LPT-1999-11 [BibTeX]
R. Hohl, Joachim Blum, M. Buchholz, Torsten Lüttich, H. Auracher, Wolfgang Marquardt:
Model-based experimental analysis of pool boiling heat transfer with controlled wall temperature transients
International Journal of Heat and Mass Transfer, 2001, 44, 2225-2238
Abstract:
A model-based approach for the design, control, operation, and evaluation
of pool boiling experiments with controlled steady-state and transient
wall temperature up to 50 K/s is presented. Throughout all phases of the
described approach, the requirements on the experimental infrastructure
for reproducible boiling experiments is addressed by the integration of
theoretical and experimental investigations. In the early design phase,
these are concerned with heater design as well as the development
and optimization of a control concept. Systematic experiments were
carried out with the flourinert FC-72. The liquid boiled on top of
a horizontally positioned copper heater with a diameter of 18.2 mm
and 5 mm thickness. Temperature measurements by sheathed thermocouples
implanted inside the heater are used to obtain transient boiling curves by
solving a one-dimensional inverse heat conduction problem. In all boiling
regimes boiling heat flux increases with increasing wall temperature
slopes. Transient cooling leads to lower transferred heat fluxes. Very
close to the boiling surface, temperature fluctuations as a result of
evaporation are measured by six microthermocouples. Analysis of the data
shows that there seems to be no distinct difference in the fluctuations
with respect to steady-state and transients runs.
Keywords:
Transient pool boiling, experiment design, control, stability analysis, inverse heat conduction problem.