Design of a Solar Desiccant Cooling System

Abstract: The division of Building Services Engineering at Chalmers University of Technology, Göteborg, has an air handling unit comprising a desiccant cooling system with an electric heater and intends to install the system in its laboratory. The aims of this project are making a comprehensive proposal including how to design the system in order to use solar energy for regeneration of the desiccant wheel (design of a solar desiccant cooling system), where to install the system in the laboratory, how to use it in order to cool the whole or some parts of the laboratory, how to use it in order to do experiments and how to establish a lab for undergraduate students in order to show them the performance of the system.Firstly, the building where the solar desiccant cooling system is supposed to be installed was described and drawn. In order to find it is better to use the existing desiccant cooling system to cool whole laboratory or some parts of it, the cooling load for the whole laboratory and offices were estimated separately. So, it was known that the cooling load of offices more suits to the cooling capacity of the existing desiccant system.Secondly, the most appropriate types of the solar collectors for the project were determined. Liquid-based and air-based glazed flat-plate and also evacuated-tube solar collector were selected as the proper alternatives. After general description of those types and making comparison among them, liquid-based flat-plate solar collector was selected as the most proper type because of being more common and available than others. So the detailed design was carried out based on this type of collector. The detailed design section is divided to two main parts. In the first part of detailed design, system with liquid-based flat-plate solar collector is analyzed and designed comprehensively. Closed loop at low pressure filled with a glycol mixture-partial evaporation was selected as the collector circuit in the designed solar system. The solar system was designed in order to heat the regeneration air of desiccant wheel from 35°C to 55°C. Two individual control units were presented in order to control both solar and desiccant cooling system operation. The proper place for installation of system in the laboratory was also found and showed in Autocad format. Then the components of the solar system were sized and selected from catalogues. In the second part of the detailed design, system with air-based flat-plate solar collectors was analyzed briefly. Finally, a lab guide for undergraduate students was made in order to make them familiar with the principles of the system and show them what the important parameters and figures of merit are due to the components of the system and how to achieve those parameters basically.