The Determination of Heat Transfer Coefficient on Water-ice Surface in a Free Convection

Abstract

In ice ridges consolidation, the convective heat flux term comes critical due to the larger contact areas and surface temperature differences compare with those from level ice. In this paper, a submerging experiment was designed to determine the heat transfer coefficient (h) between fresh ice and fresh water in a free convection. A thermistor string was used to measure temperature changes while ice growth was recorded by photograph. To study the factor, the tests were carried on different ice thickness (4.9cm to 20.5cm) and initial temperatures (-20oC and -32oC). The result shows that the h exponential increased with temperature difference from 0.3 W/m2K to 175 W/m2K. On the other hand, the variation of initial thickness and temperature was not a direct influence for h. For convective heat transfer, the boundary layer condition is central for understanding the convection between ice surface and water flowing past it. From the governing equation, the water flow in a free convection is caused by density difference, which is driven by the thermal expansion. A large temperature difference between surface and environmental water creates a thicker boundary layer, which leads to a higher h.