Forthcoming and Online First Articles

International Journal of Exergy

International Journal of Exergy (IJEX)

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International Journal of Exergy (24 papers in press)

Regular Issues

  • Exergy analysis for determining the salinity gradient energy potential in solutions of multiple salts   Order a copy of this article
    by Yunus Emami, Seyed Mehdi Pesteei, Oscar Andres Alvarez Silva 
    Abstract: This paper applies exergy analysis and the aqueous sodium chloride solution model (ASCSM) to assess salinity gradient energy potential. For the first time, the effects of two additional salts on the potential besides sodium chloride (NaCl) -i.e., magnesium chloride (MgCl2) and magnesium sulfate (MgSO4)- are investigated, leads to achieving more accurate assessments. The rivers flowing into the hyper-saline Urmia Lake in Iran are used as an exemplary case. MATLAB software is applied to analyze data. This research reveals that 9% of the additional potential is associated with MgCl2, and MgSO4.
    Keywords: Exergy Analysis; Salinity Gradient; Renewable Energy.

  • Analysis of main engine various waste heat cascade recovery systems under different evaporation pressure   Order a copy of this article
    by Changxin Liu, Huaan Li, Shanshan Yu, Zhenyu Du, Gaohui Li, Tianxiang Yu, Jingming Dong, Zhitao Han 
    Abstract: The TEG (Thermal power generation)-ORC (Organic Rankine Cycle) combined cycle system is a method suitable for ships cascade utilization of multiple waste heat, and the feasibility has been verified. Keeping the TEG/ORC bottom cycle ratios (BCR) at 0.615, the R245fa is employed to study the variation of the main parameters such as the system net power output (Wnet), system thermal efficiency (?s), power-production cost (Cg), and waste heat utilization of main engine flue gas (fg) under different evaporation pressure(P). As the P increases, the Wnet, ?s, and fg increase, and Cg decreases. When the P is 0.75Mpa, the output performance of the system parameters is optimal. the Wnet, ?s, waste heat utilization power (Wp), Cg, and rate of fg, is 483.25 W, 8.34%, 5796.72 W, 0.3464 $/kWh, and 69.05 %, respectively. The performance of the combined cycle system was improved by employing R245fa organic working fluid while being environmentally friendly.
    Keywords: Ships waste heat; Energy efficiency; Cascade utilization; TEG-ORC combined cycle; Evaporation pressure;.

  • Novel Hybrid Active Greenhouse Solar Dryer with Evacuated Tube Solar Collector: Energy and Exergy Analysis   Order a copy of this article
    by Pushpendra Singh, Manoj Kumar Gaur 
    Abstract: A novel hybrid active greenhouse solar dryer (HAGSD) attached with an evacuated tube solar collector is developed for faster drying of high moisture crops. Bottle gourd is taken as the drying product and dried to 10% moisture content. The energy balance of the greenhouse room air, crop surface, floor, and PV module has been established using the first law of thermodynamics. The exergy balance is also established to predict the heat loss through the dryer more accurately. The maximum exergy efficiency of the dryer is 7.92%, and the overall thermal efficiency of the setup is 7.88%.
    Keywords: Energy balance; Exergy balance; Hybrid dryer; Greenhouse; Bottle gourd.

  • Multi-objective Optimization of a Novel Organic Rankine-Goswami Cycle Operating with Different Refrigerants in the Organic Rankine Cycle   Order a copy of this article
    by Mert Sinan Turgut 
    Abstract: This paper tackles the multi-objective design optimization and comparative investigation of a cascade Organic Rankine-Goswami Cycle (ORC-GW) operating with various refrigerants, namely R600, R236ea, and R245fa, in the Organic Rankine Cycle (ORC). The solution of the multi-objective optimization problem is achieved by applying the African Vultures Optimization Algorithm (AVA). The results show that the ORC-GW operating ammonia-water/R600 working fluid pair has increased total cost and second law efficiency compared to its competitors, respectively 24.575 M and 0.440.
    Keywords: Multi-objective optimization; Goswami Cycle; Organic Rankine Cycle; Thermal design.

