Evaporator Temperature Control of a Solar-Powered Adsorption Façade System

Rising global temperatures lead to an increasing cooling demand in residential buildings. Utilizing solar energy for air-conditioning can improve the CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> balance of cooling systems. An adsorption façade system (AFS) provides cooling through direct use of solar power. The cooling potential is stored by dehydrating the adsorber and realized by connecting an evaporator with the adsorber. While switching between these different operational phases has to be realized using supervisory control, this paper focuses on the subordinate control algorithm to keep the evaporator temperature at the desired value within the cooling phase. Earlier works showed that a two point bang-bang control is not feasible for this application due to physical limitations. Therefore, this paper proposes a design modification in combination with a PI-control law for the cooling phase. This proposed controller respects comfort temperature limits and prevents condensation of air humidity, while achieving maximal cooling rates.