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The development of sustainable bioenergy technologies is positioned as a fundamental pillar for the development of local economies and a promising solution for the energy sector decarbonization. In the aim to contribute to these efforts, the present research considers a comprehensive process evaluation for a sustainable fuel production. Furthermore, chicken fat waste is considered as feedstock for the production of biodiesel with two glycerol valorization roots: The first configuration suggests a glycerol—biodiesel blend combustion for energy supply to the transesterification process, while the second process propose hydrogen production through in-site glycerol reforming. These two configurations were simulated using Aspen Plus software. Then, in order to select the optimal process configuration, multiple decision criteria including fundamental process engineering assessment tools such as energetic, exergetic, environmental and economic assessments were performed. Results revealed that hydrogen case presents a better thermal efficiency with 79.34% compared to 70.33% in the heat integrated configuration. The exergetic efficiency of the two configurations are 76% and 65% in hydrogen case and heat integrated case respectively. Environmental results indicate that 1 GJ of energy produced from chicken fat generates approximately 13.63 kg CO2-eq via hydrogen case and 26.75 kg CO2-eq by Heat integrated cases. From an economic point of view the hydrogen case is found more profitable. [ABSTRACT FROM AUTHOR]

Plastic waste can exist naturally for hundreds of thousands of years and harm humans, animals, and the environment. In this study, the energy and exergy performances (absorbed energy, energy efficiency, absorbed exergy, and exergy efficiency) of LDPE (low-density polyethylene) plastic particles assisted by microwave heating based on the experimental data as affected by microwave power, feeding load, and chamber volume were evaluated and analyzed. The results showed that as the microwave power raised from 500 to 900 W, the feeding load changed from 10 to 30 g, and the chamber volume decreased from 200 to 100 ml, (a) the absorbed energy at the heating time of 60 min increased from 19.73 kJ, 5.84 kJ, and 22.71 kJ to 37.69 kJ; (b) the energy efficiency for the whole heating process increased from 1.10%, 0.32%, and 1.26% to 2.09%; (c) the absorbed exergy at the heating time of 60 min increased from 0.308, 0.091, and 0.091 to 0.724 kJ; and (d) the exergy efficiency for the whole heating process increased from 0.017, 0.005, and 0.023 to 0.040%, respectively. [ABSTRACT FROM AUTHOR]

Freeze desalination is a promising technique for wastewater treatment and zero/minimum liquid discharge systems, often requiring multiple stages to produce potable water. This research focuses on developing a Multiple Effect Freeze Desalination (MEFD) system based on experimental data for Single-Stage Desalination Efficiency (SSDE) and Single-Stage Recovery Rate (SSRR). The study analyzes various MEFD setups, calculating cooling energy consumption and correlating it with electrical usage through the coefficient of performance (COP). Comparisons with Reverse Osmosis (RO), Multi Effect Evaporation (MEE), and Multi-Stage Flashing (MSF) suggest that MEFDs may face challenges in matching RO efficiency but can compete with MEE and MSF within specific operational ranges. Exergy assessments indicate difficulties against even 10-stage MSF systems. Achieving SSDE and SSRR levels above 65% enables MEFDs to rival 10-stage MSF plants in terms of energy efficiency, surpassing MEE and MSF at over 85% efficiency. Despite these challenges, MEFDs offer benefits for treating high salt concentrations and resisting corrosion. [ABSTRACT FROM AUTHOR]

This study delves into the comprehensive analysis of four conventional mixed refrigerant liquefaction processes, namely C3MR-Linde, C3MR-APCI, SMR-Linde, and SMR-APCI, emphasizing energy and exergy perspectives. According to the energy analysis, C3MR-Linde demonstrates a lower energy consumption than the other systems, at 0.271 kWh kg−1 liquefied natural gas, while SMR-Air Products achieves the highest coefficient of performance (COP) at 2.67 kWh kg−1. The exergy analysis provides insights into the exergy efficiency and destruction of components, highlighting the C3MR-Linde process as the most exergy-efficient process, attaining 47.55%. Notably, compressors are identified as the primary sources of exergy destruction, accounting for 52.11%, 52.51%, and 45.39% of the overall cycle exergy destruction in the C3MR-APCI, C3MR-Linde, and SMR-APCI cycles, respectively. Furthermore, this study investigates how certain operational factors affect the COP, specific energy consumption (SEC), and exergy indices. It is observed that each cycle exhibits an optimal pressure drop in the expansion valves, with deviations resulting in a decreased COP and increased SEC. Additionally, changes in the refrigerant molar flow rates demonstrate an inverse relationship between the exergy efficiency and COP, with the SEC being notably more sensitive to such variations than the COP within the studied parameters. [ABSTRACT FROM AUTHOR]

The cooling system of an electric vehicle can be affected in various ways by vibrations, potentially impacting its performance and reliability. This encompasses damage to the components, potential leaks, noise, and discomfort, which may impact the performance. The impact of vibrations on electric vehicle cooling systems utilizing nanofluids as their primary working fluids remains insufficiently explored. Ongoing research aims to elucidate the specific influence of vibrations on these cooling systems implemented in such vehicles. The study of vibrations with amplitudes of up to 5 mm and frequencies of up to 25 Hz has been conducted. In the numerical model, a 2% volume concentration Al2O3 solution was utilized as the working fluid, with water serving as the base fluid, and Reynolds numbers ranging from 10,000 to 20,000 in the turbulent regime. The present study is focused on performing exergy and entropy analysis utilizing the second law. On inducing vibration onto the system, the Nusselt number rises to a maximum of 170% compared to the static tube. Entropy generation increases with increasing intensity of vibration. A similar trend is observed for second law efficiency which reaches a maximum of 60.81% at 5 mm amplitude and 25 Hz frequency at 20,000 Reynolds number. But with increasing intensity of vibration, dimensionless number of irreversibility (ϕ ) shows a negative trend with a minimum of 0.715 at 25 Hz frequency and 5 mm amplitude of vibration. Introducing controlled vibrations can significantly enhance system availability and efficiency, leading to considerable improvements in energy usage and cost-effectiveness. [ABSTRACT FROM AUTHOR]

Rising concerns over fossil fuel depletion and plastic pollution have driven research into biodegradable alternatives, such as polylactic acid (PLA). Microbial fermentation is preferred for lactic acid production due to its ability to yield enantiomerically pure lactic acid, which is essential for PLA synthesis, unlike the racemic mixture from chemical synthesis. However, commercial lactic acid production using first-generation feedstocks faces challenges related to cost and sustainability. Macroalgae offer a promising alternative with their rapid growth rates and carbon capture capabilities. This review explores recent technological advancements in macroalgae physicochemical characterization, optimization of fermentation conditions, and innovative pretreatment methods to enhance sugar conversion rates for L-LA production. It also covers downstream processes for L-LA recovery, presenting a complete macroalgal biorefinery system. Environmental impacts and economic prospects are assessed through exergy and techno-economic analyses. By valorizing macroalgae detritus, this study underscores its potential to support a sustainable biorefinery industry, addressing economic feasibility and environmental impact. [ABSTRACT FROM AUTHOR]

The tomato pomace (TP), which is a by-product of the production of tomato paste, was dried in a novel custom-designed daylight simulated photovoltaic assisted dryer (DPVD). The different light applications (daylight, UV light, daylight + UV light, and without light), different air velocities (1.5 and 2 m/s), and different heating source modes (hot air and infrared) were applied to dry TP having a moisture content of 80.60 ± 0.73% to the moisture content of 7.66 ± 1.72%. The average water activity values of all dried samples were measured as 0.52 ± 0.08. Analysis was conducted to compare sun drying with the effects of process conditions on the quality (color properties, lycopene, β-carotene, and total mesophilic aerobic bacteria count) and performance (energy efficiency, exergy efficiency, specific moisture evaporation rate, and improvement potential) characteristics of TP. The effects of process conditions for each heating source mode were determined separately, and the improvement of the system performance for each mode was investigated. The effect of the process conditions on total aerobic mesophilic bacteria (TAMB) count was similar in general. In the infrared heating mode, the loss in lycopene and β-carotene contents was 59.55 ± 2.22 and 57.87 ± 2.51 minimum for 1.5 m/s air velocity without light application and for 2 m/s with ultraviolet + daylight application. In general, the performance of the system decreased in case of using ultraviolet light. The retention in the lycopene and β-carotene contents was higher in the infrared mode with light applications compared to hot air mode without light. The optimum drying conditions were air velocity of 2 m/s with "daylight" assistance in the hot air heating mode and with "ultraviolet + daylight" assistance in the infrared heating mode. All the energy and the daylight source used in drying applications were obtained from the sun, a renewable energy source, thanks to the photovoltaic panel and the solar tube units in the novel custom-designed drying system. [ABSTRACT FROM AUTHOR]

