Ghalib Y. Kahwaji
Rochester Institute of Technology, Dubai Campus, UAE
Title: Modeling of the coupled conduction-convection ice formation on a horizontal finned tube under density inversion conditions
Biography
Biography: Ghalib Y. Kahwaji
Abstract
The freezing of water around finned and unfinned horizontal tubes inside an insulated tank is analyzed and numerically simulated. The coupled conduction-convection heat transfer with phase change moving interface is solved numerically using finite difference technique. Adaptive grid generation is performed by elliptic partial differential equations coupled with a proportional, iterative smoothing algorithm. The effect of density inversion with temperature on flow patterns is also considered. For validation, the present results are compared with experimental studies reported in the literature. The flow patterns are similar in both cases as there is one main vortex in the liquid region when there is no inversion in water density. The vortices of water existing before and after the inversion process are also similar. The inversion in density was found to disturb the flow patterns and the isothermal lines in the liquid region. The presence of fins complicates the local Nusselt Number distribution along the solid-liquid interface in comparison with the unfinned cylinder. The impact of natural convection on the rate of ice formation is limited to the initial starting time only. Its effect on unfinned tube is more obvious than that on the finned tube due to the increase of contact area, which speeds the cooling of the liquid region. It is observed that the mass of ice formed under the effect of natural convection is less than that formed for conduction controlled freezing by about 27%.
