Mechanism of Frost Formation and Growth over a Compact Finned-tube

The purpose of this study is to observe frost formation and growth patterns as well as their effects on free stream regime of air around a horizontal finned-tube under natural convection heat transfer. Unlike of frost formation for forced convection, there is a large difference between frost growth on top and bottom of a finned-tube. For a compact finned-tube, the blockage due to developed frost on the top happens in the early stages, depending on the experimental conditions while the bottom of finned-tube is still at the stage of needle-like pattern. The blockage on the bottom half takes place after a considerable long time implies that small spacing between the fins has a noticeable influence on velocity, temperature, and concentration boundary layers. Flow visualization also conducted for studying the effect of frost growth on airflow. The observations revealed that there is an insignificant distinction between air streamlines, with and without presence of frost at early stages. For long duration, a horizontal flat region is formed on the bottom of the finned-tube which separates the airflow boundary layer and produces a different pattern from the common circular shape.

Keywords:

Finned-tube , Frost growth , Free convection , Visualization