The adsorption chiller generates cold water by using hot water instead of electricity as a source of energy. The hot water is sourced from water-cooled CPUs. The unit saves up to 80% of electricity compared to conventional chillers. In addition, it does not require any synthetic refrigerants, making it immune against tightening F-gas regulations.
The new, compact chiller can generate up to 16 kW of chilled water from 34 kW of hot water, for a total cooling capacity of up to 50 kW. Temperature levels and drops are adjustable.
Adsorption chillers are already in use at large data centers such as Leibniz Supercomputing Centre (LRZ) near Munich. As Matthias Hoene, CEO of the Fraunhofer Institute spin-off, explains: “The new rack integrated chiller offers the same energy savings and benefits as our larger units, and in addition it makes planning and commissioning much easier.” These advantages especially benefit smaller installations.
When hot water-cooled nodes and the adsorption chiller are integrated in the same rack, no additional hot water piping is needed within the data center, because the hot water circuit stays within each rack. When the cold water is used for cooling rear-door heat exchangers, there could even be a mixed installation of hot water-cooled and air-cooled nodes within one rack. Other configurations are also possible, such as using the adsorption chiller to generate cold to maintain room temperature.
Adsorption cooling works through the principle of evaporation: An adsorbent material attracts water, causing it to evaporate and cool down. When the adsorbent is saturated, heat – such as from CPUs – regenerates it, and the cycle repeats. The technology enables highly energy efficient cold generation, as long as heat is available to drive the process.