Extension of the CTSS Test Method Towards Solar Cooling Systems

Abstract

Due to the worldwide increasing demand for cooling and the fact that cooling requirements of buildings and high solar radiation largely coincide, the next evolution step of solar thermal technology are solar cooling systems and in particular so-called SolarCombiPlus systems. These systems provide domestic hot water, space heating and space cooling. Cooling is performed by means of a thermally driven sorption chiller integrated into the system. To support the market entry and to enhance the market penetration of solar cooling systems, it is necessary to have standardised procedures for the overall assessment of such systems. This requires both, performance test methods as well as procedures for the determination of the overall environmental impact. In order to develop the required testing and assessment procedures for solar thermal cooling systems and thermally driven heat pumps (i.e. heat transformers), the project “SolTrans” was started at ITW in 2008. Due to the broad spectrum of locations for the operation of solar cooling and SolarCombiPlus systems and the widely different system designs of solar cooling and SolarCombiPlus systems, a component based test approach, such as the CTSS-method (component testing - system simulation) was found to be the most promising approach. To-date, solar thermal collectors are mostly used in systems for domestic hot water preparation and space heating. Due to the worldwide increasing demand for cooling and the fact that cooling requirements of buildings and high solar radiation largely coincide, the next evolution step of solar thermal technology are solar cooling systems and in particular so-called SolarCombiPlus systems. These systems are solar combisystems which provide domestic hot water, space heating and space cooling. Cooling is performed by means of a thermally driven sorption chiller integrated into the system. The performance testing of solar domestic hot water and solar combisystems is based on the CTSS-method (Component Testing and System Simulation) already standardised in CEN/TS 12977 series. Up to now there exists no standardised performance test method for solar cooling or SolarCombiPlus systems. The reason therefore is that standards are always developed with a certain time delay compared to the development of products and systems. This delay may be a barrier for the new products to enter the market, as no testing and certification is possible - or existing standards do not express the benefits of the new products. To remove market barriers and to enhance the market penetration of solar cooling systems and SolarCombiPlus systems, the availability of standardised procedures for the overall assessment of such systems is necessary. This requires both, performance test methods as well as procedures for determination of the overall environmental impact (i.e. LCA: Life Cycle Assessment).