Configuration selection methodology for combined power/refrigeration generation ammonia-water cycles

In this paper, ammonia-water systems are analyzed for the cogeneration of refrigeration and power. Some general principles for the system integration are summarized, for better recovery of both the external and internal heat and pressure exergy, and reduction of the exergy destruction in the condensation process. Based on these principles, three ammonia-water systems are proposed and analyzed. The plants operate in combined cycle mode with ammonia-water Rankine cycle(s) and an ammonia refrigeration cycle, interconnected by absorption, separation and heat transfer processes. It is found that the cogeneration systems have good thermal performances, with energy and exergy efficiencies of similar to 28% and 55 similar to 60%, respectively, for the base-case studied (at maximum heat input temperature of 450 degrees C). That efficiency is, by itself, excellent for cycles using heat sources at these temperatures, and comparable to that of nuclear power plants. When using the waste heat from topping gas turbine power plants, the total plant energy efficiency can rise to the remarkable value of about 57%. The hardware proposed for use is conventional and commercially available, no hardware additional to that needed in conventional power and absorption cycles is needed.