An experimental investigation on combustion behavior of n-heptane in ice cavities of various depths with cross airflow

Author: Zhong, X. P., Hu, L. H., Wang, X. R., Yuen, R. K. K., Chen, Y. H., Zhang, X. L., Kuang, C.

Journal: Fuel

DOI:  10.1016/j.fuel.2019.116464

Keywords: Ice cavity, Pool fire, N-heptane, Cross airflow, Mass loss rate, Burning efficiency, oil pool fire, crude-oil, burning behavior, diffusion flames, layer, wind, boilover

Abstract: 

The present paper reports the combustion characteristics of ice cavity pool fires in cross airflow, in contrast to previous works mainly limiting to quiescent air. Experiments were conducted by employing ice cavities of different depths (4, 6, and 8 cm) with same diameter of 5 cm with n-heptane as fuel for various cross flow air speeds (0-1.5 m/s). The evolutions of ice cavity expansion, mass burning rate and burning efficiency were quantified. It was found that: 1) the cross flow would result in significant asymmetric expansion of the ice cavity. Cross flow has a less influence on ice cavity expansion in windward side compared with the downstream direction. With increase of the initial cavity depth, its final cavity expansion length increased while the asymmetry of cavity expansion decreased; 2) larger initial ullage to cavity size ratio (h/D) can significantly promote the mass burning rate in cross flow. Three typical burning phases are identified: initial restrain stage, continuous increase stage and rapid decline stage. With increase of cross flow air speed, the average mass burning rate and burning efficiency first increased then decreased; 3) the burning efficiency in ice cavity is generally higher with a cross flow than that in still air, but much lower than that on open water. Related in-depth heat transfer mechanisms was discussed. This work provides basic experimental data and understanding of combustion behavior of ice cavity pool fire of various depths in cross flows, which is essential concerning the in-situ burning in Arctic regions with wind.