Enhanced performance and reduced payback period of a low grade geothermal-based ORC through employing two TEGs

Document Type : Research Paper


School of Mechanical Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran


In this paper, a novel integrated system is proposed to improve the performance of a conventional low-grade geothermal-based organic Rankine cycle (ORC). The main idea is to utilize two TEG units to recover the waste heat of the condenser and geothermal brine. The proposed model is investigated and compared with simple ORC from the energy, exergy, and exergoeconomic viewpoints through the parametric study. Furthermore, the payback period of the systems is calculated to investigate the economic aspects of the model in more details. Results show that the exergy efficiency of the proposed system would be 56.81% at the base case (4.67% higher than the simple geothermal-based ORC system) and the total product cost of the proposed integrated system is 24.55 $/GJ at the base case (5.5% lower than simple ORC), while the payback period of the suggested system is 2.422 years (15 days lower than the simple ORC cycle). Furthermore, the net power output of the novel proposed system is 75.24 kW (9% higher than the simple ORC cycle). Comprehensive paramedic study and comparison of the exergy and exergoeconomic aspects reveal that the proposed system is a promising method to optimize such systems from exergy/exergoeconomic viewpoints.


[1] Braimakis K., Karellas S., Energetic optimization of regenerative Organic Rankine Cycle (ORC) configurations, Energy Conversion and Management  159: 353–370 (2018).
[2] Yang F., Zhang H., Bei C., Song S., Wang E., Parametric Optimization and Performance Analysis of ORC (organic Rankine cycle) for Diesel Engine Waste Heat Recovery with a Fin-and-Tube Evaporator, Energy, 91:128–141 (2015).
[3] Aali A., Pourmahmoud N., Zare V., Exergoeconomic Analysis and multi-Objective Optimization of a Novel Combined Flash-Binary Cycle for Sabalan Geothermal Power Plant in Iran, Energy Conversion and Management, 143: 377–390 (2017).
[4] Xi H., Li M.J., Xu C., He Y.L., Parametric Optimization of Regenerative Organic Rankine Cycle (ORC) for Low Grade Waste Heat Recovery Using Genetic Algorithm, Energy, 58:473–482 (2013).
[5] Wang J., Yan Z., Wang M., Ma S., Dai Y., Thermodynamic Analysis and Optimization of an (Organic Rankine Cycle) ORC Using Low Grade Heat Source, Energy, 49: 356–365 (2013).
[6] Zare V., A Comparative Exergoeconomic Analysis of Different ORC Configurations for Binary Geothermal Power Plants, Energy Conversion and Management, 105: 127–138 (2015).
[7] Ma Q., Fang H., Zhang M., Theoretical Analysis and Design Optimization of Thermoelectric Generator, Applied Thermal Engineering, 127:758–764 (2017).
[8] Lv S., He W., Jiang Q., Hu Z., Liu X., Chen H., et al., Study of Different Heat Exchange Technologies Influence on the Performance of Thermoelectric Generators, Energy Conversion and Management, 156: 167–177 (2018).
[9] Demir M.E., Dincer I., Development of a Hybrid Solar Thermal System with TEG and PEM Electrolyzer for Hydrogen and Power Production, International Journal of Hydrogen Energy, 42: 30044–30056 (2017).
[10] Chávez-Urbiola E.A., Vorobiev Y. V., Bulat L.P., Solar Hybrid Systems with Thermoelectric Generators, Solar Energy, 86: 369–378 (2012).
[11] Zare V., Palideh V., Employing Thermoelectric Generator for Power Generation Enhancement in a Kalina Cycle Driven by Low-Grade Geothermal Energy, Applied Thermal Engineering, 130: 418–428 (2018).
[12] Ziapour B.M., Saadat M., Palideh V., Afzal S., Power Generation Enhancement in a Salinity-Gradient Solar Pond Power Plant Using Thermoelectric Generator, Energy Conversion and Management, 136, 283–293 (2017).
[13] Maraver D., Royo J., Efficiency Enhancement in Existing Biomass Organic Rankine Cycle Plants by Means of Thermoelectric Systems Integration, Applied Thermal Engineering, 119, 396–402 (2017).
[14] Yilbas B.S., Sahin A.Z., Thermal Characteristics of Combined Thermoelectric Generator and Refrigeration Cycle, Energy Conversion and Management, 83: 42–47 (2014).
[15] Vorobiev Y., González-Hernández J., Vorobiev P., Bulat L., Thermal-Photovoltaic Solar Hybrid System for Efficient Solar Energy Conversion, Solar Energy, 80: 170–176 (2006).
[16] Siddique A.R.M., Mahmud S., Heyst B. Van, A Review of the State of the Science on Wearable Thermoelectric Power Generators (TEGs) and Their Existing Challenges, Renewable and Sustainable Energy Reviews, 73: 730–744 (2017).
[17] Dinc╠žer I., Rosen M., Ahmadi P., Optimization of Energy Systems, John Wiley & Sons (2017).
[18] Ogriseck S., Integration of Kalina Cycle in a Combined Heat and Power Plant, a Case Study, Applied Thermal Engineering, 29: 2843–2848 (2009).
[19] Yari M., Exergetic Analysis of Various Types of Geothermal Power Plants, The journal, Renewable Energy,  35:112–121 (2010).