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In arid and semi-arid regions with low relative humidity, it is difficult to obtain drinking water from the air humidity. The water supply in Mashhad faces many challenges. The water production from atmospheric humidity is one method of supplying water in Mashhad. The aim of this study was to investigate a small-scale hybrid atmospheric water generator (AWG) that utilizes a desiccant wheel to adsorb and desorb air humidity. The proposed AWG was mathematically modeled in order to determine its efficiency and performance. A complete energy, exergy, and economic (3E) analyses were conducted on the proposed system. In order to validate the mathematical model, a numerical simulation was performed using the ANSYS 2022R1 software. The water generation rate, energy consumption, specific energy consumption, and energy-exergy efficiency of the proposed system were presented in months. According to the results, the WGR is highest in July at 156 L day−1 and lowest in December at 23 L day−1. Additionally, July and December had the highest and lowest SECs during the year, with 1.5 kWh L−1 and 10 kWh L−1, respectively. Additionally, July and December recorded the highest and lowest energy and exergy efficiencies, respectively, with 22.1%, 1.25% and 4.8%, 0.14%. [ABSTRACT FROM AUTHOR]

One of the promising approaches to compensate for imminent depletion of fossil energy resources and their adverse global impacts is enhancing the efficiency of systems utilizing low-temperature heat sources. The initial target of the research is to present a promising system for simultaneous production of power, refrigeration, heat, and hydrogen utilizing a combination of the absorption power cycle, the vapor compression refrigeration cycle, and a proton exchange membrane electrolyzer. On this subject, a comprehensive modeling of the energy and exergy of the proposed set-up is presented, and its thermodynamic performance is scrutinized. Furthermore, a comprehensive study of various parameters is performed to evaluate their impacts on system performance. The research aims to enhance and optimize the use of energy and various resources, contributing to the development of more sustainable efficient energy systems. Thermodynamic analysis of the multiple generation system shows that under baseline conditions and initial design, the system has the capability to produce net electrical power of approximately 17.12 kW, cooling power of about 201.5 kW, heating power of around 697.1 kW, and produce pure hydrogen at a rate of 0.153 kilograms per hour. The system exhibits an energy efficiency ratio of 1.364 and an exergy efficiency of 36.58 %. Moreover, optimization with single and multiple objectives with different weighting coefficients reveals that higher values of these parameters can be obtained. In other words, in the MOOM optimization mode, exergy efficiency increases to 7.16 %, and the energy performance ratio rises to 85.73 % compared to the BM mode. Additionally, through a parametric assessment to define the effect of input parameters on system performance, it demonstrates that increasing the temperature of the heat source may simultaneously increase the exergy efficiency and energy performance ratio of the system. The Grassmann diagram also indicates that the total exergy of the input fuel is about 196.9 kW. From this amount, approximately 121.5 kW are destroyed through the components of the system. Furthermore, about 3.39 kW are lost through the absorber coolant and waste from the hydrogen production unit. About 72.4 kW are attributed to products. [ABSTRACT FROM AUTHOR]

Thermal power plants account for 39 % of Sudan’s electricity grid. Consequently, enhancing the performance of these plants is crucial for bolstering the Sudanese energy sector. This paper presents an analysis of energy, conventional exergy, and advanced exergy for 180-MW Garri “1” combined cycle power plant in Sudan. The study focuses on assessing the enhancement potential of this power plant to provide guidance for performance improvement and identify optimal areas for enhancement within the plant’s components. The energy and classical exergy analyses results indicated that the highest energy losses occur in the stacks (55.1 %), while the largest source of exergy destruction is combustion chambers (50.98 %). Furthermore, the lowest contributions to energy and exergy losses are from the deaerators (0.15 % energy and 0.32 % exergy) and auxiliary systems (0.22 % energy and 2.85 % exergy). The overall energy and exergy efficiencies of the plant were found to be 36.1 % and 34.1 %, respectively. The advanced exergy analysis exhibited that the ratios of unavoidable to avoidable exergy destruction and endogenous to exogenous exergy destruction are 87.95 % to 12.05 % and 68.3 % to 31.7 %, respectively. Moreover, it was shown that the primary source of avoidable endogenous exergy destruction is the combustion chambers (48.53 %). Furthermore, the improvement potential in the plant’s exergy efficiency was found to be only 3 %, suggesting the need for optimization of operational parameters to enhance overall performance. The current paper offers valuable insights into enhancing efficiency of Sudanese energy sector, with implications for optimizing the energy sector in similar developing countries.

This work focuses on the structure, working, and testing of a new mixed solar cooker using a linear Fresnel collector, evacuated tube and box‐type cooker. The low‐cost components used in the construction of this cooker can help it satisfy the needs of both urban and rural inhabitants who need steady cooking temperatures above 140°C. A family of five can prepare four meals using this modified solar cooker, which costs about $250. The designed solar cooker was tested by conducting no‐load and full‐load tests. For the no‐load test, the maximum temperature of the absorber plate and oil for the new mixed cooker was recorded as 160.26°C and 172.72°C, respectively. The absorber plate of the new mixed cooker and its oil both reached their highest temperatures during the full‐load test at 141.14°C and 157°C, respectively. The energy efficiency of the new cooker is 58.776%, while its exergy efficiency is 13%. The heat transfer coefficient increased to 100.16 W/m² °C. This cooker provides an additional time savings of 60 min. An improvement of 27.5% in the highest temperature reached was seen when the developed cooker's performance was compared with those reported in the literature. Additionally, the new cooker's heat‐storing capability enables up to 3 h of autonomy. The Levelized Cost of Cooking a Meal for the innovative mixed solar cooker is $0.034 per meal. [ABSTRACT FROM AUTHOR]

A photovoltaic panel without cooling capabilities shows low efficiency and this efficiency deteriorates further during peak periods. In contrast, a photovoltaic/thermal (PV/T) system achieves higher electrical efficiency through a cooling mechanism that limits efficiency drops even during peak periods. This research centers on exploring the influence of temperature on the current, voltage, power, and efficiency of PV/T modules and the associated thermal system. Additionally, experimental investigations are conducted to examine the enhancement of PV/T power. Furthermore, the study involves the implementation of an Artificial Neural Network (ANN) for modeling the system, aiming to predict and analyze the performance of PV/T systems under the weather conditions prevalent in Oman and the Gulf region.Neural network models, such as multilayer perceptron (MLP), Second Order Volterra Model (SOVM), and Support Vector Machine (SVM) have been constructed to simulate and forecast the output power of the PV/T system. The SVM model demonstrated the lowest mean absolute percentage error (MAPE), registering at 0.0358, surpassing both Self-Organizing Feature Map (SOFM) and MLP with MAPE values of 0.0524 and 0.0601, respectively. In terms of root mean squared error (RMSE), SOFM exceeded MLP and SVM, yielding a lower error of 0.2235. However, when considering R2, MLP exhibited a notably high value of 0.9554, signifying a robust relationship. It is worth noting that R2 values approaching one indicate a strong correlation. The MLP model highlighted superior performance, achieving outstanding metrics with values of 99.67 %, 0.0631, and 0.2512 for R2, MAPE, and RMSE, respectively. This collective evidence solidifies the effectiveness and reliability of the proposed neural network models in predicting the PV/T system's output power.

