Secondary Cooling: Heat Transfer Measurement - Comparison of Different Methods
Sprache des Vortragstitels:
4th ESTAD Conference
Sprache des Tagungstitel:
In secondary cooling of continuous casting it is very important to know the cooling heat-flux for the actual spray cooling situation with respect to various parameters like the local position, the nozzle types and distances, and the water and air flow rates, in order to be able to control the cooling conditions precisely. Since heat-flux measure-ments on a casting machine are too challenging, experimental laboratory test rigs have been designed and used for measurements by different research groups. In these experiments, metal probes of different dimensions and materials are heated up to the desired temperature (around 900 to 1200 °C) and then exposed to spray nozzles. The heat-flux is usually measured by temperature sensors immersed in the probe body, and the heat flux is then determined from the measured temperature by using inverse modelling methods. In this contribution, the differ-ences between the real and laboratory conditions are focused using a mathematical heat transfer simulation model. The influence of strand surface temperature, nozzle spray water flow conditions and Leidenfrost effect are pointed out. The effect of the temperature sensor immersion depth and the sampling rate on the accuracy of the inverse modelling process under different cooling situations will be shown. A procedure to use heat-flux data measured on a test rig for the cooling control on a real caster despite of the different conditions is proposed.