SF-98-12-1 -- Local Heat Transfer Coefficients for a Flush-Mounted Glazing Unit PDF

This paper presents an attempt to extract local, indoor insulating glazing unit (IGU) heat transfer coefficients based directly on indoor IGU surface temperature measurements. Determination of a local heat transfer coefficient profile for window assemblies is needed to study local phenomena such as condensation. The use of non-isothermal surface thermographic temperatures is another distinguishing feature of this work. Best estimates of heat transfer coefficient profiles are presented based on thermographic measurements from two laboratories and for two IGUs: a foam and an aluminum edge-seal, clear, double-glazed, flush-mounted IGU. In addition, good temperature profile agreement is obtained for both the foam and aluminum edge-seal IGUs between experimental data from Lab #1 and an independent, theoretically derived, vertical-flat-plate, laminar, free-convection flow, heat transfer coefficient profile equation. The equation involves only one nonarbitrary unknown variable that accounts for the unknown start location above the IGU of the free-convection boundary layer. In addition, observations suggest the possibility of better characterizing fenestration laboratory facilities by its ability to generate a particular local heat transfer coefficient.

Units: Dual