Development and Progress in Solar Cooling Technologies with Sorption Systems

Sorption cooling technologies are well known as energy efficient cooling supplying apparatuses where heat as driving energy is used from waste heat sources, trigeneration systems (engines), solar thermal plants, etc. Especially in the air-conditioning business often a strong correlation exists between insolation and cooling requirement. Therefore, the interest in solar cooling systems prevails since several decades. Some hundred systems have been installed all over the world and operate, some satisfactorily and some others not. However, no really cost-competitive system for widespread application exists. A step forward can only be expected by innovative design of collectors or chillers, by improved system integration and enhanced control strategies, or by expanded application, e. g., the use as a heat pump in the heating period as well. The state of the art was reported several times. Here three important topics are highlighted: the role of collector and process development, the primary energy demand (in combination with the conventional back-up system and auxiliary energy needs), and the role of the double use of the system during summer and winter time (i.e. collectors for both heat and cold, sorption apparatus as chiller and heat pump). The paper is focusing on solar air conditioning rather than solar refrigeration.