Thermodynamic and Exergoeconomic Analysis of Utilizing a Modified Kalina Cycle for a Recompression Supercritical CO2 Cycle Waste Heat Recovery

This research introduces a new combined cycle system, coupling supercritical CO
2
(sCO
2
) with a modified Kalina cycle (MKC). By replacing the traditional throttle valve with an expander between the separator and regenerator of this latter unit, expansion work is recaptured that had previously been lost during throttling processes. An exergoeconomic comparison between the combined sCO
2
/MKC and singularly operating sCO
2
cycle has been conducted to determine how specific decision variables affect system performance. To do so, researchers developed a parametric analysis based on a self-developed thermodynamic simulation platform using Engineering Equation Solver (EES) software. Our results demonstrate that maximizing system performance is achieved through a positive balance between the main compressor pressure ratio (RP), and evaporating pressure (P
EV
). Moreover, obtaining lower pinch points between evaporation temperatures along with higher ammonia water masses appears to yield desirable outcomes. Our findings demonstrate that the sCO
2
/MKC offers enhanced exergy efficiency, with an advantage of up to 12.8% over its sCO
2
cycle counterpart. This is accompanied by a reduction in total product cost for the former, with savings reaching 6.7%.