ABSTRACT
The two main market-available thermal cooling technologies with regeneration temperatures below 100°C are evaluated in this chapter. For closed cycle absorption chillers and open desiccant cooling systems, efficiencies, costs and optimization potentials are analysed. Measurements and simulation studies from realized demonstration projects are presented. If properly designed, both technologies offer significant primary energy savings. However, as coefficients of performance (COPs) are generally lower than for electrically driven compressor chillers, care has to be taken to reduce auxiliary energy demand. While measured average thermal COPs are between 0.6 and 0.7 for absorption chillers, desiccant units can reach higher values, as they often operate with evaporative cooling only. The electrical COPs can be as high as 11 for absorption systems with efficient cold distribution and recooling units and is about 7–8 for desiccant systems with an air-based distribution system. The total costs of both desiccant and absorption cooling systems are dominated by capital costs so that high full-load hours are crucial for an economic performance.
