Comparison of Vacuum Glazing Thermal Performance Predicted Using Two and Three Dimensional Models and Their Experimental Validation

Fang, Yueping; Hyde, Trevor; Hewitt, Neil; Eames, Philip C.; Norton, Brian

doi:10.1115/ht2008-56054

Cited by 5 publications

(7 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Similar hypotheses can also be found in references [26,29,30]. The gaseous conductive and convective heat transfer is negligible in a vacuum environment of 0.1 Pa or less.…”

Section: Heat Transfer Analysissupporting

confidence: 76%

See 1 more Smart Citation

Modelling analyses of the thermal property and heat transfer performance of a novel compositive PV vacuum glazing

et al. 2021

View full text Add to dashboard Cite

“…Similar hypotheses can also be found in references [26,29,30]. The gaseous conductive and convective heat transfer is negligible in a vacuum environment of 0.1 Pa or less.…”

Section: Heat Transfer Analysissupporting

confidence: 76%

“…2 for vacuum glazing. This approach is deemed adequate to predict the thermal responses of vacuum glazing given its symmetric structure, and has been adopted in many existing studies to reduce the computation time [29].…”

Section: Heat Transfer Modelmentioning

confidence: 99%

Modelling analyses of the thermal property and heat transfer performance of a novel compositive PV vacuum glazing

et al. 2021

View full text Add to dashboard Cite

“…The total glazing area contains the edge effects, whilst the centre-of-pane does not [30]. The ASTM [31] testing conditions are followed, in which the internal and external surface heat-transfer coefficients h were set to 8.3 Wm −2 K −1 and 30 Wm −2 K −1 , respectively [32], and the internal and external surface air temperatures were set to be at 21.1 • C and −17.8 • C, respectively. The glass surface-to-surface thermal transmittance of the total glazing (U t ) and the centre-of-pane glazing (U c ) is defined by Equations (18) and (19).…”

Section: Methodsmentioning

confidence: 99%

Effect of Cavity Vacuum Pressure Diminution on Thermal Performance of Triple Vacuum Glazing

2018

View full text Add to dashboard Cite

Featured Application: Triple Vacuum glazing is regarded as a smart window technology and a robust solution of retrofitting it to existing buildings for the reduction of demand side carbon emissions and improving the energy efficiency of buildings.Abstract: Long-term durability of the vacuum edge seal plays a significant part in retrofitting triple vacuum glazing (TVG) to existing buildings in achieving progress towards a zero-energy building (ZEB) target. Vacuum pressure decrement with respect to time between panes affects the thermal efficiency of TVG. This study reports a 3D finite element model, with validated mathematical methods and comparison, for the assessment of the influence of vacuum pressure diminution on the thermal transmittance (U value) of TVG. The centre-of-pane and total U values of TVG are calculated to be 0.28 Wm −2 K −1 and 0.94 Wm −2 K −1 at the cavity vacuum pressure of 0.001 Pa. The results suggest that a rise in cavity pressure from 0.001 Pa to 100 kPa increases the centre-of-pane and total U values from 0.28 Wm −2 K −1 and 0.94 Wm −2 K −1 to 2.4 Wm −2 K −1 and 2.58 Wm −2 K −1 , respectively. The temperature descent on the surfaces of TVG between hot and cold sides increases by decreasing the cavity vacuum pressure from 50 kPa to 0.001 Pa. Nonevaporable getters will maintain the cavity vacuum pressure of 0.001 Pa for over 20 years of life span in the cavity of 10-mm wide edge-sealed triple vacuum glazing, and enable the long-term durability of TVG.Triple vacuum glazing (TVG) has the ability to curtail heat flow between the warm side and cold side of a window, i.e., to provide preeminent thermal insulation, so-called thermal transmittance (U value) [6]. TVG consists of three panes of 4 mm thick glass, with an evacuated gap 0.13 mm high, separated by 0.13 mm high and 0.3 mm diameter stainless-steel support pillars. TVG edges are sealed with airtight material such as solder glass, indium alloy, or Cerasolzer CS186. The reason TVG has the potential for retrofitting to existing buildings is because its U value is less than 0.5 Wm −2 K −1 , compared to triple air-filled glazing, which has a U value of 2.8 Wm −2 K −1 . It also would allow increasing the window-to-wall area ratios because of its U value being closer to that of cavity wall insulation. Nevertheless, TVG has associated challenges; this paper presents the findings of the effects of diminution of vacuum pressure on the U value. The U value of TVG primarily depends on the thickness of the glass panes, vacuum pressure in the space between the glass panes, emissivity of the coatings on the glass panes, frame, and type of spacers that separate the panes of glass and type of window frame. The total U value consists of the influence of the frame and the area of the edge seal. The edge seal area is dependent on the width and the type of edge-sealing material. The airtight edge seal of a TVG must be able to perpetuate a vacuum pressure below 0.1 Pa for quelling gaseous heat conduction for long-term duration [7]. Benson et al. [8] investigate...

show abstract

“…The overall heat transmission of the simulated 0.5 m × 0.5 m TVG has found to be 32.6 % greater than that of the 1 m × 1 m TVG, since heat conduction through the edge seal of the small glazing has a larger contribution to the total glazing heat transfer than that of the larger glazing system. Fang et al [30] have analysed thermal performance of vacuum glazing by using 2D finite element and 3D finite volume models. In the 2D model, the vacuum space, including the pillar arrays, has been represented by a material whose effective thermal conductivity is determined from the specified vacuum space width, the heat conduction through the Welded edges pillar array and the calculated radiation heat transfer between the two interior glass surfaces within the vacuum gap.…”

Section: Literature Reviewmentioning

confidence: 99%

Aerogel-Assisted Support Pillars for Thermal Performance Enhancement of Vacuum Glazing: A CFD Research for a Commercial Product

Cüce

Riffat

2015

Arab J Sci Eng

View full text Add to dashboard Cite

Vacuum glazing is an up-and-coming and rapidly developing technology which has a great potential to reduce heating and cooling demand of buildings in winter and summer, respectively. In this paper, the world's first commercially available vacuum glazing product is numerically investigated through a CFD-based research. Accuracy of the CFD model is compared with the manufacturer's thermal performance report, and an excellent agreement is observed. Then, translucent aerogel support pillars are recommended for commercial vacuum glazing, and impact of this replacement on the thermal performance of the glazing is numerically analysed. Number of support pillars at any section is also studied in terms of its impact on the U -value. The results indicate that the U -value of vacuum glazing can be reduced to 0.67 W/m 2 K with aerogel support pillars, whereas it is 1.20 W/m 2 K for the existing product. Moreover, the U -value might be lower than 0.40 W/m 2 K if the number of support pillars at each section is optimized.

show abstract

Comparison of Vacuum Glazing Thermal Performance Predicted Using Two and Three Dimensional Models and Their Experimental Validation

Cited by 5 publications

References 10 publications

Modelling analyses of the thermal property and heat transfer performance of a novel compositive PV vacuum glazing

Modelling analyses of the thermal property and heat transfer performance of a novel compositive PV vacuum glazing

Effect of Cavity Vacuum Pressure Diminution on Thermal Performance of Triple Vacuum Glazing

Aerogel-Assisted Support Pillars for Thermal Performance Enhancement of Vacuum Glazing: A CFD Research for a Commercial Product

Contact Info

Product

Resources

About