International Journal of Exergy (14 papers in press)

Regular Issues

• Exergy and Entransy Performance Analysis of an Unmodified 4-Stroke CI Engine Fuelled With CuO, Gr and Al2O3 Nano-Catalyst-Diesel Blend at Different Engine Speed  
  by Prabhat Patel  
  Abstract: This study evaluates diesel engine performance and fuel economy with copper oxide (CuO), graphene (Gr) and aluminium oxide (Al2O3) nanoparticles. Exergy and entransy analyses examined a diesel engine energy output with Al2O3, CuO and Gr) nanoparticle blends at five different concentrations. At full load, engine speed varied between 1500-2500 rpm. Nanoparticles (5 mg/l, 44 mg/l, 102 mg/l,160 mg/l, 200 mg/l) in diesel blends enhanced brake thermal efficiency by 12.35%, exergy efficiency by 7.5%, and entransy efficiency by 18.5%. Additionally, brake specific fuel consumption decreased by 11%, entropy generation by 5.5%, exergy destruction by 7.5% and entransy destruction by 18.5%. At 2100 rpm, the Gr based diesel with 160 mg/l nanocatalyst achieved maximum energy efficiency among all diesel nanocatalyst blends.
  Keywords: Exergy; Entransy; Engine Performance; Nanoparticles; Nanodiesel.
  DOI: 10.1504/IJEX.2025.10072090
   
  
• A Comprehensive Review on Advanced Exergy, Exergoeconomic, and Exergoenvironmental Analyses for Sustainable Thermal Energy Systems  
  by Uchenna Azubuike, Howard Njoku, Val Ekechukwu, Tien C. Jen 
  Abstract: Advanced exergy, exergoeconomic, and exergoenvironmental analysis (A3E) address weaknesses in conventional exergy, exergoeconomic, and exergoenvironmental methods (C3E) by evaluating system interactions and improvements. This review highlights the limited application of A3E analysis in thermal systems, with fewer than 15% incorporating these techniques. Studies on endogenous exergy destruction remain scarce, and A3E assessments are lacking. To ensure sustainability, the economic and environmental impacts of exergy destruction must be evaluated. Further research is needed, particularly in thermal power plants and other thermal systems, to enhance the application of A3E analysis.
  Keywords: exergy; advanced exergy; exergoeconomic; exergoenvironmental; sustainability; thermal systems; avoidable; unavoidable; endogenous; exogenous; environmental impact.
  DOI: 10.1504/IJEX.2025.10072212
   
  
• Optimising Processes for Exergo-Sustainability to Enhance System Efficiency in Low-Temperature Applications  
  by Olarewaju Ogini, Bukola Bolaji, Adedotun Adetunla, Tien C. Jen 
  Abstract: This study evaluates the exergo-sustainability of a vapor compression refrigeration system, proposing a process optimization model for efficient low-temperature use. Using R410A and R404A refrigerants, the system achieved -35C for 110 minutes, preserving plasma integrity for 72 hours during a power outage. Key performance metrics, including coefficient of performance (COP), exergy efficiency, and sustainability index, were analysed across low and high temperature cycles. Results showed a COP of 2.0, exergy efficiency of 97%, and cooling capacity of 170.7 kJ/kg. This system reduces energy losses and supports portable freezers for preserving heat-sensitive medicines in energy-deficient regions, helping save lives in hot climates.
  Keywords: Ambient temperature; boiling point; entropy; exergy loss; process optimization.
  DOI: 10.1504/IJEX.2025.10072513
   