Performance enhancement of a system is always preferred. The thermal efficiency of currently available simple solar water heater (SSWH) are generally in between 50 and 60%. The present work describes the use of different inserts like twisted tapes and springs on the performance enhancement of flat plate collector (FPC) of modified solar water heater (MSWH) under natural and forced convective situations for the performance enhancement. The experimental studies has been carried out at Nagpur ((21.1241° N, 79.0023° E) to investigate the performance of FPC of a MSWH with different inserts. Two different experimental setups were analyzed and compared for the investigation of performance. The first experimental setup investigated without any modification and under natural convection while other setups are investigated with modifications and under natural and forced convective situations. The experiments have been performed with plain twisted tape (PTT) inserts having five twisted ratios (y/W) viz. 2.0, 2.5, 3, 3.5 and 4, twisted tape with helical coil spring inserts (TTS) having three twisted ratios (y/W) viz. 2.0, 3 and 4, and traverse twisted tape (TTT) having three twisted ratios (y/W) viz. 2.0, 3 and 4. The PTT, TTS & TTT inserts are used with a fixed thickness of 1 mm, width 12 mm and length 1900 mm. The experiments has conducted for the different Reynolds number of, 4000 ≤ Re ≤ 24,000 using water as a working fluid. In all the cases Nusselt number increases with Reynolds number but the friction factor decreases. Some conclusions and recommendations based upon the above experimentation are presented at the end. [ABSTRACT FROM AUTHOR]

Energy waste from power plants, typically emitted into the atmosphere, contributes to climate change and resource depletion. Integrating heat recovery systems into power plants can improve overall efficiency. This study focused on utilizing waste heat from a 500-MWe coal-based supercritical standalone plant through the organic Rankine cycle. The power plant uses Indian coal as a fuel input, and five distinct working fluids, R245fa, methanol, acetone, ethanol, and benzene, are considered working fluids for the ORC system. Thermodynamic analysis indicates that the standalone plant exhibits energy and exergy efficiencies of 27.33% and 25.01%, respectively. Following the integration of ORC, an overall efficiency improvement is observed. The increment in efficiency is because of the waste heat utilization, where the ORC generates additional electricity generation with outputs of 9.91 MWe for R245fa, 13.71 MWe for methanol, 13.97 MWe for acetone, 14.04 MWe for ethanol, and 14.11 MWe for benzene. Additionally, the study reveals a substantial reduction in CO2 emissions compared to the coal-based power plant with the same production of power, amounting to approximately 216.43 tons for R245fa, 299.43 tons for methanol, 305.10 tons for acetone, 306.63 tons for ethanol, and 308.16 tons for benzene. The thermodynamic investigation identifies the superior performance of the benzene-based ORC among the chosen fluids, and the economic study concludes that the ethanol-based ORC stands out as the most favorable option among the considered alternatives. [ABSTRACT FROM AUTHOR]

This research paper figures out thermal performance analysis for vapor compression refrigeration (VCR) driven by the organic Rankine cycle (ORC) implementing MATLAB software. The ORC system is powered by improved evacuated tubes and compound parabolic collectors. The paper evaluates the overall exergetic efficiency and coefficient of performance using the working fluid Pentane/R245fa. The result of the present paper indicates that optimum COP of 0.75 and exergetic efficiency of 28% is obtained at 340 K of collector output temperatures, 0.1/0.9 of fractional mass of the working fluid, and 285, 300 K for VCR condenser and evaporator temperature, respectively. Sensitivity analysis pointed out that condenser temperature was the most impactful parameter for both exergetic efficiency and COP owing to higher F-value 'of 156.06' and '89.28,' respectively. Further, collector output temperature and fractional mass of the working fluid were the least impactful parameters owing to lower F-value '1.95' and '1.02' for exergetic efficiency and COP, respectively. [ABSTRACT FROM AUTHOR]

The study performs energy and exergy analyses for each component such as boilers, buildings, distribution networks and heat exchangers of a new generation district heating system. Energy and exergy efficiencies are compared for all system components, and energy and exergy losses are presented using Sankey and Grassman diagrams. Three flue gas condensers with finned bundles are designed for different capacities of boilers that intend to recover water and heat from the waste flue gas in the district heating system due to high flue gas energy losses. Colburn-Hougen and one-dimensional finite difference methods are used to design the flue gas condensers with the MATLAB program. The exergy analysis showed that the exergy input to the system is lost by 4.52% from the distribution networks, 4.15% from all buildings and 2.18% from the flue gas. In the system, the energy and exergy efficiencies of the boilers are calculated to be 87.23% and 17.32%, respectively, and the heat loss from the flue gas is found to be 12%. The design results show that the values of mass convection coefficient (km) for all flue gas condensers decrease from 0.0706 at the inlet condensation zone to 0.0354 towards the outlet. The total condensation rate and condensation efficiency are found to be 86 kg/h and 60%, respectively, for the 2500 kW boiler. [ABSTRACT FROM AUTHOR]

The present investigation proposes an innovative hybrid energy system based on solar energy equipped with a parabolic trough collector, a supercritical CO2 Brayton cycle (SCBC), a recuperative organic Rankine cycle (RORC), a proton exchange membrane electrolyzer (PEME), and a two-tank direct thermal energy storage system. To ensure the stable operation of the system despite fluctuations in the amount of sunlight received during the day, the mass flow rate (MFR) of the heat transfer fluid in the solar collector is regulated to maintain a consistent inlet temperature for the SCBC and RORC. Additionally, the MFR of the HTF from the hot tank to the bottoming cycles also remains constant. This approach allows the entire system to operate around the clock and under stable conditions. The energy and exergy performance of the entire system is evaluated under varying solar irradiance and ambient temperature over a 24-h period. The results revealed that the system could generate 1.5 MW of net power, 4.47 kg of hydrogen per day, and 18.48 kg/s of hot water with a total energy efficiency of 51.30% and exergy efficiency of 55.7%. The solar collector possessed the lowest exergy efficiency of 33.89% due to a high exergy destruction rate. The PEME possessed maximum energy efficiency of 58.85%, followed by RORC and SCBC with 26.38% and 14.84%, respectively. It is concluded the proposed system can provide a reliable and sustainable supply of electricity, hydrogen, and hot water, demonstrating a promising and viable poly-generation technology for both grid-connected and off-grid applications. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive thermodynamic analysis was performed to evaluate and optimize the performance of a solar-powered single-effect lithium bromide-water absorption chiller system. A computational model was developed to systematically investigate various design parameters, including the impact of inlet generator, absorber/condenser, and evaporator temperatures on the system's energy and exergy efficiency. Additionally, the study evaluated the influence of solution heat exchanger effectiveness and hot source temperatures. Key performance indicators such as cooling production capacity, coefficient of performance, exergy efficiency, and overall solar cooling system efficiency were considered. The results indicated that a condenser/absorber temperature of 30 ℃ improved the coefficient of performance to 0.8, and the cooling capacity to 30.05 kW while varying the evaporation temperature between 4.5 to 10.5 ℃ improves the coefficient of performance by approximately 10.38%. Increasing the solution heat exchanger effectiveness resulted in a 16.77 and 16.076% enhancement for both the coefficient of performance and exergy efficiency, with generator temperatures of 74 and 90 ℃. The system achieves its highest performance within a hot source temperature range of 70–75/ ℃. Proper selection of heat exchanger temperatures significantly improved the performance of the absorption subsystem. The intensity of solar irradiance and ambient conditions influenced the system's efficiency. [ABSTRACT FROM AUTHOR]

