International Journal of Exergy (18 papers in press)

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  Exergetic Comparison of a Novel to a Conventional Small-Scale Power-to-Ammonia Cycle ( Free Full-text Access )

  by Pascal Koschwitz, Daria Bellotti, Cheng Liang, B. Epple 
  Abstract: Green ammonia is a promising carbon-free energy vector and means to store hydrogen efficiently. Employing the software Aspen Plus®, this work presents an exergetic comparison of a novel small-scale power-to-ammonia system, to be tested in 2023 and designed for low investment cost and dynamic flexibility, to a conventional system. For a thorough evaluation six equations of state, one provided by an industry partner, as well as chemical exergies with and without excess values are compared. With 64.59%, the novel design has a 4.87% lower exergetic degree of efficiency. The difference can be attributed to the simplified design of the novel cycle, mainly to the use of an electrical preheater instead of an internal gas-gas heat exchanger and a recycle valve instead of a recycle compressor. However, an upcoming exergy economic analysis will show that the novel cycle is more economical overall, as its investment costs are lower.
  Keywords: exergy analysis; power-to-ammonia; P2A; process design comparison; Aspen Plus® process simulation.
  DOI: 10.1504/IJEX.2023.10058600
   
  
• Exergoeconomic analysis of a photovoltaic plant for different panel types  
  by FATIH AKKURT, Aysel Özselçuk 
  Abstract: In this study, exergoeconomic analyses of a 1166 kWp nominal power PV system for Polycrystalline, PERC Monocrystalline-Hulf Cut and PERC Monocrystalline panel types were carried out for the climatic conditions of Konya province in Turkey. The annual energy and exergy efficiencies were determined as 17.2% and 18.5% for PERC Monocrystalline-Half Cut, 16.8% and 18.1% for PERC Monocrystalline, 13.8% and 14.8% for Polycrystalline, respectively. The SPECO method was used for exergoeconomic analysis. The annual electricity generation costs were determined as 35, 41 and 37$/MWh while the payback periods were calculated as 48, 63 and 53 months for Polycrystalline, PERC Monocrystalline-Half Cut and PERC Monocrystalline, respectively.
  Keywords: PV system; exergy enalysis; exergoeconomic analysis; electricity generation cost; payback period.
  
  
• Energy, Exergy, Exergoeconomic Analysis of a General UAV  
  by Suha Orçun MERT, Mehmet Hakan DEMIR, Habibe DEMIR, Ceyda KOK 
  Abstract: A 3E -energy, exergy, exergoeconomic- analysis of a rotary wing UAV that is used for general purpose has been accomplished in this study. In the study a parametric investigation regarding the velocity, altitude and distance has also been investigated for identifying energy and exergy efficiency as well as exergoeconomic cost of operation. Looking at the results, while the distance increased from 0 m to 1200 m, the total energy increased up to 90000 J and the motor energy increased up to 65000 J. Parallel to this situation, energy efficiency reached 50% and exergy efficiency reached 40%. However, the exergoeconomic cost decreased from 0.0013 S/s to 0.001 S/s. While the velocity increased from 0 m/s to 14 m/s, the motor energy decreased to 10000 J and the total energy to 15000 J. As the velocity increased, the energy and exergy efficiency decreased to 20% and 15%, respectively. However, unlike energy and efficiency, the exergoeconomic cost increased as the velocity increased and was measured as approximately 0.00045 $?s. Finally, while the altitude parameter was increased from 0 m to 200 m, the total energy and motor energy increased by 20000 J and 17000 J, respectively. Contrary to this situation, while the altitude was increasing, the energy and exergy efficiencies decreased and reached up to 17% and 14%, respectively. The exergoeconomic cost increased with the speed increase and took the value of about 0.000455 $/s.
  Keywords: UAV; Energy; Exergy; Exergoeconomy; Drone; Cost; Analysis.
  