  • Exergetic growth efficiency of Kluyveromyces fragilis on complex organic and minimal inorganic media   Order a copy of this article
    by Mustafa Özilgen 
    Abstract: Kluyveromyces fragilis is the kefir yeast, it has been renamed and taxonomically reclassified many times during the recent decades. Exergetic efficiency of cultivation of Kluyveromyces fragilis on glucose or lactose containing complex organic and minimal inorganic media has been evaluated. Although the maximum cellular mass was produced in the complex organic media, exergetic efficiency of cultivation was higher in the minimal inorganic media. Crabtree effect was thought to reduce the exergetic efficiency in the glucose containing organic medium, such an effect was not observed in the glucose containing minimal inorganic medium. Exergetic efficiency was the highest, 61.2%, in the glucose containing minimal inorganic medium and the lowest, 24%, in the glucose containing minimal organic medium.
    Keywords: Kluyveromyces fragilis; cultivation on minimal inorganic media; cultivation on complex organic media; exergy efficiency; Crabtree effect.

  • Marine Engine Efficiency Improvement with Supercritical-CO2 Rankine Waste Heat Recovery   Order a copy of this article
    by Turgay Koroglu, Irfan Cavus, Muhammed Umar Bayer 
    Abstract: The efficiency of marine energy systems gain more and more importance considering economic and environmental effects. Additional power is produced by annexation of a supercritical CO2 Rankine cycle (sCO2-RC) via utilization of the exhaust of a marine engine. A parametric study on sCO2-RC is carried out to optimize objective functions such as ECOP, maximum net power output with respect to the outlet temperature of the exhaust stack, and the maximum pressure of the cycle. Then, energy and exergy analyses are applied to the system. Results show that the sCO2-RC system improves thermal efficiency by 8.17% and provides a 7.54% better fuel economy, while exergy efficiency of the sCO2-RC is 51.3% with a net power output of 321.7 kW and ECOP of 1.09. Hence, the results lead to the optimization order of the investigated system components for the improvement in overall efficiency, and the reduction of fuel consumption and environmental effects.
    Keywords: Supercritical CO2 Rankine cycle; Waste heat recovery; Exergy; Environmental effects; Fuel economy; ECOP.

  • Study on evaluation method for the rural solid waste fixed bed gasification using the AHP-FCE based on exergy analysis   Order a copy of this article
    by Xuehua Zhou, Xianan Xiang, Chenhua Wang, Zhiya Deng, Deyong Peng, Yongsuo Li, Jun Zhou 
    Abstract: An Analytic Hierarchy Process- Fuzzy Comprehensive Evaluation method (AHP- FCE) based on exergy analysis is proposed to evaluate the rural solid waste fixed-bed gasification process. The influence of gasification temperature, Equivalence Ratio (ER) and gasification agent on the gasification evaluation score are studied. Firstly, the exergy efficiency of gasification system is calculated by exergy analysis. Secondly, the AHP method is used to establish the optimal gasification process model, and the weight of the selected evaluation indexes is determined. The evaluation indexes include exergy efficiency, gas production rate, lower heating value (LHV) of producer gas, greenhouse gas emissions and waste residue emissions. Finally, the priority ranking of different gasification processes is obtained by the FCE method. The results show that when the gasification temperature is 1000
    Keywords: Exergy; AHP-FCE; Rural solid waste; Gasification;Fixed bed.

  • Thermoeconomic analysis of a solar combined cycle with Brayton, Kalina, and Organic Rankine Cycle   Order a copy of this article
    by Mukundjee Pandey, Biranchi Narayana Padhi, Ipsita Mishra 
    Abstract: The power from the sun intercepted by the earth is approximately 1.8
    Keywords: Low-temperature power cycles; Kalina cycle; Brayton cycle; Organic Rankine cycle; combined power cycles.

