LPT-1996-12 [BibTeX]
Joachim Blum, R. Hohl, Wolfgang Marquardt, H. Auracher:
Controlled transient pool boiling experiments - methodology and results
Eurotherm Seminar No. 48 Pool Boiling, Paderborn, September 1996
Abstract:
A new approach to the measurement of transient heat transfer under
pool boiling conditions is presented. An experimental apparatus was
designed to measure heat transfer under steady-state conditions and
with controlled temperature transients. The entire boiling curve was
measured for the Fluorinert FC-72 on a horizontal copper
heater. Experiments with heating transients of up to 10 K/s were
performed while cooling transients were limited by the thermal inertia
of the heater. The control system showed good performance in
controlling the wall temperature along the entire boiling curve both
in steady-state and transient experiments. Two schemes for the
solution of the Inverse Heat Conduction Problem arising from the
evaluation of transient heat transfer experiments were implemented and
compared with respect to estimation quality and computational
requirements. Regularization was chosen as the algorithm for data
evaluation. First results show that the critical heat flux rises
significantly for fast heating transients (~10 K/s) and drops
significantly even for moderate cooling transients (~2 K/s). In film
boiling, the heat flux rises with increasing heating transients while
no difference was measured for the slow cooling transients.
Keywords:
Boiling heat transfer, transient experiments, pool boiling, inverse heat conduction problem, temperature control.