  
• Performance investigation and simulation of a diesel engine operating on seven-process cycle based on energy and exergy criteria  
  by GÜVEN GONCA, Ibrahim Genc, Bahri Sahin 
  Abstract: This work investigates energetic and exergetic performances of seven-process cycle which is combination of Dual-Miller and Takemura cycles based on parametrical and grid curves. The impacts of design parameters on the maximum performance characteristics are examined. In the results, the energy (1. law) and exergy (2. law) efficiencies maximize enhance by a determined range and then they minimize with raising engine speed. Power enhances with enhancing engine speed at constant compression, Takemura cycle, equivalence and cut-off ratios. Power and efficiencies increase with raising cycle pressure ratio at constant compression, Takemura cycle, equivalence and pressure ratios. Power and efficiencies decrease with increasing exhaust temperature ratio and cut-off ratio at constant compression ratio, Takemura cycle ratio, equivalence ratio and engine speed. They enhance with increasing pressure ratio and cycle temperature ratio at constant compression ratio, Takemura cycle ratio, engine speed and cut-off ratio.
  Keywords: Takemura cycle; Dual Miller cycle; Exergy; Performance optimization; Internal combustion engines.
  
  
• Exergy Analysis and Optimization of a Hybrid Solar-Geothermal Power Plant  
  by Mahya Moghadam, Mohammad Hasan Khoshgoftar Manesh, Ana Maria Blanco Marigorta 
  Abstract: The present study aims at the Energy, Exergetic, Exergoeconomic, Exergoenvironmental analysis of a hybrid solar-geothermal power plant. In addition, the emergy-based approach based on exergoeconomic and exergoenvironmental analysis has been performed. Genetic programming and artificial neural networks have been used to generate correlations for objective functions to reduce computational time. Advanced exergy, exergoeconomic, and exergoenvironmental analyses have been done to evaluate the system better based on exogenous/endogenous and avoidable/unavoidable parts of exergy destruction. Thermodynamic simulations have been verified with high accuracy with PETROSIM software and reference data. Results analysis show that the proposed cycle produces about 59.2 MW of net power.
  Keywords: Solar; Geothermal; Exergetic; Exergoeconomic; Exergoenvironmental.
  
  
• Design and 4E Analyses of a Novel Concentrated Solar Power Sourced Multigeneration System Using Thermochemical Cycle, Steam Rankine Cycle, Heat Pump and Multistage Flash Distillation as a Bottoming Cycles  
  by Ayşenur Özdemir, Yıldız Koç, Hüseyin Yağlı 
  Abstract: This paper focuses on a novel solar-based multigeneration system designed for the city of Iskenderun in Hatay The system consists of five subsystems to produce hydrogen, freshwater, electricity and domestic hot water: Solar power tower system, UT-3 thermochemical cycle, steam Rankine cycle heat pump and multi-stage flash distillation system The system performance was examined by using energy, exergy, economic and environmental analysis methods The effects of monthly average solar direct normal irradiance and ambient temperature on the energy and exergy efficiencies of the system designed throughout the year were investigated As a result of the calculations, it was found that the change of solar direct normal irradiance year-round did not affect energy efficiency But exergy efficiency increased towards the summer months The solar power tower system subsystem caused the maximum energy destruction in the system The average energy and exergy efficiency of the designed multigeneration system year-round were calculated as 37.82% and 36.6%, respectively. Outputs of the system were increased in the months of high direct normal irradiance. The payback period of the designed system was found 5.8 years. Thanks to the system, a reduction of 122,617 tons of CO2 emissions was achieved throughout the year.
  Keywords: Multigeneration system; solar power tower (SPT); UT-3 thermochemical cycle; steam Rankine cycle (SRC); heat pump (HP); multi-stage flash distillation (MSF) system.
  DOI: 10.1504/IJEX.2023.10057215
   
