Lead Performer: Fraunhofer USA, Center for Sustainable Energy Systems (CSE) – Boston, MA
Partner: Virginia Commonwealth University (VCU) – Richmond, VA
DOE Total Funding: $495,000
FY17 DOE Funding: $220,000
Cost Share: $135,921
Project Term: October 1, 2017 – November 30, 2019
Funding Type: Buildings Energy Efficiency Frontiers & Innovation Technologies (BENEFIT) – 2017 (DE-FOA-0001632)
The project effort is a two-year development program focused on isocyanurate-based nanofoam for building and industrial applications. The main target of this early stage innovation project is to develop a PIR-based super insulation at atmospheric pressure (SIAP) that (1) can attain an R-12 hr·ft2·°F/Btu·in (λ=12 mW/m·K) via creating nanoporous morphology, (2) is mechanically robust and (3) is cost-competitive to the conventional rigid foam boards. We will be employing a low-cost freeze-drying method for pore solvent removal instead of the cost-prohibitive supercritical drying method, usually used in aerogel production. PIR-based SIAP has several benefits over the conventional foams (expanded polystyrene, EPS; expanded polystyrene, XPS; polyurethane, PU; PIR) – it has twice as high R-value, exhibits no thermal aging, and does not use blowing agents. Compared to currently produced silica aerogels, the proposed PIR SIAP is mechanically stronger, more elastic, significantly less expensive, and dust free. PIR is the only commercial plastic insulation available in the North America that can attain over R-7.0 hr·ft2·°F/Btu·in. PIR, typically manufactured as rigid foam boards. We anticipate that the proposed high-performance, mechanically robust, nailable and cost-competitive PIR-based SIAP (nanofoam) will revolutionize the building plastic foam insulation industry in the U.S. by gaining a significant market share of the traditional foam roofing and wall sheathing applications.
The research program has three following primary objectives:
Objective 1: To demonstrate polyisocyanurate (PIR) SIAP produced using freeze drying. This objective is to produce aerogels using PIR precursors and freeze-drying processing. We will focus on polymeric aerogels formed from a trifunctional aromatic isocyanate. For the initial tests, we will follow the earlier-developed procedure that we have already utilized with success for the silica gels.
Objective 2: To decrease the average pore size of PIR SIAP produced using freeze drying to ~50 nm, enabling thermal performance improvements. We will optimize the nanofoam fabrication process to yield materials with the lowest thermal conductivity. Thermal conductivity depends, in first approximation, on mean pore size and connectivity between the nanoparticles making up the aerogel skeleton. Our goal is to attain a thermal conductivity below 14 mW/m·K (stretch goal being thermal conductivity below 12 mW/m·K), implying that the cellular structure needs to be in nanoscale (~50 nm). In freeze drying, care must be taken to prevent formation of pores with a diameter larger than about 30 nm, after which convection becomes relevant, and to prevent agglomeration of the skeletal nanoparticles, which would increase connectivity and thus thermal conduction through the solid phase. Solvent diffusion stresses and large crystal growth will be minimized by rapid cooling.
Objective 3: To scale up the sample size produced using freeze drying to length-scales of the building insulation. We aim to validate the technical feasibility of increasing the production size to the building-scales.
The proposed PIR nanofoam technology adds to the portfolio of new thermal insulation materials which are expected to significantly impact the existing markets. Besides, they will allow a variety of new applications, which due to either technological reasons, or space restrictions, require high-performance thermal control strategies. Using BTO Market calculator and a conservative estimate of 20% reduction in energy consumption with PIR aerogel compared to the best performing commercial insulation (i.e. PIR foam) for same thickness installations, we evaluate a primary energy-saving technical potential of this enabling technology development to be 0.7 quad (=20%*[2.5 quad for residential sector + 2 quad for commercial sector]). Equally important is the fact that the new insulation will have the ability to improve the overall thermal resistance of building envelopes between 30% to 50% without changing the dimensions of the structural components or sheathing.
White, L.S., Echard, D.R., Bertino, M.F., Gao, X., Donthula, S., Leventis, N., Shukla, N., Kośny, J., Saeed, S. and Saoud, K. “Fabrication of native silica, cross-linked, and hybrid aerogel monoliths with customized geometries”. Translational Materials Research 3 015002/2015