Aurinkojäähdytys ja -lämmitys Pohjois- ja Keski-Euroopassa: Suomen ja Saksan t&k-yhteistyöprojekti Euroopan SET-strategiasuunnitelmassa

Solar heating and cooling technologies are compatible with almost all sources of backup heat and almost universally applicable due to their ability to deliver hot water, hot air and cold air. In the solar cooling process, the demand and supply of cooling will meet each other. The general objective of this Finnish-German cooperative research project has been to develop an innovative energy system for solar heating, cooling and domestic hot water preparation so as to broaden the application of improved solar thermal systems and absorption heat pumps/chillers for domestic and industrial buildings in Northern and Central European countries. In this project a small scale (10 kW) solar cooling and heating (25 kW) system with a compact absorption chiller/heat pump and improved foil collectors has been developed and successfully demonstrated at the Savo-Solar office building in Mikkeli, Finland. By use of thermally-driven absorption instead of electrically-driven compressor heat pump technology, no additional grid stress or reserve capacity, either in summer or in winter, is caused. The demonstration consists of a solar-heatdriven (36 m2 collectors) absorption chiller, heat storage and district heating or biomass boiler backup (15 kW) for the chiller. The absorption machine can be operated as a chiller or heat pump. Based on simulations, the most suitable V/S (heat storage volume/collector surface) is 55.6 l/m2, so it means 2 m3 in the Savo-Solar case. A practical feasibility study of a biomass (wood chip) -driven double-stage absorption machine was conducted also at the ZAE Bayern laboratory in Munich, Germany. By adding a foil between the glass and aperture area, front-side heat losses have been reduced significantly by up to 11%, especially at higher temperatures, which are required to drive the absorption chiller during summertime. As the future of the solar thermal collector industry is seen to be in large scale applications, it is suggested that the developed techniques are transferred to larger scales as well.