Transient Pool Boiling of Water on a Vertical Surface With a Step in Heat Generation

This paper is based on the PhD thesis investigation by H. Lurie [1] on the transient heat transfer from a vertical submerged metallic ribbon undergoing a step in Joule heating leading to boiling on its surface. The tests were made in deaerated distilled water at atmospheric pressure with pool temperatures at saturation and 112 deg F subcooled, and with heat generation rates per unit of ribbon surface area from nonboiling to 1.6 × 10⁶ Btu/ft²hr. Although the heat capacity of the ribbon is low, the surface temperature overshoot compared to the steady-state temperature is minor with values of less than 10 deg F. The time required to reach this overshoot, or the time required to reach steady state, is very short and decreases with increasing heat flux. These values are short compared to Goldstein and Eckert [2] and Siegel’s [3] estimates of the time required to develop the hydro-dynamic and thermal boundary layers in natural convection, and indicate that nucleate boiling heat transfer is probably a weak function of the fluid circulation. Some further support for this is evidenced by calculated transient temperatures based on steady nucleate boiling heat transfer which are in reasonable agreement with the measured performance.