Effect study of bridge voltage on measurement of thermal conductivities of liquids by thermal probe method

The thermal probe method can be conveniently and rapidly used to measure the thermal conductivities of liquids. But the bridge voltages chosen differently would have large effect on output electric voltage signal ΔV which would directly influence the results of experiments. To obtain the best value of voltage, the effects of different bridge voltages on thermal conductivities of samples were studied by experiments and theoretical analysis of heat transfer and numerical simulation. The results showed that the deviation of thermal conductivities were below 2 % when the bridge voltage was at 2.0V~8.0V. The number of GrPr was 1×10³~0.98×10⁴ which was less than 1×10⁴. Each measurement was completed within one minute and the temperature rise was less than under 1 °C. It can effectively reduce the effect of convection and radiation to obtain accurately the thermal conductivity of liquid.