The test runs were carried out under controlled conditions to assure a detailed characterisation of the complete system including storage module and heat sources under steady state and dynamic operation conditions. The objectives were to run specific test cycles and gain operation experience of the storage. The data were analysed and evaluated regarding energy flows, storage capacity and temperature level achieved. A major objective was to find suitable operation modes, control strategies and recommendations for a redesign of the system for a broader use. The gained experience will now be used as a feedback for the development of the second generation prototype.

The development of an optimised control cycle which will be able to operate the storage in a reliable and automatic way is an important goal of the new project. For this reason, a control program was written. The pressure in the various components was used as one of the main control parameters. The following cycle operation was implemented:

• Measurement of the pressure in the condensate storage module

• Measurement of the pressure in the adsorption reactor

• The measured pressures are compared and the valves for charging or discharging of the storage are opened according to the predefined program

• A fourth step is reserved for the relaxation of the system

First tests showed that long-term heat storage using solid sorption processes with water vapour as working fluid is technically feasible.