hilit aerogel window

Energy Environment & Sustainable DevelopmentThematic Network on Energy in the Built Environment

HILIT AEROGEL WINDOW

HILIT

Highly Insulating and Light transmitting aerogel glazing for window (JOR3-CT97-0187)

EnerBuild participant number: 44

Thematic group 5 – Buildings components(incl. windows, facades)

Co-ordinator: Karsten I. Jensen

Dept. of Buildings and Energy (IBE)Technical University of Denmark (DTU)



BACKGROUND

Two JOULE II projects

French aerogel projects (=> patent)

Danish project (assembly apparatus)

Swedish pilot plant for aerogel production (high temperature process)



PROJECT OBJECTIVES

Main objectives:

• pre-industrial elaboration process evaluation for the chemical part (aerogel process) and the glazing assembly process of aerogel window

• to estimate the energetic interest of such glazings.

Other objectives:

• Flat aerogel sheets of about 60 x 60 x 2 cm3 with a solar transmittance of 90 % or more and the lowest heat conductivity ever reported for such material.



Other objectives:

• Flat aerogel sheets of about 60 x 60 x 2 cm3 with a solar transmit-tance of 90 % or more and the lowest heat conductivity ever re-ported for such material.

• The aerogel material exhibits only negligible image blur i.e. the optical quality is at the same level as ordi-nary glass panes.

• Feasibility study which analyses the technical potential of aerogel windows.



Other objectives:

• Prototypes of 60 x 60 cm5 evacu-ated aerogel glazing (aerogel thickness of 20 mm) made by the proposed process and having a centre heat loss coefficient (U-val-ue) below 0.4 W/m5 K, an overall U-value below 0.5 W/m5 K and a solar energy transmittance (g-val-ue) above 75 %. Finally, the life-time of the glazing with respect to maintaining the gas pressure be-low 50- 100 hPa will be at least 30 years.



Other objectives:

• Technical and economic evaluation of an industrial production of aerogel glazings for windows.

• Analysis of market potential of aerogel windows



At the end of the project:

• A supercritically CO2 based

process with recovery, that can give flat aerogel tiles of 60 cm square as well as a glazing assembly process, suited for an industrial production, for the same size

• A general scheme for demonstration of the new technology will be drafted.



Observations:

At the end of year two of three(ends on 31 October next year).

• Potential energy savings and markets – due in year three.

• The same for the technical and economic evaluation of an industrial production of aerogel glazings.

• The aerogel process:The patented process is scaled up from a few cm sq to 55 cm sq.So-called ultra flat and crack-free aerogel tiles are obtained.Installation of separation and recycling of CO2 has begun.



Observations (cont.):

The aerogel material:

• Due to ultra flatness, the image blur related to the surfaces is decreased.

• Improvements still needed on the bulk related image blur.

• Heat conductivity – ~ 16 mW/m K (amb. gas pressure)~ 8 mW/m K (gas pressure below

50 hPa)




The glazing:

• Five prototypes made by means of the Aerogel Glazing Evacuation and Assembly (AGEA) apparatus.




The latest prototype is made with aerogel produced within the project.

• Aerogel thickness: 18 mm

• 4 mm low iron glass panes,60 cm x 60 cm

• Rim seal; plastic foil and butylIt failed (leaked), but is going to be repaired.

• Outdoor measurement:Solar transmittance (direct-hemispherical): 72%.

Application of “non-reflective coating” can increase the value by 2 –3 points




Prototype number five:



Observation (cont.):

The present optical quality sufficient for so-called secondary applications, i.e.

• sky lights

• bath rooms

• day lighting

• green houses

• white goods etc.

Or as transparent insulation;

• solar collectors

• solar walls etc.



Observation (cont.):

Strengths:

• high solar transmittance and high insulation at the same time

Weaknesses:

• the aerogel must be protected from liquid water,

• rough vacuum (gas pressure below 50 – 100 hPa) required

Problems:

• the optical quality of the aerogel material not at the same level as for ordinary glass panes



Project status

• progress in good accordance with the work programme

• both the material process and the glazing process are shown to be feasible

• the material process – safe and low temperature is possible

• the glazing process – evacuation and assembly within a few minutes

• the glazing – high solar transmittance and low U-value and almost no cold bridge at the edge

• no problems of paramount importance encountered – so far



CONCLUSION

• Both the material process and the glazing process have been improved much

• It seems possible to develop an aerogel glazing with an overall U-value close to the centre U-value

• The optical quality of aerogel still needs to be improved for application as ordinary glazings, but sufficient for secondary applications

OUTLOOK

• Demonstration phase planned

• Other applications considered

hilit aerogel window

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