Transferencia de calor em vidros

The Influence of Isolation on the Thermal Performance of Triple Vacuum Glazing
Yueping Fang, Trevor J Hyde, Neil J Hewitt School of the Built Environment, University of Ulster, BT37 0QB, Newtownabbey, Northern Ireland, UK
Energy Performance in Buildings 17

Abstract
The thermal performance of triple vacuum glazing subjected to various solar insolation levels was simulated using a finite volume model. Simulation results show that with increasing insolation, the temperatures of the three glass panes increase; however the rate of temperature increase of the middle glass pane is the largest. This is due to the high thermal insulation provided by the vacuum gaps either side of the middle glass pane; consequently the heat absorbed from the sun by the middle glass pane cannot be easily transferred to the indoor and outdoor environments. For 0.5 m by 0.5 m and 1 m by 1 m triple vacuum glazing exposed, to isolation levels greater than 200 W.m-2 and 180 W.m-2 respectively with four 0.03 emittance coatings, the middle glass sheet temperature is larger than that of the indoor and outdoor glass sheets. Thus the heat absorbed from solar radiation by the middle glass sheet flows to both the indoor and outdoor glass sheets. When the insolation is less than 200 W.m-2 and 180 W.m-2 for 0.5 m by 0.5 m glazing and 1 m by 1 m glazing respectively, the heat flows from the indoor glass sheet to the middle glass sheet and then to the outdoor glass sheet. For a 0.5 m by 0.5 m triple vacuum glazing with four 0.18 emittance coatings, when insolation is greater than 400 W.m-2, the middle glass sheet temperature is higher than that of indoor glass sheet.

of a large range of soft low-emittance (low-e) coatings and tempered glass which would otherwise degrade at high sealing temperatures. Using the low temperature indium based edge seal, samples have been fabricated with a heat transmission U-value of 0.90 W.m2 .K-1 in the centre-of-glazing area for a 0.5 m by 0.5 m sample. More recently