The distillation tower's reboiler is one of the largest energy consumers in petrochemical facilities, and reducing its energy consumption is a crucial issue. This study proposes two optimal methods, namely Direct Vapor Recompression (DVR) and External Vapor Recompression (EVR), to reduce the consumption of cold and hot utilities in a petrochemical deethanizer tower. The Pars petrochemical in Iran is taken as a case study, and the proposed methods are compared with the base case using energy, exergy, and economic approaches, simulated through Aspen HYSYS software in the steady-state design conditions. Exergy analysis reveals that the EVR and DVR methods reduce the exergy destruction of the deethanizer tower by about 70.06 % and 67.29 %, respectively, compared to the base case. Moreover, the EVR method allows for complete recycling of low-pressure vapor, reducing the total exergy destruction rate from 0.871 to 0.261 GJ/tethane. The feed separation cost for the base case, DVR, and EVR are estimated to be around 28 $/kgfeed, 21.57 $/kgfeed, and 21.14 $/kgfeed, respectively. The EVR method results in reduced utility and ethane separation cost rates from 5.153 to 3.274 $/tethane and 17.64 to 15.78 $/year. Overall, the findings suggest that both DVR and EVR methods are effective in reducing the energy consumption and costs associated with deethanizer tower operations. Moreover, real-time optimization techniques can be developed to monitor and adjust the deethanizer tower's operating parameters, such as feed flow rate, reboiler duty, and reflux ratio. [ABSTRACT FROM AUTHOR]

The present study introduces a novel cascade ejector intercooler refrigeration cycle (CEIRC) and a novel cascade ejector booster refrigeration cycle (CEBRC), which are designed to improve ultralow temperature (ULT) refrigeration system performance based on various refrigerants in terms of energy, exergy, and environment. Through the analysis conducted with eco‐friendly refrigerants for CEIRC, the refrigerant pair exhibits the highest performance that is found to consist of RE170 for high‐temperature cycles and R170 for low‐temperature cycles. These refrigerants have very low global warming potential and are eco‐friendly. The coefficient of performance (COP) reveals improvements of 3.20–9.51%, 10.55–19.12%, and 31.96–65.97% over the CEBRC, cascade ejector refrigeration cycle (CERC), and cascade vapor compression refrigeration cycle (CVCRC), respectively, resulting in corresponding exergy efficiency improvements of 3.18–9.49%, 10.48–19.12%, and 31.87–65.98%. The total compressor power and exergy destruction are also compared, indicating that the CEIRC exhibits the best performance among the four. CEIRC achieves a COP increase of 11.6% compared with the cascade refrigeration cycle, which is considered the cycle with the highest performance operating at ultralow temperatures in the literature, which is CERC. The kg CO2 effect of the CEIRC is 11.35% lower than that of the CERC. [ABSTRACT FROM AUTHOR]

This paper suggests a novel framework to retrieve the squandered heat of the Naphtha Hydrotreating Unit of the petrochemical plants. In this idea, the distillation tower's output of the hydrotreating naphtha unit of the plant is employed as the working fluid to run an organic Rankine cycle with benzene. The procedure is evaluated comprehensively from energy, economic and exergetic point of view using Aspen Haysys software. An advanced case study, including sensitivity analysis, is provided for the Bouali petrochemical plant in Iran to realistically indicate the performance of the suggested configuration. The air cooler in the distillation unit of the aforementioned plant removes (squanders) about 3418 kW of energy, which an organic Rankine cycle can recover. Based on the findings, the exergetic and thermal efficiency of the suggested cycle is 82.53 % and 13.28 %, respectively, with a 1,3620kWh/day rate of energy production. According to the exergetic analysis, the ORC turbine has the highest exergy destruction rate of about 178.76 kW. Also, using the distillation tower squander heat as the heat source to the organic Rankine cycle leads to the least exergy destruction rate. Besides, the output exergy ratio of the whole integrated system to its input is 0.907. The suggested integrated system reduces the total energy consumption from 0.4 to 0.29 GJE/tonFeed with a total investment cost of 11.97 M$, in which the turbines have the highest portion of about 11.2 M$. Hence, the suggested plan's total income is around 31.94 M$/year. [ABSTRACT FROM AUTHOR]

This work proposes a novel transparent solar cooker design, and its performance is evaluated using a set of experiments. The cooker is fabricated from transparent and non-transparent, and lightweight material. The study was conducted at the Renewable energy laboratory in India (MNNIT Prayagraj). For thermal performance assessment of Box-type standard solar cooker with an inclined cover (BTSCIC) is compared with a box-type standard solar cooker (BSSC). The area, heat input, and thermal efficiency have all increased significantly. The total absorbing area increases by 32%, total solar radiation by 189%, absorber plate temperature by 19.8%, inner air temperature by 16.5%, pot water temperature by 17.1%, and inner wall average temperature by 58%, as compared to box-type Standard Solar Cooker. The average exergy was 4.2% (BTSCIC) and 2.61% (BSSC), respectively. The cost payback period of BTSCIC was 2.22 years and BSSC 1.5 years. [ABSTRACT FROM AUTHOR]

The mixture of nanoparticles with base fluid for heat transfer fluid’s performance enhancement has received wide research attention recently. These nanofluids have been proposed by researchers as a better alternative in different thermal systems. However, the detailed comparison of these fluids is limited in the existing literature. Therefore, in this paper, a detailed parametric comparison of mono/hybrid nanofluids with other fluids’ applications in solar thermal collectors is presented. Specifically, the flat plate and solar parabolic trough collectors are considered within the scope of this study. While the flat plate collectors are modeled for low-temperature applications, the parabolic trough collectors are considered for high-temperature applications. Five nanofluids with different nanoparticles, namely; Al2O3, SiO 2, CuO, Al2O3-ZnO, and Al2O3-Fe are compared with four normal fluids (water, salt (7NaNO 3_40NaNO 2_53KNO2), Therminol_VP1, and Dowtherm_Q). From the energy/exergy efficiencies and useful energy output results of this study, the nanofluids had a better performance when applied in the flat plate collectors and parabolic trough collectors. Also, the working fluids with higher temperature output had lower energy efficiencies and useful energy output. Hence, the base (normal) fluids are more suitable for some specific temperature applications in a flat plate and parabolic trough collectors.

Vapor compression refrigeration (VCR) systems operating in hot climates suffer from high condenser temperatures that reduce their performance. One interesting approach being investigated to improve VCR performance is incorporating phase change materials (PCMs) into VCR systems that have not yet been expanded experimentally. So, this work experimentally studies the effect of using tubular PCM heat exchanger to cool the VCR condenser. The impact of two PCMs types suitable for warm climate conditions: SP24 and SP26, and combination of them on the VCR energy and exergy performance is investigated for two inlet ambient air temperatures. The impact on the exit air and PCMs temperatures, and VCR unit's pressure-enthalpy curve, VCR coefficient of performance, and power consumption is also examined. The results show that PCM-equipped systems significantly enhance the VCR exergy efficiency and coefficient of performance, especially at higher ambient temperature. Compared to the system without PCM, the power consumption can be reduced by up to 10.4% with PCM, while the exergy efficiency and coefficient of performance can be improved by 13.7% and 13.4%, respectively. While PCM SP24 provides the best performance, PCM SP26 has longer effective cooling period. A combination of SP24 and SP26 balances the performance and effective cooling period.

Novel sustainable solar powered combined desalination and hot water system is investigated based on energy, exergy and economic performances experimentally. For the purpose, evacuated tube collector integrated serpentine based active desalination unit is fabricated to fulfil the potable water and hot water supply especially in hospitals, hill station buildings and remote locations. Experimental investigations are performed for various mass flow rates in serpentine at different basin water depth (0.03, 0.04 and 0.05 m) over nine typical days. Effect of solar insolation and atmosphere temperature on potable water yield and system energy and exergy efficiencies are analyzed under real weather conditions. Measurements reveal that, maximum daily potable water yield, energy efficiency, exergy efficiency and hot water temperature are obtained as 5.10 kg/m2·day, 42.39%, 4.45% and 67°C, respectively at 0.03 m water depth and lower mass flow rate. Additionally, potable water cost per litre (CPL) found minimum as 0.04073 $/L/m2 for 25 y of operating life of system. [ABSTRACT FROM AUTHOR]

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A cost-effective alternative for lowering carbon emissions from building heating is the use of flat-plate solar collectors (FPSCs). However, low thermal efficiency is a significant barrier to their effective implementation. Favorable nanofluids' thermophysical properties have the potential to increase FPSCs' effectiveness. Accordingly, this study evaluates the performance of an FPSC operating with Fe3O4-water nanofluid in terms of its thermo-hydraulic characteristics with operating parameters ranging from 303 to 333 K for the collector inlet temperature, 0.0167 to 0.05 kg/s for the mass flow rate, and 0.1 to 2% for nanoparticles' volume fraction, respectively. The numerical findings demonstrated that under identical operating conditions, increasing the volume fraction up to 2% resulted in an improvement of 4.28% and 8.90% in energy and energy efficiency, respectively. However, a 13.51% and 7.93% rise in the friction factor and pressure drop, respectively, have also been observed. As a result, the performance index (PI) criteria were used to determine the optimal volume fraction (0.5%) of Fe3O4 nanoparticles, which enhanced the convective heat transfer, exergy efficiency, and energy efficiency by 12.90%, 4.33%, and 2.64%, respectively. [ABSTRACT FROM AUTHOR]

