Experimental proof of a model-based real-time control of adsorption chillers

Adsorption chillers have been considered for waste heat utilization in both stationary and mobile applications, e.g. using waste heat from data centers and from internal combustion engines. Several efforts were made to improve the performance of such systems, mostly in terms of materials and components. However, a proper control strategy, adaptable to operating conditions that are continuously varying is paramount for the market development of adsorption chillers and heat pumps. The present work demonstrates the possibility of using a model-based control strategy that can be easily implemented in the standard PLCs of the chillers, without the need of expensive hardware. To this aim, an adsorption chiller prototype with nominal cooling power of 6 kW was tested and a simulation model was realized in Modelica/Dymola, which was then used for running several simulations and deriving an optimal “map of set-points”. The beneficial effect of using the modified set-points for cycle time and flow rates was then proved experimentally by means of dedicated tests carried out with the optimal parameters. Results highlighted that there is always an improvement compared to the original conditions in the range of 6 %–31 % for the cooling power and, for the COP, is in the range 3 %–11 %.