Development of Optimal System Design and Operation of Solar Desiccant Cooling to Provide Air-Conditioning in Sub-Tropical Hong Kong

Since Hong Kong has the sub-tropical climate, with long hot and humid summer, provision of air-conditioning is therefore indispensable. Refrigeration and air-conditioning consume the highest proportion of electricity in Hong Kong. Different measures of energy efficiency have been considered, except the amount of hot and humid ventilation air cannot be reduced for the sake of occupants. If good indoor air quality is required by introducing more outdoor air, it is inevitable to result higher energy consumption to tackle the ventilation load. However, if such ventilation load, as well as the space cooling loads, is not handled by the traditional electric-driven refrigeration but the solar energy, both sustainability and good air quality can be achieved. In the recent years, research works of solar or thermally driven cooling have been started. Heat is used to drive the absorption or adsorption refrigeration cycle, or to regenerate the desiccant material for cooling purpose. Among these technologies, desiccant cooling is the one able to promote air quality upon cooling. The application potential of solar desiccant cooling in Hong Kong has been confirmed from the previous simulation studies. It is worthy to have empirical studies in order to develop an in-depth and optimal solar cooling system for Hong Kong.Solar desiccant cooling system is incorporated with a series of component equipment, the essential ones are the desiccant wheel, heat recovery unit and solar air collectors. In this project, a prototype of the solar desiccant cooling system and an environmental chamber would be built. Initially, the performances of the desiccant wheel and heat recovery unit due to different operating conditions would be studied, and their mathematical models would be developed accordingly. Then the overall system performance of solar desiccant cooling would be studied in response to different simulated climatic and operating conditions through the experiments. The empirical results are useful to develop and validate the simulation model of the entire system. In this regard, the design and operation parameters of the involved component equipment can be optimized by the robust evolutionary algorithm. The opportunity of building integrated design would also be worked out. The life-cycle cost analysis would be conducted, so that recommendations to the Hong Kong government about the financial incentive of solar cooling and solar thermal installation can be delivered. In the long run, wider application of solar thermal technology can be promoted in Hong Kong, as well as the adjacent areas with sub-tropical climate.