Abstract
Jet impingement quenching heat transfer of LN2 on rock surface was experimentally investigated. The test plate was circular in shape and was 16 cm in diameter and 2 cm in thickness. An aluminum alloy specimen with the same configuration as the rock plate was also used to highlight the characteristics of rock material in affecting the LN2 jet impingement boiling heat transfer. Comparing to the aluminum, rock has a low thermal conductivity and the rock surface was distributed with micro pores and cavities. This surface character enabled a 100 °C increase of the rewetting temperature. An attempt was made to quantitatively explain the rewetting temperature enhancement using the local cold spot theory. The stagnation point on rock surface was directly wetted by LN2 jet without film boiling, for which the high rewetting temperature and fast temperature drop were proposed as the reasons. The maximum heat flux and wetting front velocity were investigated for both quenching samples and the results were compared to correlations in the literature.
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