Exergoenvironmental Evaluation Research Articles

Near-zero emission trigeneration system coupling molten salt methane pyrolysis with solid oxide fuel cell based on carbon capture and utilization: Thermodynamic and exergoenvironmental evaluation

Natural gas-based energy systems have garnered widespread attention for their potential to facilitate the transition from traditional to renewable energy sources. Among these, methane pyrolysis technology stands out as a promising pathway. Consequently, a novel methanol-electricity-carbon trigeneration system featuring methane pyrolysis coupled with chemical looping combustion, methanol synthesis, and solid oxide fuel cell unit was designed. To validate this innovative concept, thermodynamic model of the process was developed. Compared to conventional single-generation system, the proposed system demonstrated superior thermodynamic performance, with energy efficiency of 69.51 %, representing improvement of 28.78 %. Sensitivity analysis indicated that optimal carbon utilization-to-storage ratio of 0.68 effectively balanced environmental benefits with energy conversion efficiency. Additionally, the CO2 capture rate and emission of the proposed system reached impressive 99.24 % and 2.15 kg/MWh, respectively, confirming its carbon mitigation potential. Based on this, exergoenvironmental analysis demonstrated that rb,k of the novel system was 21.14 %, indicating room for further environmental impact reduction. Moreover, due to the high rb,k of 16.61 % for the preheater-2 identified as a key component for optimization. Finally, the economic analysis verified the system’s feasibility, showing the annual net income of 6774.06 k$. This novel concept highlights the potential of natural gas-based systems in optimizing carbon utilization and energy efficiency, contributing to a more environmentally sustainable energy infrastructure.

Exergy, exergoeconomic optimization and exergoenvironmental analysis of a hybrid solar, wind, and marine energy power system: A strategy for carbon-free electrical production

In this research, aligned with global policies aimed at reducing CO2 emissions from traditional power plants, we developed a holistic energy system utilizing solar, wind, and ocean thermal energy sources, tailored to regions optimal for ocean thermal energy conversion (OTEC). The selected site, characterized by favorable wind and solar conditions close to areas with high OTEC potential, is designed to meet the electricity needs of a coastal community. The system's core components include an Organic Rankine Cycle, turbines, thermoelectric elements, pumps, a heat exchanger, a wind turbine, and a solar collector. A detailed system analysis and thermodynamic evaluation based on thermodynamic principles were carried out using the Engineering Equation Solver (EES) software. Key factors such as wind speed, solar radiation, and collector area were critical in determining system performance. To enhance the system's effectiveness, we conducted a comprehensive comparison of optimization algorithms, incorporating the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) and utilizing a Pareto front for value optimization. This approach significantly outperformed other algorithms such as Particle Swarm Optimization (PSO), Genetic Algorithm (GA), and Simulated Annealing (SA) in terms of system efficiency and cost-effectiveness. The developed system achieved an exergy efficiency of 14.46 % and a cost rate of $74.98 per hour, demonstrating its suitability for its intended functions. Moreover, exergoenvironmental evaluation was conducted for the proposed plant. The findings revealed that key component HEX has a high exergoenvironmental factor due to their use of hot water, which has zero unit exergoenvironmental impact. Additionally, pumps demonstrated a zero exergoenvironmental impact factor, indicating negligible component-related environmental impacts. Sensitivity analysis further evaluated critical performance parameters, revealing that increases in solar irradiation lead to decreased total system cost rates, while higher turbine temperatures resulted in a remarkable 14.08 % reduction in the system's cost rate. These results underscore the economic viability of operating the system at higher temperatures and strengthen the argument for its adoption from a financial perspective.

