Solar Cooker Glass Failure Analysis

Abstract

The failure of a pane of glass from a solar box cooker made and used in Sabana Grande, Nicaragua, was analyzed to determine the cause of failure and to recommend possible solutions. Background research into solar box cookers, the environment in which the failure occurred, characteristics of glass and wood, methods of fractography, and glass cutting tools and methods was carried out. The type of glass used in the solar cooker was unknown, so the observable physical properties, an energy dispersive spectroscopic scan, and thermal analysis of the glass were used to identify the glass as soda-lime glass. The properties of the glass, the conditions of use, and an analysis of the fracture pattern and fracture surfaces were used to determine that the glass had been weakened by cutting processes and that the fracture occurred as a result of thermal stresses. Several recommendations were presented including altering the design of the solar cooker to provide more clearance for the glass panels, incorporating the use of improved glass cutting techniques and sanding the edges of the glass.