European research on solar-assisted air conditioning

The utilization of waste heat, on the one hand, and solar heat, on the other, in order to energize sorption chillers is an important issue for increasing the energy efficiency of cooling machines. Especially in the air-conditioning business, a tight correlation often exists between insolation and cooling requirements. Therefore, the interest in solar cooling by sorption systems has prevailed for several decades. Some hundred systems have been installed all over the world and operate satisfactorily. However, no really cost-competitive system for widespread application exists. A step forward can only be expected by innovative design of the collectors, chillers, or both.This paper reports on trends which might lead to such innovations. The sources are mainly papers and discussions at workshops held in 1994 in Dresden and 1995 in Freiburg and Garching, Germany. Although in these workshops mainly European experiences have been discussed, the conclusions are valid world-wide: generally, it can be stated that several new ideas, both in collectors and chillers, have gained ground. Cheaper collectors providing higher temperatures have become available and specially designed chillers for use with low-grade heat as input are being investigated.In this paper we highlight the most important developments reported on in the workshops mentioned above.