The conversion of solar energy into thermal energy using a solar water heating system seems to be a viable technology. Nanofluids are a well-established method of increasing the solar water heater's heat output. Solar thermal collector receiver tube heat transfer enhancers and geometrical characteristics have been analyzed for their impact on energy and exergy efficiency. Assessments of energy and exergy can greatly improve the performance of solar collectors and reduce their irreversibility. This challenge aims to generate full document research on various solar thermal collectors' energy and exergy assessments. Various heat transfer enhancers and geometrical characteristics of the receiver tube of a solar thermal collector have been developed and evaluated for their effects on energy and exergy efficiency. This paper suggests a solar water heating system using zinc oxide-based nanofluid (SWHS-ZO-NF). Distilled water/zinc oxide nanofluids are employed in the recommended solar water heating systems strategy with parabolic trough solar collectors. It is necessary to apply a surfactant to keep the nanoparticles from settling. Although the addition of surfactant increased the nanoparticle's stability in the base fluid, it will harm the nanofluid's thermophysical properties. The system's exergy loss is reduced when the nanofluid's volume concentration increases. The experimental result of the suggested SWHS-ZO-NF improves the energy analysis and exergy analysis, viscosity and thermal conductivity, exergy loss and entropy generation, electrical power and electrical efficiency, and thermal power and thermal efficiency. [ABSTRACT FROM AUTHOR]

Efficient power generation systems are an essential way to reduce carbon emissions. To avoid the complex effects of high-pressure conditions on the solid oxide fuel cell (SOFC) and gas turbine (GT) hybrid systems, while further improving energy efficiency. A SOFC-GT hybrid system based on the reverse Brayton cycle (RBC) is proposed, in which the SOFC operates at near atmospheric pressure conditions and GT expands below atmospheric pressure. Solar energy is integrated to further enhance system performance. Rigorous assessments of the novel system and the pressurized system are conducted utilizing energy, exergy and economic analysis. The sensitivity analysis of environmental parameters on the novel system's performance is performed. The results show that the novel system generates power and efficiency better than the conventional system when the GT compression ratio is 3 and 6, respectively. The power generation and exergy efficiency of the novel system at the design point is 60.47 % and 58.57 %, respectively. The largest exergy destruction occurred in the SOFC. The lowest exergy efficient components are the parabolic dish collector (PDC) and heat exchanger 2. The novel system is more cost-effective due to the higher lifetime of the SOFC, with the levelized cost of energy (LCOE) is 0.1418 $/kWh. • The reverse Brayton cycle is applied to solid oxide fuel cell and gas turbine hybrid system. • Solar energy is coupled to further improve system performance. • The comparison between the novel system and the conventional system is analyzed. • The influence of external environmental factors on the novel system is analyzed. [ABSTRACT FROM AUTHOR]

This paper proposes a single basin fourfold slope solar still, which includes a fourfold slope glass cover plate used for solar heat collection and steam condensation. In order to show the efficiency of the fourfold slope solar still, comparative experiments are conducted under the winter climate conditions in Hangzhou for testing the operational performance of a double slope type solar still (DOSS) and the fourfold slope still (FOSS), so as to make a comparative analysis between them. Results show that the productivity of the fourfold slope still is 19.51% higher than that of the double slope still, and the fourfold slope solar still enhances the average hourly energy efficiency by 31.11%. According to the energy method, the energy payback time values of the fourfold slope solar still and double slope solar still are 64.88 months and 75.42 months respectively. According to the environmental parameter method, FOSS and DOSS reduce 5.47 tons and 4.58 tons of CO2 respectively. The corresponding values based on the exergy environment parameters are 0.21 and 0.18 tons of CO2, respectively. The fourfold slope solar still has a more obvious emission reduction function than the double slope solar still. The cost of the distilled water of the fourfold slope solar still is 0.28 RMB/kg, and the cost of the double slope solar still is 0.30 RMB/kg. In addition, the environmental and economic parameters of the fourfold slope still and double slope still are 79.29$ (561.37RMB) and 66.35$ (469.76RMB), respectively. While, the corresponding values based on the exergoenvironmental parameter are 3.05$ (21.59RMB) and 2.56$ (18.12RMB), respectively. From the analysis of exergoeconomic and exergoenvironmental parameters, the fourfold slope single basin solar still appears to be more effective. HIGHLIGHTS A novel solar still with fourfold slope is developed and evaluated.; Fourfold slope single basin solar still increases the still's productivity by about 19.51%.; Fourfold solar still enhances the average hourly energy efficiency by 31.11%.; Fourfold still mitigates more CO2 compared to a conventional one based on energy and exergy.; Fourfold solar still's enviroeconomic and exergoenvironmental parameters are 79.29$ and 3.05$.;

In this paper, a dome slope single basin solar still for water treatment and desalination is presented. This new solar still device is based on installing a dome slope cover on the walls of the solar still. The main objective of such a still is to concentrate more sunrays at the still's bottom basin, through the increased area of the dome glass cover. Experiments are conducted under the climate conditions in Hangzhou city, China, for testing the operational performance of the dome slope type solar still and the fourfold slope still, so as to make a comparative analysis between them. Assessment of the dome slope still's feasibility is performed based on energy, exergy, exergoeconomic, and enviroeconomic methodologies, as well as energy payback time. Results show that the productivity of the dome slope still is 36% higher than that of the fourfold slope still, and the dome slope solar still enhances the average hourly energy efficiency by 34%. Due to the higher energy and exergy outputs of the dome slope solar still throughout its lifetime, the novel solar still proposed in this study mitigates more CO2 compared with the fourfold slope still. Overall, incorporation of the dome slope cover with the still is found to be promising in terms of freshwater yield, cost, and energy payback time compared with the conventional one. The dome slope single basin solar still appears to be effective from exergoeconomic and exergoenvironmental parameter analysis. HIGHLIGHTS A novel solar still with dome slope is developed and evaluated.; Dome slope single basin solar still increases still's productivity by about 36%.; Dome solar still enhances the average hourly energy efficiency by 34%.; Dome still mitigates more CO2 compared with a conventional one based on energy and exergy.; Dome solar still's enviroeconomic and exergoenvironmental parameters are 53.74$ and 3.25$.;

In recent years, renewable sources of energy have become an encouraging solution to the environmental and availability problems arising from using fossil fuels for power generation. In the present study, solar and biomass (sawdust) are incorporated into large-scale gas and steam turbines to form a resourceful and efficient system. Furthermore, two hybrid configurations (fuel economy and energy boosting modes) of the proposed combined system are modelled using the Cycle Tempo software. The system's performances reveal that at 9 bar inlet pressure, the net power, energy and exergy efficiencies generated in the fuel economy mode (49 MWe, 61%, and 55%) and energy boosting mode (51 MWe, 64% and 57%) are significantly higher than those obtained in the standard biomass combined cycle system without solar fields (28 MWe, 35% and 31%). Moreover, the addition of solar energy brings about an increment of around 21 MWe in the fuel economy mode and 23 MWe in the energy boosting mode. The exergy transmitted from the fuel economy and energy boosting modes also yields greater GT combustor efficiency (89%) than the standard mode (79%). The proposed hybrid system through the incorporated clean energy offers better performance and could serve as an alternative to existing fossil fuel plants. [ABSTRACT FROM AUTHOR]