  
• Variation Characteristics of Personnel Exergy Transfer under Different Environmental Conditions  
  by Guoshan Wu, Heqing Liu, Yiming Huang, Bo You, Shiqiang Chen 
  Abstract: In this paper, the exergy method is combined with the Prediction Heat Strain model to establish a worker exergy model and study whether exergy transfer can express the thermal comfort of workers. The results show the exergy transfer changes in a "single peak" curve with the temperature increase. Exergy transfer reflects the influence of temperature, humidity, wind speed, and labor intensity. A method was proposed to judge workers' thermal comfort based on the difference between the current exergy transfer and the maximum exergy transfer. This provides a new idea for studying workplace thermal comfort and ventilation cooling.
  Keywords: Exergy analysis; exergy transfer; worker; thermal environment.
  DOI: 10.1504/IJEX.2025.10072675
   
  
• Exergoenvironmental Decision-Making for Urban Energy Systems  
  by Xuecong Zhou, Rasool Bux Khoso 
  Abstract: The transition to sustainable urban energy systems is essential for addressing climate challenges and resource constraints. This study presents a novel exergoenvironmental decision-making framework integrating advanced multi-criteria methodologies, including Fuzzy Cognitive Maps, Grey Systems Decision-Making, and dynamic weighting algorithms. The framework evaluates urban energy configurations across technical, environmental, economic, and social dimensions, emphasising exergy efficiency and carbon emissions. Findings highlight the superiority of hydrogen-based energy systems and renewable integration in optimizing efficiency and reducing emissions. The methodology ensures adaptability to evolving sustainability priorities, offering actionable insights for policymakers and industry stakeholders while advancing sustainable urban energy transitions on global scale.
  Keywords: Exergoenvironmental Optimisation; Urban Energy Systems; Multi-Criteria Decision-Making; Renewable Energy Integration; Hydrogen-Based Energy; Sustainable Urban Development.
  DOI: 10.1504/IJEX.2025.10072681
   
  
• A Comprehensive Analysis of Thermo-Electrical Parameters in Photovoltaic Thermal (PVT) Systems Utilising Diverse Nanofluids  
  by Sourav Diwania, Maneesh Kumar, Pavan Khetrapal, Rajeev Kumar, Varun Gupta, Vivek Saxena, Ankur Maheshwari, Vanya Goel 
  Abstract: This study examines the thermo-electrical performance of a photovoltaic-thermal unit experimenting with various coolants namely water, Cu/water, TiO?/water, and Cu/TiO?/water. Using solar data from Ghaziabad (28.6692Cu/water, TiO2/water, and Cu/TiO2/water. Using solar data from Ghaziabad (28.6692Cu/water, TiO2/water, and Cu/TiO2/water. Using solar data from Ghaziabad (28.6692N, 77.4538E), India, the analysis revealed average system temperatures of 42.11C, 40.52C, 35.68C, and 33.85C respectively for each coolant. The Cu/TiO2/water hybrid nanofluid achieved the highest electrical efficiency compared to mono-nanofluids for PVT systems. Results showed that the hybrid nanofluid (50% Cu + 50% TiO2) outperformed mono-nanofluids, improving overall system efficiency by 14.09 % using Cu/TiO2/water hybrid nanofluid (2 vol. %) compared to water-cooled PVT system.
  Keywords: Hybrid Photovoltaic-Thermal (PVT) system; nanoparticles; thermo-physical properties; electrical efficiency; viscosity.
  DOI: 10.1504/IJEX.2025.10072714
   
  
• Understanding the Processwise Entropic Framework in an Industrial Heat-Powered Refrigeration Cycle  
  by Prathvi R.A.J. Chauhan, S.K. Tyagi 
  Abstract: This article presents a theoretical investigation of entropy generation rate (EGR) analysis to identify energy losses in an industrial adsorption refrigeration cycle using a silica gel-water pair. The system features two single-stage beds, with water serving as refrigerant, coolant, and hot fluid. EGR is observed to rise abruptly during valve-switching operations. For a complete cycle, the EGR contributions from external components like heat source and heat sink, are 18.03% and 21.56%, respectively. The internal heat transfer process contributes 11.37 kW/kg-K, nearly 9.97 times higher EGR than that of the internal mass transfer process, highlighting major inefficiencies within the system.
  Keywords: adsorption refrigeration; entropy generation; heat transfer; mass transfer; silica gel-water.
  DOI: 10.1504/IJEX.2025.10072834
   
