Refrigeration, a fossil fuel-intensive industry causing ozone depletion, is exploring energy-efficient alternatives like absorption chillers. Ejectors show promise in improving absorption chiller efficiency. Four ejector-assisted single-effect absorption chillers using LiBr as refrigerant were examined. The ejectors are used in different locations of the cycle in each configuration. Results reveal that Type D performs best (COP of 1.4 and lowest condenser heat rejection). The study also demonstrates the efficacy of artificial neural networks in accurately predicting cycle performance, which is useful for HVAC applications. Additionally, the genetic algorithm is employed to determine the optimal performance of the selected configuration.
This experimental study investigates the destruction values of exergy of air source heat pump (ASHP) components with R404a refrigerant. The destruction values of exergy of the components were observed according to the atmospheric air temperatures between 24.8 degrees C to 28.4 degrees C. It was resulted that the destruction values of exergy in the evaporator, condenser and the compressor increased with increasing values of atmospheric air temperatures, while that of the expansion valve decreased. In particular, the highest destruction values of exergy were obtained in the compressor with values ranging from 904.2 W to 959.2 W.
In this research, a novel geothermal power-based combined plant is planned for various valuable products generation. A flash-binary geothermal plant, an organic Rankine cycle plant, a transcritical-CO2 plant, a hydrogen production plant, and a magnetic refrigeration plant are integrated together to generate beneficial products. In the evaluation part of the paper, thermodynamic analyses, validation studies, and parametric studies are performed. According to the assessment outputs, the total power production is found as 20,220 kW, the heating capacity is 8,726 kW, and the cooling generation rate is 1,341 kW. In addition, the hydrogen production rate of the designed energy plant is 0.0124 kg/s.
In this study, exergoeconomic analyses of a 1,166 kWp nominal power PV system for polycrystalline, PERC monocrystalline-half cut and PERC monocrystalline panel types were carried out for the climatic conditions of Konya Province in Turkey. The annual energy and exergy efficiencies were determined as 17.2% and 18.5% for PERC monocrystalline-half cut, 16.8% and 18.1% for PERC monocrystalline, 13.8% and 14.8% for polycrystalline, respectively. The SPECO method was used for exergoeconomic analysis. The annual electricity generation costs were determined as 35, 41 and 37$/MWh while the payback periods were calculated as 48, 63 and 53 months for polycrystalline, PERC monocrystalline-half cut and PERC monocrystalline, respectively.
Ostwald process for nitric acid production was simulated using Aspen HYSYS. Effects of input parameters on concentration of nitric acid in the product show increase in mole fraction with increasing ammonia and air flow rates but decrease as feed water flow rate increases. Separator has highest exergetic efficiency of 90.4%. Optimum conversion for absorber, feed water temperature and flow rate are 70%, 25.5 degrees C and 3,000 kg/h, respectively for exergetic efficiency and 69.8%, 25.49 degrees C and 3,500 kg/hr, respectively for irreversibility. Flow rate for economical operation of the plant was 800 and 12,000 kg/h for ammonia and air, respectively.
This study was aimed at assessing the exergetic and exergoeconomic implications of adopting a recuperative (SUB-REGEN) instead of a non-recuperative (SUB) organic Rankine cycle (ORC) plant for power production from an abandoned oil well. The geometric parameters of a typical oil well in Nigeria were adopted for simulating the heat source. The specific exergy costing (SPECO) approach was employed for the exergoeconomic assessment. Results showed that for the SUB ORC, the evaporator had the highest exergetic efficiency of about 86% and the condenser the highest cost rate of exergy destruction of about 47%. For the SUB-REGEN ORC, the condenser had the highest contribution ratio of 0.41 to the total irreversibility with a cost rate of about 19.1 k$/h. Overall, the integration of a recuperator would increase the ORC exergetic efficiency from around 55% to 58%, albeit with a consequent increase in the cost rate of system irreversibility by about 24%.
