`PRMCOOLSEC`: The sheet cooling section process modelling site

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Frequently asked questions (FAQ) on Sheet Cooling Section Process Modelling

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What is the HTC concept?
The heat transfer coefficient (HTC) α concept is used to determine the surface heat flux from the actual local surface temperature and the cooling water temperature q=α$nbsp(T_S-T_W). This concept can also be used if α itself is a complex function.

These models use laboratory data instead of HTC's determined from real plant data. Why are the results realistic?
The conventional approach is to measure T_in and T_out in a real cooling section and to determine something like a mean HTC for that parameter setting. Models using such HTC data have no non-trivial prediction or extrapolation capability. Since the HTC depends on the local water impact density (for the spray cooling case) and the local surface temperature, mean values from plant measurements are only usefull as long as the temperature control requirements are low, e.g. the task is simple to reach a specific end temperature T_out - not taking care about surface quenching effects or inhomogenous cooling rates. Our approach is to determine the principal parameter dependencies of the HTC with maximum accuracy in optimized laboratory tests. Since spray water cooling the main parameters are the surface temperature and the water impact density V_S (see References). As there is a superposition principle for V_S, the real plant set values (e.g. nozzle positions and mass flows) can be calculated from the predicted local water impact density. The process model thus allows to determine the local temperature history inside the sheet material and the inverse models allow a set value prediction for a specific cooling task.