Investigation of an Innovative Solar-Driven Solid Desiccant Evaporative Cooler for Hot and Humid Climates

In the last decade, desiccant assisted evaporative cooling (DAEC) has emerged as an alternative air conditioning (A/C) method to conventional vapor compression (VC) systems due to its lower operating costs and environmental impacts. However, for enabling wider usage of DAEC systems, new low cost, natural and locally available desiccant materials and evaporative cooling pad materials (ECPMs) need to be sought. Moreover, development of novel DAEC processes and their integration with solar energy are essential. In that regard, the primary objective of the study was to develop a fixed bed DAEC system integrated with solar energy, that uses novel composite sorbent to be utilized as a coolth storage in hot-humid climate. To achieve this objective, initially, different natural ECPMs in a fixed-bed solid DAEC system, containing a novel desiccant material (Vmc-CaCl2), were experimented in laboratory environment. During the tests, consecutive cycles with different operating conditions were performed for comprehensive performance evaluation of each candidate material. Additionally, DAEC and evaporative cooling (EC) processes were comparatively investigated with the use of different ECPMs. Results showed that the DAEC provides between 17-62% higher cooling rates than EC. In the second part of the study, a solar-driven DAEC system was developed and tested under real climatic conditions of North Cyprus (NC). Average thermal coefficient of performance (COPth) and wet bulb effectiveness (εwb) of the system were found 0.60 and 121.6% with the use of Vmc-CaCl2/WoC as the working materials. Furthermore, a numerical analysis using Transient System Simulation software (TRNSYS) was performed to assess the cyclic performance of solar assisted DAEC system. Simulation results showed that, system using silica gel/WoC couple can provide average COPth and εwb of 0.32 and 104.2%, respectively. In addition, economic analysis and life cycle assessment (LCA) were performed to investigate the feasibility of the proposed solar-driven DAEC system in comparison with a typical A/C split unit under the climatic conditions of NC. According to the performed economic analysis, SIR = 3, IRR = 31% and SPP = 3 years were obtained. Moreover, based on the performed LCA, the developed system produces 0.23 kg/year CO2, which shows that it is environmentally friendly and economically feasible for using in residential buildings in NC.