BOILING ON A CONICAL SPINE

This article investigates the heat transfer performance and stability characteristics of a uarying-cross-sectional-area pin fin subject to boiling. Heat transfer performance is evaluated numerically by solving the conduction/convection equations, while the corresponding stability is explored via linear stability analysis. Three types of pin fins are considered: truncated conical spines, straight fins, and reversed truncated conical spines. At afixed base temperature and base area, the base heat transfer rate would follow: truncated conical < straight < reversed truncated conical spine. The linear stability analysis reveals that for one-mode boiling, transition boiling alone on a fin of all three types of fins would become unstable at a fin length exceeding critical value. A similar result is valid for the film +transition boiling mode in multimode boiling. On the basis of the same base area and fin length, the operational region where boiling can carry on smoothly shrinks markedly for a truncated conical spine. However, under the constraint of constant base area and fin volume, contracting fin exhibits a greater range of base superheat to prevent burnout. Experimental investigations are reported to verify the theoretical findings.