非定常プローブ法による食品の熱物性値の新規同時推算法 [in Japanese] New Method of Simultaneous Estimation of Thermophysical Properties of Foods by Transient Heat Flow Method Using Probe [in Japanese]
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非定常プローブ法により食品の3種の熱物性値 (熱伝導率, 熱拡散率, 比熱) を同時に, かつ容易に推算することができる方法を提案した。その推算方法は, プローブの温度変化を熱伝導方程式の近似解析解にあてはめて, その解析解におけるパラメータ<I>A, B</I>の値と, プローブ定数<I>Pc</I>, 温度補正係数<I>Ic</I>の値を用いて熱伝導率および熱拡散率を求め, さらに熱伝導率と熱拡散率の値と密度の値を熱拡散率の定義式に代入して試料比熱を決定する方法である。<BR>Δθ=<I>A</I>・ln <I>t</I>+<I>B</I><BR><I>A</I>=<I>q</I>'×<I>Pc</I>/4πλ, <I>B</I>+<I>Ic</I>=<I>q</I>'×<I>Pc</I>/4πλ(ln4<I>x</I>β/<I>r</I><SUP>2</SUP>)=<I>A</I>(ln4<I>x</I>β/<I>r</I><SUP>2</SUP>)
The thermophysical properties of five kinds of foods (sucrose solution, sodium chloride solution, milk, ground pork, and whole milk powder) were measured by the transient heat flow method using a probe at 20°C. In this study, a new method of estimating three kinds of thermophysical properties, namely, thermal conductivity, thermal diffusivity, and specific heat, was proposed. The measured data for the temperature changes of the probe inserted in the sample were fitted to an approximate solution of the heat conduction equation, and the values of two parameters in the solution were determined. For a long period of time (more than 30 seconds), the measured results agreed well with the results calculated from the solution. Using the obtained values for two parameters, the thermal conductivity and the thermal diffusivity of the sample were determined. The specific heat of the sample was estimated by substituting the thermal conductivity and, thermal diffusivity of the sample, and the density of the sample or the bulk density of the sample packed bed into the definition equation of thermal diffusivity.
- journal of the japanese society for cold preservation of food
journal of the japanese society for cold preservation of food 34(1), 11-18, 2008-01-30
Japan Association of Food Preservation Scientists