This research focuses on possible sequences for the distillation of quaternary mixture to assess the performance of a system, where the general design heuristics are contradictory. In cases of contradictory heuristics, the most fitting operating scenarios for referencing each heuristic have not been explored in previous publications. The main objective of this research is to identify the most environmentally friendly and thermodynamically efficient processes, as well as to gain a better understanding of the effect of the objective function on the synthesis of separation trains, through environmental, economic and exergy analyses. To address this, 855 simulations are carried out with capital costs (CAPEX) and total annual costs (TAC) evaluations and environmental impact assessment. Global warming potential (GWP), along with exergy analysis results are also presented. The results of the current study reveal that in contrast to the heuristic criteria and recommendations, it is possible that a heuristically discouraged separation train may work very well, depending on operating conditions. It was also discovered that switching from liquid to vapour feed significantly reduces the direct sequence's superiority. Moreover, it was shown from exergy analysis that selecting the most thermodynamically efficient process does not guarantee optimal solutions in terms of economic and environmental aspects.
The purpose of this study is to optimise cumulative energy and exergy consumption to increase the sustainability and renewability of wheat production by using data envelopment analysis (DEA) technique. Data were collected from farmers in Khuzestan Province, Iran. Cumulative energy and exergy consumption are 50,227 and 29,656 MJ/ha, respectively, which in the target scenario based on DEA, is reduced to 37,891 and 25,671 MJ/ha, respectively. The average technical efficiency score of wheat producers in terms of cumulative energy and exergy consumption was 0.784 and 0.960, respectively. The results showed that 80.70% and 77.2% of farmers were inefficient in energy and exergy consumption, respectively. Cumulative degree of perfection and renewable index were 0.72 and -0.185, respectively. In the optimal scenario, these indices increased by 15.3% and 79.5%, respectively. The highest amount of exergy saving was related to chemical fertilisers and diesel fuel.
The present work focuses on the energy, exergy, and economic study of a compression ignition engine working with waste plastic oil (WPO). Blends like 10% to 30% by volume of WPO with diesel are prepared and investigated experimentally to evaluate the performance parameters. The thermal efficiency and exergetic efficiency are found to be increased by 3.38% and 6.92% with an increase in WPO blend up to 20% compared to the neat diesel case. The cost rate of inlet fuel for WPO20 is found to be decreased substantially from that of diesel. Moreover, the sustainability index (SI) of WPO20 by 1.38% higher than diesel ensured the extended durability of the engine and lesser damage to ecological factors.
Can exergy be used to reflect the environmental issues of a fuel? This article elaborates if and how exergy can be used to reflect the environmental issues of a fuel, and details the processes for some typical fuels. The results show that the exergy method can be well used to reflect the environmental issues of a fuel. The case studies further show that coal samples (1,324.99-1,437.47 kJ/kg) have higher total environmental impacts than the biomass samples (381.02-1,078.81 kJ/kg), and the environmental impacts are mainly contributed by CO2 (52.72%-99.37%), followed by ash (0.18%-35.93%), SO2 (0%-11.77%) and NO2 (0.16%-8.75%).
In this study, the production of sesame in traditional and mechanised systems was evaluated in terms of cumulative energy, exergy consumption, and environmental impacts. Data of traditional system were collected from 83 farmers in Khuzestan province in Iran and data of mechanised systems were obtained from Shahid Rajaei Agricultural Production Company in Iran. The findings showed that the energy and exergy efficiency in mechanised farms, were higher. Total cumulative exergy consumption in traditional and mechanised systems were 40,148 and 35,373 MJ/ton, respectively. Cumulative degree of perfection (CDP) and renewability index (RI) were obtained for traditional system 0.50 and -0.98, and for mechanised systems 0.57 and -0.74, respectively, indicating that the sesame production process is non-renewable. Life cycle assessment (LCA) indicated that sesame production in the mechanised system has less harmful environmental and health effects. The findings showed that the use of renewable electricity significantly increases the renewability of the sesame production process.
Ammonia is a promising carbon-free energy vector with potential applications for low carbon energy storage, transportation, power production, and fertilizer use. Small-scale renewable Power-to-Ammonia (P2A) is particularly suited for remote, agricultural areas. Employing real cost data, this work presents an exergoeconomic comparison of a novel to a conventional prototype containerized P2A system. The novel system is designed for low investment cost and is going to be tested in late 2023. Both systems have an installed 18 kWel electrolyzer capacity, yielding 1.5 kg/h of ammonia. However, the novel system has 90 000 € lower purchased equipment costs of 400 000 € and 1 800 € lower operating and maintenance costs of 20 000 €/y. The exergoeconomic analysis rightly identifies the key component in the novel design, the recycle valve, as the highest operation cost driver. However, the investment cost advantage of the valve compared to a recycle compressor in the conventional layout results in a slightly lower Levelised Cost Of Ammonia (LCOA) of 161 €/kg for the novel compared to 173 €/kg of the conventional cycle, making the novel layout overall cost superior. These values are well above values reported in literature of below 1 €/kg. However, the data presented in this work refer to a research prototype application, whose costs are strongly affected by the high engineering cost and the low number of operating hours. A mass produced prototype with a higher utilization will have much lower costs.
