Potential of thermoelectric waste heat recovery in a combined geothermal, fuel cell and organic Rankine flash cycle (thermodynamic and economic evaluation)

The present work aim is performance improvement of an integrated geothermal system by proposing the integration of organic Rankine flash cycle (ORFC) with the Proton exchange membrane fuel cell (PEMFC) and waste heat recovery from condensers using thermoelectric generator (TEG) modules. To achieve this goal, a novel integrated system is proposed, thermodynamically modeled, investigated, and compared with the conventional system. To assess the performance of proposed system, thermodynamic and economic evaluations are performed. The results indicate that R123 as working fluid, has the best performance for the conventional and proposed systems. The findings demonstrate that with employing TEG modules an increase of 2.7% and 2.8%, for the first and second law efficiencies can be obtained respectively. Additionally, the results of parametric analysis indicate that however the geothermal fluid temperature increment decreases the first and second law efficiencies of the system, it leads to the net output power enhancement. Also, enhancement of the flash vessel pressure ratio increases the first and second law efficiency as well. Additionally, the simple payback method showed that a payback time between 1.25 years and 25 years according to the TEG modules cost can be achieved. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.