Adaptive insulation layer to enable thermal activation of building structures: Thermochemical reactor as control unit

Abstract

Thermal activation of existing building masses can significantly increase the energy efficiency of buildings by using them as thermal energy storage. To achieve this, it is essential to control the heat transfer across the massive components such as walls or ceilings. This can be achieved by applying a controllable insulation layer, which combines the gas pressure-dependent thermal conductivity of porous structures with reversible gas-solid-reactions.The heat transfer mechanism in porous insulation materials is dominated by the Knudsen effect, which describes the S-shaped thermal conductivity depending on the prevalent gas pressure in the insulation panel. By employing thermochemical materials, the gas pressure in the vacuum insulation panel can be precisely controlled along the equilibr ium line by adjusting the reaction temperature. This allows for precise control of the heat flux through the insulation panel and enables the thermal activation of building masses. The thermochemical reactor is a key component in the integral adaptive insulation system. The contribution will outline a novel reactor concept addressing the central challenges of accurate pressure adjustment, system dynamics and energy efficiency. We will introduce the novel reactor design and present substantial experimental results on the reactor characterization as well as the proof of concept of the controllable insulation layer as an further development of a switchable insulation layer.