Introduction Food is composed of various compounds, and when the food quality expires, it becomes inappropriate for consumption and the end of life leads to some pathogenic microorganisms in food. So food processing is essential. In recent years, various heat treatments have been considered that have various disadvantages, so researchers are looking for alternative technologies in industrial processing to overcome these problems. Electric treatments play an important role in food heating technology and one of the methods of electric thermal processing is ohmic processing, that ohmic heat is based on the flow of electricity through a product. The purpose of this study was to investigate the effect of voltage and weight loss on the amount of energy and exergy during this process in order to obtain the best amount of energy consumed during the heating process, since the most common way to heal the heating is by heating. In addition to maintaining the product's qualitative characteristics, the product has to carefully monitor its own system parameters. Materials and Methods The sour oranges were purchased from a garden located in the city of Gorgan, Golestan province. The prepared oranges were washed and divided into two halves in the middle and immediately after purchase, all samples of juice were taken manually in the same conditions and the samples were prepared to conduct the test during the ohmic process with voltage gradients and the percentages of different weight loss to investigate the amount of energy efficiency, exergy efficiency, exergy loss, and improvement potential during the process. For the heating process, three voltage gradients of 8.33, 10.83 and 13.33 V cm-1 and three percentage values of weight loss of 10% (from 90 g to 81 g), 20% (from 90 g to 72 g), and 30% (from 90 g to 63 g) were selected. Then, the energy and exergy consumed during the process were calculated and analyzed using a factorial experiment in a completely randomized design with SAS statistical software. Results and Discussion Based on the results, it can be concluded that the voltage gradient and weight loss percentages are significant for energy efficiency, exergy efficiency, exergy, and potential improvement at 1% level. Increasing the voltage gradient increases the efficiency of energy and exergy and reduces the potential for recovery and exergy is wasted. The highest energy efficiency was 91.6% in the 13.83 V cm-1 voltage gradient and the weight loss percentages 10% and the lowest value was 51.51% in the voltage gradient of 8.33 V cm-1 and the weight loss percentages 30%. The maximum improvement potential was 8.33 V cm-1 and the weight reduction was 30% and the lowest value was at 13.33 V cm-1 voltage gradient and 10% weight loss percentages. The highest exergy efficiency of 59.51% was found in the 13.83 V cm-1 voltage gradient and the weight loss percentage was 30% and the lowest value was 31.88% on a voltage gradient of 8.33 V cm-1 and a weight percentage of 10%. Conclusions - By increasing the voltage gradient, the energy efficiency had increased and there was a significant difference between all the volatility gradients. - For exergy efficiency, when the voltage gradient increased, the exergy efficiency amount increased, and in all percentages weight loss was a significant difference between the voltage gradient. - By increasing the voltage gradient, the amount of exergy loss decreased significantly and with increasing percentage weight loss, this amount was significantly increased. - The improvement potential was reduced by increasing the voltage gradient and there was a significant difference between the voltage gradients for the improvement potential.

Solar desalination has captivated consideration to overcome the problem of the scarcity of freshwater, with simple-design, economic, and environment-friendly solutions. This study navigates a novel solar-evacuated glass tube collector integrated with a collective condenser heat pipe system for solar desalination. A newly designed heat pipe array was represented in this work by affixing all the evaporator tube units of the heat pipes to a single condenser unit and was attached to the evacuated tube solar collector. The innovative assembly of the heat pipe provided uniform heating of water and rapid steam generation. The present system acts as a solar collector and as a stand-alone basin for freshwater formation. The performance assessment of the neoteric system was conducted based on half-filled and three-fourth-filled conditions of the water flow pipe kept within the collective condenser heat pipe. The maximum heat pipe temperature recorded during the half-filled state was 156.9°C and 151.48°C in the three-fourth-filled state. The half-filled state of the water flow pipe delivered a total distilled water content of 8,050 ml/day, whereas the three-fourth-filled state delivered 5,925 ml/day of distilled water. The maximum energy and exergy efficiency of the presented system was 19.27% and 3.92%, respectively. The economic minimum unit cost of freshwater by the present system is 4.27 INR, and the payback period is 2.9 years. The present eco-friendly energy system saves 4.25 kWh of electricity and 4.16 × 10−3 tons of CO2 equivalent per year.

Despite the major challenges facing fossil fuels, they are now utilized to supply nearly 80% of the world's energy requirements. Of this amount, about 30% relies on coal-based power plants. Such power plants emit large volumes of pollutant gases into the atmosphere, which has led to serious environmental crises. Therefore, the exploitation of green technologies and/ or the integration of environmentally friendly systems in existing power plants are essential. The aim of the article is to introduce and conceptual-thermodynamic design of a lignite coal-based plant that is integrated with monoxide-hydrogen fueled solid oxide fuel cell (SOFC), and parabolic trough solar collector (PTSC) based-solar farms. The present paper provides energy, exergy, and thermodynamic analyzes with considering entropy generation and emission rate of the power plant. In addition, a comparison of system performance when using anthracite instead of lignite is also provided. Also, real climatic data (i.e., Yazd, Iran) have been used to evaluate the behavior of solar fields. The results showed that nearly 93.7 kg/s of gas is raised from the power plant after the combustion process. In addition, proposed power plant has energy and exergy efficiencies of 70.95% and 35.7%, respectively. Moreover, the PTSC2 solar farm in a lignite-fired power plant should have approximately 6.76-fold larger area than that of anthracite. [ABSTRACT FROM AUTHOR]

• A novel combined PVT and ST system is developed. • Different kinds of hybrid nanofluids for improving system performance are studied. • The SiC/Gr hybrid nanofluid has the best performance compared to others. • In the combined system, ST produces more entropy generation compared to PVT. Because of the low outflow temperature of the conventional photovoltaic thermal systems and lack of electrical production of the solar thermal collectors, a novel combined system is proposed to solve the two mentioned drawbacks. This novel system is achieved by connecting a photovoltaic thermal unit to a solar thermal collector in series. To increase the overall performance of this novel combined system, different hybrid nanofluids include (1) multiwall carbon nanotube-aluminum oxide (2) multiwall carbon nanotube-silicon carbide (3) graphene-aluminum oxide, and (4) graphene-silicon carbide are compared. The investigation is performed based on the three-dimensional simulation, and the Eulerian-Eulerian model is selected for the simulation of hybrid nanofluids. To estimate the performance of this novel combined system, the first and second laws of thermodynamics are used. Moreover, the share of entropy generation in all components of the system is calculated. The results indicate that the multiwall carbon-silicon carbide hybrid nanofluid with the average electrical and thermal energy efficiency of 13.85% and 56.55%, respectively, has the best performance compared to other fluids. Furthermore, in the combined system, different components of the solar collector produce more entropy generation than the components of the photovoltaic thermal module. [ABSTRACT FROM AUTHOR]

In recent years, there have been many studies on the widespread use of liquid fuels derived from biomass. A common emphasis in such studies is on fewer exhaust gas emissions and the expansion of renewable fuel production. Biodiesel is considered to be an important type of biomass fuel that is already produced commercially. But the production of biodiesel is laborious and comprises combination of several chemical processes. This study examines the effects of using oil used in biodiesel production with oxygen-rich chemicals on combustion (in-cylinder pressure (Cp), heat release rate (HRR), rate of pressure rise (RoPR), and cumulative heat release (CHR)), exhaust emission values, energy and exergy analysis. In this study, the effects of butyl di glycol use were also investigated and compared with commercially used ethanol and n-butanol. A transesterification method produced from canola oil the biodiesel used in the experiments. The experimental fuels were mixed volumetrically. For this purpose, experiments were carried out with canola biodiesel produced at 20% (D80B20) in diesel fuel and the results of the experiments were recorded. Under the same conditions, experiments were carried out by adding ethanol (D60C20E20), n-butanol (D60C20B20), butyl di glycol (D60C20G20) at a rate of 20% by volume to the canola oil added to the diesel fuel. The lowest values in terms of thermal and exergy efficiency were obtained in D60C20G20 fuel at all engine loads. Also, the highest entropy generation was calculated at all engine loads for this fuel blend.

Energy and exergy based thermal analysis was conducted for a solar assisted yogurt processing unit capable of performing required heating and cooling processes in a single container. The system consisted of a round-shaped fermentation chamber connected with a hot water storage tank coupled with an evacuated tube collector and a pillow plate at the bottom of the chamber for cooling through a PV-operated refrigeration unit. Experiments were conducted using three different volumes of cow’s raw milk (30, 40, and 50 L). Energy analysis showed that 40% of the total energy was consumed during the heating process of raw milk in all cases, with an overall heat transfer efficiency of more than 80%. The specific product energy was calculated to be lower (485 kJ/kg) for the higher volume of milk (50 L). The exergy losses in the compressor of the refrigeration unit were calculated almost constant (1.0037 kW), while the exergy recovered during the refrigeration process was found in the range of 0.48–4.54 kJ/kg, 1.35–3.96 kJ/kg, and 0.84–6.18 kJ/kg for 50, 40, and 30 L of batches, respectively. Out of the total available power (2218 W) at the evacuated tube collector, 69.70% of energy was available for milk heating. The study is useful for designing optimization based on the distribution of energy and losses at various system components.

