CORRELATION OF WATER FROST POROSITY IN LAMINAR FLOW OVER FLAT SURFACES

摘要

A dimensionless correlation has been proposed for water frost porosity expressing its dependence on frost surface tem-perature and Reynolds number for laminar forced flow over a flat surface. The correlation is presented in terms of a dimensionless frost surface temperature scaled with the cold plate temperature and the freezing temperature. The flow Reynolds number is scaled with reference to the critical Reynolds number for laminar-turbulent transition. The proposed correlation agrees satisfactorily with the simultaneous measurements of frost density and frost surface tem-perature covering a range of plate temperature, ambient air velocity, humidity, and temperature. It is shown that the frost porosity depends primarily on the frost surface and plate temperatures and the flow Reynolds number, and is only weakly dependent on the relative humidity. The results also point out the general character of frost porosity displaying a decrease with an increase in flow Reynolds number.