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International Journal of Exergy

International Journal of Exergy (IJEX)

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International Journal of Exergy (34 papers in press)

Regular Issues

    by Hayati Tore, Ali KILICARSLAN 
    Abstract: The energy and exergy analyses of a heat pump were experimentally carried out for refrigerants R134A, R404A, R407C. The effect of the environmental temperature (outdoor air temperature) between 25
    Keywords: Heat pump; Coefficient of performance; Exergy destruction; Exergy efficiency; R134A; R404A; R407C.

  • Exergy, can it be used to reflect the environmental issues of a fuel?   Order a copy of this article
    by Yaning Zhang, Tao Liu, Mengmeng Guang, Wenming Fu, Bingxi Li 
    Abstract: Can exergy be used to reflect the environmental issues of a fuel? This article elaborates if and how exergy can be used to reflect the environmental issues of a fuel, and details the processes for some typical fuels. The results show that the exergy method can be well used to reflect the environmental issues of a fuel. The case studies further show that coal samples (1324.99-1437.47 kJ/kg) have higher total environmental impacts than the biomass samples (381.02-1078.81 kJ/kg), and the environmental impacts are mainly contributed by CO2 (52.72%-99.37%), followed by ash (0.18%-35.93%), SO2 (0%-11.77%) and NO2 (0.16%-8.75%).
    Keywords: exergy; fuel; environmental issue; coal; biomass.

  • Energy and Exergy Analyses of Passive Solar Still Augmented with Nanoparticles   Order a copy of this article
    by Vikas Kumar Thakur, Manoj Kumar Gaur 
    Abstract: The paper presents the comparative energy and exergy analysis of passive solar still (SS) with two different nanoparticles and without nanoparticles. The analytical expressions of condensing cover, base fluid, and basin liner temperature are developed for both the cases. The daily yield of the SS with plain water, ZnO and CuO nanofluid is 1620, 2305, and 3365 mL/m2 respectively. The diurnal energy efficiency with CuO nanofluid is 26.56% and 39.14% higher than the ZnO nanofluid and plain water respectively. Moreover, the diurnal exergy efficiency with CuO nanofluid is 42.67% and 107.76% more than SS with ZnO and without nanofluid respectively.
    Keywords: Solar Still; Distillation; Energy efficiency; Exergy efficiency; Nanoparticles.

  • Energetic and exergetic investigation on a solar powered integrated system of ejector refrigeration cycle and Kalina cycle   Order a copy of this article
    by Ayman J. Alazazmeh, Abdul Khaliq, Shiv Lal 
    Abstract: Energetic and exergetic investigation of a solar powered system which simultaneously produce power and refrigeration is reported. Solar field is applied to drive the Kalina cycle bottoming with the ejector refrigeration cycle. Performance was analyzed after altering influencing operating parameters to investigate their effect on expander power, refrigeration load, exergy of refrigeration, energy efficiency, and exergy efficiency of the system. Results shows power output, energy efficiency, and the exergy efficiency of system increases while the energy and exergy of refrigeration are declined as the hot oil outlet temperature rises. Increase in concentration of ammonia-water basic solution results in the significant increase of expander power and increase in systems energy and exergy efficiency. From 100% energy supplied 25.4% appears as power and 10.52% produces as refrigeration, and rest 65.08% is lost. From 100% solar exergy supplied to system, 26.63% produced exergy, 1.85% is the exergy loss, and remaining 71.52% is destroyed.
    Keywords: Solar power tower; Kalina Cycle; ERC; Energy; Exergy.

  • New Optimum Multi-Generation System Configuration for Cooling, Heating, Power, Natural Gas and Hydrogen Production   Order a copy of this article
    by Mohammad Javad Mehrabian, Mojtaba Babaelahi, Mohammad Hasan Khoshgoftar Manesh 
    Abstract: One of the vital problems is access to energy systems that produce multiple products simultaneously. This paper aims to provide an optimal power plant that simultaneously generates cooling and heating loads, power, natural gas, and hydrogen. The proposed cycle includes various thermodynamic processes. The proposed system was evaluated using thermodynamics's first and second laws. In this research, Thermoflex software was used for system evaluation. Finally, multi-objective optimization is performed to achieve maximum efficiency.
    Keywords: Cooling; Heating; Power; Hydrogen; Optimization.