This research presents an exergy analysis of a gas turbine power plant situated in Assiut, Egypt, operating under high-temperature conditions. The aim of the study is to assess the performance of the simple gas turbine cycle and identify the sources of thermodynamic inefficiencies using the second law of thermodynamics as a basis for analysis. To accomplish this, a model was developed in EES software utilizing real operational data obtained from the plant's control system. The investigation focused on the impact of varying ambient temperature on the exergy efficiency, exergy destruction, and net power output of the cycle. The results revealed that the combustion chamber accounted for the highest exergy destruction, amounting to 85.22%. This was followed by the compressor at 8.42% and the turbine at 6.36%. The overall energy and exergy efficiencies of the system were determined to be 28.8% and 27.17%, respectively. Furthermore, the study examined the effects of increasing ambient temperature from 0 to 45°C on the system's performance. It was observed that as the temperature rose, the overall exergy efficiency decreased from 27.91 to 26.63%. Simultaneously, the total exergy destruction increased from 126,407 to 138,135 kW. Additionally, the net power output exhibited a decline from 88,084 to 84,051 kW across the same ambient temperature range. These findings highlight the significant influence of ambient temperature on the thermodynamic performance of gas turbine power plants. As temperature rises, a greater amount of exergy is lost, resulting in reduced efficiency and diminished net power output. Therefore, optimizing the design of the combustion chamber is crucial for mitigating the adverse effects of hot weather conditions. The insights obtained from this study can be utilized to enhance the design and operation of gas turbine plants operating in hot climates. [ABSTRACT FROM AUTHOR]

The exergy analysis of a direct method for the conversion of natural gas to methanol is reported in this work. The study is part of a process development effort to identify areas of improvement to the technology of direct conversion of natural gas to methanol. Prior to the exergy analysis, different configurations of the direct conversion process were developed and simulated. Two heat-integrated configurations designated as Case I and Case II were considered plausible. The exergy efficiency, excluding exergy of the rejected heat, of Case I and Case II were determined as 33% and 36%, respectively. The 9% increase in efficiency of Case II relative to Case I did not justify the installation of an expander and was therefore screened out. Exergy balance in Case I showed that a total of 56% of the exergy input was lost to internal consumption. The majority of exergy destruction was found to be due to the methanol synthesis reactor (36.0%), heat exchangers (30.1%) and combustion (25.0%). Further analyses of the losses across all heat exchangers indicated a nonlinear relationship between exergy destruction contribution and minimum approach temperature (ΔTmin), with a minimal at ΔTmin of 10 °C. The methanol product was determined to represent 18% of exergy input, excluding the air separation unit. The overall process efficiencies were found to be 18% (LHV) and 24% (LHV) for recycle split fractions of 90% and 98%, respectively. The results of this work would provide further insight into the exergy viability of the technology of direct conversion of natural gas to methanol. [ABSTRACT FROM AUTHOR]

Urban energy issues have attracted global attentions due to the key role in controlling climate change. As one of the world's largest metropolises, Beijing has been focusing on improving urban energy performances to achieve green transition and sustainable development during the past decades, for which purpose the measurement and decomposition of energy performance is of vital importance. In this paper, exergy is introduced as one of the indicators under the frame of index decomposition analysis. An hierarchical framework is constructed to reveal the contributions from different level of urban energy system to overall energy performance. Beijing's energy and exergy consumption and intensity are then analyzed and compared from the city and sector level during 2008–2017. Results suggest that Beijing's city and sector-level energy performance has been improving during the last 10 years and technical improvements contribute significantly from both energy and exergy perspectives. Meanwhile, changes from Beijing's industrial structure and energy supply structure display neutral contributions, which probably indicate the underestimation of structural contribution is caused under the IDA framework. [ABSTRACT FROM AUTHOR]

Paddy parboiling in rice industries is an energy-intensive process that requires huge attention for energy conservation, fuel economy, and sustainability. Thus, several research initiatives have been undertaken to adopt a suitable energy conversion system in such industries to improve thermal efficiency and reduce environmental impact. In this study, exergy performance and exergy-based sustainability indicators have been investigated on a reversible bed paddy dryer coupled with a rice husk-fuelled downdraft gasifier. The experiment was conducted at the optimum operating conditions such as an equivalence ratio of 0.2 in the gasifier and a drying air temperature of 80℃ in the dryer. The exergy efficiency of the reversible bed dryer and the gasifier were 65.53% and 70.92% respectively. The lowest exergy efficiency of 35.29% was seen in the combustion chamber since a huge exergy destruction of 2.75 kW occurred. Therefore, the combustion chamber has a high potential improvement of about 1.66 kW. Due to less exergy destruction, the gas cooler and air duct showed high exergy efficiency of 62.36% and 76.2% respectively and the lowest values in exergy-based sustainability indicators. The assessment of environmental and sustainability factors on each component showed that the combustion chamber has a high waste exergy ratio of 0.688, environment effect factor of 1.95, exergy destruction coefficient of 0.69, and exergy sustainability index of 0.51. [ABSTRACT FROM AUTHOR]

The use of agro-industrial and urban organic waste to produce energy seems to be one of the most attractive options for the future of energy supply. Anaerobic digestion is a promising process for treating organic waste and producing biogas. Biogas is a mixture of gases, primarily consisting of methane, carbon dioxide, and hydrogen sulfide, that can be used for electrical and thermal energy generation or as fuel. However, it is still necessary to improve the technology associated with its production, adapting it to an efficient, safe, and competitive scale. Various methodologies are used to support the decision on process parameters and operating conditions to find the most effective and sustainable ones. In this study, an exergy analysis was performed to determine the exergetic efficiency and exergy destruction in the biogas process produced from the anaerobic digestion of vinasse. The analysis was performed through mass, energy, and exergy balances using literature data and computer simulation and considering the use of a continuous stirred tank reactor. The results show that the exergy destroyed in the CSTR biodigester was 1338.9 kW, accounting for 57.2% of the overall exergy destruction in the process. The heat exchanger showed the highest exergy efficiency (99.95%), with only 5.77 kW of exergy being destroyed. The authors suggest for future works that it would be interesting to perform a life cycle assessment (LCA) and exergoeconomic analysis to evaluate the environmental and economic impacts associated with biogas production from the anaerobic digestion of sugarcane vinasse. [ABSTRACT FROM AUTHOR]

In the present investigation, thermodynamic/eco/environmental analysis of the relationship between time-dependent particle deposition and thermal-based losses and incident solar radiation intensity on the PV front cover glass during the months with the least precipitation in the city of Samsun (Turkey) was performed. To evaluate the effect of dust accumulation, controlled experiments were carried out where the surface of one set of PV panels was periodically cleaned with water and the other one was left to natural contamination. The results showed that over three months, the difference in energy loss rates between cleaned and uncleaned PV arrays ranged from 2.53% to 8.1%, with the exergy efficiency difference measured at 1.3%–2.44%. According to the energy-based analyzes, August was the most effective month, with cleaned PV arrays reducing CO2 emissions by 401.5 kg and saving $6.02, compared to uncleaned PV arrays which reduced emissions by 362.21 kg and cost $5.43, respectively. Similarly, in the exergy-based evaluation, August was the most efficient month, with cleaned PV arrays decreasing CO2 emissions by 401.5 kg and saving $6.02, compared to uncleaned PV arrays, which dropped CO2 emissions by 362.21 kg and costing $5.43, respectively. While the cleaned surfaces were initially positive, a decrease was observed over time. However, the efficiency of PV decreased with increasing panel temperature. The study concludes that PV surfaces need to be cleaned at certain intervals, depending on the location's weather conditions. [ABSTRACT FROM AUTHOR]

