Simulated Thermal Performance of Triple Vacuum Glazing

The simulated triple vacuum glazing consists of three, 4 mm thick glass panes with two vacuum gaps with each internal glass surface coated with a low emittance coating. The two vacuum gaps are sealed by an indium based sealant and separated by a stainless steel pillar array with a height of 0.12 mm and a pillar diameter of 0.3 mm spaced at 25 mm. Both solder glass and indium based sealants have been successfully applied in vacuum glazing previously. The thermal performance of the triple vacuum glazing was simulated using a finite volume model. The simulation results show that although the thermal conductivity of solder glass (1 W.m⁻¹.K⁻¹) and indium (83.7 W.m⁻¹.K⁻¹) are very different, the increase in heat transmission of triple vacuum glazing with a 10mm frame rebate resulting from the use of an indium edge seal compared to a solder glass edge seal was 0.48%. Increasing both edge seal widths from 3 mm to 10 mm led to a 24.7% increase in heat transmission of the triple vacuum glazing without a frame and an 18.3% increase for a glazing with a 10 mm frame rebate depth. Increasing the rebate depth in a solid wood frame from 0 to 15 mm decreased the heat transmission of the triple vacuum glazing by 32.9%. The heat transmission of a simulated 0.5 m by 0.5 m triple vacuum glazing was 32.2% greater than that of 1 m by 1 m triple vacuum glazing.