wauan-gil, Bongdam-eup, Hwaseong-si, Gyeonggi-do 445-743, Korea

ighwang@suwon.ac.kr

Korean Chemical Engineering Research, April 2014, 52(2), 199-204(6), 10.9713/kcer.2014.52.2.199 Epub 1 April 2014

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Abstract

2성분 응고계에서 다공성 mush 층에서의 조성 대류는 생성되는 제품의 질에 영향을 준다. 본 연구에서는 일정한 속도로 응고되는 mush 층을 고려하였다. 선형 안정성 이론을 사용하여 mush 층에 대한 교란방정식을 유도하였고, 기본상태 온도장과 mush 층에서 기공률의 분포를 수치해법으로 조사하였다. 과열량이 클 때 mush 층의 두께는 열경계층의 두께에 비해 상대적으로 작았다. 과열량이 감소함에 따라 mush 층의 두께를 기준으로 한 Rayleigh 수는 증가하였고, mush 층은 조성 대류에 대해 안정해졌다. mush 층의 윗면에 등온조건을 적용한 경우보다 온도 및 열속의 연속조건을 액체- mush 계면에 적용한 경우에 임계 Rayleigh 수가 더 작게 얻어졌다.

In binary solidification compositional convection in a porous mushy layer influences the quality of the final products. We consider the mushy layer solidifying from below with a constant solidification velocity. The disturbance equations for the mushy layer are derived using linear stability theory. The basic-state temperature fields and the distribution of the porosity in the mushy layer are investigated numerically. When the superheat is large, the thickness of the mushy layer is relatively small compared to the thickness of the thermal boundary layer. With decreasing the superheat the critical Rayleigh number based on the thickness of the mushy layer increases and the mushy layer becomes stable to the compositional convection. The critical Rayleigh number obtained from the continuity conditions of temperature and heat flux at the mush-liquid interface is smaller than that from the isothermal condition at the upper boundary of the mushy layer.

Keywords

Binary Solidification Compositional Convection Mushy Layer Rayleigh Number Linear Stability

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