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The utilization of waste heat from power plants, which is generally lost to the atmosphere, can reduce energy wastage significantly. Heat recovery systems are necessary for power plants to utilize the waste heat, which improves overall efficiency and reduces the need for additional fossil fuel consumption and its associated carbon emissions. This study uses the organic rankine cycle (ORC) to recover waste heat from the flue gas exhaust of an integrated gasification combined cycle (IGCC) power plant. A detailed thermodynamic analysis is conducted to study the outcomes from a 400 MWe IGCC plant and IGCC integrated with ORC. The IGCC plant is a reconfigured 400 MWe pressurized pulverized combined cycle power plant. The ORC uses R245fa as its working fluid, and high-ash Indian coal is used as a fuel input for the IGCC plant. The modelling and simulation of different plant configurations have been done using the software "Cycle-Tempo". The thermodynamic analysis reveals that the IGCC plant has energy and exergy efficiencies of 45.50% and 41.62%, respectively, and the IGCC-ORC plant has energy and exergy efficiencies of 45.84% and 41.92%, respectively. This study also shows that the combustion chamber and cooling water system in condenser experience maximum exergy and energy losses. Moreover, the ORC produces a net additional power output of 2.34 MWe with energy and exergy efficiencies of 12.48% and 42.54%, respectively. This additional power generation helps in avoiding around 51 tonnes/day of CO2 when similar amount of power is produced from a coal-based thermal power plant. [ABSTRACT FROM AUTHOR]

The hybrid energy storage system of wind power involves the deep coupling of heterogeneous energy such as electricity and heat. Exergy as a dual physical quantity that takes into account both 'quantity' and 'quality, plays an important guiding role in the unification of heterogeneous energy. In this paper, the operation characteristics of the system are related to the energy quality, and the operation strategy of the wind power hybrid energy storage system is proposed based on the exergoeconomics. First, the mathematical model of wind power hybrid energy storage system is established based on exergoeconomics. Then, wind power experiments of three forms of thermal-electric hybrid energy storage are carried out, and RSM is used to analyze the power quality and exergoeconomic characteristics of the system, and the optimal working conditions of the experiment are obtained. Finally, an optimization strategy is proposed by combining experiment and simulation. The system efficiency, unit exergy cost and current harmonic distortion rate are multi-objective optimization functions. The three algorithms evaluate the optimal solution based on standard deviation. The results show that the exergoeconomics can effectively judge the production-storage-use characteristics of the new system of ' wind power + energy storage'. The thermal-electric hybrid energy storage system can absorb the internal exergy loss of the battery, increase the exergy efficiency by 10%, reduce the unit exergy cost by 0.03 yuan/KJ, and reduce the current harmonic distortion rate by 8%. It provides guidance for improving the power quality of wind power system, improving the exergy efficiency of thermal-electric hybrid energy storage wind power system and reducing the unit cost. [ABSTRACT FROM AUTHOR]

In this paper, the performance of a parallel two-stage compression (PTC) cycle on the domestic refrigerator-freezer in a laboratory according to the IEC 62552–2015 standard is investigated. The relatively large temperature difference between the fresh food compartment (FFC) and the refrigerant in the fresh food compartment evaporator (FFCE) leads to high compression and irreversible losses in the refrigeration circuit. To avoid the mentioned problems and reduce energy consumption, a PTC cycle is used. The innovation of this article is the 4E analyses (energy, exergy, exergoeconomic, exergoenvironmental) for the PTC cycle using the results obtained from the laboratory. Ultimately, the multi-objective optimization of the PTC cycle is conducted. For optimizing the PTC cycle, the total cost rate and the exergy efficiency are set as targets and the evaporator pressure and condenser pressure as variables. MATLAB and REFPROP 9.1 are used to model the system. Results showed that the highest exergy destruction rate is associated with the FFCE (0.349 kW) and compressor (0.183 kW). The highest exergy efficiency among the equipment is evaporators. The maximum exergoeconomic factor is related to the freezer compartment evaporator (FZCE) (98.70%) and then the compressor (98.62%). FZCE has the highest environmental impact (99.9%). [ABSTRACT FROM AUTHOR]

A new power and refrigeration cycle is examined in the present study. The system proposed is a combination of organic Rankine cycle (ORC) and an ejector refrigeration cycle (ERC). An ERC is introduced into the ORC to recover heat from partial expansion of the ORC fluid. The heat recovery is enhanced with the incorporation of recuperator, evaporator and superheater as heat exchangers. Among the various working fluids opted for, R245fa and R236ea have been considered in the present work. The properties of the combined cycle state points are evaluated through Engineering Equation Solver (EES) software. The impact of decision variables (such as hot source temperature, turbine expansion ratio, extraction ratio, and separator temperature) on performance parameters (such as exergy destruction, energy efficiency of power generation, exergy efficiency of power generation, energy efficiency of combined system, exergy efficiency of combined system, COP, and cooling power ratio) is examined and reported. The series heater configuration in ORC has improved system performance by recovering waste heat more effectively. At the same parametric conditions, the energy and exergy performances of R245fa are higher than those of R236ea. [ABSTRACT FROM AUTHOR]

The use of renewable energy sources to maintain appropriate thermal humidity and temperature conditions in food drying technologies, especially in humid climate zones, is a current area of research. In the Eastern Black Sea Region, the high relative and specific humidity of the atmospheric air lead to a low drying rate of the products. Therefore, in this study, to enhance the drying rate of the products, three models and their psychometric cycles were studied on decreasing the specific humidity of the drying air and increasing the moisture saturation degree of the drying air. The innovative hazelnut drying models proposed for the climatic conditions of the Eastern Black Sea region incorporate several components, including thermoelectric modules (TEM), photovoltaic thermal (PV/T) systems, desiccant wheels (DW), heat pipes (HP) and heat exchangers (HX). The thermodynamic analysis was conducted on the theoretical cycles belonging proposed models. Emphasis was given to the development of Model-C, taking into account the drying conditions specific to hazelnuts in the Eastern Black Sea region, among the cycles named Model-A, Model-B and Model-C. The energy efficiencies and SEMER values of Model-A, Model-B and Model-C were presented based on selected atmospheric conditions. Each model is valid under its characteristic operating conditions, and the energy efficiencies, SEMER values and the exergetic efficiencies for Model-A, Model-B and Model-C were determined as (4.66%-0.271 kg-H2O kWh−1–62%), (9.87%-0.1542 kg-H2O kWh−1–22%) and (9.13%-0.1381 kg-H2O kWh−1–10%), respectively. Also, presented models of hazelnut drying supported by renewable energy have achieved high sustainable index (SI) values. Consequently, these models ensure the sustainability of energy in the drying sector and facilitate the assessment of their environmental, economic and social impacts. The utilization of renewable energy in the models will lead to a reduction in CO2 emissions during the drying process. These results indicate that TEM systems are a viable option for food drying in the future. [ABSTRACT FROM AUTHOR]

Double-pipe helical heat exchangers (DPHHXs) are widely used for cooling and heating applications. In this study, a combination of two methods is used to enhance the performance of DPHHX. The thermal–hydraulic performance is investigated using a nanofluid of silicon dioxide and water (SiO2/water) as well as spring wire insert (SWI) experimentally and numerically. The numerical model is validated with the experimental results. The parameters such as Nusselt number, pressure drop, exergy efficiency, and thermal–hydraulic enhancement factor are investigated for Reynolds number range from 4500 to 7000. The results show the Nusselt number is enhanced with nanofluid employment and SWI. Nusselt number increases by 34% when 0.1% volume concentration of nanofluid is used and by 43.5% when spring wire is only used compared to base water. The configuration with a 0.3% volume concentration and SWI achieves the highest Nusselt number enhancement ratio, exhibiting a 174% increase compared to other configurations. In the same case, the pressure drop ratio reaches its peak at 157%. The exergy efficiency improves with an increase in nanoparticle volume concentration, with the 0.3% concentration with SWI showing the highest values, ranging from 54 to 65%. Among different concentrations, the SiO2/water nanofluid with a 0.2% volume concentration with SWI demonstrates the highest thermal–hydraulic enhancement factor, making it the optimal choice. The results prove that spring wire inert is more effective than nanofluid in the DPHHX. The contours, streamlines, and vectors of the temperature, velocity, and pressure distributions give more understanding for the heat transfer and fluid flow. [ABSTRACT FROM AUTHOR]