  • Avoidable thermodynamic inefficiencies evaluation of a sewagewater source heat pump system   Order a copy of this article
    by Aysegul Gungor Celik, Arif Hepbasli 
    Abstract: The performance of a sewagewater source heat pump system is assessed through conventional/enhanced exergy-based methods in this present study. The experimental data used in the analyses are based the cooling mode. According to the conventional-based results, the condenser has the lowest exergy efficiency. Beside this, the enhanced exergy-based analysis results show the sewagewater heat exchanger should be considered as the most significant component as it has the highest avoidable exergy destruction rate in the whole system and takes the improvement priority. Based on the enhanced exergy analysis, 56% of the total exergy destruction belongs to the avoidable part.
    Keywords: advance exergy analysis; sewagewater source heat pump; conventional exergy analysis; waste heat.

  • Thermo-economic assessment of upgrading a basic gas turbine power plant into CHP plant   Order a copy of this article
    by Sofiane ABERKANE, Hamza Semmari, Abdelkader Filali, Noura Rebai, Mustapha BELKADI 
    Abstract: This paper presents thermo-economic analyses of upgrading an existing Algerian gas turbine power plant into a CHP system. The proposed system includes a permanent upper steam rankine cycle combined with a flexible ORC system during the summer period or a waste heat recovery exchanger during the winter period. The results revealed an increased energy efficiency by 16.9% and 21.59 % for summer and winter configurations, respectively. Additionally; an increased exergy efficiency has been observed by 15.5 % for both proposed configurations compared to the simple gas cycle with a positive environmental impact in terms of carbon footprint the reduction. The economic study highlights that the proposed solution is more attractive for international market rather than the local Algerian market that is characterized by a lower energy price.
    Keywords: Waste heat recovery; Combined Heat and Power; Organic Rankine Cycle; Economic analysis; Aspen HYSYS.

  • Assessment of carbon neutrality of building materials using emergy parameter   Order a copy of this article
    by Tilba Thomas, Praveen A., Ajitha T. 
    Abstract: Development of appropriate tools and techniques are essential for the reliable assessment of carbon footprint of building systems. Comprehensive assessment of both energy and carbon emissions attributed to different building materials and correlating it with the Emergy values is established as an effective tool for assessing the sustainability. This research further emphasizes the utility of Unit Emergy Value of carbon dioxide emissions for various building materials to assess their carbon neutrality potential. Thus, significance of Emergy parameters in the judicious selection of building materials to curb carbon accumulation is established here.
    Keywords: Emergy; Carbon neutrality; Recyclability; Sustainability; Footprint.

  • Experimental exergy analysis of Low-GWP R290 refrigerant and derivation of exergetic performance equations with regression algorithms   Order a copy of this article
    by Oguzhan PEKTEZEL, Mehmet DAS, Halil Ibrahim ACAR 
    Abstract: This study analyzes derivation of performance equations for a refrigeration system operating with R290 and R404A refrigerants using different regression models. Results of Pace regression for coefficient of performance, second law efficiency, and total exergy destruction showed mean absolute error of 0.0993, 0.0159, and 0.0066, respectively. In all cases, Pace regression made better predictions than Elastic Net regression. It was concluded that predictions made with regression models showed a good agreement with the actual experimental results. The derived equations can be utilized for refrigerants working in similar operational ranges.
    Keywords: exergy analysis; machine learning; equation derivation; GWP; R290; R404A.

  • Energy and Exergy Analysis of a Geothermal Energy Sourced Hot-air Drying System   Order a copy of this article
    by Huseyin Utku Helvaci, Nazli Keles, Gulden Gokcen Akkurt 
    Abstract: A geothermal energy-sourced drying system was tested for the thin-layer drying process of tomato slices at air temperatures of 40, 50 and 60? and velocities of 0.5 and 1.5 m/s to investigate system performance in terms of the first and second laws of thermodynamics. The energy and the exergy efficiency of the system were found to be 6.6% and 22.31%. The energy utilization and energy utilization ratio were calculated in the range of 1.271-5.102 kW and 9.644-39.56%, respectively. The exergy destruction, exergy efficiency and improvement potential of the drying chamber varied between 0.0198-0.2621 kW, 59.74-81.95% and 0.00486-0.07396 kW, respectively.
    Keywords: Geothermal Energy; Tomato drying; Sustainable drying; Energy analysis; Exergy analysis.

