Development of improved Desiccant Evaporative Cooling control system for full year operation including greenhouse buffer plants

The control of a Desiccant Evaporative Cooling (DEC) system has to solve quite complex requirements to achieve the desired indoor conditions (temperature, humidity), especially when the device is used the whole year. The control strategies used so far are aiming to achieve constant set points for long time periods (summer, winter) with a maximum humidity ratio for the supply air in summer. The evaluation of the ENERGYbase1 solar driven DEC system, which is in operation since 2009 showed several disadvantages with regard to indoor comfort and energy efficiency. Therefore, a new control concept was set up within a research project (SolarCoolingOpt, ongoing) in cooperation with Siemens Facility Management and Munters GmbH. This paper contains the preliminary analysis of the existing DEC control strategies, details of the new control strategies and experiences from changing a whole control system during operation.