The thermal conductivity of glass-sieves: I. Liquid saturated frits

• Transport of heat in liquid-saturated glass sieves.
• Measured by the transient hot bridge technique.
• Theoretically described using a simple prediction model.

The thermal conductivity of eight liquid-saturated glass sieves of pore sizes between 1 μm and 500 μm is presented as measured at room temperature. The liquids used as saturants cover a range in thermal conductivity from 0.135 W m−1 K−1 to 0.598 W m−1 K−1. The experimental results are successfully fitted to a simple two-dimensional composite model for the heat transfer in porous media. The experimental runs were carried out using a transient hot bridge (THB) measuring instrument. Unique for a transient technique, the fast and reliable THB instrument is characterized by a constant probing depth. This feature is of special importance when seeking for potential convective heat transfer inside the pores of a saturated porous medium. Here, any onset of convection could neither be detected nor predicted for the measured range of pore sizes. Investigations on the volumetric specific heat of the saturated glass sieves furnish their individual porosities or enable to assure their actual degree of saturation. Measurement uncertainties in thermal conductivity and in specific heat are assessed to 3 %–5 % and to 5 %–10 %, respectively.