Effects of inclination on the frosting process on cold surface of copper heat exchanger

Abstract

Frosting is a natural phenomenon, which, albeit ubiquitous, requires further exploration. Here, we have experimentally investigated this phenomenon by realizing frosting processes on cold surfaces with different tilt angles and recording the number and the size of droplets produced on those surfaces. We have also monitored the changes in temperature and humidity of the passing air, whence the effect of inclination on the heat and mass transfer mechanisms, as well as the phase change of the droplets was analyzed. Our results indicate that the tilt angle has a significant influence on the droplet growth. In particular, cold surfaces with large tilt angles (30° and 60°) can produce a larger number of droplets, whose size increases much less in comparison with those produced on cold surfaces with small tilt angles (0° and 15°). Moreover, the component force of gravity along the inclined cold surface may offset part of the drag force, which inhibits the coalescence of droplets and promotes the uniformity of frost. Hence, we anticipate that our study will provide further insight in the influence of the tilt angle on the frosting process, in this way leading to its greater control in relevant applications.