Summary: Metallic solder based PCMs possess higher thermal conductivities, larger storage masses and exhibit lower subcooling effects compared to their organic or inorganic counterparts. It is thus justified to investigate their potential usage for medium temperature applications. These solders are relatively expensive and can be combined with cheaper PCMs in cascaded storage systems which are more thermodynamically efficient compared to single PCM systems as reported recently. The aim of the research is thus to compare two packed bed storage systems during discharging cycles using eutectic solder (Sn63/Pb37), that is widely available worldwide. The single PCM system (40 capsules) consists of encapsulated spheres of eutectic solder, whereas the second cascaded system consists of encapsulated spheres of eutectic solder and erythritol in an equal storage ratio in the tank. For the cascaded system, the eutectic solder capsules are placed at the top and erythritol at the bottom of the storage tank (20 capsules at the top and 20 at the bottom). The effect of the discharging flow‐rates of 4 mL/s, 6 mL/s and 8 mL/s is investigated in relation to the temperature profiles, energy rates and exergy rates. Increasing the flow‐rate, increases heat transfer rate thus shortening the discharging time as well as increasing thermal profile reversals during discharging. The peak energy and exergy rates increase with the increase in the flow‐rate for the two storage systems. The single PCM system shows slightly higher average energy and exergy rates compared to the cascaded system possibly due to its higher thermal conductivity. The cascaded PCM system shows higher average stratification numbers at all the flow rates considered. The non‐cascaded system exhibited slightly higher exergy recovery efficiencies compared to the cascaded PCM system possibly due to its higher thermal conductivity at all flow‐rates considered. The effect of the initial discharging temperature is also investigated with a discharging flow‐rate of 6 mL/s after charging with set heater temperatures of 260°C, 280°C and 300°C, respectively. Comparable thermal profiles are seen for both systems for the three set temperatures; however, the single PCM system shows slightly higher storage temperatures. The single PCM shows slightly higher but comparable peak and average discharging energy rates compared to the cascaded system. The exergy rates for the two systems are also comparable. However, the cascaded system shows slightly higher exergy rate values for the lowest set temperature whereas the single PCM system shows slightly higher exergy rate values for the other two set temperatures. Energy and exergy rates are almost independent of the initial storage tank temperatures induced by different set charging temperatures. The average stratification number shows no correlation with set temperature for both storage systems. The cascaded system shows slightly higher average stratification numbers at different set temperatures. Exergy recovery efficiencies for different set heater temperatures are comparable for the two storage systems and vary only marginally with the increase in the set temperature. Overall, the effect of the flow‐rate is more pronounced than the effect of the set heater temperature. [ABSTRACT FROM AUTHOR]

In this study, the design, development, and performance analysis of novel thermal energy storage integrated evacuated tube heat pipe solar dryer was investigated. A new common condenser heat pipe system having thermal energy storage was incorporated into the solar collector of the dryer. Therminol 55 was used as the thermal storage medium. The performance analysis was carried out with air mass flow rates between 0.003 kg/s to 0.02 kg/s and a combination of two mass flow rates 0.015 kg/s and 0.0065 kg/s. The maximum outlet temperature of the air delivered by the solar collector during the study was 118 °C. The average energy and exergy efficiency of the solar collector varied between 10%-30% and 1.9%-5.6% respectively. Agricultural products like tomatoes and carrots were dried in the dryer. The effect of moisture diffusivity variation for tomatoes and carrots with the mass flow rate of air and product thickness was analyzed in this study. The Newton model fairly demonstrated the solar drying characteristics of tomatoes. The combined mass flow rate method increased the average collector outlet temperature to 67 °C against 56 °C during a single mass flow rate and decreased the drying time by 2 h. The payback period for the dryer was 2.6 years. [Display omitted] • Novel thermal storage integrated evacuated tube heat pipe based solar dryer. • Suitable for drying applications with wide range of temperatures. • A new common condenser heat pipe arrangement for thermal storage. • High-temperature air was obtained even during off sunshine hours. • The solar dryer is an economic and environment-friendly one. [ABSTRACT FROM AUTHOR]

Three different domestic solar cookers are compared experimentally during water heating experiments using different loads. The solar cookers experimentally tested using energy and exergy thermal performance parameters are: a solar box cooker without a reflector, a solar box cooker with a reflector and a parabolic dish solar cooker. The rate of heat losses is more detrimental to the performance of the parabolic solar cooker since the cooking vessel is exposed more to the ambient weather conditions. Heat losses seem to have little effect on the performance of the solar box cookers. The solar box cooker with the reflector shows the highest average energy efficiencies, which increase with the water heating load. The parabolic solar cooker shows the lowest average energy efficiencies with the lower loads, which increase to be higher than those of the solar box cooker without the reflector at the higher loads. The solar box cooker with the reflector shows the highest average energy and exergy efficiency values, which are not dependent on the water load. The parabolic dish solar cooker shows average exergy efficiencies, which increase with the water heating load. The greatest cooking potential in terms of the speed of cooking is shown by parabolic dish solar cooker. The best overall thermal performance is shown with the solar box cooker with a reflector, but its cooking speed is rather slow when compared to the parabolic dish solar cooker. The solar box cooker without the reflector shows the worst thermal performance in most of the tested parameters except for the heat losses where it shows the lowest heat loss factors for all the experimental tests. [ABSTRACT FROM AUTHOR]

Introduction Food is composed of various compounds, and when the food quality expires, it becomes inappropriate for consumption and the end of life leads to some pathogenic microorganisms in food. So food processing; is essential. In recent years, various heat treatments have been considered that have various disadvantages, so researchers are looking for alternative technologies in industrial processing to overcome these problems. Electric treatments play an important role in food heating technology and one of the methods of electric thermal processing is ohmic processing, that ohmic heat is based on the flow of electricity through a product. The purpose of this study was to investigate the effect of voltage and weight loss on the amount of energy and exergy during this process in order to obtain the best amount of energy consumed during the heating process, since the most common way to heal the heating is by heating. In addition to maintaining the product's qualitative characteristics, the product has to carefully monitor its own system parameters. Materials and Methods The sour oranges were purchased from a garden located in the city of Gorgan, Golestan province. The prepared oranges were washed and divided into two halves in the middle and immediately after purchase, all samples of juice were taken manually in the same conditions and the samples were prepared to conduct the test during the ohmic process with voltage gradients and the percentages of different weight loss to investigate the amount of energy efficiency, exergy efficiency, exergy loss, and improvement potential during the process. For the heating process, three voltage gradients of 8.33, 10.83 and 13.33 V cm-1 and three percentage values of weight loss of 10% (from 90 g to 81 g), 20% (from 90 g to 72 g), and 30% (from 90 g to 63 g) were selected. Then, the energy and exergy consumed during the process were calculated and analyzed using a factorial experiment in a completely randomized design with SAS statistical software. Results and Discussion Based on the results, it can be concluded that the voltage gradient and weight loss percentages are significant for energy efficiency, exergy efficiency, exergy, and potential improvement at 1% level. Increasing the voltage gradient increases the efficiency of energy and exergy and reduces the potential for recovery and exergy is wasted. The highest energy efficiency was 91.6% in the 13.83 V cm-1 voltage gradient and the weight" loss percentages I0% and the lowest value was 51.51% in the voltage gradient of 8.33 V cm-1 and the weight loss percentages 30%. The maximum improvement potential was 8.33 V cm-1 and the weight reduction was 30% and he lowest value was at 13.33 V cm-1 voltage gradient and 10% weight loss percentages. The highest exergy efficiency of 59.51% was found in the 13.83 V cm-1 voltage gradient and the weight loss percentage was 30% and the lowest value was 31.88% on a voltage gradient of 8.33 V cm-1 and a weight percentage of 10%. Conclusions - By increasing the voltage gradient, the energy efficiency hd increased and there was a significant difference between all the volatility gradients. - For exergy efficiency, when the voltage gradient increased, the exergy efficiency amount increased, and in all percentages weight loss was a significant difference between the voltage gradient. - By increasing the voltage gradient, the amount of exergy loss decreased significantly and with increasing percentage weight loss, this amount was significantly increased. - The improvement potential was reduced by increasing the voltage gradient and there was a significant difference between the voltage gradients for the improvement potential. [ABSTRACT FROM AUTHOR]