Passive inserts, notably twisted turbulator inserts (TTI) and perforated twisted turbulator inserts (PTTI) loaded with water-based ternary hybrid nanofluid (THNF), are employed in plain tube heat exchangers to enhance thermal performance. The investigation focuses on how THNF replacement inserts will impact energy utilization, exergy consumption, and the environment in the decades to come. Nanoparticles of copper oxide (CuO), aluminum oxide (Al2O3), and titanium oxide (TiO2) are dissolved in water, which functions as the working fluid, and the resulting THNF is injected at three distinct concentrations (0.06, 0.09, and 0.12%). Certain aspects of the flow of a control fluid are investigated in terms of energy, exergy, and emissions. The experimental findings demonstrate that utilizing TTI and PTTI in conjunction with THNF substantially enhances the compact air heat exchanger's thermal and hydraulic efficiency. Heat transfer, friction factor, exergy change, and reversibility are greatly improved when turbulator inserts with PTTI and TTI are employed in plain tubes containing 0.12% (v/v) THNF. The CO2 discharge rises by 2.6–2.1 when PTTI or TTI turbulator inserts are inserted in the tube's core. Using PTTI with a concentration of 0.12% (v/v) THNF as the working fluid and a tube insert will provide PEC values in the range of 1.075–1.04. The thorough examination of heat transfer enhancement, friction factor, exergy efficiency, and environmental effect suggests that PTTI is a better passive device insert for heat transfer efficiency, particularly when combined with 0.12% (v/v) THNF. [ABSTRACT FROM AUTHOR]

In this research paper, a solar air heater with triangular fins has been experimentally analysed and optimized. Initially, an experimental set-up of a solar air heater having triangular fins has been developed at the location of 28.10°N, 78.23°E. The heat transfer rate through fins and fins efficiency has been determined by the Finite Difference Method model equations. The experimental data and modeled data of response parameters have been optimized in MINITAB-17 software by the Response Surface Methodology tool. For creating the response surface design, three input parameters have been selected namely solar intensity, Reynolds number, and fin base-to-height ratio. The range of solar intensity, Reynolds number, and fin base-to-height ratio is 600 to 1000 W/m2, 4000 to 6000, and 0.4 to 0.8 respectively. The response surface design has been analyzed by calculating the outlet temperature, friction factor, Nusselt number, fin efficiency, thermal performance factor, and exergy efficiency. The optimum settings of input parameters: solar intensity is 1000 W/m2; Reynolds number is 4969.7, and the fin base to height ratio is 0.6060, on which these response: namely outlet temperature of 92.531°C, friction factor of 0.2350, Nusselt number of 127.761, thermal efficiency of 50.836%, thermal performance factor of 1.4947, and exergy efficiency of 8.762%. [ABSTRACT FROM AUTHOR]

This study reviews the efforts made regarding thermal desalination systems, focusing on the exergetic aspect. Each plant has a component, which limits the magnitude of thermal energy improvement; however, the target should be an effort to minimize the exergy destruction. It was found that all stand-alone systems required modification or integration with other desalination plants due to their low exergy efficiency. Furthermore, the exergy-destructive components in humidification–dehumidification (HDH) systems as a domestic desalination process, in poly-generation systems by the ability of freshwater production and energy generation, and in combined cooling–heating–power (e.g., MEE-CCPP) cycles as the recent desalination technologies were introduced. The exergy efficiency of a desalination plant increased by coupling to a solid oxide fuel cell or heat pump, using surplus low-pressure or makeup steam and optimization of the effect and stage numbers. Designing a poly-generation system capable of producing power, desalinated water, as well as liquefied natural gas heating/cooling could improve the system exergetically. Desalination systems were found to benefit from increasing the evaporation temperature caused by a Rankine cycle. Coupling the HDH system to a reverse osmosis unit or thermo-compressor vapor compression–reverse osmosis plant was found to improve the system performance exergetically. [ABSTRACT FROM AUTHOR]

In this work, the cross-linear system, a recently developed concentrated solar power technology, is investigated for process heat application to mitigate the drawback of cosine loss at higher latitudes in current concentrated solar power technologies. The mathematical model for energy and exergy analysis has been developed and validated using computational analysis and experimental work previously performed. The simulation was conducted under the average direct normal irradiance of 756.47 W/m2 considered for 8 h (Sunny hours) for April 2017. The primary goal of the thermal investigation is to identify the optimal inlet parameters for the heat transfer fluid (HTF) while considering significant value of HTF outlet temperature, energy, and exergy efficiency of the receiver. The mathematical model is developed and simulated using Engineering Equation Solver software. Following an in-depth examination of the outcome, the optimum inlet HTF temperature and mass flow rate are established with noteworthy energy and exergy efficiency. The analysis demonstrates the utilisation of the cross-linear system for process heat applications at higher latitude locations (> 30°N) to circumvent the weakness of other existing concentrated solar power technologies due to the air's wide operating temperature range as HTF. The observed results show that this system provides hot air from 180 °C to 200 °C at a thermal efficiency of 45% −50% and exergy efficiency from 25% to 30% for the low inlet temperature of 60 °C to 100 °C. Even at higher latitudes (> 30°N), the cosine effect of 0.9 for 4 h duration is a unique advantage of this system. [ABSTRACT FROM AUTHOR]

In this study, the thermodynamic performance of a real operating three-stage turbo/centrifugal type main air compressor for the air separation unit in an iron-steel industry was evaluated using both conventional and enhanced exergy analyses. Furthermore, the interaction and the potential for improvement of system components at two different airflow rates, 210,000 Nm3 h−1 and 240,000 Nm3 h−1, were investigated under real operating conditions. The results indicated that the conventional exergy analysis of the system yields efficiency rates of approximately 21.3% and 25.0% for these airflow rates, respectively. It was found that implementing operating conditions proposed by the enhanced exergy analysis could increase the system's exergy efficiency to about 40.8% and 80.7%, respectively. The primary causes of exergy destruction in the compressor are generally attributed to frictions occurring in the impeller, diffuser, and volute, as well as shock waves and air circulation during the compression process. It was observed that system efficiency could potentially increase to 80.7% with improvements in compressors and pump. The study also determined that enhanced exergy analysis is beneficial for identifying losses in system components and is seen as a tool that complements conventional exergy analysis. [ABSTRACT FROM AUTHOR]

In this study, the partial heating supercritical CO2 power cycle for waste heat recovery is investigated to understand more about the true potential of thermodynamic and economic performance improvement of each system component, as well as a more profound comprehension of the simultaneous interactions between the system components using advanced exergy and advanced exergoeconomics analysis. In addition, the affirmative or nugatory impact of the inefficiency of each component on the exogenous exergy destruction and exogenous costs in other system components separately, as well as the effect of the inefficiency combination of other components on the desired component (mexogenous effect) have been determined. The results demonstrated that according to the technological constraints in the system, the maximum exergy efficiency that can be achieved is 59.8%, and 38.4% (926.9 kW) of the total exergy destruction and 46.18% (32.52 $ h - 1 ) of the total exergy destruction cost of the system is avoidable. According to the mexogenous exergy destruction, the simultaneous interplay among other system components affects the turbine performance most. The priority of improving the components based on the highest avoidable endogenous exergy destruction cost is related to the turbine, cooler, and compressor. The results of this study revealed that 97.8% (79.73 $ h - 1 ) of the system's total cost is relevant to the endogenous part, which shows that the cost caused by the interaction among the components is very small. The turbine and compressor have the most significant cost-saving potential, while the heaters have the lowest. [ABSTRACT FROM AUTHOR]

