Comparative thermoeconomic analysis of trigeneration systems based on absorption heat transformers for utilizing low-temperature geothermal energy

Abstract

Two novel trigeneration cycles are proposed based on Absorption Heat Transformers (AHTs) to generate power and produce freshwater, and heating effect from low-temperature geothermal energy. Simulation models are developed to examine the thermodynamic and thermoeconomic performances of the systems based on the single-stage, double and double-effect AHTs. The power is generated in an Organic Rankine Cycle (ORC) and a single-stage evaporation desalination system is employed to produce freshwater. The exergy performance parameters are determined, and the levelized cost of energy (LCOE) and water (LCOW) are considered as the criteria for the thermoeconomic assessment. According to the results, a maximum of 191.1 kW of power can be generated by the proposed systems, for a geofluid with a temperature of 95 °C and mass flow rate of 50 kg/s, that belongs to the double-effect AHT based system. This is 18.6 and 60.9 kW more than the single-stage and double AHT based systems power, respectively. Also, the energy and exergy efficiencies, as well as LCOE and LCOW for this system, are calculated to be 40.07%, 57.38%, 0.04636 $/kWh, and 34.85 $/m3, respectively. Moreover, a parametric study revealed the notable influences of temperatures of AHT components on the performance parameters of the systems.