Simple models for wet-snow accretion on transmission lines: snow load and liquid water content

Abstract

A simplified heat and mass transfer model is proposed for wet-snow accretion on an overhead transmission line conductor. The accretion processes near the tower and the center of the span are formulated using the large relaxation time approximation (LRTA) and the cylindrical-sleeve approximation (CSA), respectively. The heat and mass transfer equations governing the snow evolution process are solved analytically to yield predictions for the snow load and the liquid water content of the snow matrix as a function of the wind speed, relative humidity, air temperature, precipitation rate, and diameter and thermal properties of the conductor. The interactive roles of these meteorological and physical variables are analyzed for the one-dimensional problems of snow accretion in a plane layer and cylindrical-sleeve growth on a conductor, and for the two-dimensional problem of snow accretion by axial growth. Effects due to wet-snow densification and the accretion factor for snowflake impaction are also incorporated.