Compared with the single-stage compression, the two-stage compression cycle shows high efficiency and application potential under both severe heating and refrigerating conditions. Therefore, to improve the performance of the two-stage vapor-compression cycle furtherly, this study introduces three ejector-assisted two-stage compression cycles (E1, E2, and E3), and a conventional two-stage vapor-compression cycles (C1) also selected as the comparison. The energetic and exergetic efficiency of the systems using various refrigerants (R152a, R1234yf, R32 and R290) is investigated and compared based on the validated theoretical model for both the severe refrigerating and heating application. The result shows that the ejector improves the system's performance significantly. Under the refrigerating mode, System E3 using R32 is recommended to be applied. Compared with Systems C1, E1, and E2, the maximum refrigerating coefficient of performance (COPR) of System E3 using R32 is improved by 16.1, 12.4, and 9.1%, respectively, with the evaporation temperature of −40 °C and condensation of 30 °C. Systems E2 and E1 using R152a are recommended under the heating mode. Compared with Systems C1 and E3, the heating coefficient of performance (COPH) of Systems E1 and E2 using R152 is improved by 3.0 and 4.5%, respectively, with the condensation temperature of 70 °C and evaporation temperature of −5 °C. The result provides a deep understanding of the potential advantages of the ejector-assisted two-stage compression cycle applied in the refrigerating and heating field. [ABSTRACT FROM AUTHOR]

Over the past decade, there has been a rapid expansion in the utilisation of process integration for incorporating renewable energy sources and energy storage systems (ESSs). Using different methods to achieve an ESS with higher efficiency is important; the originality of this study arises from two key points: initially, it proposes an inventive arrangement to harness geothermal energy for various purposes and store it in Liquid Hydrogen ( LH 2 ). Additionally, it employs cold energy from a geothermal source through a refrigeration cycle to cool down hydrogen gas prior to its entry into the liquefaction cycle. The proposed multi-generation system uses geothermal energy to produce heat (2.5 kg s - 1 hot water at 60 ℃), fresh water (41 kg s - 1 at 25 ℃), power (5200 kW) and LH 2 (79 kg h - 1 at − 253 ℃), including two-stage instant evaporation, Organic Rankine cycle, internal water heater, proton membrane electrolyser, and reverse osmosis unit. This system is analysed from the point of view of energy, exergy, and economy by focusing on the LH 2 production cycle. GA codes are utilised to optimise the LH 2 production cycle. The total annual cost of 1.74 M$ year−1 including C CAPEX,a (1.46 M$), C OPEX , a (0.25 M$), and C O & M , a (0.03 M$) is calculated for the LH 2 production cycle. Specific liquefaction cost is 2.26 $ kgLH2−1, while the minimum selling price is 2.65 $ kgLH2−1 by considering three years payback period. The LH 2 production cycle has SEC of 8.69 kWh kg Lh 2 - 1 which is less than that of similar small-scale liquefaction processes. [ABSTRACT FROM AUTHOR]

In projects such as highway bridges and offshore wind farms, understanding the kinematics of soil layers and their displacement is important for accurately predicting the behavior of caissons and monopiles under lateral loads. To better predict the distribution of soil deformation around the foundations, this paper presents an extensive usage of the energy-based variational method in laterally loaded deep foundations (caissons or monopiles) with very large diameters. By adding an assumption of soil deformation in multilayered soils, the displacement distribution around the foundations can be better described. The responses of deep foundations were obtained by minimizing the potential energy and virtual work of the foundation-soil system. After that, static lateral loading tests on two caissons with the same embedment depth of 36 m and the same diameter of 6 m were performed, and the displacement field in soils and the deflection profiles of the caissons were measured. Results show that the lateral displacement and the decay distribution fields calculated from the theory in this paper agree with the measured data from the static loading tests and the corresponding finite differential method (FDM) results. At last, a series of case studies performed by MATLAB and FDM analyses were also conducted to study the influence of uz on the response of foundations, as well as the influence of foundation parameters and soil modulus on the value of ϕz. [ABSTRACT FROM AUTHOR]

The thawing process is a common processing method used in the meat industry. To ensure provide food safety and protect meat quality, the thawing process should be carried out carefully. Ohmic thawing (OT) is one of the novel thawing methods. In this study, a custom-designed ohmic thawing prototype was set up and used to thaw frozen minced beef samples in different shapes (X: 13 × 4 × 3 cm3; Y: 13 × 6 × 2 cm3; Z: 13 cm height × 3.91 cm diameter) at 3 different voltage gradients (10–13-16 V/cm) by using 3 different electrode designs (E1, titanium foil; E2, needle type titanium electrode; E3, titanium embossed). The optimum OT condition resulting in a high-quality product with the highest process efficiency was determined. As an optimization procedure, a three-level general factorial design was performed. Thawing time, drip loss, thawing ratio, maximum temperature, ohmic power consumption, energy efficiency, and exergy efficiency values were used as responses. The cylindrical sample shape resulted in higher changes in quality and decreased performance of the process. The optimum ohmic thawing condition was a 16 V/cm voltage gradient for Y-shaped samples by using an E2 electrode design. The thawing time for the optimum condition was 2074s corresponding ohmic power consumption of 15.84 W. The drip loss during thawing was measured at 1.20%. The maximum temperature reached during the thawing process was recorded as 15.90 °C. Energy efficiency and exergy efficiency values were greater than 35%. Based on these results, the overall desirability of the ohmic thawing method was evaluated as 0.755. The obtained desirability value indicated the ohmic thawing method to be highly efficient and effective in achieving optimal thawing outcomes. The results of this study could give valuable information on the design of industrial-scale ohmic heating units to be used with solid foods, especially for thawing purposes. [ABSTRACT FROM AUTHOR]

Current biodiesel production research has focused on improving its energy performance and identifying and decreasing inefficiencies. To this end, exergy analysis can help develop, assess, and enhance biodiesel production plants. This study presents the exergy assessment of microalgae biodiesel production, which includes mixers, a photobioreactor (PBR), centrifuges, pumps, dryers, an extractor, tanks, heat exchangers, reactor, a washer, a distillation column, flash valve, and hydro-cyclone. The first phase is algae cultivation, followed by oil extraction. The third phase is transesterification, where algal oil is separated by methane into biodiesel and glycerin. The fourth phase is biodiesel purification, followed by methanol recovery/glycerin separation. The model of the biodiesel production plant is based on mass, chemical species, energy, and exergy balances. It was verified that 93.4% of the inlet exergy originates from sunlight, with a low exergy efficiency (11.46%) obtained for the PBR. This component presented a very low energy efficiency (2.7%) and the highest destruction of exergy: 2287 GJ is destroyed, corresponding to 99.36%. The highest exergy efficiency was obtained for dryer #3 (99.99%), but other components also presented values over 99%. Finally, this study critically compares the results obtained herein with scientific literature data, highlighting data gaps and inconsistencies. The exergy assessment presented a detailed biodiesel production process from microalgae and can be used to support the improvement of production costs to motivate widespread adoption. [ABSTRACT FROM AUTHOR]

The photovoltaic thermal systems can concurrently produce electricity and thermal energy while maintaining a relatively low module temperature. The phase change material (PCM) can be utilized as an intermediate thermal energy storage medium in photovoltaic thermal systems. In this work, an investigation based on an experimental study on a hybrid photovoltaic thermal (PV/T) system with phase change material has been carried out under the weather condition of north India to compare its output with a standalone photovoltaic system. The organic phase change material (melting point range 37 °C to 42 °C) was utilized to store thermal energy on the backside of the photovoltaic module. A sheet and tube type absorber was constructed with a spiral-shaped cooling water circulation channel within a PCM container to extract the stored heat. The energy and exergy-based analyses were performed to evaluate the performance of the PV/T PCM system in comparison to the regular PV module. A maximum reduction of 27% in module temperature was found at a water flow rate of 1 LPM. PV/T PCM system achieved the highest electrical, exergy, and thermal efficiencies of 14.32%, 15.59%, and 53.78%, respectively, while the regular PV module achieved the highest electrical efficiency of 12%. [ABSTRACT FROM AUTHOR]

