Abstract
In order to clarify the mechanism of heat transfer during melting of a clathrate in rectangular cells, two melting processes, namely, two-dimensional melting process with natural convection from a vertical wall and one-dimensional melting process by heat conduction from an upper horizontal wall, are studied experimentally.
The R-141b was used for generating clathrate. One experiment was carried out by melting the clathrate filled into a 150mm high and 100mm wide rectangular cell from a vertical wall. And in the other experiment, the clathrate was melted from the upper horizontal wall of a rectangular cell with 88mm height and 180mm width. The temperature distributions in cells were measured. The melting front was measured by pictures taken on fixed times. The concentration of freon in the melt was measured by gas-chromatography.
The following results are obtained.
(1) In the melting process, the clathrate decomposes into an emulsion region which is a water-freon mixture and a liquid freon region under the emulsion.
(2) Concentration gradient of freon in the emulsion plyas an important role in the natural convection in the melt. The Nusselt number on the heated vertical wall is depressed by the concentration gradients.
