The design analysis of a water sourced district heating and cooling system for a neighborhood development project

On the basis of the principles of Green Infrastructure and Building (GIB) in LEED for Green Neighborhood Development (LEED-ND), this paper studies the technical feasibility, economic soundness, and environmental effectiveness of a water-sourced energy system in a 6.5 million square feet mixed-use neighborhood development project in Changsha, Hunan Province, China. Two energy systems proposed for the project are compared in the study by using scientific fundamentals and engineering principle. The two energy systems are • System One: Use Xiangjiang River as cooling water for absorption chillers to generate chilled water for all buildings. • System Two: Use traditional cooling towers providing cooling water for absorption chillers to generate chilled water for all buildings. The system performance analyses of study show that system one has better energy, environmental and economic performance than system two. Compared to system two, system one is predicted to have a saving of 32% in electricity, 11% in natural gas, and 675 ton/year in CO2 emission; and its system payback year is 8 years. This paper also investigated the impact of system one on the Xiangjiang River by using Fluent computational fluid dynamics (CFD). The results of the CFD simulation indicated that there no significant changes of river temperature over time. Finally, some suggestions on design and operation have been provided for system one to be implemented.