  • Performance comparison of solar powered cogeneration and trigeneration systems via energy and exergy analyses   Order a copy of this article
    by Shadab Ahmad, Mohd Parvez, Tasmeem Ahmad Khan, Suhail Ahmad Siddiqui, Osama Khan 
    Abstract: The study focuses on the comparison of solar-operated cogeneration and trigeneration energy systems. The prime objective of the system is to develop a novel solar thermal driven combined heat and power system at the first stage and then to extend the concept for the simultaneous production of electric power, process heating, and cooling at the second stage. The computed results present the energetic output which increased from 58% to 63% while shifting the mode of operation from cogeneration to trigeneration. The combined setup for the trigeneration exhibited higher efficiency of 66.63% in comparison to the cogeneration setup of 34.5%.
    Keywords: cogeneration; trigeneration; absorption refrigeration; exergy analysis; exergy destruction.

  • Exergetic assessment and exergoeconomic diagnosis of a sugarcane plant in northeastern Brazil   Order a copy of this article
    by Edmilson Junior, Carlos Santos, Markus Porangaba, Rafael Oliveira, Adriano Marques 
    Abstract: The increase in industrial needs increased the demand for fuels, electricity and the growth of climatic effects. This study performs an exergoeconomic evaluation in a sugar, ethanol and electricity production plant located in the Northeast of Brazil. The objective is to identify thermoeconomic inefficiencies, exergy destruction and efficiencies, determine the costs of exergy flows and a step by step of exergoeconomic diagnosis using the SPECO method. The results show the greatest inefficiencies presented in boiler 1 (48 MW, 28%), boiler 2 (43 MW, 25%) and boiler 3 (31 MW, 18%). The production of steam costs R$ 63.88 for each GJ of energy. The total cost of exergy destruction in the boilers is R$ 3808 per hour of operation which means about 84% of all exergy destroyed in the plant. The exergoeconomic diagnosis concludes that the equipment that needs optimization primarily are the deaerator (5904% rk) and the condenser (1674% rk).
    Keywords: Exergoeconomic; Exergy Destruction; Specific exergy cost; Sugar cane; Thermodynamic analysis.

  • Exergy Analysis of a Hybrid Thermoelectric Generator/Two-Stage Double-Lift Aqua-Ammonia Absorption Cooling System   Order a copy of this article
    by Hamza Tahaineh 
    Abstract: Nowadays, absorption refrigeration cycles using renewable energy or waste heat are very attractive. A hybrid thermoelectric generator/two-stage double-lift ammonia-water absorption refrigeration cycle powered by an evacuated tube solar collector was examined. A detailed thermal analysis was carried out by means of the Engineering Equation Solver. The typical location to install a thermoelectric generator was found to be after the evaporator and desorber 2. The coefficient of performance improves from 0.2 to 0.5 when the temperature difference after desorber 2 is raised from 5
    Keywords: Thermoelectric generator (TEG); Absorption Refrigeration System (ARS); Exergy; Coefficient of Performance (COP); Power.

  • Exergy Analysis of Purified Water Plant in a Pharmaceutical Industry   Order a copy of this article
    by Yigit Kupcu, Mahir Ince, Mahmut Bayramoglu 
    Abstract: Thermodynamic optimization of manufacturing plants at design or operation stages is known to be a complex process, resulting from the consideration of various design and operation parameters. Exergy analysis is an appropriate tool to implement the thermo-economical optimization of processes in a convenient way. In this study, exergy analysis was applied to a purified water plant in the pharmaceutical industry composed of various units such as ultrafiltration (UF), activated carbon columns, softener columns, reverse osmosis (RO), degasser, and continuous electro deionization unit (CEDI) process, and the exergetic efficiencies were found to be 75.47, 84.70, 64.78, 37.67, 96.88, and 85.50%, respectively. Considering the exergetic efficiency of the entire plant of 4.35%, significant opportunities are available to increase the energy and exergy efficiencies of this purified water plant by means of structural as well as parametric optimization tasks. By considering that most of the energy destruction in this plant stems from pump motors, especially in the RO unit, energy recovery devices such as pressure ex-changers and Pelton wheels may be used to increase the energy efficiency of the plant.
    Keywords: desalination; exergy; pharmaceutical industry; plant performance.

  • Experimental investigation and analyses of CI engine fueled with different blends of waste plastic oil and diesel   Order a copy of this article
    by Amar Kumar Das, Sudhansu Sekhar Sahoo, Achyut Kumar Panda 
    Abstract: The present work focuses on the energy, exergy, and economic study of a compression ignition engine working with waste plastic oil (WPO). Blends like 10% to 30% by volume of WPO with diesel are prepared and investigated experimentally to evaluate the performance parameters. The thermal efficiency and exergetic efficiency are found to be increased by 3.38% and 6.92 % with an increase in WPO blend up to 20% compared to the neat diesel case. The cost rate of inlet fuel for WPO20 is found to be decreased substantially from that of diesel. Moreover, the Sustainability Index of WPO20 by 1.38% higher than diesel ensured the extended durability of the engine and lesser damage to ecological factors.
    Keywords: Waste plastic oil; Compression ignition engine; Exergy analysis; Economic analysis; Sustainability index.

