International Journal of Exergy (8 papers in press)

Regular Issues

• Energy Exergy and Environmental Analyses of Mango Leather Drying in Greenhouse Solar Dryer with Evacuated Tube Collector and Finned Tray  
  by Amit Shrivastava, Manoj Kumar Gaur, Parul Saxena 
  Abstract: This research evaluates the performance of a hybrid greenhouse solar dryer (HGSD) combined with an evacuated tube collector (ETC) for drying mango pulp. The experiments were conducted in June 2021 using a finned aluminium tray placed inside the drying chamber. The system demonstrated significant environmental advantages, including the mitigation of approximately 86.21 tons of CO2 emissions. The average exergy efficiency was 4.62%, with a corresponding sustainability index of 1.048. The energy payback period was calculated as 3.98 years, and the carbon credit earned $817.31. The findings highlight the system's potential for optimization to improve efficiency and sustainability.
  Keywords: Mango leather; energy balance; exergy balance; solar energy; greenhouse.
  DOI: 10.1504/IJEX.2026.10074718
   
  
• Enhancing Performance by Incorporating Solar Feedwater Heating instead of Steam Bleeding of an Existing Steam Power Plant: Energy and Exergy Analyses  
  by Sayan Mandal, Sudip Simlandi, Nilkanta Barman 
  Abstract: This study presents energy and exergy analyses to improve the performance of a 500 MW thermal power plant by adding a direct solar feedwater heating system, rather than steam bleedings, resulting in a significant increase in energy efficiency. The energy efficiency increases from 44.33% to 48.50%, if off-bleeding is considered at the reheater inlet or at low- and intermediate-pressure turbines. A lower solar energy requirement of 134 MW is found when off-bleeding is established at the reheater inlet, but it demands an increase in temperature to 337.40C. The approach enhances energy efficiency and introduces a new concept.
  Keywords: Existing thermal power plant; reduce bleedings; direct solar heating; increasing efficiency; energy and exergy analyses.
  DOI: 10.1504/IJEX.2026.10075150
   
  
• Investigating the Sectional Thrust and Exergy Efficiency of a Turbojet Engine  
  by Mustafa Akbas, Onder Altuntas, Arif Hepbasli 
  Abstract: This study delves into the performance characteristics of a turbojet engine, focusing on the impact of varying compressor pressure ratios and component geometries on thrust and exergy efficiency. The effects of Mach number and compressor pressure ratio on exergy utilisation efficiency at varying altitude values are also examined. Utilising the MATLAB, the analysis was conducted within a range of sea level to 12,000 m altitude. The results obtained provide valuable insights into the potential for optimising turbojet engine performance through strategic adjustments to pressure ratios and component geometries.
  Keywords: Exergy Analysis; Energy Analysis; Exergy Utilization Efficiency; Aeroengine Performance; Turbojet Engine.
  DOI: 10.1504/IJEX.2026.10075252
   
  
• Energy and Exergy Analysis of a Solar Air Collector with Evacuated Tubes under Different Flow and Reflector Configurations  
  by Nitin Panwar, Rajesh Attri 
  Abstract: This study investigates the energy and exergy performance of a solar air collector (SAC) integrated with evacuated tubes under varying air flow rates and reflector configurations. Experiments conducted from 08:0018:00 h showed outlet air temperatures up to 105.2. This study investigates the energy and exergy performance of a solar air collector (SAC) integrated with evacuated tubes under varying air flow rates and reflector configurations. Experiments conducted from 08:0018:00 h showed outlet air temperatures up to 105.2C. Energy efficiency ranged between 3571%, while exergy efficiency varied from 2.165%. Exergy input, output and loss averaged 104.6, 3.0 and 101.6 kJ/kg, respectively. Efficiency decreased near midday but improved later. Overall, the reflector-assisted high-flow system demonstrated superior thermal and exergy performance, highlighting its potential for sustainable and efficient solar air heating applications.
  Keywords: Evacuated tube; Solar air collector; Thermal Performance; Exergy; flow rates.
  DOI: 10.1504/IJEX.2026.10075494
   
