地中の熱拡散率の一測定装置について

DOI Web Site

書誌事項

タイトル別名
  • On the Arrangement to measure the Thermal Diffusivity

抄録

Dr. S. SUZUKI & S. SHIGETOMI have computed the thermal diffusivity of soil by using the equation<br>K=Δθ/Δt/Δ2θ/Δz2……(1)<br>In practice, the value of Δ2θ/Δz2 is determined by the following approximate formula.<br>Δ2θ/Δz2=(θ1-θ2/z1-z2-θ2-θ3/z2-z3)/(z1+z2/2-z2+z3/2)<br>=θ1-2θ2+θ3/(Δz)2……(2)<br>where θ1, θ2 and θ3 are soil temperature at z1, z2 and z3 respectively, and we are to take z1-z2=z2-z3.<br>The difficulty arises in attempt to get accurate value of Δ2θ/Δz2, since they used the glass thermometer.<br>The authors deviced a combination of two thermocuples to get the accurate values of (θ1-2θ2+θ3) as shown in Fig. 1. This arrangement is able to obtain the above value to the order of 0.02C.<br>It is noted that the diffusivity by using the equation (1) has to be used only in the case of ∂θ/∂t≠0 and ∂2θ/∂z2≠0 in the distribution of the soil temperatures in time and depth. From our experience, the proper length of Δz is from 2 to 3cm. Soil moisture contents are obtained by the Soil Moisture Ohm meter (Fiberglass Soil Moisture Unit Modls 351 & 375).<br>Observation have shown that the diffusivity of the soil decreases with the increase of the soil moisture contents, as the water content is greater than 28%. (see Tab. 1, and Fig. 2.)

収録刊行物

  • 農業気象

    農業気象 11 (4), 121-123, 1956

    日本農業気象学会

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