More efficient material developed for adsorption chillers

More efficient material developed for adsorption chillers


German researchers have developed a highly-porous material for use in adsorption systems which enables the efficient use of unused waste heat from, for instance, district heating systems, data centres or heat from solar thermal collectors.

According to, it was a research team at the Institute of Inorganic Chemistry at Kiel University, together with the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, which has developed this new material.

Sorbents used in cooling systems are traditionally crystalline zeolites or silica gels, which can easily absorb water due to their structure. The new substance, highly-porous aluminium isophthalate, known as CAU-10-H, can absorb a lot of water very quickly and release it quickly again – even at a low increase in temperature.

The Kiel working group has already worked on new metal organic frameworks (MOF) for a long time. For transfer to an industrial application, they worked with colleagues from the Fraunhofer ISE to coat commercially available heat exchangers with their material.

“The survey of the heat exchanger under application-related conditions shows the high potential of the material,” says Dr Stefan Henninger from the ISE. In the laboratory, the material can already be produced in kilogram quantities under mild reaction conditions, such as at a temperature of 100°C with water as a solvent.

“In order to produce the material for an industrial use on a larger scale, our next step is to contact other companies,” says Stock. They have already applied for a patent for their production method.

“This could also make an important contribution to the use of renewable energies,” says Professor Norbert Stock from the Institute of Inorganic Chemistry. For environmentally friendly systems like this the material has two key advantages: “The systems consume less power, and we can produce the material in an eco-friendly manner,” explains the inorganic chemist.

The research team will present the material and its applications at this year’s Hannover Messe 2018 trade fair in Germany from 23 to 27 April 2018.