  • Historical Research Trends and Overview about Exergy: A Comprehensive Analysis   Order a copy of this article
    by Ibrahim Ozsari 
    Abstract: This study examines the contributions of researchers from around the world in the field of exergy over the past 30 years (1/1/1992-1/1/2022). Various aspects of the studies have been analyzed such as publication type, research areas, and keywords. In addition, countries, authors, journals, and institutions that have worked in the field of exergy were examined. Thus, the detailed results of the 5 most influential authors, 7 journals, and 15 institutions in the field of exergy in terms of publication, citation, PIP, and h-indexes are presented over the years. The effects of all countries broadcasting from the field of exergy in terms of publication and citation are shown. As a result of the analysis of all parameters, it has been shown that the most effective countries are China, Iran, and Turkey. Besides, it has been determined that Dr. Ibrahim Dincer is the most influential author who in terms of contributing authors.
    Keywords: Exergy; Bibliometric Analysis; Energy Systems; Research trends; Altmetric; Scientometric.

  • 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.

  • Sustainability assessment of sugarcane and sugar beet production systems by energy and exergy approaches: A case study   Order a copy of this article
    by Abbas Asakereh, Mostafa Kyani Deh Kiani, Mohsen Soleymani 
    Abstract: This study aims to determine cumulative energy and exergy consumption in sugarcane and sugar beet production systems in Iran and evaluate their environmental performance. Cumulative energy and exergy consumption, cumulative degree of perfection, and renewability index for sugarcane production were 66500 MJ/ha, 82561 MJ/ha, 6.21, and 0.86, respectively, and these values were 48267 MJ/ha, 67984 MJ/ha, 165831 MJ/ha, 6.42, and 0.84 for sugar beet production, respectively. The GHG emissions for sugarcane and sugar beet production were 4785 and 2851 kg CCO2-eq/ha, respectively, of which about 90% is due to direct and indirect energy consumption for irrigation irrigation.
    Keywords: Cumulative degree of perfection; Cumulative exergy consumption; Energy efficiency; Renewability index; Sugar beet; Sugarcane; Sustainability.

  • Optimized Coker Unit Design Integrating Heat Exchange Network and Exergy Analysis   Order a copy of this article
    by Ayat Ghallab, Ahmed Kishta, Reem Ettouney, Mahmoud El-Rifai 
    Abstract: Two approaches are applied for reducing energy consumption in an actual delayed coking plant converting vacuum residue into lighter and higher value hydrocarbon products. Pinch analysis is applied with a view to optimize the pinch temperature approach and structure of the existing 7 heat exchangers network. This resulted in about 27% reduction of the total annual cost corresponding to an annual saving of about US $ 1.9 million. Exergy analysis is also conducted on other main process plant equipment which revealed a possible annual saving of US $ 0.75 million through generation of medium pressure steam in the blowdown tower.
    Keywords: Delayed coker; Pinch analysis; Process optimization; Exergy analysis; Energy efficiency.