Design, economic analysis, and environmental assessment of an innovative municipal solid waste-based multigeneration system integrating LNG cold utilization and seawater desalination

This paper presents a novel integrated solution for harnessing energy from biomass alongside liquefied natural gas cooling. The process is investigated and evaluated in various scenarios. This integrated system yields electricity, hydrogen, cold water, hot water, and fresh water. Thermodynamic analysis of the process is conducted under different scenarios. Moreover, the overall environmental damage effectiveness factor is calculated using exergo-environmental evaluation, revealing that heat exchanger E-103 exhibits the highest effectiveness factor of environmental damage, with an exergy efficiency of 37.3 %. Simulation results indicate an overall energy efficiency and overall exergy efficiency of 58.24 % and 31.97 %, respectively. Energy efficiencies of the process are found to be 32.15 %, 34.85 %, 36.71 %, and 58.24 % in single generation, combined heat and power, combined cooling, heating, and power, and multi-generation scenarios, respectively. The study evaluates the simultaneous effects of pressure and flow rate variations of liquefied natural gas fluid, input flow rate variations of municipal solid waste biomass, and cyclohexane working fluid pressure variations in the organic Rankine cycle on other variables. Finally, an economic evaluation of the new process outlines its annual cost and the levelized energy cost parameter under base design conditions, which amount to 9,383,042 $ and 0.092 $/kWh, respectively.

Enhancing green hydrogen production via improvement of an integrated double flash geothermal cycle; Multi-criteria optimization and exergo-environmental evaluation

The environmental advantages of hydrogen as a clean energy carrier are more prominent when it is produced utilizing renewable resources. In this regard, a novel geothermal energy driven electricity generation system integrated to hydrogen production plant is developed and investigated in this research. In the developed plant, a PEM electrolyzer is employed for hydrogen generation such that its required electricity is provided by an improved double-flash geothermal cycle. A self-superheater is applied for superheating the vapor at the steam turbine inlet using the geothermal resource to enhance the hydrogen production capacity. To evaluate feasibility of such superheating process and to examine its effects on hydrogen production, thermodynamic models are developed based on first and second laws. Also, environmental considerations are considered in evaluation of the proposed plant performance based on exergo-environmental indices. The influences of first and second flashing pressure, geothermal source temperature and current density of water electrolyzer on energy and exergy efficiency, hydrogen production rate, and environmental damage index are investigated. After carrying out a parametric study, the optimum operation point of the plant is determined via a two-objective optimization based on the hydrogen rate and environmental damage index (EDI). It is found that, under optimum operation, the system can produce 25.48 kg/h of hydrogen, while its environmental damage index is calculated to be as 0.00645.

A comparative exergoenvironmental assessment of thermochemical copper-chlorine cycles for sustainable hydrogen production

Hydrogen is one of the highly promising clean solutions to address the concerns of energy security in the future given the rapid rate of depletion of naturally occurring hydrocarbon sources. However, it is of immense importance that hydrogen is obtained through sources that ensure sustainability. Thermochemical water-splitting processes are among such routes of hydrogen production that are both sustainable and environmentally benign. Thus, this study focuses on assessing the copper-chlorine thermochemical cycles that are among the more promising cycles of the chlorine family in terms of efficiency and cost-effectiveness. Moreover, this study considers a comparative exergoenvironmental evaluation of the four variants of the copper-chlorine cycle that vary in the number and the nature of steps. A comparison in this regard is carried out between the various steps of each cycle in terms of the component-associated environmental impact rates and environmental impact rates of energy transfer as well as the overall environmental impacts of all cycles. In addition, a comparison of the global warming potential of hydrogen synthesized through utilizing various electricity sources is also performed. Based on our evaluations, hydrolysis and electrolysis are the common steps in the five-step cycle, the four-step cycle, and the three-step cycle configuration 1 yielding the highest component-associated environmental impact rates and environmental impact rates of energy transfer, respectively. Conversely, in the three-step cycle configuration 2, the electrolysis and thermal decomposition steps yield the highest corresponding values, respectively. In addition, the three-step cycle configuration 2 (4,869 mPts/h) and the five-step cycle (3,194 mPts/h) have the highest and the lowest component-associated environmental impact rates, respectively while the five-step (530,694 mPts/h) and the four-step (248,050 mPts/h) cycles result in the highest and the lowest environmental impact rates of energy transfer, respectively.

