Journal of Soil and Groundwater Environment (한국지하수토양환경학회지:지하수토양환경)

Korean Society of Soil and Groundwater Environment (한국지하수토양환경학회)
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An Experimental Analysis of Effective Thermal Conductivity of Porous Materials Using Structural Models

구조모델을 이용한 다공성 매질의 유효열전도도 분석

  • Cha, Jang-Hwan (Department of Geoenvironmental Sciences, Kongju National University) ;
  • Koo, Min-Ho (Department of Geoenvironmental Sciences, Kongju National University) ;
  • Keehm, Young-Seuk (Department of Geoenvironmental Sciences, Kongju National University)
  • 차장환 (공주대학교 지질환경과학과) ;
  • 구민호 (공주대학교 지질환경과학과) ;
  • 김영석 (공주대학교 지질환경과학과)
  • Received : 2010.10.06
  • Accepted : 2010.10.13
  • Published : 2010.12.31
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Abstract

The effective thermal conductivity of porous materials is usually determined by porosity, water content, and the conductivity of the matrix. In addition, it is also affected by the internal structure of the materials such as the size, arrangement, and connectivity of the matrix-forming grains. Based on the structural models for multi-phase materials, thermal conductivities of soils and sands measured with varying the water content were analyzed. Thermal conductivities of dry samples were likely to fall in the region between the Maxwell-Eucken model with air as the continuous phase and the matrix as the dispersed phase ($ME_{air}$) and the co-continuous (CC) model. However, water-saturated samples moved down to the region between the $ME_{wat}$ model and the series model. The predictive inconsistency of the structural models for dry and water-saturated samples may be caused by the increase of porosity for water-saturated samples, which leads to decrease of connectivity among the grains of matrix. In cases of variably saturated samples with a uniform grain size, the thermal conductivity showed progressive changes of the structural models from the $ME_{air}$ model to the $ME_{wat}$ model depending on the water content. Especially, an abrupt increase found in 0-20% of the water content, showing transition from the $ME_{air}$ model to the CC model, can be attributed to change of water from the dispersed to continuous phase. On the contrary, the undisturbed soil samples with various sizes of grains showed a gradual increase of conductivity during the transition from the $ME_{air}$ model to the CC model.

Keywords

References

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