Measurement of Cooling Rates and Boiling Curves of Thin Plates during Quenching

A method for measuring cooling rates and boiling curves of thin plates during quenching in liquid is proposed. The method is demonstrated by using tinplates of thickness less than 1 mm. A specimen is composed of a couple of tinplates held together with a thin layer of ceramic adhesive, in which a thermocouple is settled. One-and two- dimensional heat transfer analyses in the specimen during quenching are carried out. The results indicate that the temperature difference in the specimen is so much that temperature and heat flux on the surface should be estimated from the measured temperature value even if the specimen thickness is less than 1 mm, though thermal disturbance induced by the thermocouple does not affect the temperature distribution over the specimen surface. In measurements of cooling rates and boiling curves, the specimen after heating to about 600K is quenched in pure water in a range of subcooling from 10 to 50K. It is found that critical heat flux increases and superheat at the point becomes higher with increase of subcooling while the boiling curve in the nucleate boiling region is practically independent of subcooling, as indicated by previous works conducted with large specimens.