Thermodynamic, exergetic and environmental evaluation and optimization of a bio-fuel fired gas turbine incorporated with wind energy derived hydrogen injection

The fluctuating nature of wind energy and shortage of biomass resources, as two types of renewables, can be fulfilled via their hybridization. In this respect, present research proposes a hybrid biomass/wind energy driven power generation framework based on combined gas turbine-Rankine cycle scheme. The gas turbine includes a reheat stage where the produced hydrogen is added to the combustion chamber for increasing flue gas temperature to enhance output power. The injected hydrogen is generated via a water electrolyzer which is powered by electricity from the wind turbines. The proposed scheme of biomass/wind powered system leads to a reduction in biomass consumption and will fulfill the fluctuations and non-continuous availability of wind energy. To appraise the feasibility of developed hybrid scheme, thermodynamic first and second law-based analyses were performed. Also, the exergo-environmental evaluation of the hybrid plant is conduced using three exergo-environmental indices. Finally, optimum operation conditions of the proposed hybrid plant is determined based on the minimization of environmental damage index. The results under optimum operation indicate that, the proposed hybrid power generation plant yields exergy efficiency of 47.35 % with environmental damage index of 0.0104.

A comparative exergoenvironmental evaluation of chlorine-based thermochemical processes for hydrogen production

Environmental impact assessment of energy generation processes is essential to evaluate their contributions toward the global carbon footprint. Even though hydrogen is a non-carbonaceous energy source, the pathways undertaken for its production can have harmful environmental implications. Thus, this study focuses on investigating the exergoenvironmental performances of the copper-chlorine, iron-chlorine, and magnesium-chlorine thermochemical hydrogen generation processes. This study also performs a comparative exergoenvironmental analysis of the three processes. The performances of the various processes are examined based on of the environmental impact rates of exergy destruction, component-related environmental impact rates, cumulative environmental impact rates, and exergoenvironmental factors. The global warming potentials of the thermochemical cycles are also evaluated and compared for various electricity sources to obtain hydrogen. The modeling and simulation of each process are performed using Aspen-plus by considering various heat recovery approaches for thermal management. The results suggest that the environmental impact rates of exergy destruction are relatively much higher compared to the environmental impact rates associated with the components for all processes. Furthermore, the hydrolysis step yields the highest component-associated environment impact rate for all thermochemical cycles considered (Fe–Cl: 3497 mPts/h, Cu–Cl: 1997 mPt/h, and Mg–Cl: 910 mPts/h). Moreover, the magnesium-chlorine cycle results in the highest environmental impact rate of exergy destruction (650,328 mPts/h) while the iron-chlorine cycle has the highest component-related environmental impact rate (5219 mPts/h) among the three cycles. In addition, the global warming potential of the magnesium-chlorine cycle is relatively higher compared to the copper-chlorine cycle for several electricity sources.

Economic, Exergoeconomic and Exergoenvironmental Evaluation of Gas Cycle Power Plant Based on Different Compressor Configurations

The decision-making process behind the selection of a gas turbine engine (GT) is crucial and must be made in accordance with economic, environmental, and technical requirements. This paper presents the relevant economic, exergoeconomic and exergoenvironmental analyses for four GT engines with different compressor configurations. The GT engine configurations are identified according to the type of compressor: axial, axial-centrifugal, two-stage centrifugal, and centrifugal-centrifugal. The performances of the four GT engines were validated against manufacturer supplied data using specialized software. The economic analysis, a detailed life cycle costing considering the cost to be paid per unit net power obtained from the GT, and subsequent shortest payback period showed that the GT with centrifugal-centrifugal compressor was most economically feasible. This was followed, in order, by the GT-axial, GT-axial-centrifugal, and finally the GT-two-stage centrifugal configuration, where the cost of ownership for a 20 year plan ranges between 8000 USD/kW to about 12,000 USD/kW at different operational scenarios during the life cycle costing. Exergoeconomic assessment provided useful information to enhance the cost-effectiveness of all four systems by evaluating each component separately. The axial-centrifugal configuration registered the lowest CO2 emissions (about 0.7 kg/kWh); all environmental indicators confirmed it is the most environmentally friendly option.

