Abstract
A numerical parameter sensitivity analysis of the design parameters of the recently published solar selective thermal insulation system (SATIS) has been carried out to enhance its thermal and optical properties. It turned out that the insulation properties of SATIS can be effectively improved by reducing the length of the glass closure element. Increasing the area share of the light conducting elements (LCEs) and decreasing their length-to-diameter (L/D) ratio were identified as key parameters in order to increase the solar gain. Two SATIS variants were compared with the same wall insulation without SATIS in a yearly energetic performance assessment. The SATIS variant with 10 mm length of the closure element, 44.2% area share of LCE, as well as front and rear diameters of 12 mm/9 mm shows an 11.8% lower transmission heat loss over the heating period than the wall insulation without SATIS. A new methodology was developed to enable the implementation of the computed solar gains of SATIS in 1D simulation tools. The result is a radiant heat flow map for integration as a heat source in 1D simulation models. A comparison between the 1D and 3D models of the inside wall heat fluxes showed an integral yearly agreement of 98%.
Highlights
Published: 30 June 2021From a thermal point of view, conventional opaque insulation materials reduce transmission heat losses by increasing the thermal resistance
When transparent insulation materials (TIMs) are used as passive facade heating systems, the transmission heat losses can be further reduced, and additional solar gains can be obtained to compensate for other energy losses [4]
The yearly energy balances of the solar selective wall constructions #1 and #2 are compared with that of the wall structure insulated with the same thermal insulation plaster and thickness, but without selective thermal insulation system (SATIS) (“conventional wall construction”)
Summary
Published: 30 June 2021From a thermal point of view, conventional opaque insulation materials reduce transmission heat losses by increasing the thermal resistance. In the construction of TIMs, it is important to choose the main design parameters in such a way that the heat loss is kept as low as possible and, at the same time, a high solar gain in winter months is ensured. For this purpose, numerical parameter studies of the main design features can be carried out, since they can often be realized more quickly and at lower cost than experimental investigations. In order to perform such numerical investigations on TIMs, validated models are required that reflect the main
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