A study of deposition in a mesh-filled cold trap for purifying liquid sodium

After partially filling a 100 1 experimental cold trap with NaH under controlled conditions, the cold trap was dismantled for an examination of the distribution, composition and morphology of the deposits. The trap contained four grades of stainless steel mesh, the densities of which increased along the flow path. Flow patterns in the trap were identified separately using a water model which was subsequently found to give a good indication of where deposition might be expected. The deposits were analysed to determine the composition and mass transfer per unit area of mesh. The crystallization morphology was also examined by scanning electron microscopy which showed that the crystals grew from the mesh wires as faceted dendrites only in regions of trap where the sodium was being cooled. (author)