Techno-economic analysis of partial evaporation and sub-critical organic Rankine cycle systems integrated with an absorption heat transformer

Integrating organic Rankine cycles with lithium bromide absorption heat transformers boosts energy efficiency by effectively recovering low to medium-grade waste heat, transforming it into useable energy. This paper presents a comprehensive techno-economic analysis comparing three configurations of organic Rankine cycles, including sub-critical organic Rankine cycles (in two different configurations), and a partial evaporation organic Rankine cycle, integrated with an absorption heat transformer to generate electricity from low-grade waste heat. There are no previous analyses available in the open literature for integrated partial evaporation organic Rankine cycles with absorption heat transformers. A single-stage absorption heat transformer is employed to elevate the temperature of waste heat from 90 °C to 120 °C for effective utilization in the three organic Rankine cycles. To fully utilize the available heat sources, pinch analysis and process integration methodologies are applied. The results indicate that the partial evaporation organic Rankine cycle exhibits better performance from a thermodynamic point than the sub-critical organic Rankine cycle. The heat transformer integrated sub-critical organic Rankine cycle achieves a maximum electrical power output of 372.3 kW with a total electrical efficiency of 7.4 %. Meanwhile, the heat transformer integrated partial evaporation organic Rankine cycle attains a peak electrical power generation of 385.5 kW–488.1 kW with total electrical efficiency of 7.6 %–9.6 %, depending on the performance of the two-phase expander. From a techno-economic perspective, the results suggest that while the system with a sub-critical organic Rankine cycle has a levelized cost of electricity of 0.081 €/kWh, the system utilizing the partial evaporation organic Rankine cycle achieves a levelized cost of electricity in the range of 0.072 €/kWh to 0.101 €/kWh, depending on the cost increase of the two-phase expander.