International Journal of Exergy (15 papers in press)

Regular Issues

• Solar Radiation Estimation Modelling through the Maximum Entropy Principle  
  by Atteeq Razzak, Zoobia Khalid, Shafiq Urrehman, Muhammad Mustaqeem Zahid, Muhammad Adeel 
  Abstract: Pakistan has great potential for gathering solar energy due to its geographical position. In this paper, we have estimated three types of radiation, global solar radiation, bean solar radiation, and diffused solar radiation, through the maximum entropy principle for eight cities of Pakistan which are geographically apart at least 500 km; this principle maximises the entropy function based on some constraints. The maximum entropy principal distribution results generate the best curve representing these radiations. There are three plots for each city corresponding to three radiations for each city; the plot shows that the fitted curves are excellent and give the best knowledge about the radiations.
  Keywords: solar radiations; entropy; maximum entropy principle; ASHRAE model.
  DOI: 10.1504/IJEX.2024.10064414
   
  
• Performance Analysis of a Photovoltaic Thermal-Thermoelectric Cooler Air Collector Integrated with a Mixed-Mode Greenhouse Solar Dryer  
  by Ajay Pratap Singh, Sumit Tewari, Harender Sinhmar 
  Abstract: In the present article, a PVT-TEC air collector integrated with an MMGHSD has been evaluated, and a mathematical model has been derived for finding distinct parameters, namely, the temperature of the solar cell, TEC, air from PVT-TEC, crop, and room. The outcome shows that with TEC, the electrical efficiency increased by 2.23% compared to basic PV. Further, the impact of air mass flow rate on energy, exergy, electrical, and thermal efficiency has been computed. The system's exergy and exergy efficiency were in the range of 18.9165.55 Wh and 11.9616.44%, respectively, for a 0.01 kg/s mass flow rate.
  Keywords: photovoltaic thermal; PVT; thermoelectric cooler; TEC; mixed-mode greenhouse dryer; MMGHSD; energy; exergy efficiency; mathematical modelling.
  DOI: 10.1504/IJEX.2024.10065331
   
  

Special Issue on: Exergetic Evaluation of Sustainability Energy System – Part 2

• Assessment of conventional and enhanced exergy analysis of the natural gas liquefaction plant  
  by Arif Karabuga, Zafer Utlu 
  Abstract: The liquefaction method has become increasingly important in the natural gas trade as a result of both the cost and application difficulties associated with pipe transfer. In this study, enhanced exergy analysis of the cryogenic method used in the liquefaction of natural gas is discussed. When each component is examined, the highest exergy destruction was obtained in the turbine as 1,164 kW. The exergy efficiency of the overall system was calculated as 52.52%. In this study, the most significant consequence of exergy destruction n the turbine was discovered to be caused by unavoidable exergy destruction.
  Keywords: liquefied natural gas; LNG; enhanced exergy analysis; liquefaction system; cryogenic.
  DOI: 10.1504/IJEX.2024.10064052
   
  
• Impact of support pillars geometry on thermal insulation performance of vacuum glazing: CFD research and exergy analysis  
  by Pinar Mert Cuce, Erdem Cuce, Harun Sen 
  Abstract: Vacuum glazing technology is based on evacuating the gas between the double glasses and aims to prevent heat losses by eliminating convection effects. This study evaluates the effect of thermal conductivity and column design on the window heat transfer coefficient with a 2D CFD study, taking 200 × 350 mm vacuum glass as a reference. The effect of changing the glass thermal conductivity between 0.1-0.4 W/mK on the window heat transfer coefficient (U_w) is analysed. For thermal conductivity of support pillars, solutions in the range of 0.04-0.20 W/mK are taken. Model results are evaluated for convergent and divergent column design. The reference U_w value of 1.21 W/m²K was determined as 0.76 W/m²K in the converging cylindrical column design and 0.92 W/m²K in the divergent one.
  Keywords: vacuum glazing; heat transfer coefficient; support pillar design; thermal resistance; exergy analysis.
  DOI: 10.1504/IJEX.2024.10063157
   
  
• Occupancy and occupant number detection for energy saving in smart buildings via machine learning techniques  
  by Zeynep Turgut, Gökçe Akgün 
  Abstract: In this study, various machine learning techniques are applied for occupancy detection to provide occupancy-based energy savings in smart buildings. Occupancy detection can be achieved using environmental data obtained via various environmental sensors placed in smart environments. This study focuses on energy saving in smart buildings with occupancy detection, and avoiding unnecessary sensor use by determining which features are more effective in detecting occupancy by utilising a sample dataset. Sensor information considered as features and tested using various machine learning algorithms. In this context, both occupancy detection and occupant number detection classification are realised, and an exergy analysis is presented.
  Keywords: occupancy detection; internet of things; IoT; machine learning; energy saving; smart buildings.
  DOI: 10.1504/IJEX.2024.10063797
   
