Convegni ATI - Accesso riservato soci CTI

Autore: S. Puleo, A. Caronia, M. Di Liberto, M. Ciofalo

Collana: CA - 60 - Roma 2005

Note:
Heat transfer from hot walls to cold water sprays was investigated by a technique based on the transient cooling of a planar Al target, previously heated up to 450°C. The midplane temperature was recorded during the transient, and an inverse conduction problem was solved to obtain wall temperature and heat flux.
To heat the target, the induction method was chosen, which allows power to be released rapidly and uniformly in the target without heating the surrounding structures. A 50 Hz induction heater was built by winding copper wire around a transformer core, in which a few mm gap was cut to accommodate the target. Calculations based on the self- and mutual-inductance of the coils and preliminary tests led to the choice of 4 concentric coils in parallel, each including 200 windings (~50 m wire length).
Power was supplied by a 3200 VA auto-transformer. Thermal measurements provided an estimate of ~1000 W for the power dissipated at T=25°C in the target volume (~22 cm3). As T increased, the heating power decreased due to changes in the Al properties, and an increasing fraction of it was released by radiation to the environment. However, it was still possible to heat the target to ~450°C in ~90 s.