非定常線熱源法の再検討 : 第2報,自然対流の影響の解析的考察

抄録

In this paper, weak natural convection effects in the transient hot wire method of liquid thermal conductivity measurement are investigated analytically. Precise numerical calculations are performed using the FDM, concerning the slow natural convection liquid flow around a single thin hot wire and the distribution of the modified temperature term due to the flow. Then, the time dependencies of the apparent thermal conductivity, including the natural convection effects, are shown for various measuring conditions. The errors in measurement are also shown for the case where two hot wires, having different lengths, are set in the Wheatstone bridge circuit to decrease the edge effects. It is shown, as a result, that slight natural convection effects appear even in short time measurements where the effects on accuracy have been considered negligible.