Exergoenvironmental evaluation of kalina power generation system

ABSTRACT The basic needs of man are food, clothing, and shelter besides air and water. In providing these needs, power generation systems play a crucial role. Day by day, for various reasons such as explosion of population, the demand for power is increasing tremendously. Power generation systems need to generate more power. A novel power generation system suitable for recovering waste heat at a medium temperature range is examined in the present work. To assess the performance of a power generation system, energy and exergy measures are necessary. Energy measures provide enough details about the performance of the system. To know the systematic performance analysis, detailed exergy analysis alternatively profound as advanced exergy analysis and environmental impact are to be investigated. Exergoenvironmental analysis on the proposed Kalina power generation system has been carried out under hot sink conditions. Considering the proposed decision variables relative exergy destruction (ĖD/ĖP), relative environmental impact (Ẏ/ĖP), and relative investment cost (Ż/ĖP), the performance of the system has been assessed. The exergy destruction and the destruction cost rate of 29.23 kW and 0.478 $/hr at turbine inlet conditions of 185°C and 45 bar have been achieved. The exergoenvironmental factor fb and the relative difference rb have revealed that the components with high environmental impact have to be minimized. Turbine and HE4 are the components that contribute to higher total exergy and devise related impact on the environment.

Development and life cycle assessment of a novel solar-based cogeneration configuration comprised of diffusion-absorption refrigeration and organic Rankine cycle in remote areas

The increasing power demand in the world’s energy basket and the focus on reducing carbon emission, in tandem with upgrade constraints on conventional grids, has elicited the employment of renewable energies. Specifically, answering the power and cooling/heating demands of remote areas where the grid cannot or can merely supports using locally available and utilizable renewable energies is a focal topic. Herein, a cogeneration system driven by solar energy through parabolic trough collector (PTC) utilization integrated with organic Rankine cycle (ORC), and diffusion absorption refrigeration (DAR) cooling system is proposed. The system is backed up by phase-change material (PCM) and battery bank for solving the intermittence nature of solar energy, and targeted at being employed in a residential building in Shahr Asb, a village in Yazd province, Iran, with a population of less than 600. The system is appraised through exergy evaluation to gauge the efficiency and performance of the system, and life cycle assessment analyses (exergoenvironmental evaluation), to present beneficial data on the mutual impact of the system’s performance and environmental conditions. The HYSYS, MATLAB, TRNSYS, and HOMER software and programming environments were utilized to model the cogeneration system. The exergy analysis indicated that the PTC field contributed to the highest exergy destruction (31.80 kW) of the system (67.89 kW) with PTC and system exergy efficiency of 55.23% and 67.89%, respectively. Consistent with the exergoenvironmental analysis, the highest values of cumulative environmental impacts were pertinent to EX-101 expander, (204.02 Pts/h - 29.49%) and E-102 heat exchanger (154.44 Pts/h - 22.33%), individually. Consequently, to mitigate the system’s undesirable environmental impacts, the operating conditions of these devices must be amended. The parametric analysis showed that the rise in mole fraction of hydrogen as the inert gas of the DAR system positively affects the evaporator duty and temperature. The required power (10.76 kW) and cooling (44.55 kW) are provisioned by utilizing 80.76 kW and 364.30 kW of heat duty in the DAR and ORC system, respectively, which is met by the battery bank and PCM when solar energy is absent during the night.

Development of a sustainable multi-generation system with re-compression sCO2 Brayton cycle for hydrogen generation

Current research aims to develop, design, and analyze a novel solar-assisted multi-purpose energy generation system for hydrogen production, electricity generation, refrigeration, and hot water preparation. The suggested system comprises a solar dish for supplying the necessary heat demand, a re-compression carbon dioxide-based Brayton cycle, a PEM electrolyzer for hydrogen generation, an ejector refrigeration system working with ammonia, and a hot water preparation system. The first law and exergy analyses are implemented to determine the performance of the multi-generation plant with various outputs. Besides, the exergo-environmental evaluation of the plant is conducted for the environmental impacts of the plant. Furthermore, parametric analyses are executed for investigating the system outputs, exergy destruction rate, and system efficiencies. According to the results, the rate of hydrogen generated by means of the multi-generation power plant is determined to be 0.062 g/s which corresponds to an hourly production of 0.223 kg. Besides, with the utilization of the supercritical closed Brayton cycle, a power generation rate of 74.86 kW is achieved. Furthermore, the irreversibility of the overall plant is estimated as 535.7 kW in which the primary contributor of this amount is the solar system with a destruction rate of 365.5 kW.