  
• Numerical Investigation Flat Plate Solar Collector Performance in Baghdad Base on Exergy Analysis  
  by Fadhil Kareem, Noor Lafta, Afaq Jasim 
  Abstract: The purpose of this study is to test the solar collector in Baghdad-Iraq (33.3 north latitude, 44.2 east longitude) the energy efficiency, exergy efficiency, exergy destruction, and exergy utilisation for the flat plate collector, aluminium absorber area of 1 m2 and thickness of 0.25 mm, sloped angle of 40
  Keywords: efficiency; energy; exergy; solar collector; flat plate.
  DOI: 10.1504/IJEX.2023.10057218
   
  
• Optimization of cumulative energy and exergy consumption of irrigated wheat production system using Data Envelopment Analysis approach  
  by Jaafar Habibi Asl, Abbas Asakereh 
  Abstract: The purpose of this study is to optimise cumulative energy and exergy consumption to increase the sustainability and renewability of wheat production by using data envelopment analysis (DEA) technique. Data were collected from farmers in Khuzestan Province, Iran. Cumulative energy and exergy consumption are 50,227 and 29,656 MJ/ha, respectively, which in the target scenario based on DEA, is reduced to 37,891 and 25,671 MJ/ha, respectively. The average technical efficiency score of wheat producers in terms of cumulative energy and exergy consumption was 0.784 and 0.960, respectively. The results showed that 80.70% and 77.2% of farmers were inefficient in energy and exergy consumption, respectively. Cumulative degree of perfection and renewable index were 0.72 and0.185, respectively. In the optimal scenario, these indices increased by 15.3% and 79.5%, respectively. The highest amount of exergy saving was related to chemical fertilisers and diesel fuel.
  Keywords: cumulative degree of perfection; cumulative energy and exergy consumption; CExC; data envelopment analysis; DEA; energy efficiency; renewability index.
  DOI: 10.1504/IJEX.2023.10057481
   
  
• Investigating cumulative energy and exergy consumption and environmental impact of sesame production systems, a case study  
  by Mohammad Hosein Noorani, Abbas Asakereh, Mohammad Reza Siahpoosh 
  Abstract: In this study, the production of sesame in traditional and mechanised systems was evaluated in terms of cumulative energy and exergy consumption, and environmental impacts. Data of traditional system were collected from 83 farmers in Khuzestan province in Iran and data of mechanised systems were obtained from Shahid Rajaei Agricultural Production Company in Iran. The findings showed that the energy and exergy efficiency in mechanised farms, were higher. Total cumulative exergy consumption in traditional and mechanised systems were 40,148 and 35,373 MJ/ton, respectively. Cumulative degree of perfection (CDP) and renewability index (RI) were obtained for traditional system 0.50 and 0.98, and for mechanised systems 0.57 and 0.74, respectively, indicating that the sesame production process is non-renewable. life cycle assessment (LCA) indicated that sesame production in the mechanised system has less harmful environmental and health effects. The findings showed that the use of renewable electricity significantly increases the renewability of the sesame production process.
  Keywords: CDP; energy productivity; exergy analysis; indehiscent capsules; LCA; renewability index; RI.
  DOI: 10.1504/IJEX.2023.10057807
   
  
• Multi-objective optimization of a transient solar absorption chiller from energetic, exergetic, and economic viewpoints  
  by Vajihe Davoodi, Mahdi Deymi-Dashtebayaz, Ehsan Amiri Rad 
  Abstract: An integrated solar absorption system is investigated in the present study. It consists of evacuated tube collectors, an auxiliary heater, a storage tank, and a LiBr-water absorption chiller. The system is conducted hourly from April to September. Variables of generator temperature, storage tank volume, and solar collector area are considered for the investigation. An optimization method is performed to find the optimum point from energetic, exergetic, and economic viewpoints. By using the TOPSIS method, the optimum point is obtained at a generator temperature of 100
  Keywords: Solar absorption chiller; Exergy efficiency; Multi-objective optimization; TOPSIS method.
  
