Exergoeconomic Analysis of a Novel Hybrid System by Integrating the Kalina and Heat Pump Cycles with a Nitrogen Closed Brayton System

Abstract

In recent years, attentions are focused on the application of cutting-edge reactors to utilize the remarkable virtues such as safety and also higher thermal efficiency. Sodium-cooled fast reactors (SFRs) are midst the promising types of fourth generation reactors for their non-reacting behavior and packed configurations, which are considered as heat source of various thermodynamic systems. Accordingly, nitrogen Brayton cycle could be devised as power conversion system (PCS) of the mentioned sodium cooled reactors, due to its simple arrangement. In present study, proposing the topping system of nitrogen Brayton cycle as a power generation system which is driven by the sodium reactor system, Kalina and heat pump cycles, as bottoming cycles, were designed to increase the performance of the overall system by integration with topping system. Subsequently, energy, exergy and exergoeconomic analyses were carried out to examine the reliability of the proposed system. The results displayed that under operating conditions, thermal efficiency, exergetic efficiency of the proposed system are 34% and 62%, respectively. Furthermore, using the exergy point of view, it was revealed that steam generator heat exchanger, SGHX, is the foremost cause of exergy destruction. Also, in order to attain an inclusive insight over the system, a parametric analysis was conducted. Therefore, investigating the influence of alterations in key features of the overall cycle, several optimum working conditions, such as optimal basic concentration of ammonia in Kalina cycle, optimal turbines (I&II) expansion ratio and low-pressure compressor pressure ratio etc., were derived.

Keywords

• Nitrogen Brayton cycle
• Kalina cycle
• Heat pump cycle
• Exergoeconomic
• Exergy