  
• Thermodynamic Analysis of a Heat Pump Polygeneration System  
  by Vajeer Baba, Srinivas Tangellapalli, Rajeev Kukreja 
  Abstract: To accomplish the drinking water, air cooling/heating, and hot water requirements for small-scale and domestic industries, a solar-powered heat pump polygeneration system is incorporated with the least floor area. It operates by extracting heat from a low-temperature source for heating or cooling. Key variables include airflow rate, temperature, and humidity. Using simulation tool, at 75% humidity and 40C, the GOR and COP become 2.3 and 1.85. Additionally, the plant has an ECF of 2.2 and its cycles ECF is 2.9. Furthermore, at 25C and 75% humidity, the cycle and plant ECF were found to be 3.8 and 2.37, respectively.
  Keywords: Solar Energy; Heat Pump; Thermal Pollution; Desalination; Polygeneration.
  DOI: 10.1504/IJEX.2025.10072837
   
  
• Double-Flash Geothermal Plant: Clean Energy, Hydrogen, and Cooling Solutions  
  by Yunus Emre Yuksel, Fatih Y?lmaz, Murat Ozturk 
  Abstract: This study presents the thermodynamic performance evaluation of a novel double-flash geothermal power plant integrated with Kalina and trans-critical Rankine cycles for power, hydrogen, and cooling production. The results indicate that the designed system achieves a total power production of 3,854 kW, 0.005835 kg/s of hydrogen, and a cooling capacity of 385 kW. The overall energy and exergy efficiencies are calculated as 15.62% and 37.03%, respectively. Parametric studies reveal that increasing the geothermal source temperature and mass flow rate significantly enhances power and hydrogen production but reduces cooling performance. Additionally, variations in Kalina and Rankine cycle turbine pressures impact system performance. The study highlights the potential of geothermal energy as a sustainable solution for clean energy production, contributing to enhanced exergy efficiency and reduced environmental impact.
  Keywords: energy efficiency; exergy efficiency; thermodynamic analysis; geothermal energy; hydrogen production.
  DOI: 10.1504/IJEX.2025.10072851
   
  
• Energy and Exergy Efficiency Optimisation for Solar-Integrated Hydrogen Fuel Stations with Synergy of Electrocatalysis and Chemical Reactions  
  by Yan Tao, Anqi Wu, Xiaoshuang Hu 
  Abstract: A hybrid model combining is proposed for accurate direct normal irradiance (DNI) forecasting. The model significantly outperforms SARIMAX and GRU benchmarks, with an average R2 of 0.975. Enhanced DNI prediction enables optimised operation of a photovoltaic-powered hydrogen refuelling station, aligning solar input with hydrogen production needs. A techno-economic analysis confirms system feasibilidesign.ty, achieving a levelised cost of hydrogen of 3.20/kg and a net present cost of $2.14 million. Exergy analysis shows the rising irreversibility (1035 kW) with PV array size (3,0006,000 m2), revealing key energy-efficiency trade-offs for optimal system.
  Keywords: Electrolyzer; Histogram Gradient Boosting Regression; Photovoltaic panel; Refueling Station; Solar Irradiance Prediction; Solar power integration; Techno-Economic Analysis; Variational Mode Decomposit.
  DOI: 10.1504/IJEX.2025.10072890
   