• Complete simulation of renewable power to methanol production process; • Comprehensive analysis from energy, exergy, economy, and the environment perspectives; • Renewable power cost dominates the system's profitability; • Levelized cost of the renewable power to methanol is 840.50 $/ton. • Different CO 2 calculation boundaries lead to opposite carbon emissions results; The integration of renewable power for hydrogen production, carbon capture, and methanol synthesis process presents a novel approach to produce green methanol and promote renewable energy utilization. There are few studies on full process modeling, and the impact of CO 2 boundaries on carbon emissions and levelized costs has not been thoroughly analyzed. A complete modeling of the renewable power-to-methanol process was conducted in this work, considering energy, exergy, economy, and the environment perspectives. Thermodynamic and economic models were established, and a life cycle assessment model was conducted to evaluate the CO 2 emissions. The renewable power-to-methanol process achieved energy and exergy efficiencies of 36% and 30%, respectively. The methanol levelized cost is 840.50 $/ton. The main factor affecting the levelized cost is the price of renewable energy. Different CO 2 calculation boundaries lead to opposite carbon emissions results. [ABSTRACT FROM AUTHOR]

This work presents performance analysis of a novel multi-pass solar air collector with perforated fins (MPSACF) in winter conditions, Ankara province, Turkey. The aim of this work is to experimentally test and compare the performance of the two different design of solar collectors in the same climatic conditions. In addition, a double-pass solar air collector without fins (DPSAC) at the same absorber area was manufactured and tested as a control group. The total absorber area of both solar collectors is 0.325 m2. Thermal effects for performance improvement of the collectors have been designated. Average thermal efficiency values of DPSAC and MPSACF were calculated as 47.85% and 51.86%, 67.10% and 72.86%, respectively in experiments performed at 0.0069 kg/s (0.7 m/s air velocity) and 0.0087 kg/s (0.9 m/s air velocity) mass flow rates. Exergy efficiency of DPSAC and MPSACF were 2.10-17.12% and 8.74-23.97%, respectively. Coefficient of performance(COP) values were ocomputed 4.63 and 4.94, 3.18 and 3.48 respectively in experiments performed at 0.0069 kg/s and 0.0087 kg/s mass flow rates. Although the MPSACF has high efficiency values, COP values are lower due to the presence of dual fans. Because of their high thermal efficiency, both collectors can be effectively practiced for applications such as preheating, space heating and ventilation, greenhouse heating and product drying ©2019. CBIORE-IJRED. All rights reserved Article History: Received May 16th 2018; Received in revised form October 16th 2018 ; Accepted January 6th 2019; Available online How to Cite This Article: Aktaş, M., Sözen, A., Tuncer, A.D., Arslan, E., Koşan, M., Çürük, O. (2019) Energy-exergy analysis of a novel multi-pass solar air collector with perforated fins. International Journal of Renewable Energy Development, 8(1), 47-55. http://dx.doi.org/10.14710/ijred.8.1.47-55

CO 2 based power and refrigeration cycles have been developed and analyzed in different existing studies. However, the development of a CO 2 based comprehensive energy system and its performance analysis have not been considered. In this study, the integration of a CO 2 based solar parabolic trough collector system, a supercritical CO 2 power cycle, a transcritical CO 2 power cycle, and a CO 2 based cascade refrigeration system for hydrogen production and multigeneration purpose is analyzed thermodynamically. This study aims to analyze and compare the difference in the thermodynamic performance of comprehensive energy systems when CO 2 is used as the working fluid in all the cycles with a system that uses other working fluids. Therefore, two comprehensive energy systems with the same number of subsystems are designed to justify the comparison. The second comprehensive energy system uses liquid potassium instead of CO 2 as a working fluid in the solar parabolic trough collector and a steam cycle is used to replace the transcritical CO 2 power cycle. Results of the energy and exergy performance analysis of two comprehensive energy systems showed that the two systems can be used for the multigeneration purpose. However, the use of a steam cycle and potassium-based solar parabolic trough collector increases the comprehensive energy systems' overall energy and exergy efficiency by 41.9% and 26.7% respectively. Also, the use of liquid potassium as working fluid in the parabolic trough collectors increases the absorbed solar energy input by 419 kW and 2100 kW thereby resulting in a 23% and 90.7% increase in energetic and exergetic efficiency respectively. The carbon emission reduction potential of the two comprehensive energy systems modelled in this study is also analyzed. [Display omitted] • Thermodynamic study of a CO 2 based solar-powered comprehensive energy system. • Comparison of the CO 2 based systems' performance with another multigeneration system. • The CO 2 -based energy systems' overall energy and exergy efficiencies are 0.298 and 0.19 respectively. [ABSTRACT FROM AUTHOR]

Flat plate solar collectors lose a massive part of heat accumulated near the contact region because of the poor thermal characteristics of the working fluid. A new cost-effective design is numerically studied to cover up such deficiency by equipping the flat plate collector with revolutionary tubes and magnetic field inducer to affect Fe 3 O 4 /water working nanofluid in the collector tubes. Results substantiate that each of the applied rotary tubes and magnetic field inducer improves the convection mechanism in the tubes by circulating the flow inside the tubes and saves more of available solar energy. Results reveal that 27.8% and 10.44% of lost energy are restored in the solar collector equipped with the magnetic inducer and rotary tubes, respectively. Manipulating the flat plate collector by both rotary tubes and inducer is more influential in comparison with each individual method, and there is an optimal rotational speed in each magnetic field intensity to achieve the best performance. This hybrid technique increases the energetic performance of the plate solar collector from 44.4% to 61.7% which implies that roughly 300 W of the lost energy can be restored in the collector. [Display omitted] • Convection mechanism is improved by employing rotary tubes, magnetic field inducer, and nanofluid. • Simultaneous installation of rotary tubes and magnetic field inducer with nanofluid is more effective. • Energy efficiency of the collector increased from 44.4% to 61.7% by the hybrid technique. • Equipping the collector with both rotary tubes and inducer saves 31% of the energy loss. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel thermal storage integrated evacuated tube heat pipe solar air heater. • Suitable for high temperature air heating applications. • A new common condenser heat pipe arrangement was introduced in the system. • High temperature air was obtained during off sunshine hours. • This new solar air heater is an efficient and environment friendly device. This study aims to present a novel thermal energy storage integrated evacuated tube heat pipe solar air heater suitable for high-temperature applications. A new heat pipe arrangement was introduced in this study by attaching all the evaporator tubes of heat pipes to a common condenser section. A thermal energy storage medium was kept in a chamber within the common condenser unit of the heat pipe to obtain uniform outlet air temperature from the system when there is fluctuation in solar radiation. Therminol 55 was used as the sensible heat storage medium in the system. The Performance evaluation of the system was conducted by varying four airflow rates 0.03 kg/s, 0.1 kg/s, 0.2 kg/s and 0.3 kg/s, respectively. 0.03 kg/s resulted in a maximum outlet air temperature of 128 °C and the system delivered more than 100 °C of hot air until 10 h of operation. The maximum thermal and exergy efficiency obtained during each airflow rate was 38%, 77%, 85%, 89%, and 5.01%, 5.21%, 5.34%, and 5.76% respectively. An average of 6200 kJ energy was collected by the present system during its operation. The total money saved per month during the operation of TS-ETHPSD was 445 INR. The Payback Period for the system is 69 months. The solar air heater can be considered as an environment-friendly device as it can save 73 kg/month of Co 2 from entering the atmosphere. [ABSTRACT FROM AUTHOR]