  • Practical method for measuring exergy   Order a copy of this article
    by Ekaterina Yushkova, Vladimir Lebedev 
    Abstract: Today, the enthalpy method is most often used to study technological installations for energy efficiency. Exergy analysis gives the most complete and objective assessment of various types of energy. Study presents an experimental setup that simulates a heating system to which an exergy meter is connected. As a result of the experiment, it turned out that the amount of heat remains constant if the temperature difference between the inlet and outlet is constant. However, the exergy method showed that exergy increases with an increase in the inlet temperature (even with a constant temperature difference); therefore, fuel consumption also increases with an increase in the initial temperature. The heat meter was invented a long time ago, but the device for measuring exergy did not yet exist. The device will give an impetus for a more active development of exergy analysis.
    Keywords: exergy; exergy measuring device; account of exergy; energy efficiency; exergoeconomic.
    DOI: 10.1504/IJEX.2022.10050697
  • Thermodynamic analysis of a coal fired supercritical thermal power plant integrated with molten carbonate fuel cell powered by coal gasification   Order a copy of this article
    by A. Pruthvi Deep, Sujit Karmakar 
    Abstract: A detailed thermodynamic analysis is carried out to study the outcomes from a 500 MWe steam power plant upon integrating molten carbonate fuel cell (MCFC). The modelling and analysis of the power plants are performed using a computer software program, Cycle-Tempo. The proposed plant with carbon dioxide (CO2) utilisation factor, ϕf = 90%, has improved the steam power plant's net energy efficiency by 17.87%. The integrated plant produces 724.11 MWe net power output with energy and exergy efficiencies of 37.91% (higher heating value basis) and 34.69%, respectively.
    Keywords: energy; exergy; high ash coal; gasification; molten carbonate fuel cell; MCFC; CO2 utilisation factor.
    DOI: 10.1504/IJEX.2022.10050698
  • Exergy analysis of a coal-fired thermal power plant in Kangal District of Turkey   Order a copy of this article
    by Sevgi Erzen, Halil Ibrahim Acar, Oguzhan Pektezel 
    Abstract: In this study, thermodynamic analysis of Kangal thermal power plant operating in Turkey was performed. Energy and exergy values of 35 points in the power plant were calculated. Energy and exergy equations of all components were derived to analyse the system performance. Exergy destruction, the second law efficiency and the efficiency defect were calculated for the system components. Also, the effect of ambient temperature on exergetic performance of the turbines and the condenser was analysed. Results were presented in graphs. The boiler was determined as the equipment that caused the greatest exergy destruction with 91.7%. The second high pressure feed water heater showed the greatest second law efficiency with 94.39. Thermal and the second law efficiency of the power plant were found to be 32.8% and 52.6%, respectively. It was found that increase in ambient temperature had a positive effect on condenser while had a negative effect on turbines.
    Keywords: exergy analysis; thermal power plant; ambient temperature; efficiency defect; Turkey.
    DOI: 10.1504/IJEX.2022.10050699
  • Determination of optimum PV/T configuration on horizontal plane for maximum exergy output   Order a copy of this article
    by Halit Bas, Atilla Biyikoglu, Birol Kilkis 
    Abstract: The optimisation of PV/T flat-plate water collector groups depending on the variable values of mass flow rate, tube diameter, tube spacing and number of collectors was made based on exergy efficiency. Two different hydronic configurations, namely, series and series-parallel connection arrangements were investigated. An analytical model was developed to obtain exergy efficiencies. The results showed that when all other parameters were kept constant, the total exergy gain for any operating condition was higher at the series connected collector arrangement than at the series-parallel one.
    Keywords: PV/T collector; collector configuration; exergy efficiency; exergy-based optimisation.
    DOI: 10.1504/IJEX.2022.10050700
  • Exergy evaluation of integrated liquefier-cryocondensation and cryosorption helium purification systems based on experimental data   Order a copy of this article
    by Trijit Kumar Maiti, Sandip Pal, Balaram Kundu, Parthasarathi Ghosh 
    Abstract: The present investigation conducts on two different methods of cryogenic helium purification processes with the identical input (1.50%v/v N2 impurity) and output (grade 4.5). Accordingly, exergy analysis has been performed with experimental data on two kinds of commercial purifiers, viz., an integrated liquefier-purifier (cryocondensation) and a cryosorption purifier. The current study evaluates quantitatively the superiority of cryosorption purifier and assesses the exergy performance of helium liquefier on being integrated with different methods of purification systems. The key findings are useful for selecting, augmenting, and developing an efficient purification process.
    Keywords: helium; purifier; liquefier; exergy; energy; cryo-condensation; cryosorption; specific power consumption; SPC; figure of merit; FOM.
    DOI: 10.1504/IJEX.2022.10050701

Special Issue on: TUBA WCEST-2021 The Role of Exergy in Energy Science and Technology

  • Exergy analysis and multiobjective optimization of ORC using NSGA-II   Order a copy of this article
    by Ashwni Ashwni, Ahmad Faizan Sherwani 
    Abstract: A detailed analysis of the organic Rankine cycle is carried out using environmentally friendly working fluids such as butane, isobutane, hexane, etc. in this study. Moreover, its performance is optimized using the non-dominated sorting algorithm-II. The results indicate that evaporator temperature and the condenser temperature have a major influence on the ORCs exergetic performance. ORC has an optimal exergetic efficiency of 60.49%, 1.6 years payback period with a $7846 life cycle cost using hexane.
    Keywords: Exergy; Sensitivity; Organic Rankine cycle; NSGA-II.