Life cycle assessment and exergoeconomic analysis of the multi-generation system based on fuel cell for methanol, power, and heat production

The main purpose of present investigation is to evaluate a multi-generation process by Life Cycle Assessment (LCA) and exergoeconomic analysis methods. This integrated system is composed of Methanol Synthesis Process, Molten Carbonate Fuel Cell (MCFC), and Combined Heat and Power system.This exergy – based evaluation is comprised of three items: (1) exergy evaluation to assess the efficiency and performance of the multi-generation system, (2) exergoeconomic evaluation to express a relationship between overall costs and the performance of the hybrid system, (3) exergoenvironmental evaluation to present useful information about the mutual impact of the process’s performance and environmental conditions. By applying the exergoeconomic and exergoenvironmental analyses, The process simulation and exergetic evaluation are conducted by the Aspen HYSYS V 11 and MATLAB software, respectively.This configuration provides 271.7 kgmole/h pure methanol, 110,544 kW net power, and 65398.7 kgmole/h hot water (at 80 °C). The total exergy efficiency and destroyed exergy rate of this multi-generation configuration are obtained to be 58.4% and 128549 kW, respectively. About 41.28% of the total exergy destruction rate occurred in the MCFC. The results of exergoeconomic assessment illustrate that the highest overall cost is associated with MCFC (4836.87 $/h). In addition, the burner has the least value of exergoeconomic factor (1.47%). So, to improve the cost-effectivity of the system, the burner should be re-designed. According to the exergoenvironmental analysis, the greatest values of overall environmental impacts belonged to MCFC (4033.13 Pt/h) and burner (1501.99 Pt/h), respectively. Accordingly, to decline the negative environmental impacts of the system, the operating conditions of selected devices must be modified. Finally, the 3D sensitivity analyses for four main devices are implemented. By using this sensitivity evaluation, the thermodynamic parameters that need to be optimized are specified.

LCA and Exergo-Environmental Evaluation of a Combined Heat and Power Double-Flash Geothermal Power Plant

This study deals with the life cycle assessment (LCA) and an exergo-environmental analysis (EEvA) of the geothermal Power Plant of Hellisheiði (Iceland), a combined heat and power double flash plant, with an installed power of 303.3 MW for electricity and 133 MW for hot water. LCA approach is used to evaluate and analyse the environmental performance at the power plant global level. A more in-depth study is developed, at the power plant components level, through EEvA. The analysis employs existing published data with a realignment of the inventory to the latest data resource and compares the life cycle impacts of three methods (ILCD 2011 Midpoint, ReCiPe 2016 Midpoint-Endpoint, and CML-IA Baseline) for two different scenarios. In scenario 1, any emission abatement system is considered. In scenario 2, re-injection of CO2 and H2S is accounted for. The analysis identifies some major hot spots for the environmental power plant impacts, like acidification, particulate matter formation, ecosystem, and human toxicity, mainly caused by some specific sources. Finally, an exergo-environmental analysis allows indicating the wells as significant contributors of the environmental impact rate associated with the construction, Operation & Maintenance, and end of life stages and the HP condenser as the component with the highest environmental cost rate.