  
• Exergy analysis and optimization of nitric acid production plant  
  by Oludare Odejobi, Atilade Oladunni, Grace Gbadebo 
  Abstract: Ostwald process for Nitric Acid production was simulated using Aspen HYSYS. Effects of input parameters on concentration of Nitric acid in the product show increase in mole fraction with increasing ammonia and air flow rates but decrease as feed water flow rate increases. Separator has highest exergetic efficiency of 90.4%. Optimum conversion for absorber, feed water temperature and flow rate are 70%, 25.5 ? and 3000 kg/h, respectively for exergetic efficiency and 69.8%, 25.49 ? and 3500 kg/hr, respectively for irreversibility. Flow rate for economical operation of the plant was 800 and 12000 kg/h for ammonia and air, respectively.
  Keywords: Nitric acid plant; exergetic efficiency; irreversibility; optimization; Aspen HYSYS.
  
  
• Thermodynamic Investigation of a Novel Synergetic Integration of Solar Based Kalina Cycle and Ejector Refrigeration Cycle  
  by Tawfiq Al-Mughanam, Abdul Khaliq 
  Abstract: This study is aimed to investigate the solar operated combined cycle consisting of tower solar collector, Kalina cycle, and ejector refrigeration cycle (ERC). Mathematically formulated model and numerical simulation through CFD using ANSYS-FLUENT package are employed to ascertain the impact of coil diameter (dc) and oil entry temperature on pressure and temperature of solar heat transfer fluid (SHTF). For entry temperature of 98
  Keywords: helically coiled tubes central receiver; Kalina cycle; ejector refrigeration cycle; ERC; cogeneration.
  DOI: 10.1504/IJEX.2023.10058064
   
  
• Daily energetic, exergetic, electricity and environmental analyses of photovoltaic thermal panel integrated with parabolic trough solar collector in four months  
  by Ayhan At?z, Mehmet Karakilcik, Mustafa Erden 
  Abstract: The energetic, exergetic, electricity, and environmental analyses of a Photovoltaic-Thermal (PV-T) panel combined with a parabolic trough solar collector (PTSC) are numerically for four selected sunny days in January, April, July, and October. The system essentially generates electricity and thermal energy. Thermal energy is produced by increasing the cooling water temperature used for the PV-T with the help of the PTSC. The system's maximum energy and exergy efficiency was obtained at 57.42% and 14.80% in July and January. Also, total carbon savings and electricity generation were found as 6.4881 kg, 12.0555 kg, 15.9464 kg, and 11.2239 kg and 18.3077 MJ, 26.72 MJ, 31.906 MJ, and 25.637 MJ a day in January, April, July, and October, respectively. The average temperature of the water was increased from 31.76
  Keywords: thermal energy storage; parabolic trough solar collectors; photovoltaic thermal collector; energy and exergy efficiency; carbon saving.
  DOI: 10.1504/IJEX.2023.10058065
   
  
• Exergetic Performance Analysis of Concentric Tube Heat Exchanger with V-Cut Twisted Tape Inserts and Al2O3+MWCNT Nanofluid  
  by SUMIT KUMAR SINGH, MAYARAM SAHU, Weon Gyu Shin 
  Abstract: This study investigates the performance of Al2O3+MWCNT hybrid nanofluid of volume concentration of 0.01% in concentric tube heat exchangers using V-cut twisted tape inserts. The effect of various flow rates (525 lpm) and geometric parameters (V-cut depth ratio, V-cut width ratio, and Twist ratio) on exergetic performance parameters were analysed. Results revealed that exergy and irreversibility rate increase with twist and depth ratios while decreasing with width ratio. Second law efficiency increases with twist and width ratios but declined with the depth ratio. Altering the V-cut inserts affects thermal and frictional entropy generation. These findings can optimise heat exchanger design for industrial applications.
  Keywords: concentric tube heat exchanger; V-cuts twisted tape; exergy; hybrid nanofluids; irreversibility; entropy generation.
  DOI: 10.1504/IJEX.2023.10058079
   