In this paper, the topic of human catabiosis has been explored from the vantage of thermodynamics. Research works on human catabiosis based on non-equilibrium thermodynamics are summarised. The origin of the human species, reproduction, growth, and ageing are reviewed from the perspective of thermodynamics, and finally, the future direction of the subject is discussed. The choice of dietary patterns and geographical locations influencing the ageing process are also discussed in this article.
Carbon dioxide emissions have risen sharply in recent years, and the solution is to switch to carbon-free energy sources. One of the renewable technologies with bright prospects is solar PV. To maximise performance, increasing the amount of irradiation and maintaining the operating temperature is required. This study suggests an easy modification for an existing solar PV system, with a combination of a single, dual aluminium reflector and spray cooling. NIT Kurukshetra is the site of the present investigation; a water spray recirculation system has been designed. Experiments were run comparing the performance of a reference configuration to those run with a single and a dual reflector. When using just one reflector and intermittent cooling, the average power generation efficiency increase was 5.74% compared to the reference system and when using a dual aluminium reflector with intermittent cooling it was 10.53%. An economic analysis and exergy analysis of the two methods and their comparison have also been made.
In this study mathematical model of the organic Rankine cycle driven by multiple evacuated collectors is made in MATLAB 2018a. Results reflect that heat gain 2.726 x 10(5) W and output temperature 130(degrees)C for the collector were highest for collector no.6 at 13:00 hrs. Moreover, the highest system thermal efficiency 14.92%, and exergetic efficiency 56.99% were seen for collector no. 6 at 13:00 hrs. The major exergy loss of 42% was seen in the evaporator continued by the condenser of 32%, expander of 25%, and a minimal 2% in the pump.
This study investigates the generation of entropy in a fully developed turbulent flow through a twisted elliptical tube with a constant wall temperature. The impacts of the dimensionless temperature difference and mass flow rate on entropy production are considered. The influences of the aspect ratio (1.25-5) and twist pitch ratio (5-200) of the twisted elliptical duct are also studied. The results demonstrate that total dimensionless entropy generation increases as the mass flow rate and dimensionless temperature discrepancy increase. The results also illustrate that the geometric configuration of the twisted elliptical duct is an essential factor in influencing entropy generation.
This study presents a novel solar-geothermal hybrid co-generation system for electricity and desalinated water production. The system couples a parabolic trough solar collector with a multi-effect desalination unit integrated with geothermal energy. Thermodynamic analysis was conducted to evaluate the energy and exergy efficiencies. Exergy destruction is quantified to identify inefficiencies. Life cycle assessment incorporated to determine environmental impacts. The parabolic trough collector exhibited the lowest exergy efficiency of 34%, contributing to 48% of total exergy destruction. The analysis provides insights into the system's performance and sustainability. Findings emphasise enhancing collector efficiency and optimisation for efficiency improvements and reduced environmental impacts.
In this study, an exergoeconomic analysis was conducted for a grid-connected photovoltaic system with a nominal power of 1,166 kWp to be installed in all provinces of Turkey. First, energy input, exergy input and electricity generation of the system were calculated depending on the hourly climatic condition of each province. Next, annual energy and exergy efficiencies of the system were determined. Last, unit electricity generation costs were obtained with exergoeconomic analysis by using SPECO method. All annual results were presented in maps. The minimum electricity generation cost was determined as 31 USD/MWh in Nigde, while maximum electricity generation cost was in Giresun as 54 USD/MWh. The maximum energy and exergy efficiencies were determined as 17.4%-18.7% in Kars, as one of the coldest provinces; the lowest energy and exergy efficiencies were determined as 16.4%-17.6% in Sanliurfa, as one of the warmest provinces, respectively.