  • Exergy Analysis and Multiobjective Optimization of ORC Using NSGA-II   Order a copy of this article
    by Mohammad Ali Sabbaghi, Mohammad Sefid 
    Abstract: In this paper, thermodynamic analysis and optimization studies are investigated on an ORC for multigeneration using geothermal and biomass energies. Results indicated that the ORC is responsible for 65% of the total exergy destruction rate. The produced hydrogen and freshwater rates are 1.264 lit/s and 5.9 kg/s, respectively. By increasing the temperature of the geothermal source from 400 to 430 K, the hydrogen and freshwater production rates increase to 19.6 and 17.6 %. If all energy is supplied by biomass, the amount of emitted CO2 will increase to 60.3%.
    Keywords: Organic Rankine Cycle; Exergy; Environmental; Hydrogen; Desalination; Optimization.

  • Thermodynamic re-assessment of a geothermal binary power plant operated in a moderate-temperature geothermal field   Order a copy of this article
    by Zeynep Ozcan, Gulden Gokcen Akkurt 
    Abstract: An existing Organic Rankine Cycle Power Plant which uses isobutane as working fluid, is re-evaluated for different working fluids. The plant is first modelled by EES software, then the model is simulated for different working fluids obtaining heat transferred through the heat exchanger, net work output, energy and exergy efficiencies, and mass flowrate of the working fluid. Two parametric studies are conducted to evaluate the thermodynamic performance of the plant under a range of turbine inlet temperature (130-155
    Keywords: binary geothermal power plants; working fluid selection; energy analysis; exergy analysis.

  • Exergy Analysis of a Steam Power Plant at Full and Partial Load Conditions   Order a copy of this article
    by Uchenna Azubuike, Linus Egbuhuzor, Howard Njoku, Onyemaechi Ekechukwu 
    Abstract: Exergy performances were investigated for a 220 MW gas-fired steam turbine power plant operating at full and partial loads. Analyses relied on full and partial plant load design data. Compared to other components, boiler exergy efficiencies - 42.8%, 42.5% and 41.8% were the least at 100%, 75% and 50% loads, respectively. The condenser exergy efficiency was least (40.29%) at 25% load. Exergy efficiencies of high pressure heater 6 were the highest across all the loads. For the entire plant, overall exergy efficiencies increased from 28.29% at 25% load to 33.18% at 100% load.
    Keywords: exergy analysis; exergy efficiency; exergy destruction; steam power plant; design load; operating loads; full load; partial load; off-design.

    by Nizar BEN EZZINE, Raoudha GARMA, Monia CHATTI, Ahmed BELLAGI 
    Abstract: In this paper, we present the experimental and simulation results of our investigations of a fully self-circulating thermal absorption refrigerator driven by a bubble pump and using R718-LiBr refrigerant-absorbent mixture. The performed tests on the prototype designed with 10 mm diameter bubble pumps show that each bubble pump requires about an energy input of 41W, and consequently a refrigerant temperature of 65
    Keywords: Experimental study; Absorption refrigeration; Design; R718/LiBr; Bubble pump; Modelling and Simulations.

    by Nizar BEN EZZINE, Rouadha GARMA, Monia CHATTI, Ahmed BELLAGI 
    Abstract: In this work, a new configuration of the hydrogen-R717-water diffusion-absorption refrigeration cycle is proposed, investigated and compared to the basic standard Platen-Munters configuration by numerical simulation. Basing of the results of the exergy analysis, the original cycle is modified by incorporating components for internal rectification heat recovery. The calculations show that the performances of the modified cycle are largely improved: a minimum evaporation temperature of ?24
    Keywords: Hydrogen; Absorption Refrigeration; R717; Enhancement design; COP; Internal heat recovery; Simulation.

  • Exergetic analysis of a newly geothermal power-based integrated system for various outputs   Order a copy of this article
    by Yunus Emre YUKSEL, Fatih YILMAZ, Murat Ozturk 
    Abstract: In this research, a novel geothermal power-based combined plant is planned for various valuable products generation. A flash-binary geothermal plant, an organic Rankine cycle plant, a transcritical-CO2 plant, a hydrogen production plant, and a magnetic refrigeration plant are integrated together to generate beneficial products. In the evaluation part of the paper, thermodynamic analyses, validation studies, and parametric studies are performed. According to the assessment outputs, the total power production is found as 20220 kW, the heating capacity is 8726 kW, and the cooling generation rate is 1341 kW. In addition, the hydrogen production rate of the designed energy plant is 0.0124 kg/s.
    Keywords: Geothermal energy; exergetic analysis; integrated plant; efficiency; multi-generation.