  
• Assessment of entropy-based approach for the environmental impact of the cooling process in clinker production  
  by M. Ziya Sogut 
  Abstract: Cement clinker production is an energy-intensive process that results in significant environmental pollution. This study analyses the environmental effects and exergy performance of the cooling process in dry-type cement production using an entropy-based approach. The process' useful exergy efficiency was found to be 17.4%, while the waste-induced exergy was 51.1%. The useful exergy EPI value was 0.685, with a development rate of 65.87% and an energy efficiency rate of 56.52%. The process has an energy efficiency rate of 27.18%. Based on the results, measures to improve environmental sustainability by reducing entropy production in the cooling process were recommended.
  Keywords: cement; cooling process; exergy; entropy; environmental performance.
  DOI: 10.1504/IJEX.2024.10064257
   
  
• Evaluation of exergy destructions of different refrigerants in a vaccine cooling system with artificial intelligence  
  by Elif Altıntaş Kahriman, Alişan Gönül, Ali Köse, İsmail Cem Parmaksızoğlu 
  Abstract: Nowadays, low-temperature storage and distribution of many vaccines are as important as their production. In this study, the performance of a storage device operating in a vapour compression refrigeration cycle designed to provide low-temperature cooling between 201 K and 275 K using R134a, R1234yf, R502, and R717 fluids is evaluated by both thermodynamic and artificial neural network (ANN) methods. Levenberg-Marquardt, Bayesian regularisation, and scaled conjugate gradient algorithms are compared with thermodynamical calculations to predict the energy efficiency and exergy destruction of the cooling system. All the considered artificial intelligence algorithms are found to accurately predict the expected outputs with R² values greater than 0.9.
  Keywords: low temperature cooling; artificial intelligence; exergy analysis; vaccine storage unit; artificial neural network; ANN.
  DOI: 10.1504/IJEX.2024.10063963
   
  
• Using advanced exergy analysis to select an optimal working fluid pair in an absorption refrigeration cycle  
  by Hamid-Reza Bahrami, Peyman Rafie 
  Abstract: This study has been done to compare LiNO₃-NH₃, LiBr-H₂O and LiCl-H₂O for using in absorption chillers using advanced exergy analysis (AEA) where LiCl-H₂O showed the highest COP and ECOP, and has in turn the lowest unavoidable exergy destruction. AEA results indicate that only 26% of the total exergy destruction in the cycle is preventable. The desorber has the highest exergy destruction with only 88% of it being unavoidable. The solution heat exchanger and the absorber could be improved as over 50% of their exergy destructions are avoidable. The research highlights how AEA provides insights into exergy destruction sources and potential improvements in absorption chiller systems.
  Keywords: advanced exergy analysis; absorption chiller; second law of thermodynamics; coefficient of performance; exergy coefficient of performance; heat transfer.
  DOI: 10.1504/IJEX.2024.10064259
   
  
• Exergy analysis and performance improvement of direct steam-generated solar-based transcritical CO₂ Rankine cycle with energy storage  
  by Serpil Celik Toker, Onder Kizilkan, Hiroshi Yamaguchi 
  Abstract: In this particular study, the researchers conducted energy and exergy analyses of a solar-based transcritical CO₂ Rankine cycle in order to improve its performance by integrating a regenerator and an energy storage unit. For the assessment, the system's features are drawn from genuine experimental research undertaken at Doshisha University in Kyoto, Japan. The effects of employing a regenerator and an energy storage tank were examined theoretically in order to determine the potential for enhancing the performance of the cycle. According to the data analysis, there has been a substantial boost in the energy produced, registering an impressive 22.7% improvement.
  Keywords: solar energy; transcritical CO₂ Rankine cycle; energy; exergy; heat storage.
  DOI: 10.1504/IJEX.2024.10065409
   
  
• Energy and exergy analysis of a novel multi-fluid heat exchanger for sustainable space and water heating application  
  by Belal Almasri, Taraprasad Mohapatra, Sudhansu S. Mishra 
  Abstract: The novel multi-fluid heat exchanger (NMFHE) is a modified double-tube exchanger, tested under various flow rates, temperatures, and flow configurations. The overall heat transfer coefficient (U_o), effectiveness, Colburn factor (j), JF factor, exergy efficiency, and sustainability index (SI) are determined as the thermal and sustainability parameters for this study. The maximum (U_o of 276.1 W/m².K and 22.03 W/m².K are observed at 300 LPH flow rate, 80°C inlet temperature of HF1, and CF1 configurations. The maximum (j, JF factor, exergy efficiency, and SI were 0.006, 0.08, 0.785, and 4.066, respectively, at 100 LPH flow rate and 60°C inlet temperature of HF1.
  Keywords: multi-fluid; brazed helix tube; BHT; heat transfer; exergy efficiency; sustainability index.
  DOI: 10.1504/IJEX.2024.10064739
   