Emergy-based exergoeconomic and exergoenvironmental evaluation of a combined power and cooling system based on ORC-VCR

Ensuring efficient operation of energy conversion systems in terms of economics and ecology is a prime objective that should be addressed within the design, optimization, and development stages of such systems. Adopting appropriate measures for accurate assessment and comprehensive evaluation of thermodynamic systems is a sheer necessity for accomplishing this purpose. In this study, the newly developed emergy-based exergoeconomic (i.e., emergoeconomic) and emergy-based exergoenvironmental (i.e., emergoenvironmental) analyses have been employed to assess a combined power and cooling system, including a gas turbine cycle, a steam Rankine cycle, and an integrated organic Rankine cycle-vapor compression refrigeration (ORC-VCR) subsystem serving as a waste heat recovery unit. The merit of emergy-based methods is that they can evaluate and express results by an identical unit of measurement (i.e., sej) which enables us to undertake a fair and accurate comparison between the methods in question. The results showed that the combustion chamber, with the total economic emergy rate of 6.83E13 (sej h−1) and the total ecological emergy rate of 6.05E14 (sej h−1), was the most critical component in the entire system from both the economic and ecological viewpoints. Moreover, a parametric study was carried out on the entire system, as well as the ORC-VCR unit, to examine the effect of design parameters on the emergy-based monetary and ecological performances. Increasing the air compressor pressure ratio from 6 to 11 enhanced the entire system’s both emergy-based performances by almost 8%, followed by improvements made by the gas turbine isentropic efficiency and combustor inlet temperature, with 6.5% and 5.5%, respectively. However, other design parameters exerted limited impact. Regarding the ORC-VCR, raising the ORC turbine inlet temperature and the isentropic efficiencies associated with the ORC turbine and VCR compressor improved the emergy-based performances, while the reverse was observed for the ORC condenser and evaporator temperature rise.

Exergoeconomic and exergoenvironmental evaluation of a solar-energy- integrated vacuum membrane distillation system for seawater desalination

Exergoeconomic and exergoenvironmental evaluation of a solar-energy- integrated vacuum membrane distillation system for seawater desalination

Life cycle assessment and comparative exergoenvironmental evaluation of a micro-trigeneration system

The cascading use of energy distinguishes trigeneration systems from simple heat recovery strategies and conventional separate electric and thermal energy systems. Small-scale trigeneration is referred to as micro-trigeneration, and is a potentially sustainable energy solution. Despite the demonstrated benefits from economic, energy, and environmental perspectives, the adoption of micro-trigeneration systems has been undoubtedly underexplored in the tertiary sector. This study presents a detailed Life Cycle Assessment for a natural gas-fueled micro-trigeneration system, encompassing the equipment and energy flows. Two endpoint environmental assessment methods were employed, the Eco-indicator 99 and ReCiPe. The environmental data was utilized to develop exergoenvironmental assessments. The specific environmental impact for both methods, despite presenting different absolute values, show the same behavior. The highest environmental impacts are found at the internal combustion engine and steam generator. Regarding the evaluation of exergoenvironmental parameters, the absorber heat exchanger and steam generator should be the focus of improvement efforts. This study contributes to improving the understanding of which processes within a micro-trigeneration system contribute the most to exergy destruction and generation of environmental impacts.

Design and multi-criteria optimisation of a trigeneration district energy system based on gas turbine, Kalina, and ejector cycles: Exergoeconomic and exergoenvironmental evaluation

A novel trigeneration district energy system (TDES) is designed and evaluated from energy, exergy, exergoeconomic, and exergoenvironmental points-of-view. By recovering the wasted heat of a regenerative gas turbine cycle, a heat exchanger is utilized for heating applications, a Kalina cycle is run for generating some additional power, and an ejector refrigeration cycle is used for producing some cold. The problem is firstly modeled through developing a precise code in Engineering Equation Solver program and then optimal conditions are sought by coupling the outputs of modeling procedure with Artificial Neural Network, and Non-dominated Sorting Genetic Algorithm II approaches. Three new functions of integrated weighted efficiency, exergoeconomic criterion, and exergoenvironmental criterion are defined as the system’s evaluation criteria. From a robust parametric study, it is demonstrated that the system’s evaluation criteria have the highest and lowest sensitivity on the variation of pressure ratio of compressor and pinch-point temperature difference of heat exchanger 2, respectively. From the optimisation procedure, the optimum values of the system’s primary energy ratio, exergetic efficiency, exergoeconomic criterion, and exergoenvironmental criterion are 76.9%, 30.8%, 58.4 $/GJ, and 42.7 kg/GJ, respectively. At these conditions, the capacity of the TDES is 1025.9 kW, 1642.3 kW, and 304.9 kW with the associated cost of production of 149.6 $/GJ, 7.8 $/GJ, and 60.1 $/GJ for power, heat, and cold, respectively.

