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Thermal Performance of Vacuum Glazing with Tempered Glass Panes

  • Yueping Fang
  • Trevor J. Hyde
  • Farid Arya
  • Neil Hewitt
Conference paper

Abstract

The thermal performance (U-value) of 0.4 × 0.4 m and 1 × 1 m double vacuum glazing (DVG) and triple vacuum glazing (TVG) using annealed and tempered glass panes with pillar separations of 25 and 50 mm respectively was simulated. It was found that (1) for both dimensions of DVG with 0.03 emittance low-emittance (low-e) coatings, the U-values at the centre of the glazing area of the DVG made of annealed and tempered glass panes were 0.57 and 0.30 Wm−2 K−1, a reduction of 47.4 %; (2) for both dimensions of TVG with 0.03 emittance low-e coating, the U-values at the centre of glazing area of the TVG with annealed and tempered glass panes were 0.28 and 0.11 Wm−2 K−1, a reduction of 60.7 %. The reduction in U-values for both DVG and TVG results from the significant reduction in pillar number, leading to the large reduction in heat conduction through the pillar arrays. The reduction in U-values from using tempered glass panes instead of annealed glass panes for TVG is larger than that for DVG; this is because the radiative heat transfer of TVG with three glass panes is much lower than that in DVG with two glass panes; therefore, the heat conduction through the pillar array in TVG plays a larger role compared with that in DVG. The reduction in pillar number in TVG results in a larger reduction in U-value compared to DVG; thus, using tempered glass panes in TVG confers a greater advantage compared to DVG, given that DVG can also achieve a large reduction in U-value when switching from using annealed glass panes to tempered glass panes.

Keywords

Annealed glass Tempered glass Vacuum glazing U-value and pillar separation 

Nomenclature

a

Radius of support pillar (m)

h

Surface heat transfer coefficient (Wm−2 K−1)

k

Thermal conductivity (W m−1 K−1)

p

Pillar separation (m)

R

Thermal resistance (m2 K W−1)

t

Thickness of glass pane (m)

T

Temperature (°C)

U

Thermal transmission (Wm−2 K−1)

Greek letters

ε

Hemispheric emittance of a surface

σ

Stefan-Boltzmann constant (5.67 × 10−8) (Wm−2 K−4)

Subscripts

1–6

Surfaces of glass panes shown in Fig. 20.1

I, II, III

First, second and third glass panes

i,o

Refer to warm and cold ambient temperatures

g

Glass

m

Glass pane number of TVG

n

Vacuum gap number

p

Pillar

r

Radiation

tot

Total resistance of TVG

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Copyright information

© Springer International Publishing Switzerland 2017

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Authors and Affiliations

  • Yueping Fang
    • 1
  • Trevor J. Hyde
    • 1
  • Farid Arya
    • 1
  • Neil Hewitt
    • 1
  1. 1.School of the Built EnvironmentUlster UniversityLondonderryUK

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