This study investigates the exergetic and exergoeconomic analyses of a diesel engine operated on dual-fuel mode with fuelled both diesel fuel–boron nitride nanofuel and biogas purchased commercially. The experiments were performed for diesel fuel, diesel + 100 ppm boron nitride nanoparticle, diesel + 100 ppm boron nitride nanoparticle + 0.5 L min−1 biogas, diesel + 100 ppm boron nitride nanoparticle + 1.0 L min−1 biogas and diesel + 100 ppm boron nitride nanoparticle + 2.0 L min−1 biogas at various engine loads (2.5 Nm, 5.0 Nm, 7.5 Nm, and 10.0 Nm) and fixed crankshaft speed of 1500 rpm. The obtained experimental data were used to realize exergetic and exergoeconomic analyses. Among the fuels considered in this study, diesel + 100 ppm boron nitride nanoparticle nanofuel had the best exergetic and exergoeconomic results. As a result, at engine load of 10 Nm, the exergy efficiency of test engine and specific exergy cost of crankshaft work were obtained to be 29.12% and 124.86 US$ GJ−1 for diesel + 100 ppm boron nitride nanoparticle nanofuel, respectively. These values were 27.35% and 125.19 US$ GJ−1 for diesel fuel, 25.50% and 141.92 US$ GJ−1 for diesel + 100 ppm boron nitride nanoparticle + 0.5 L min−1 biogas, 23.10% and 156.33 US$ GJ−1 for diesel + 100 ppm boron nitride nanoparticle + 1.0 L min−1 biogas, and 21.09% and 171.92 US$ GJ−1 for diesel + 100 ppm boron nitride nanoparticle + 2.0 L min−1 biogas, respectively. It is clear that biogas addition to combustion made worse the exergetic and exergoeconomic performances of test engine. As a conclusion, it can be said that diesel + 100 ppm boron nitride nanoparticle nanofuel can be used as alternative fuel to D100 in terms of exergy and exergoeconomics. [ABSTRACT FROM AUTHOR]

In the modern world, the vapor compression refrigeration (VCR) system is essential in various global applications, including climate control, refrigeration, and food preservation, contributing significantly to energy consumption. The significant energy demands associated with these applications highlight the urgency for sustainable and energy-efficient alternatives that can help diminish our dependence on electrical power. To reduce energy consumption and enhance energy efficiency, a dedicated mechanical subcooled (DMS) system can be integrated with a vapor compression system (VCR) system. This study aims to evaluate and optimize the dedicated mechanical subcooled-vapor compressor refrigeration system (DMS-VCR) system using refrigerant R134a for a 100 kW commercial chiller used for water cooling application. The primary objective is to assess the system from multiple angles which include energy, exergy, environmental, economic analysis (4E's) and optimizing it to enhance its overall effectiveness to reduce the system's annual cost. It is thermo-economically optimized, allowing for independent optimization of the evaporator, condenser-1, condenser-2, and sub-cooler components. The proposed system reduces electrical energy consumption by 17.24% and CO2 emissions by 12.4%. The DMS-VCR system outperforms the standalone VCR system. The DMS-VCR system's annual operating costs are 6.71% lower than an equivalent VCR system, and optimization further reduces costs by 1.88% (case-I: irate = 10%, Ny = 5 years, and toper = 4000 h) and 16.36% (case-II: irate = 2%, Ny = 10 years, and toper = 5000 h).The study underscores the importance of subcooling within the DMS-VCR system, highlighting its desirability as it varies with the recovery factor and annual operation period. As a result of the DMS-VCR system's better efficiency, design engineers are likely to find it more attractive. [ABSTRACT FROM AUTHOR]

The present research has analyzed the energy and exergy of a combined system of simultaneous power generation and cooling. To provide a comprehensive data sheet of this system, the system has been investigated in the temperature range of 300–800 °C, and 6 working fluids, including air, carbon dioxide, nitrogen, argon, xenon, and helium, have been investigated. The parameters affecting the performance of the system, namely the compressor inlet pressure, the compressor pressure ratio, and the intermediation pressure ratio were investigated. The power produced by the Brayton cycle at a pressure ratio of 5.2 is the highest due to the increase in compressor power consumption and turbine power generation. The results of the parametric study showed that the exergy efficiency of the system has the maximum value at the pressure ratio of 4.73. The results of the parametric study showed that increasing the pressure of the compressor does not have a significant effect on the electricity consumption and the temperature of the working fluid due to the constant pressure ratio. The input energy to the heat exchanger of the absorption chiller decreases with the increase in the Brayton cycle pressure ratio, and as a result, the cooling created by the chiller also decreases. In this method, three objective functions of exergy efficiency, energy efficiency, and total production power are considered as objective functions. The most optimal value of intermediation pressure ratio was obtained after the optimization process of 1.389. Also, the most optimal value of the pressure ratio of high-pressure and low-pressure turbines was reported as 2.563 and 1.845, respectively. [ABSTRACT FROM AUTHOR]

The objective of this article is to conduct energy and exergy diagnostics on a limekiln operating with producer gas as renewable biofuel generated from eucalyptus wood gasification in an interconnected furnace. The diagnostics were realized overall and separately, encompassing the equipment in control volumes. Industrial data were collected, and mass, energy, and exergy balances involving first and second laws of thermodynamics were performed for the equipment. To complement the equipment characterizations, some literature data were utilized. The results of the diagnostics were compared and discussed with results of similar limekilns operating with fossil fuels and biomass gasifiers studied by the literature. Overall results of energy and exergy efficiencies, exergetic sustainability index, depletion number, and environmental destruction index of 42.0%, 23.6%, 1.3, 0.8, and 4.2, respectively, were obtained for the calcination process. These results are in accordance with those reported in the literature. With these results attained herein, it was possible to investigate the sustainability of the calcination process operating with biofuel and identify points for exergy recovery, such as the heat contained in the exhaust gases of the limekiln, thermal wall loss from limekiln and gasifier, and exergy of the wastes generated in the biomass gasifier. These exergy recoveries can result in biofuel savings, reduce lime production costs, and decrease the emission of polluting gases from the calcination process. The diagnostics provided may incentivize and contribute to authors in the deployment of renewable biofuels such as producer gas derived from biomass, as an alternative to traditional fossil fuels used in limekilns. [ABSTRACT FROM AUTHOR]

The main objective of this investigation is to propose a comprehensive decision-making checklist to evaluate the utilization of hybrid renewable configurations in each remote area. By considering the exergetic performance, financial, environmental, and social perspective approaches, the decision-making between the grid extension and the use of local renewable resources is performed, and the optimal solutions are recognized. To create this novel checklist, the methodologies of Geographic Information System (GIS), exergy evaluation, and HOMER Pro software are integrated. The proposed checklist also includes several sensitivity analyses to generalize the obtained findings to other remote villages. To investigate the extension of the central grid based on the geographical analysis, the breakeven point for each village is obtained. After that, by computing the value of the Cost-Effective Index (CEI), the most cost-efficient solar tracker mode could be introduced. For instance, the PV/DG/BG/Bat option with a cost of energy of 0.138 and CO2 emission of 30,917 kg/year is found as the optimum configuration for the village related to cold & dry climate. The overall exergetic proficiency is calculated to be 37.27%, as well as it was determined that about 92% of overall irreversibility belonged to the PV modules. The highest value of CEI is related to the vertical tracker mode (40.17), as well as the breakeven distance is gained as 6.21 km. By employing the vertical tracker system, the overall exergetic efficiency reached 41.31%. Evaluation of the outcomes illustrated that the presented checklist could be a powerful tool for feasibility investigation of applying combined renewable systems and grid extension for each remote rural anywhere in the world. [ABSTRACT FROM AUTHOR]

Although desalination methods have been extensively used, many of them need substantial installations and access to sophisticated infrastructure to generate fresh water. The solar still uses 0.2% reduced graphene/cerium oxide nanoparticles as a hybrid nanoparticle material and it uses coated absorber solar still. The hybrid nanomaterial is embedded in commercial black paint of absorber plate and walls of solar still. Exergy annihilations in different parts of the sun-powered stills have been determined and examined. Dissipation is quicker and the exergy of evaporation is higher at improved sunlight-based stills than that of black paint coating still. Moreover, the exergy and energy efficiencies of the improved stills are upgraded contrasted and with the black paint coating still. A short conversation concerning the impact of various boundaries on sunlight-based stills effectiveness is likewise introduced. The daytime energy productivity of reduced graphene and cerium oxide/water blends is 43.26%, yet the old style is just 30.17%. The hourly exergy efficiency increases up to 0.47% by using nanoparticle coating. It has been discovered that salty water temperature and heat transfer rate are both increased by adding graphene/cerium oxide nanoparticles to black paint. The proposed system's solar still productivity is higher than that of black paint coating on the absorber plate of the solar still. [ABSTRACT FROM AUTHOR]

