Field testing of a novel hybrid solar assisted desiccant evaporative cooling system coupled with a vapour compression heat pump

The aim of this paper is to report on a two-year operational experience with a solar driven desiccant and evaporative cooling (SDEC) system coupled with a vapour compression heat pump. The main objectives are to analyse the benefits and drawbacks of this innovative hybrid SDEC system, to compare the monitoring results against the expected theoretical ones, and to assess the system's performance with respect to a reference air handling unit. The comparison focuses on the summer key operation modes using Primary Energy Ratio (PER) as indicator of the entire system performance. The results of the detailed analysis lead to the following conclusions: the specific design of the hybrid SDEC leads to high air quality, simpler control process and low electricity consumption for partial load conditions. The monitoring results show a summer mode PER 20% lower than expected due to underperformance of the desiccant wheel. Nevertheless, this innovative system is still very efficient as its PER is twice as high as the one of the considered reference system. Lastly, suggestions for optimization of the existing system through the fine-tuning of the control strategy of its main components are presented.