벼의 물리적(物理的) 및 열적(熱的) 특성(特性)에 관(関)한 연구(硏究) -열적(熱的) 특성(特性)에 관(関)하여-

Study on the Physical and Thermal Properties of Rice Kernels - Thermal Properties -

  • 고학균 (서울대학교 농과대학 농공학과) ;
  • 노상하 (서울대학교 농과대학 농공학과) ;
  • 정종훈 (서울대학교 농과대학 농공학과)
  • 발행 : 1984.12.31

초록

This study was intended to search the thermal properties of rice which are necessary in preventing qualitative and quantitative losses in the drying and milling processes. First, the coefficient of cubical thermal expansion of brown rice was measured, which is required for analyzing the internal stress of rice, and then theoretical thermal and moisture stresses were calculated. The results are summarized as follows: 1. The coefficient of cubical thermal expansion of brown rice was about $2.81{\times}10^{-4}/^{\circ}C$ in the temperature range of $10^{\circ}C-60^{\circ}C$. 2. When the shape of brown rice was assumed to be a sphere or a cylinder, maximum thermal stress due to temperature change of $20^{\circ}C-60^{\circ}C$ was in the range of $25-100kg/cm^2$. And maximum moisture stress was in the range of $450-650kg/cm^2$ when the drying temperature was $35^{\circ}C$, initial and final moisture contents of brown rice were 20% and 14% (w.b.), and the moisture diffusion coefficient was assumed to be $6.79{\times}10^{-4}cm^2/hr$. 3. Consequently, it was concluded that crack formation in a rice kernel is mainly caused by moisture stress.

키워드

과제정보

연구 과제 주관 기관 : 산학협동재단