This work focuses on meeting the growing demand in solar energy conversion for small-scale applications. In this regard, experimental and CFD research has been done to examine the thermal performance (energy and exergy efficiencies) of a dish collector (reflector and receiver) system with different receiver models. In this work, receivers with uniform absorber cavity areas having cylindrical and hemispherical shapes were modeled for length-to-diameter ratios (L/D) of 1.5, 1, and 0.75. The modeled receivers having coil tube configurations concerning the geometrical shape of the models were tested with two different materials of aluminum and copper. The performance of the receiver models was compared by experimental and CFD methods for the average solar direct normal irradiations of 860 W/m2 by the dish reflector area of almost 12 m2. The supplied average heat flux by the dish reflector was 7 kW/m2 at the absorbing area of the cavity receivers. The energy and exergy efficiencies from the experimental and CFD analyses on the models were determined based on the cavity surface temperature distribution of receiver walls, and heat gain for different mass flow rates by the heat transfer fluid water. The receiver with copper material and L/D ratio of 0.75 has been found as the optimized one among all other models with the maximum obtained energy and exergy efficiencies of 73.64 and 7.31% when water is used as the heat transfer fluid. The performance of the optimized receiver model was also validated with a few other heat transfer fluids such as SiC + water nanofluid and therminol VP1. [ABSTRACT FROM AUTHOR]

This study compares the performance of dedicated mechanical subcooled vapor compression refrigeration (DMS-VCR) system and actual vapor compression refrigeration (VCR) system of same capacity (100 kW), and evaluates them on the basis of energy, exergy, and coefficient of structural bond (CSB) configuration. Results indicate that DMS-VCR system outperforms VCR system at constant condenser temperature (Tcond = 40° C) with varying evaporator temperatures (Tevap = 0 °C, 5 °C and 10 °C).The most significant results occurs at 0 °C, resulting in a coefficient of performance (COP) 4.60 % higher than actual VCR system's COP and exergetic efficiency 4.38 % higher than actual VCR system's exergetic efficiency, making it a more favourable choice for water chilling applications. Additionally, the study investigates the potential of the CSB method in improving system efficiency by reducing irreversibility rate in a specific component. It finds that improving the efficiency of a component can significantly decrease the total irreversibility rate of the system. The CSB value of condenser-1 and evaporator are observerd to be highest (i.e. 1.96 and 2.27) and hence the performance of DMS-VCR system can be greatly improved by changing the efficiency parameter of evaporator and condenser-1 of the DMS-VCR system. [ABSTRACT FROM AUTHOR]

This study investigated the effects of methyl ethyl ketone (MEK) on a diesel engine's energy, exergy and emissions. The evaporation of a bi-component droplet of MEK and heptane was modeled. Furthermore, the soot morphology and nanostructure were quantified. Different blends were examined at other engine conditions. Running the engine under idle conditions and optimum speed considerably reduced engine emissions. MEK noticeably decreased the maximum reachable load of the diesel engine. Both specific fuel consumption and thermal efficiency increased with MEK. The exergetic efficiency increased while the fuel exergy decreased at the same work exergy. The effects of MEK on combustion characteristics were insignificant. However, a stronger premixed combustion phase was obtained where MEK evaporated first and caused a slightly longer droplet lifetime. Low percentages of MEK reduced CO emissions, while NOx emissions increased consistently with the MEK addition. The engine conditions noticeably influenced the unburned hydrocarbon emissions with MEK. Both smoke opacity and primary particle diameter decreased. The fringe analysis emphasized that MEK decreased fringe length, soot intensity, and alignment, increasing fringe tortuosity and spacing. Clearly, methyl ethyl ketone suppressed soot formation in a diesel engine and decreased its reactivity. [ABSTRACT FROM AUTHOR]

The current theoretical study analyzes a performance comparison of a two-stage variable leg-shaped thermoelectric generator (TEG) with the combination of dissimilar p-type and n-type materials. For the cold side of the TEG configuration, water, MXene/Water, MXene/CNT, MXene/Graphene, and MXene/CNT/Graphene ternary hybrid nanofluid as new coolants have been considered. The objective of the present study is to ascertain the effect of flow parameters on hot and cold side fluids and to investigate the performance parameters of the TEG. The first stage of TEG is of a regular shape, while the later stage tapers to give a high-temperature gradient. Effect on voltage, power, conversion efficiency, second law efficiency, irreversibility, and normalized voltage with the coolant and exhaust flow rates have been investigated. The results revealed an optimum result of higher power output, second law efficiency, conversion efficiency, current, and voltage with a coolant flow rate of 0.007 kg s−1. Compared to water, MXene/Water nanofluid has 3.5% and 3.27% higher power output and second law efficiency, respectively, followed by MXene/CNT, MXene/Graphene, and MXene/CNT/Graphene ternary hybrid nanofluids. MXene/water nanofluid has 6.42% higher power output than water; MXene/CNT, MXene/Graphene, and MXene/CNT/Graphene ternary hybrid nanofluids have 4.28%, 4.23%, and 15.68% lower power output, respectively. The power output and second law efficiency of MXene/Water nanofluid are 3.5% and 6.84% greater than water. MXene/CNT, MXene/Graphene, and MXene/CNT/Graphene ternary hybrid nanofluids had 8.21%, 9.58%, and 10.95% poorer second law efficiency: with CNT and graphene-based MXene hybrid nanofluids, the improved TEG outperforms traditional units. [ABSTRACT FROM AUTHOR]

The energetic and exergetic enactments of the plate heat exchanger (corrugated) were studied theoretically using a hybrid nanofluid. Alumina–silver (Al–Ag) and magnesia–silver (Mg–Ag) nanoparticles were mixed in the propylene glycol–water brine and ethylene glycol–water brine solutions. Here, two cases were dealt with, one with a given flow rate and the other with a given area and concentration. The effect of nanoparticle concentration and hybrid nanofluid flow rate was studied on different parameters. It was observed that the overall heat transfer coefficient, pressure drop, pumping power, non-dimensional exergy destruction, entropy generation rate, and irreversibility rise with the flow rate. In contrast, the irreversibility distribution ratio reduces with the flow rate. Moreover, the trend reversed with the nanofluid volume concentration up to 0.5% concentration was observed, which can be treated as a critical parameter. In studied ranges, propylene glycol brine performs better than ethylene glycol brines. The alumina–silver combination is found to be better than the magnesia–silver combination. Increasing the flow rate is suggested as a better option than increasing the nanoparticle concentration for a given area. [ABSTRACT FROM AUTHOR]

Food insecurity is becoming a big problem due to the continuous increase in the population, for which there is a requirement of effective drying method for the storage of agricultural items which can solve this problem at global level. Hence, the present study deals with the evaluation of energy, exergy, and environmental parameters of low-cost indirect solar dryer with paraffin wax as energy storage material in rural areas for drying of wheat seeds to check its thermodynamic as well as environmental feasibility. The wheat seeds were dried in solar dryer from initial moisture of 20.2% in 6 h to achieve recommended moisture content which took lesser drying time as compared to open sun drying. The maximum value of collector exergy efficiency, exergy efficiency of drying chamber and pick-up efficiency are 1.5%, 72.62%, and 30.4% respectively. Environmental impacts assessment has revealed that the energy payback, CO2 mitigation, CO2 emission per year and carbon credit earned (at $80 per carbon credit) with present system are 1.35 years, 6.67 tons, 7.32 kg and $533.7, respectively considering the lifetime of solar dryer as 25 years. The performed study shows that the indirect solar dryer with paraffin wax is suitable for the households of rural areas with enhanced performance, lesser waste, sustainable, and lesser adverse effect on environment. This system can also be preferred for drying of other agricultural crops for a particular household. [ABSTRACT FROM AUTHOR]