Ammonia–water cogeneration cycle for utilizing waste heat from the GT-MHR plant

A combined cycle is proposed in which the waste heat from a gas turbine-modular helium reactor (GT-MHR) is utilized by an ammonia–water mixture (AWM) cycle to produce cooling and additional power. The AWM cycle is a combination of the Kalina and an absorption refrigeration cycles and has been referred to as the Goswami cycle in the literature. A detailed thermodynamic analysis is carried out for the proposed combined cycle and the effects of some important parameters such as; the compressor pressure ratio, the turbine inlet temperature, the pump pressure ratio and the boiler temperature on the combined cycle performance are investigated. The cycle performance is also optimized based on the first and second laws of thermodynamics. It is found that, at nearly optimum conditions, the energy utilization and second law efficiencies of the combined cycle are about 9–15% and 4–10% higher than those of the GT-MHR cycle, respectively. It is also concluded that superheating the ammonia vapor at the turbine entry results in a decrease of the combined cycle efficiency and output cooling.

► Utilization of waste heat from GT-MHR through an ammonia–water cogeneration cycle is investigated.
► First and second law efficiencies for the combined cycle are 9–15% and 4–10% higher than that for GT-MHR.
► The helium mass flow rate in the combined cycle is significantly lower than that in the GT-MHR.
► A cooling temperature of lower than 0 °C is achieved at the AWM turbine exhaust.
► Superheating the ammonia vapor at the turbine entrance has negative effect on the combined cycle performance.