  
• Exergo-Economic Optimisation of a Geothermal-Enhanced Cooling and Power Generation System: a Multi-Objective Approach  
  by Ali Esmaeili, Shoaib Khanmohammadi, Hossein Tamim, Ali Abbasi 
  Abstract: This study examines a multi-generation geothermal power plant, comparing a basic cycle and an advanced cycle. The basic cycle generates electricity only, while the advanced cycle simultaneously produces electricity, cooling, and hydrogen. Despite a reduction in energy and exergy efficiency, the advanced cycle offers benefits like hydrogen production and improved cooling capacity. It delivers 106.7 kW of net electricity and 21.36 kW of cooling load. Exergy destruction and parametric analyses were performed to assess system performance and efficiencies. Multi-criteria optimisation was used to identify the optimal operational conditions of the proposed system.
  Keywords: Geothermal; upgraded; refrigeration; parametric study; multi-objective optimisation.
  DOI: 10.1504/IJEX.2025.10072919
   
  
• Hybrid Optimisation Technique for Electric Vehicle Battery Charging via Wireless Power Transfer with Exergy Analysis  
  by Dharani M, Ravi R 
  Abstract: A hybrid method for Electric Vehicle (EV) charging-based wireless power transfer (WPT) system combines Sand Cat Swarm Optimization (SCSO) and Tree Hierarchical Deep Convolutional Neural Network (THDCNN), named SCSO-THDCNN. SCSO generates control signals, which THDCNN optimizes. The transmitter-coil creates an alternating magnetic field, and an AC/DC converter with power-factor adjustment converts alternating current (AC) power to direct current (DC). The design includes variable inductor control for constant-current (CC) and constant-voltage (CV) battery-charging profiles with misalignment tolerance. Implemented in MATLAB, the proposed model achieves 95% efficiency, surpassing existing methods.
  Keywords: Energy management; Wireless charging; Electric Vehicle; Battery; Wireless power transfer; Inductive power transfer; Energy efficiency; Charging performance; Exergy Analysis; Exergy Efficiency.
  DOI: 10.1504/IJEX.2025.10072996
   
  
• Performance Analysis of a Domestic Refrigerator Using R134a/CeO2 Nano-Enhanced Refrigerants: Energy, Exergy, and Economic Perspectives  
  by K. Arumuganainar, D. Palaniswamy, K. Viswanath, R. J. Eya Raj 
  Abstract: Household energy consumption is rising, with refrigerators being major contributors due to compressor load. This study explores enhancing refrigerator performance using ceria (CeO?) nanoparticle-enhanced refrigerants. Four blends R0 (R134a), R1, R2, and R3 (with 0.05%, 0.10%, and 0.15% CeO2 by volume) were tested. Results showed R3 improved cooling capacity by 7.8% (58.4 W) and COP by 14.5% (2.93) compared to R0. The exergy defect decreased by 5.5%, and exergy efficiency improved by 8.7% (23.92%). Economic analysis revealed operational costs dominate total cost. These findings highlight CeO2 additives potential in improving refrigeration efficiency, energy use, and sustainability.
  Keywords: Vapour compression; Refrigeration; R134a refrigerant; Nanoparticles; Exergy analysis; Economic analysis.
  DOI: 10.1504/IJEX.2025.10073021
   
  
• Exergoeconomic and Environmental Analyses of High Carbon Ferrochrome Production Process  
  by Sinan Kapan, Nevin Celik, Unal Camdali 
  Abstract: In this study, exergy and cost balance of a submerged arc furnace (SAF) producing High Carbon Ferro Chrome (HC FeCr) is evaluated. Exergoeconomic analysis of the HC FeCr was carried out using real operating data. The exergy cost of HC FeCr is found as 9929.32 $/h, and the cost per unit exergy is 125.74 $/GJ. The unit cost and hourly levelized cost of exergy loss are 69.32 $/GJ and 2401.13 $/h, respectively. The resource reuse rate is 84.26%. The amount of CO2 is 958.12 kg-CO2/HC FeCr-ton. The capital cost flow is very high, due to hourly levelized operating and maintenance costs.
  Keywords: High Carbon Ferrochrome; Submerged Arc Furnace; Exergoeconomics; Environmental.
  DOI: 10.1504/IJEX.2025.10073028