  
• Performance enhancement and exergy analysis of an aluminium reflector-assisted modification in existing PV system  
  by Aman Sharma, Vijay Kumar Bajpai 
  Abstract: Carbon dioxide emissions have risen sharply in recent years, and the solution is to switch to carbon-free energy sources. One of the renewable technologies with bright prospects is solar PV. To maximise performance, increasing the amount of irradiation and maintaining the operating temperature is required. This study suggests an easy modification for an existing solar PV system, with a combination of a single, dual aluminium reflector and spray cooling. NIT Kurukshetra is the site of the present investigation; a water spray recirculation system has been designed. Experiments were run comparing the performance of a reference configuration to those run with a single and a dual reflector. When using just one reflector and intermittent cooling, the average power generation efficiency increase was 5.74% compared to the reference system and when using a dual aluminium reflector with intermittent cooling it was 10.53%. An economic analysis and exergy analysis of the two methods and their comparison have also been made.
  Keywords: renewable energy; solar energy; single aluminium reflector; dual aluminium reflector; temperature-controlled spray cooling; exergy.
  DOI: 10.1504/IJEX.2023.10058935
   
  
• Integrative approach of thermoeconomics to obtain unit cost of products in power systems  
  by H-Y. Kwak 
  Abstract: In this study, it is aimed to show how the same unit cost of electricity generated by a thermal system is obtained with three different thermoeconomic approaches based on exergy analysis. These approaches are exergetic cost theory (ECT) by Lozano and Valero (1993), specific exergy costing (SPECO) by Lazzaretto and Tsatsaronis (2006) and modified productive structure analysis (MOPSA) by Kim et al. (1998). These approaches with some different modifications are applied to CGAM system. It is found that the ECT becomes SPECO when SPECO's fuel-rule and product-rule are applied to the ECT and both thermoeconomic methods offer the same unit cost of electricity from the CGAM system. The unit costs of electricity and steam by ECT and SPECO are found to be 7.34 $/GJ and 10.62 $/GJ, respectively. The unit cost of electricity and steam is determined to be 8.11 $/GJ and 10.24 $/GJ, respectively, by the MOPSA method. In this study, it is also shown how the unit cost of products calculated by ECT and SPECO for the CGAM system equals the unit cost of products obtained from MOPSA.
  Keywords: CGAM; exergetic cost theory; ECT; specific exergy costing; SPECO; modified productive structure analysis; MOPSA.
  DOI: 10.1504/IJEX.2023.10058987
   
  
• Exergy and sustainability-based optimization of flat plate solar collectors by using a novel mathematical model  
  by Aslı Tiktas, Huseyin Gunerhan, Arif Hepbasli 
  Abstract: A novel mathematical model was used to estimate optimum tilt and azimuth angles, considering exergoeconomic and sustainability aspects. This approach made the solar collector's performance evaluation independent of experimental precision. The optimal angles of (41.191
  Keywords: flat plate solar collector; tilt and azimuth angle; single and multi-objective optimisation; non-dominated genetic sorting algorithm; exergoeconomic factor.
  DOI: 10.1504/IJEX.2023.10059484
   
  
• Mathematical modelling and performance analysis of a novel auto-cascade refrigeration cycle for ultra  
  by Ibrahim Karacayli, Lutfiye Altay, Arif Hepbasli 
  Abstract: The main objective of this study is to assess both energetically and exergetically the performance of a novel auto-cascade refrigeration (NACR) cycle enhanced by an internal heat exchanger using R290/R170. In contrast to the ACR cycle with a 60
  Keywords: ultra-low temperature; refrigeration; auto-cascade refrigeration; ACR; exergy analysis; coefficient of performance; COP; second law efficiency.
  DOI: 10.1504/IJEX.2023.10059506