  • Exergetic and exergoeconomic implications of a recuperative organic Rankine cycle plant for power production from an abandoned oil well   Order a copy of this article
    by Joseph Oyekale, Abiola Adeyi 
    Abstract: This study was aimed at assessing the exergetic and exergoeconomic implications of adopting a recuperative (SUB-REGEN) instead of a non-recuperative (SUB) organic Rankine cycle (ORC) plant for power production from an abandoned oil well. The geometric parameters of a typical oil well in Nigeria were adopted for simulating the heat source. The specific exergy costing (SPECO) approach was employed for the exergoeconomic assessment. Results showed that for the SUB ORC, the evaporator had the highest exergetic efficiency of about 86% and the condenser the highest cost rate of exergy destruction of about 47%. For the SUB-REGEN ORC, the condenser had the highest contribution ratio of 0.41 to the total irreversibility with a cost rate of about 19.1 k$/h. Overall, the integration of a recuperator would increase the ORC exergetic efficiency from around 55% to 58%, albeit with a consequent increase in the cost rate of system irreversibility by about 24%.
    Keywords: Abandoned oil well retrofit; Organic Rankine Cycle; Energy Efficiency; Sustainable Energy System; Exergy and exergoeconomic analyses.

  • Exergetic Optimisation of a Solar-Biomass Hybrid Greenhouse Dryer in Drying Banana Slices   Order a copy of this article
    by Florence Kiburi, Erick Ronoh, Christopher Kanali, Gareth Kituu, Patrick Ajwang 
    Abstract: In this study, an elitist non-dominated sorting genetic algorithm was applied in exergetic optimisation of a solar-biomass hybrid greenhouse dryer in drying banana slices. To develop comprehensive relationships for objective functions under each drying mode (solar, biomass, and solar-biomass), the system was linearized around drying and exit air temperatures. The objective functions involved maximizing exergy efficiency and drying air temperature of the system. The trade-offs showed that solar and solar-biomass modes required the same airflow rate (0.05 kg/s) indicating that at these combinations the dryer received almost equal energy input. Biomass mode trade-offs indicated that a lower flow rate (0.01 kg/s) was required for drying. Further, both solar-biomass and biomass modes must maintain a fuel feed rate of 0.001 kg/s for maximum exergy efficiency (solar-biomass: 80.21
    Keywords: Exergy; Hybrid Greenhouse Dryer; Solar-biomass; Energy mode; Optimisation; Genetic algorithm; Efficiency; Drying temperature; Performance evaluation; Banana slices.

  • A Parametric Study on Energy, Exergy and Exergoeconomic Analysis of a Paint Curing Oven   Order a copy of this article
    by Zeynep Naz AYVALI, Onder Ozgener, Leyla Ozgener 
    Abstract: This study examines a drying process for paint-drying ovens with actual operating data. This process is one of the most energy consuming processes in the manufacturing process of a company that produces propeller shafts in Manisa. This paper aims to determine the energy and exergy belts on a sectoral basis in light of the examined company and make an efficiency analysis. As a result of the analysis, the exergoeconomic values are calculated as the energy loss/cost ratio in current fresh air temperature is Ren:7.368 W/$; exergy losses/cost Rex:0.318 W/$, the total energy need is reduced by 13.25%.
    Keywords: Exergoeconomic Analysis; Energy Analysis; Exergy Analysis; Efficiency Studies.