  
• Energetic and exergetic performance analysis of a double pass asymmetric CPC photovoltaic/thermal solar collector suitable for building facade  
  by Wan Nur Adilah Wan Roshdan, Hasila Jarimi, Adnan Ibrahim 
  Abstract: An asymmetric compound parabolic concentrator (CPC) photovoltaic/thermal (ACPC-PV/T) solar collector with a double-pass air channel has the potential to enhance PVT performance for facade applications. Through outdoor experiments, we compared the ACPC-PVT with the symmetric CPC PV/T and conventional flat-type PV/T. The analysis shows ACPC PV/T exhibits superior energetic efficiency by 3.95% and 10.79% compared to symmetric CPC PV/T and conventional flat-type PV/T, respectively. Exergy analysis strengthens these findings, with overall exergy efficiency higher by 3.79% and 20.07%, respectively. Economic evaluation reveals a favourable 6.84-year payback for ACPC PV/T, the lowest among the three.
  Keywords: PV/thermal; asymmetric; compound parabolic concentrator; CPC; energy; exergy.
  DOI: 10.1504/IJEX.2024.10064416
   
  
• Assessment of environmental impact by entropy-based approach for cryogenic cooling processes  
  by M. Ziya Sogut 
  Abstract: The study presented the energy and environmental performance of cryogenic refrigeration for frozen food applications and discussed the standard and cryogenic cooling performances of fruit and vegetable products with an entropy-based approach. In cryogenic processes, exergy efficiency has been shown to have a potential of 2.56 times higher than standard applications. On the other hand, when the environmental indicators according to entropy productions were examined, it was seen that the environmental pollution potential of cryogenic processes was 32.37% less than standard practice. At the end of the study, the sustainability effects of cryogenic cooling were also evaluated.
  Keywords: frozen food; exergy; entropy; environmental performance; sustainability.
  DOI: 10.1504/IJEX.2024.10064822
   
  
• Assessment of energy and exergy efficiencies of mini photovoltaic modules  
  by Ahmet Yildiz, Gulsah Cakmak, Yusuf Bilgic 
  Abstract: In this study, the electrical performance of the 2.4 W mini photovoltaic module was determined under different solar radiation conditions in June 2022. A comprehensive thermodynamic analysis was performed, involving the calculation of energy and exergy efficiency based on data from day-long experimental studies. Efficiency values obtained by considering the measured solar irradiance intensity were observed. Energy efficiency and exergy efficiency ranged from 17% to 19% and 6% to 11%, respectively. It has been observed that the exergy efficiency increases with the intensity of solar radiation and the ambient temperature has a significant contribution to this case.
  Keywords: exergy; energy; power; efficiency; mini photovoltaic.
  DOI: 10.1504/IJEX.2024.10064779
   
  
• Energy, exergy and economic assessments of wind turbine alternatives  
  by Nurdan Yildirim, Levent Bilir 
  Abstract: In this study, two wind turbine installation alternatives for a residential district of 20 detached houses in six different European cities are considered. Firstly, the installation of an individual residential scale (5 kW) wind turbine for each house is considered. Secondly, the installation of a single wind turbine having the same total installed capacity (100 kW) is evaluated. The alternatives are compared according to annual energy production, exergy efficiencies and simple payback time. The results pointed that the use of a single wind turbine is better that the use of individual residential scale wind turbines for small communities or districts.
  Keywords: wind energy; energy analysis; exergy analysis; economic analysis; simple payback time; SPBT.
  DOI: 10.1504/IJEX.2024.10065344
   
  
• Enhanced performance of a modified tc-CO₂ refrigeration system aided with an absorption chiller - an exergetic and energetic analysis  
  by Abhishek Verma, S.C. Kaushik, S.K. Tyagi 
  Abstract: The present study analyses thermodynamically a novel tc-CO₂ refrigeration system designed for low-temperature refrigeration. Subcooling is achieved through a single-effect absorption chiller, using compression-generated heat. A work recovery turbine reduces throttling losses and electricity consumption. Performance enhancements are obtained via parametric analysis and optimisation. The integrated system is compared with basic tc-CO₂ configurations with a work recovery turbine. Results show a 28.83% performance enhancement over the TCRST for an evaporator temperature of -35°C and a heat rejection temperature of 35°C. This research underscores the effectiveness of the integrated system in improving refrigeration performance under various conditions.
  Keywords: transcritical CO₂ refrigeration; waste heat; absorption; subcooling; exergy.
  DOI: 10.1504/IJEX.2024.10065347