Preparation of Monolithic Silica Aerogel for Fenestration Applications: Scaling up, Reducing Cycle Time, and Improving Performance

Abstract

The ability of a rapid supercritical extraction (RSCE) process implemented in an industrial hot press to produce silica aerogel monoliths (AMs) with properties suitable for use in fenestration products was investigated. The effects of hot-press processing parameters such as press force and heat-up and cool-down rates on the size (area) and quality (presence of cracks and optical flaws) of the AMs produced, and on the manufacturing cycle times required to produce them, were studied. AMs of 14 × 14 × 1.27 cm were produced in a 6.5 h RSCE process using a laboratory scale (267 kN) hot press. Evacuated window prototypes were prepared by packaging aerogels in the interspaces of a double-glazing system under vacuum. The aerogels were found to have high translucency (>80% transmittance) in the red portion of the visible spectrum. The double-glazing evacuated aerogel windows were found to have thermal resistivity of 1.21−1.55 K·m 2 /W.

Experimental and Numerical Energy Assessment of a Monolithic Aerogel Glazing Unit for Building Applications

“…Sci. 2019, 9, The novel interest in monolithic aerogel glazing systems is justified by the rapid production process, able to reduce costs and waste [6,7]. In this context, the aim of the present paper is the evaluation of the energy performance of a new double glazing system with monolithic aerogel in the gap, in a non-residential buildings application.…”

“…In the last years, a rapid supercritical extraction method was developed at Union College (Schenectady-NY), allowing a significant reduction in fabrication times (6-8 hours) and in solvent waste. Good optical properties can be obtained (τ v > 80%); when assembled with two glasses (total thickness 22 and 12.7 mm of aerogel), a thermal resistance of 0.86 and 1.55 m 2 K/W is obtained at atmospheric pressure and in evacuated conditions, respectively [6,7].Guoqing Zu et al evaluated the thermal performance of monolithic alumina aerogel systems, prepared by a sol-gel method combined with the ethanol supercritical drying technique [8]. The thermal conductivities at 30 • C and 400 • C were 0.028 and 0.065 W/mK, respectively [8].…”

“…Results were confirmed by Ihara et al [16], who carried out dynamic energy simulations with a translucent aerogel granulate system in an office façade. The translucent spandrels (14 mm granular aerogel in the gap between two 4 mm float glasses) reduce the energy demand in mixed and cooling dominated climates, namely Tokyo and Singapore, with respect to a double glazing façade.The novel interest in monolithic aerogel glazing systems is justified by the rapid production process, able to reduce costs and waste [6,7]. In this context, the aim of the present paper is the evaluation of the energy performance of a new double glazing system with monolithic aerogel in the…”

“…In the last years, a rapid supercritical extraction method was developed at Union College (Schenectady-NY), allowing a significant reduction in fabrication times (6-8 hours) and in solvent waste. Good optical properties can be obtained (τ v > 80%); when assembled with two glasses (total thickness 22 and 12.7 mm of aerogel), a thermal resistance of 0.86 and 1.55 m 2 K/W is obtained at atmospheric pressure and in evacuated conditions, respectively [6,7].…”

High Energy-Efficient Windows with Silica Aerogel for Building Refurbishment: Experimental Characterization and Preliminary Simulations in Different Climate Conditions

“…Silica aerogels, both in monolithic and granular translucent form, can be used in high-insulated nanogel windows: transparent monolithic panes were developed 20-30 years ago, but their application in glazing systems has still not penetrated the market, and few prototypes have been manufactured for research purposes [12,13]; for these reasons, building applications have focused on glazing systems with granular aerogels [14][15][16][17]. Different translucent daylighting systems with granular aerogel have been emerging in the market.…”