  • Performance assessment of supercritical power plant based oil fuel under sliding-pressure operation   Order a copy of this article
    by Karim Mohamed, Ali Hassan, Hussein Maghrabie 
    Abstract: Energetic and exergetic analyses of a 626 MWe supercritical power plant-based mazout oil-fired are carried out to assess the systems performance. The energy losses and exergy destruction are evaluated for each system component using real actual data. The results show that the boiler is the primary source of irreversibility with 88.62% of the total exergy destruction. The intermediate pressure turbine maintains an exergy efficiency of 97% at 100%-load. Moreover, the maximum thermal efficiency is achieved at 100%-full load by 44.85% whereas, the maximum overall exergy efficiency of 40% is acquired at the maximum continuous rate condition of 105%-load.
    Keywords: energy and exergy analyses; supercritical steam power plant; sliding-pressure operation; mazout fuel.

  • Energy-Exergy-Emission-Economic performance and Multi Response Optimization of a VCR CI engine using Bio Ethanol Blended Diesel Fuel with Al2O3 Nanoparticles   Order a copy of this article
    by Sudhansu Mishra, Taraprasad Mohapatra 
    Abstract: A variable ratio compression ignition engine is tested experimentally for different fuel type (diesel, e-diesel and Nano fuel), load (4kg, 8kg, and 12kg), and compression ratios (14, 16, and 18) to determine its performance (Energy and exergy efficiency), emission (NOx emission), and economic characteristics (% relative cost). Multiple response optimization is carried out using response surface methodology for maximum performance, minimum emissions and cost. 5.2kg load, 18CR, and Nano fuel are determined as the optimal input parameters for attaining maximum energy and exergy efficiency of 24.8% and 62.9%, minimum NOx emission and %cost variation of 208.4 ppm, and -6.5 respectively.
    Keywords: Al2O3 nanoparticles; Energy; Exergy; Economic Analysis; Multi Response Optimization; Response Surface Methodology.

    by RAJESH KUMAR, Sujit Karmakar 
    Abstract: Solar energy is the most readily available energy in India, which can be utilized in coal-fired thermal power plants for feedwater heating and Monoethanolamine(MEA) for MEA regeneration in post-combustion CO2 capture unit. The present study deals with 4-E (Energy, Exergy, Environment, and Economic) analysis of a 500 MWe Supercritical (SupC) coal-based thermal power plant with solar-assisted feedwater heating and MEA regeneration in CO2 capture unit. Results show that the plant efficiency is improved by 8.2% points, and the coal consumption rate is reduced by 18%. The Levelized Cost of Electricity (LCoE) generation is increased to INR 6, and the cost for CO2 avoided is INR 3607 per tonne of CO2.
    Keywords: Solar energy; Exergy; Supercritical; High ash coal; CO2 emissions; Monoethanolamine(MEA).

  • An optimized solar-based microgrid integrated with desalination to enhance exergy sustainability   Order a copy of this article
    by Mohammadali Kiehbadroudinezhad, Adel Merabet, Homa Hosseinzadeh-bandbafha 
    Abstract: The size of a solar microgrid system should be designed based on aspects of sustainability, such as cost, exergy, etc. This study by the division algorithm finds the optimal size with maximum reliability vs. the cumulative exergy demand. Larak Island, Iran, is used as an example of how the concept could be applied to the real world. According to the introduced optimal size, 1 m3 of freshwater generated by the solar energy system leads to an average cumulative exergy demand of 17 MJ. While integrating a diesel generator into system means exergy demand reaches 33 MJ/m3 of freshwater.
    Keywords: Solar energy; Cumulative exergy demand; Desalination; Optimization; Reliability; Division algorithm.

