Achieving ultra-high coefficient of performance in a novel solar-assisted trigeneration system integrating absorption and Rankine cycles

Abstract

A novel solar-driven trigeneration system was developed and thermodynamically assessed integrating an absorption heat transformer (AHT) a Rankine cycle (RC) and an absorption cooling cycle (ACC) into a unified configuration. The innovation lay not only in the use of an AHT to power the RC-an uncommon integration in itself-but more significantly in the full thermodynamic loop architecture that employed a single working fluid pair (LiBr-H2O) shared by both absorption subsystemswhile also driving a steam-based Rankine subsystem. This tightly coupled single-loop design enabled internal thermal cascading and eliminated the need for separate working fluids auxiliary heating or intermediate heat exchangers- unlike conventional hybrid or cascade systems which (i) rely on multiple working fluid loops for power and cooling (ii) require fossil-fueled auxiliary heaters to drive RCs or (iii) incur high irreversibility losses due to fluid-to-fluid heat exchange between subsystems. Based on the simulation results a net electrical power output of 457.90 kW an overall exergetic efficiency of 74.40 % and a RC energy efficiency of 56.30 % were obtained. The cooling coefficient of performance (COP) reached 7.03 significantly outperforming conventional single-effect absorption systems. The system was fully powered by flat-plate solar collectors (FPSCs) without requiring any fossil-based auxiliary energy. A comprehensive validation was performed using component-level comparisons with experimental studies covering pressure drops internal irreversibility and the influence of working fluid properties on performance metrics. Additionally detailed thermo-economic assessments were carried out. The total investment cost was approximately US$8.54 million with a remarkably short payback period (PP) of 2.56 years and an internal rate of return (IRR) of 24.43 %. Levelized costs of electricity cooling and heating were calculated as US$0.20/kWh US$0.024/kWh and US$0.024/kWh respectively. Comparative analysis against literature benchmarks proven that the proposed system offered superior thermodynamic and economic performance especially in cooling and heating outputs. This study showed a new design paradigm for low-grade renewable energy utilization providing both a scalable solution for high efficiency multigeneration and a practical framework for future sustainable energy systems.