This paper experimentally examines the performance of solar air heater (SAH) having a newly designed tubular absorber comprising adjacent parallel tubes called tubular SAH (T_SAH) via energy, exergy, and enviroeconomic standpoints. A comparative performance assessment between T_SAH and flat plate solar air heater (F_SAH) at diverse air mass flow rates (MFRs) of 0.075, 0.05, and 0.025 kg/s is performed. Experiments for both heaters are tested using two flow pass arrangements of single-pass (SP) and double-pass (DP). The results reveal that maximum enhancement in thermal and exergy efficiencies of 133 % and 330 %, respectively is obtained when using SP T_SAH against SP F_SAH at air MFR of 0.025 kg/s. It is found that when there is an increase in air MFR, there is a significant increment in thermal efficiency, whereas there is a reduction in exergy efficiency. Despite the performance in the case of T_SAH is more effective than F_SAH, the enhancement in the case of DP F_SAH due to using DP flow configuration is greater than that of DP T_SAH. Finally, the results indicate that the carbon credit earned regarding the amount CO 2 mitigated for SP F_SAH and SP T_SAH at MFR of 0.075 kg/s is estimated at 391.6 $/year and 561.9 $/year, respectively. [ABSTRACT FROM AUTHOR]

In this study, an assessment based on energy, exergy, economic, and environmental approaches on a double-pass (DP) solar air heater (SAH) having pin finned absorber at different air mass ratios up and down the absorber is investigated experimentally. Four air mass ratios are considered: (i) all the air mass flow passes up the absorber and returns to pass down the absorber (DP), (ii) 2/3 of the airflow passes up the absorber and returns to mix with the remainder of air to pass down the absorber (2/3 DP), (iii) the same as (ii) but 1/3 of the air passes up the absorber (1/3 DP), and (iv) all the air mass passes only down the absorber (single pass, SP). For all mass ratios, the performance of pin finned SAH (P_SAH) is compared with that of flat SAH (F_SAH). The results indicated that the air temperature rise and energy and exergy efficiencies of P_SAH are highly greater than those of F_SAH. The highest average thermal efficiency of F_SAH is 56.7% obtained at DP flow condition, whereas the highest value of P_SAH is 65.21% obtained at 2/3 DP with an increase of 17.6% compared with F_SAH. Also, P_SAH has higher average exergy efficiency of about 34.7% compared to F_SAH. Furthermore, P_SAH achieves energy payback time (EPBT) lower than that of F_SAH, while P_SAH has higher embodied energy. The findings indicated that F_SAH at SP airflow pattern has the maximum energy cost (0.0427 $/kWh), whereas P_SAH at 2/3 DP airflow pattern achieves the minimum energy cost (0.037 $/kWh). Finally, the proposed P_SAH system appears to be more viable from exergoeconomic and enviroeconomic approaches compared to F_SAH. [ABSTRACT FROM AUTHOR]

In this paper, a novel small-decentralized desalination device is presented for increasing the temperature difference between brackish water and glass cover, so as to enhance the solar still's freshwater productivity. This novel solar still device is based on installing a lens in front of the single slope solar still, and two lenses on still's both sides, and a reflector over the back side of the solar still. The main objective of such novel still is to concentrate sunrays at the still's bottom basin, through the refraction function of Fresnel lens. Furthermore, this novel still makes the reflector transferring its reflected sunrays to the solar still's basin. Experiments are conducted under the climate conditions in Hangzhou city, China, for testing the novel still's operational performance, and internal heat and mass transfer characteristics. Assessment of the novel still's feasibility is performed based on energy, exergy, exergoeconomic, and enviroeconomic methodologies, as well as energy payback time. Results show that the productivity of novel still is 32% higher than that of conventional still, and novel solar still enhances the average hourly energy efficiency by 97.73%, compared to conventional solar still. While, the corresponding value of hourly exergy efficiency is also enhanced by 43.713%. Due to the higher energy and exergy outputs of novel still throughout its lifetime, the novel solar still proposed in this study mitigates more CO 2 compared to the conventional still. Overall, incorporation three lenses and one reflector with the still is found promising in terms of freshwater yield, cost, and energy payback time compared to conventional one. Exergoeconomic and environmental parameters of the novel solar still are found more effective compared to the conventional one. • A novel solar still with lenses and reflector is developed and evaluated. • Using lenses and reflector increases still's productivity by about 32%. • Novel solar still enhances the average hourly energy efficiency by 97.73%. • Novel still mitigates more CO 2 compared to conventional one based on energy & exergy. • Novel solar still's enviroeconomic and exergoenvironmental are 324.317 $ and 22.148 $. [ABSTRACT FROM AUTHOR]

In the present study, the effects of rotary tubes and magnetic-induced nanofluid on heat transfer characteristics of a compact heat exchanger are individually investigated. Two-phase Eulerian model is employed to predict the hydrothermal and entropic characteristics of Fe 3 O 4 /water ferrofluid in the heat exchanger. Results indicate that utilizing each rotary tubes and magnetic field method can improve the energy and exergy efficiencies of the compact heat exchanger under specific circumstances by forming different types of secondary flow. It is found that employing each method individually can increase the maximum heat transfer rate by more than 60%. In comparison with methods like passive vortex and swirl generators, subtle pressure drop and entropy generation is observed in the new proposed methods since no additional obstacles were employed. Results also reveal that 12.5% of the possible maximum energy can be regenerated along with a 3.5% increase in the exergy efficiency of the heat exchanger at low Reynolds numbers by employing each method. Unlabelled Image • Two-phase model was employed in analysis of a FTCHE with Fe 3 O 4 /water ferrofluid. • Each of the employed method has a similar effect on the FTCHE. • Energy and exergy efficiencies were improved by each utilized technique. • A minimization in pressure drop and entropy generation is resulted. • Individual employment of magnetic field and rotary tubes was recommended. [ABSTRACT FROM AUTHOR]

The performance of single slope solar still with an enhanced condenser at different saline water mediums in the basin is studied and assessed based on productivity, energy, exergy, economic, and enviroeconomic methodologies. Six solar still configurations are considered: conventional solar still (CSS); modified solar still (MSS) which is a still with heat sink condenser; MSS having an umbrella (MSS + U); MSS with forced-air cooling (MSS + FA); MSS with forced-water cooling (MSS + FW); and finally, MSS with forced-water cooling and contains sand in the basin (MSS + FW + SD). Experiments are conducted under hot and cold climate conditions of Sohag city, Egypt. The results indicate that the MSS + FW + SD has a maximum daily yield of 5.37 kg/m2 in summer and 2.74 kg/m2 in winter with an increase of 36% in summer and 26% in winter compared with CSS. It was found that the maximum increase of the energy and exergy efficiency compared with CSS is achieved in the case of MSS + FW + SD of 39% and 33%, respectively. Furthermore, the maximum and minimum cost of freshwater is achieved in cases of MSS + U and MSS + FW + SD, respectively. Finally, among all studied systems, MSS + FW + SD achieves the best performance based on the exergoeconomic approach. [ABSTRACT FROM AUTHOR]

• PV/T collector integrated with infrared convective dryer. • Air cooling PV/T and it's energy, exergy and environmental analysis. • Application of sustainable solar energy PV-T dryer. It is possible to list the problems encountered in the drying of agricultural products as high energy costs and quality of the dried products. Sustainable solar dryers are needed to reduce energy costs in drying applications. The energy required to dry the product (hot air in this study) is provided by fossil fuels. This increases the amount of CO 2 released into the atmosphere. In this study, it is aimed to prevent CO 2 emitted into the atmosphere since all the energy required for drying is provided by solar energy. By using infrared technology in drying chamber the drying time of agricultural product was being shorten. In this experimental study, a new infrared-convective drying system with photovoltaic-thermal collector was designed and manufactured. Energy, exergy and environmental economics analyzes were made for different drying air mass flow rates. Excess energy is stored in batteries. Sustainable index and improvement potential values ​​were calculated using exergy analysis. As a result of this study, an average thermal efficiency of 43.75% was obtained from the PVT collector. PV panel was cooled and an average of 13.49% electrical efficiency was obtained. Average exergy efficiency was determined as 15.03%. With the use of solar energy, a system with integrated dryer was used in autumn and winter conditions. Only solar energy was used as power of the system. The use of solar energy is prevented from emitting 1.98 kg / hCO 2 to the atmosphere. In this way, a system that is environmentally friendly and compatible with nature has been obtained. CO 2 emission of the system was prevented and CO 2 cost was calculated as 2.86 ¢ / s. SI index was found in the range of 1.21–1.07 and the IP value was calculated in the range of 945–392 on average. [ABSTRACT FROM AUTHOR]

