CHF experiments on the influence of inclination and gap size

Abstract

CHF experiments for the downward-facing plate in a channel were performed varying inclination and channel gap size. A non-heating experimental methodology was employed to simulate the CHF condition based on the hydrodynamic analogy. Hydrogen gas generated on the cathode in an aqueous solution of sulfuric acid simulates vapor bubbles in the boiling system. Inclinations were varied from vertical to near downward-facing horizontal and the channel gap sizes were varied from 1 to 10 mm. In the open channel cases, the measured normalized CHF values showed similar trend with the existing heat transfer results. Considering the bubble shape variation depending on the inclination, the empirical correlation was developed. The influence of the bubble shape became prominent as the channel gap size decreased. However, for near horizontal inclination, the decreased buoyancy force became dominant so that the gap size effect was negligible.