  
• Exergy, Energy, and Exergoeconomic Assessment of a Solar Based Novel Power Generation System using Helium Brayton Cycle  
  by Achintya Sharma, Anoop Shukla, Onkar Singh, Meeta Sharma 
  Abstract: This study presents a novel solar power tower (SPT)-based power plant integrating a helium Brayton cycle (HBC) as the topping cycle and a recuperative organic Rankine cycle as waste heat recovery cycle. Energy, exergy, and exergoeconomic analyses were performed numerically. Results demonstrate that the proposed system achieved improvements of 19.86% in energy efficiency and 19.85% in exergy efficiency, however, at a 9.41% increase in overall plant cost compared to the conventional SPT-HBC configuration. Therefore, the proposed system achieved energy and exergy efficiencies of 34.45% and 36.89%, respectively, and a levelised cost of electricity of 43.23 $/MWh.
  Keywords: solar power tower; recuperative ORC; working fluid selection; helium Brayton cycle; exergoeconomic analysis.
  DOI: 10.1504/IJEX.2026.10075560
   
  
• Reinforcement Learning-Based Exergetic Analysis and Assessment of a Novel Cogeneration System for Smart Urban Energy Applications  
  by Asli Tiktas 
  Abstract: This paper presents a novel Kalina-based geothermal cogeneration system for smart urban energy applications, integrated with a reinforcement-learning-based exergetic analysis and control framework implemented in a digital twin environment coupling EES, TRNSYS and COMSOL. The configuration exploits absorber-integrated internal heat regeneration to raise the working-fluid temperature above the geothermal source without auxiliary energy input. The optimization results indicated that the reinforcement learning (RL)-based control strategy improved overall energy and exergy efficiencies by 0.066 and 0.058, respectively while simultaneously reducing CO? emissions by 0.126, levelized cost of electricity by 0.191, and the levelized cost of heating by 0.133.
  Keywords: Reinforcement learning optimisation; Digital twin modelling; Exergy-aware control; Low-grade heat recovery; Geothermal energy; Cogeneration systems; Exergy analysis; Exergoeconomic analysis.
  DOI: 10.1504/IJEX.2026.10075882
   
  
• Exergy Efficiency and Simulation of Novel Parabolic Solar Collector Influence of Turbulence Hybrid Nanotube  
  by Samaneh Baharloui, Mohammad Mohsen Peiravi, Mofid Gorji Bandpy 
  Abstract: The novelty stems from the original combination of a new collector design, interchangeable rib geometries, and advanced hybrid nanotube-based nanofluids. Determine how changeable rib geometries (square vs. triangular) combined with turbulent flow of hybrid nanotube-based nanofluids can improve the thermal efficiency of a newly designed PTSC, using 3D CFD simulations for performance analysis and optimisation. As regards the square collector increases surface incident radiation up to 0.36%. Furthermore, for the PTSC with square ribs and hybrid nanotube fluid demonstrated 0.22% to 0.81% better performance in total energy output, the triangular-rib collector showed 0.78% better performance under turbulent fluid flow conditions. At last, the use of triangular baffles improved collector thermal efficiency by 0.11%.
  Keywords: Exergy efficiency; Parabolic trough solar collector; Renewable Energy; Turbulence hybrid nanotube.
  DOI: 10.1504/IJEX.2026.10076082
   
  
• Sustainable Biodiesel Production from Waste Cooking Oil: A Thermodynamic Study with Process Simulation and Optimisation  
  by Md Nazeem Khan, Mohammad Zunaid, Amit Pal 
  Abstract: This research conducts a comprehensive simulation and optimization of biodiesel production from waste cooking oil (WCO) using alkaline catalysis, conducted through the software DWSIM software, involving acid pretreatment with sulphuric acid to lower free fatty acids and subsequent base-catalysed transesterification with potassium hydroxide. The study investigated various operational parameters, and their impacts on yield, exergetic efficiency, and exergy destruction, identifying optimal conditions that achieved a maximum yield of 90.85%. The investigation into thermodynamic principles provided valuable insights into system efficiency, revealing energy and exergy efficiencies of 92.97% and 91.02%, respectively. Furthermore, employing response surface methodology for optimisation revealed the ideal conditions, resulting in a yield of 92.88%.
  Keywords: Biodiesel production; waste cooking oil; thermodynamic analysis; DWSIM simulation; optimisation; potassium hydroxide.