• Using HSC and FW increases daily still productivity of CSS + PTC in summer by 24.7%. • MSS + PTC + FW achieves maximum energy efficiency of 19.4. • MSS + PTC + FW achieves maximum exergy efficiency while CSS + PTC has the minimum. • MSS with PTC has the minimum freshwater cost while MSS + PTC + U has the maximum. • MSS + PTSC achieves the best performance-based exergoeconomic approach. This study experimentally investigates the performance of solar still coupled with a parabolic trough solar collector (PTSC) at different cooling rates based on energy, exergy, exergoeconomic, and enviroeconomic standpoints. Different solar still systems are considered; conventional solar still (CSS), solar still with heat sink condenser (MSS) and coupled with PTSC (MSS + PTSC), MSS having an umbrella and coupled with PTSC (MSS + PTSC + U), MSS with PTSC and condenser forced air cooling (MSS + PTSC + FA), and MSS + PTSC with condenser forced water cooling (MSS + PTSC + FW). Experiments are conducted under hot climate conditions of Sohag city, Egypt. Results indicated that the freshwater yield of all studied systems in ascending order is as follow; CSS + PTSC, MSS + PTSC + U, MSS + PTSC, MSS + PTSC + FA, and MSS + PTSC + FW in summer with value of 7.74, 8.02, 8.68, 9.11, and 9.45 kg/m2, respectively. The maximum exergy efficiency of 1.34% in summer is achieved in case of MSS + PTSC + FW system. The economic analysis shows that distilled water cost is minimum for MSS + PTSC + FW (~0.02 $/L), while it is maximum for MSS + PTSC + U (~0.022 $/L). It can be concluded that high freshwater production and less distilled water cost are making the enhanced solar desalination system feasible and competitive. Minimum exergy efficiency occurs in case of CSS + PTC with a value of 1.197% and MSS has higher average daily exergy efficiency. MSS + PTSC achieves the best performance-based exergoeconomic approach. MSS + PTSC + FW is by far the best system in cutting down CO 2 emissions. [ABSTRACT FROM AUTHOR]

Thermal performances of three packed bed latent heat medium temperature thermal energy (TES) storage systems are evaluated during charging and discharging cycles at low (4 mL s−1), medium (6 mL s−1) and high (8 mL s−1) flow-rates. The three phase change materials (PCMs) used in the storage systems are adipic acid, erythritol and eutectic solder (Sn63Pb67). Each TES tank comprises of a packed bed of 40 similar aluminium spherical capsules with the three different PCMs inside each tank. The thermal performance of these systems is evaluated in terms of the temperature profiles, total energy, total exergy, useful energy and useful exergy, during charging and discharging. Erythritol did not undergo phase transition during discharging at all the flow-rates due to super-cooling. The erythritol TES system shows the greatest efficiencies with regards to all the performance parameters considered with an overall energy efficiency of about 39.1%. The efficiencies of all the TES systems generally decreased with an increase in the heat transfer fluid (HTF) flow-rate. Although the eutetic solder TES stored and discharged greater quantities of energy at all the flow-rates, its performance was reduced by the lower degree of thermal stratification in the tank and longer charging and discharging times. • Three packed bed latent heat storage systems are compared experimentally. • Eutetic solder (Sn63/Pb37), adipic acid, erythritol are used in the systems. • Erythritol shows the best thermal performance characteristics. • Eutetic solder stores and discharges greatest quantities of energy and exergy. • Adipic acid shows slightly better efficiencies than the solder. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel concept called Solar Char-Cycling Pyrolysis (SCCP) has been developed. • Solar enhanced char-cycling biomass pyrolysis process was modeled for the first time. • In SCCP process, pyrolysis has the highest exergy destruction due to no combustion. • Due to the external biochar, the SCCP process showed the highest CH 4 and CO yields. Pyrolysis is an efficient technology for converting biomass into value-added products, characterized by endothermal reactions. The introduction of induced solar irradiance can boost product yields and reduce carbon emissions associated with incineration. However, direct solar pyrolysis faces challenges due to difficulties in maintaining a clean solar window, which is essential to ensure efficient sunlight penetration. To address this issue, a novel concept called Solar Char-Cycling Pyrolysis (SCCP) has been developed. In this work, to demonstrate the potential of solar enhanced biomass pyrolysis process as a promising biomass treatment technology, energy and exergy analyses of Autothermal Pyrolysis (AP), Solar Direct Pyrolysis (SDP), and Solar Char-Cycling Pyrolysis (SCCP) processes were studied in Aspen Plus. The results showed that SCCP has the highest energy and exergy efficiencies, which were 90.81% and 76.51%, respectively. In comparison, the solar energy utilization efficiency of char-cycling was 82.18% due to the high radiative heat absorptivity of biochar. Meanwhile, the energy efficiencies for AP and SDP were 87.17% and 80.23 %, respectively. The lower efficiency of SDP was attributed to window contamination. When the solar adsorption efficiency of the SDP process falls below 82.18%, it leads to a lower efficiency than the SCCP process. Through the energy analysis, it was proved that in the SCCP process, solar energy could fully cover the pyrolysis energy requirement since it overcame the problem of window contamination. Through the exergy analysis, it was shown that the SCCP process has the highest exergy efficiency compared to AP and SDP, which was caused by avoiding biochar incineration and enhanced solar energy utilization. This study gives a comprehensive evaluation of biomass solar pyrolysis applications, with the char-cycling method presenting an innovative approach for the efficient utilization of solar energy. [ABSTRACT FROM AUTHOR]

A thermodynamic modeling and optimization is carried out to compare the advantages and disadvantages of organic Rankine cycle (ORC) and Kalina cycle (KC) as a bottoming cycle for waste heat recovery from CGAM cogeneration system. Thermodynamic models for combined CGAM/ORC and CGAM/KC systems are performed and the effects of some decision variables on the energy and exergy efficiency and turbine size parameter of the combined systems are investigated. Solving simulation equations and optimization process have been done using direct search method by EES software. It is observed that at the optimum pressure ratio of air compressor, produced power of bottoming cycles has minimum values. Also, evaporator pressure optimizes the performance of cycle, but this optimum pressure level in ORC (11 bar) is much lower than that of Kalina (46 bar). In addition, ORC's simpler configuration, higher net produced power and superheated turbine outlet flow, which leads to a reliable performance for turbine, are other advantages of ORC. Kalina turbine size parameter is lower than that of the ORC which is a positive aspect of Kalina cycle. However, by a comprehensive comparison between Kalina and ORC, it is concluded that the ORC has significant privileges for waste heat recovery in this case.

Abstract This paper describes the design and energy, exergy, exergoeconomic and environmental (4E) performance analysis of a distributed-generation solar-assisted CCHP (combined cooling, heating and power) gas turbine system. The solar energy is used by the integration of solar parabolic trough collectors (SPTC) that are used to preheat compressed air before its introduction into the Brayton cycle combustor. An absorption chiller/heater and a heat storage tank are incorporated for producing chilled/hot water for space cooling or heating and domestic hot water, respectively. The results indicated that the energy and exergy efficiencies are 83.6% and 24.9% in the cooling operation mode, and 66.0% and 25.7%% in the heating mode, respectively. Compared to the system without solar energy, the carbon emission reduction ratio per unit energy generation of the proposed hybrid system is approximately 41.0%. The off-design analysis demonstrated that the evaluation using only energy and exergy efficiencies cannot describe the contribution of solar energy in the hybrid system. Adapting the exergoeconomic method based on energy level, the unit exergy costs of electricity, chilled water in the cooling mode (or hot water in the heating mode) and domestic hot water in the market pricing strategy are 2.1, 7.8 and 8.3 times than the natural gas's cost respectively. Highlights • Propose a gas turbine DES integrated with solar parabolic trough collectors. • Present the analysis of energy and exergy performances on the design and off-design conditions. • Allocate the products' cost using the exergoeconomic method with energy level. • Discuss the carbon dioxide emission reduction benefits of the hybrid DES. [ABSTRACT FROM AUTHOR]