Advanced Exergy, Exergoeconomic, Exergoenvironmental Evaluation of a Solar Hybrid Trigeneration System Based on Solar Gas Turbine for an Office Building

Abstract In this article, optimal design and advanced exergetic, exergoeconomic, and exergoenvironmental analyses of a trigeneration system for an office building based on integration flat plate solar collector and gas turbine have been performed. The proposed system includes a heat recovery steam generator, a steam turbine, a solar plate collector, and an absorption chiller. The transient simulation for solar calculation has been done using transys software. In addition, a computer code was built to compute conventional and advanced exergy, exergoeconomic, and exergoenvironmental evaluation dynamically. Furthermore, multiobjective optimization by NSGA-II and cuckoo Search algorithm with maximum exergetic efficiency, minimum total exergetic cost, and minimum exergetic environmental impacts has been carried out simultaneously. The results demonstrate that the three objective parameters have been enhanced. Also, the endogenous, exogenous, available, and unavailable parts of exergy destruction have been determined.

Energy, exergy and exergo-environmental assessment of a novel solar powered Kalina cycle incorporated with micro-CCHP for poly-generation

In this study, a solar parabolic trough collector combined with a Kalina cycle, multi-stage flash desalination unit, a proton exchange membrane electrolyser for hydrogen production, and a micro-combined cooling, heating, and power system is presented. Systematic energy, exergy, and exergo-environmental evaluation are used to analyse the viability of the integrated systems as the most effective approach for performance assessment of integrated systems. The energy and exergy efficiencies of the overall system is observed to be 50.51% and 3.27% respectively. The rate of exergy destruction of each component and the overall cycle is determined where the parabolic trough collector is shown to have an exergy destruction rate of 234.4 kW, which is the highest among all the components. The performance of the proposed systems is also checked through a parametric study of the different key parameters.

On the exergoeconomic and exergoenvironmental evaluation and optimization of biodiesel synthesis from waste cooking oil (WCO) using a low power, high frequency ultrasonic reactor

In this study, exergoeconomic and exergoenvironmental approaches were applied to evaluate and optimize the performance of a low-energy consumption, high frequency piezoelectric ultrasonic reactor used to synthesize biodiesel from waste cooking oil (WCO). The effects of various process parameters viz. methanol/oil molar ratio (X), transesterification temperature (T), and residence time (t) on the exergoeconomic and exergoenvironmental variables were comprehensively assessed and discussed. The exergoeconomic and exergoenvironmental variables were cost and environmental impact per unit of exergy for the product, relative cost and environmental impact differences, cost and environmental impact associated with exergy destruction, and exergoeconomic and exergoenvironmental factors. An optimization study was also carried out using a coupled scheme of adaptive network-based fuzzy inference system (ANFIS) and non-dominated sorting genetic algorithm-II (NSGA-II). Two more relevant exergy-based variables, i.e., cost and environmental per unit of exergy for the product as objective functions were modeled using the ANFIS approach on the basis of process parameters. The process yield as a threshold function was similarly simulated using the ANFIS approach. The optimum operating conditions of the system were then explored by NSGA-II algorithm through minimizing both objective functions while complying with the ASTM standard on process yield (i.e., conversion efficiency >96.5%). Overall, the process parameters profoundly affected the exergoeconomic and exergoenvironmental variables. Results indicated that the ANFIS approach accurately predicted the objective and threshold functions with an R2 > 0.99. The optimum operating conditions were: X = 7.4, T = 60 °C, and t = 10 min. Under these conditions, the cost and environmental impact per unit of exergy for the product were respectively found to be 2.23 USD/GJ and 1.32 mPts/GJ, whereas the process yield stood at 96.5% meeting the ASTM standard. In general, exergoeconomic and exergoenvironmental approaches appeared to be promising complements to the conventional exergy analysis for developing thermodynamically, economically, and environmentally conscious biodiesel production systems.