Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Process Engineering, Biotechnology, Nutrition Technology
The inherent uncertainty of the critical heat flux in saturated pool boiling has been inconclusively debated for some time. In an effort to ascertain this uncertainty a series of 234 tests was conducted at atmospheric pressure with saturated water outside horizontal, a.c. heated, 0.234-in. O.D., A-nickel tubes in an open 6 × 6 × 9-in. deep pool. Approximately fifty tests were conducted with each of four test sections which were protected from physical burnout by a detector circuit which terminated the applied current before the wall temperature exceeded approximately 450°F. The maximum relative uncertainty in the derived values of critical heat flux was ±3%.For all the tests the minimum, average, and maximum critical fluxes were 0.201 × 106, 0.436 × 106, and 0.596 × 106 B.t.u./hr. sq. ft., respectively, and the average critical wall superheat was 41°F. The surface roughness of the test sections remained essentially unchanged during the program. The data show that there is an inherent uncertainty or scatter band in the critical heat flux under conditions of minimum surface variability, and that solely hydrodynamic theories of burnout do not fully represent the phenomenon, since surface condition can constitute a significant influence.
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