  • Entropy generation analysis of fully developed turbulent convection in a twisted elliptical duct with constant heat flux   Order a copy of this article
    by Junlin Cheng, Zizhao Wang, Huiyi Mao 
    Abstract: In this study, the entropy generation and exergy efficiency of turbulent flow through a twisted elliptical tube were investigated. The effects of the fluid properties, the aspect ratio (1.05-10.00) and the twist pitch ratio (4-200) were considered. The results indicated that the total dimensionless entropy generation increased whereas the exergy efficiency decreased as the twist pitch ratio increased. Moreover, the total dimensionless entropy generation decreased, whereas the exergy efficiency increased with an increase in the aspect ratio. The minimum total dimensionless entropy generation of 0.01 is obtained with an aspect ratio of 10.00 and a twist pitch ratio of 16.36.
    Keywords: entropy generation; exergy efficiency; turbulent flow; twisted elliptical duct; constant heat flux; geometry configuration.

  • Exergy analysis in a HCCI engine powered with hydrogen enriched natural gas   Order a copy of this article
    by Tawfiq Al-Mughanam, Abdul Khaliq 
    Abstract: HCCI combustion is a very promising technology as it provides low NOx and soot formations with high efficiency. In the present investigation, the performance of turbocharged HCCI engine operated with hydrogen enriched natural gas was assessed using exergy analysis. The impact of equivalence ratio, turbocharger pressure, atmospheric temperature, and hydrogen enrichment has been ascertained on the engines energy and exergy efficiencies. Special attention is given to identification and quantification of irreversibility of combustion and heat transfer processes using the concept of entropy generation and exergy loss. It is demonstrated that combustion and heat transfer irreversibilities in HCCI engine can be reduced from 55% to 43.4% and its power output is augmented from 31.4% to 38.4% if natural gas is replaced with 100% hydrogen. Overall, the results of second law analysis for engine under consideration show that variations of operational parameters examined have considerably affected the exergy transfer, irreversibilities and efficiencies.
    Keywords: CNG; HCCI; Hydrogen enrichment; Second law.

  • Work Density Analysis and Thermoeconomic Optimization of Modified Carnot Cycle Engine   Order a copy of this article
    by Asim Sinan Karakurt, Guven Gonca, Bahri Sahin 
    Abstract: The modified Carnot cycle, a novel thermodynamic cycle, is introduced, and the cycle's performance is analysed in order to more accurately depict the performance and design parameters of actual heat engines. Work output, thermal efficiency, and work density are all considered in conjunction during the performance analysis. In terms of maximum pressure, maximum volume, work density, thermal efficiency, and size, the results demonstrate that the modified cycle performs better than the classic Carnot cycle at simulating the real heat engine. In the performance analysis framework, a thermoeconomic optimization has been carried out based on an objective function defined as the total cost per unit work output, which depends on an economic parameter, work density, and thermal efficiency. The findings might be used to select the modified cycle's ideal design and operation parameters, which can be applied to actual engines.
    Keywords: Carnot cycle; Modified cycle; Work density; Performance analysis; Thermoeconomic optimization.

  • Thermodynamic analysis of a solar refrigeration system based on combined supercritical CO2 power and cascaded refrigeration cycle   Order a copy of this article
    by Eydhah Almatrafi, Abdul Khaliq, Rajesh Kumar, Ahmed Bamasag, Muhammad Ehtisham Siddiqui 
    Abstract: This communication proposed a solar driven system based on supercritical CO2 (sCO2) power cycle integrated with cascaded refrigeration cycle (CRC) to refrigerate a thermal load of below than -400C. The impact of varying solar irradiance (DNI), type of solar heat transfer fluid (SHTF), and the working fluid of CRC on refrigeration capacity and exergy efficiency of combined system is investigated. Results indicate helium as the most efficient SHTF with air to follow. It is shown that maximum refrigeration is produced when operating with helium as SHTF and propylene as the refrigerant for CRC. From exergetic point of view, propylene provides higher exergy efficiency, CO2 is the one with lower, while N2O presents intermediate results. The exergy efficiency of the system for the propylene, N2O and CO2 is determined as 9.64%%, 8.73%, and 8.47%, respectively.
    Keywords: Gaseous solar heat transfer fluids; supercritical CO2 power cycle; cascaded refrigeration cycle; deep freezing; Exergy.