Primary Energy Optimisation of a Solar Adsorption Cooling Plant Through Dynamic Simulations

This paper studies the primary energy optimisation potential of an existing large solar adsorption cooling plant (Festo company). This plant consists of 1218 m2 (net area) vacuum tubes collectors, 2 hot storage tanks of 8.5 m3 each and 3 adsorption chillers of 350 kW cooling capacity each. Measurements and previous simulation studies show a good optimisation potential especially regarding the electricity consumption of the cooling towers [1]. The purpose of this paper is to quantify this potential in terms of primary energy savings by using dynamic simulations. The work focuses on the heat rejection loop which consists of the chillers and the cooling towers. Different control strategies of cooling towers fan speed are simulated. Additionally, different hydraulics configurations of the heat rejection loop with or without buffer storage tanks are studied in order to see the effect on the fan speed control of the cooling towers. The electrical COP of the global system can be increased up to 30-40% with such controls with a minor decrease in cooling capacity. The use of a buffer store between the chillers and the cooling towers is meaningful since it smoothes the temperature wave and makes the control easier and more stable. Specific primary energy savings up to 0.25 kWhPE/kWhcooling can be achieved with simple changes in the heat rejection loop.