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A year-round study of a photovoltaic thermal system integrated with phase change material in Shanghai using transient model
摘要： In the study, the daily and monthly performance of a photovoltaic thermal system integrated with phase change material is investigated in Shanghai, China. A three-dimensional model of photovoltaic thermal system integrated with phase change material system is developed and numerically simulated. Water is considered as working fluid, and the fluid flow regime is laminar and incompressible. Both quasi-steady and transient models are compared together, and the transient model is selected because of its higher accuracy. Validation analysis is performed on the numerical model to show the reasonable agreement of current research compared to some other research. After obtaining the suitable operating time for the system, the performance of the system is studied from both energy and exergy viewpoints during the year. An environmental analysis is also conducted to show the annul carbon dioxide mitigation potential. The results show that July is the best month for operating of the system in shanghai with an operating time period of 13.5 h per day on average, while November, December, and January have the lowest operating time period. The percentage of melted phase change material in January, February, March, November and December is zero which means that the melting process does not occur in these months, due to the low ambient temperature and incident solar radiation in Shanghai. Though the overall energy efficiency of the system is higher in summer, the overall exergy efficiency is lower in this season.
关键词： Quasi-steady and transient models,Environmental analysis,Daily and monthly analysis,Energy and exergy analysis,PVT systems
更新于2025-09-23 15:21:01
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SERS-based molecularly imprinted plasmonic sensor for highly sensitive PAH detection
摘要： A novel hybrid plasmonic platform based on the synergetic combination of a molecularly imprinted polymer (MIP) thin film with Au nanoparticles (NPs) assemblies, noted as Au@MIP, was developed for surface-enhanced Raman scattering (SERS) spectroscopy recognition of polycyclic aromatic hydrocarbons (PAHs). While the MIP trapped the PAH close to the Au surface, the plasmonic NPs enhanced the molecule Raman signal. The Au@MIP fabrication comprises a two-step procedure, first, the layer-by-layer deposition of Au NPs on glass and their further coating with a uniform MIP thin film. Profilometry analysis demonstrated that the thickness and homogeneity of the MIP film could be finely tailored by tuning different parameters such as prepolymerization time or spin-coating rate. Two different PAH molecules, pyrene or fluoranthene, were used as templates for the fabrication of pyrene- or fluoranthene-based Au@MIP substrates. The use of pyrene or fluoranthene, as a template molecule to fabricate the Au@MIP thin films, enabled its ultradetection in the nM regime with a 100-fold improvement compared with the non-imprinted plasmonic sensors (Au@NIPs). The SERS data analysis allows to estimate the binding constant of the template molecule to the MIP. The selectivity of both pyrene- and fluoranthene-based Au@MIPs was analyzed against three PAHs of different sizes. The results displayed the important role of the template molecule used for the Au@MIPs fabrication in the selectivity of the system. Finally, the practical applicability of pyrene-based Au@MIPs is shown by performing the detection of pyrene in two real samples: creek water and seawater. The design and optimization of this type of plasmonic platform pave the way for the detection of other relevant (bio)molecules in a broad range of fields such as environmental control, food safety or biomedicine.
关键词： Molecularly imprinted polymers,plasmonic sensors,polycyclic aromatic hydrocarbons,SERS,hybrid nanostructures,environmental analysis
更新于2025-09-19 17:13:59
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Economic and environmental assessment of reusing electric vehicle lithium-ion batteries for load leveling in the residential, industrial and photovoltaic power plants sectors
摘要： Reaching 70–80% of primary capacity, lithium-ion batteries must be replaced in electric vehicles. However, they could be reused in other applications such as energy storage stations. In this paper, an economic evaluation of reusage of lithium-ion packs for load leveling in the residential, industrial and photovoltaic power plants sectors have been investigated from subscriber and government aspects. Several repurposed electric vehicle battery packs have been taking into account for different tariffs and scenarios. It is found that utilization of battery can reduce electricity bill for residential consumers by 14.25% based on the current electricity market and 39.75% if the fine of the peak time consumption is tripled. However, the current subsidy rate in the electricity tariffs is the main barrier in terms of the payback period for homeowners. Moreover, it is found that decrease in the battery prices by 2035 as the only factor will not justify usage of repurposed battery in residential sector, furthermore, tariffs must also be regulated. Sensitivity analysis declared that a 20% reduction in the price of battery in residential sector, affects the internal rate of return by 164%. Meanwhile, increasing in the on-peak tariff can fluctuate it by 44%. Reusing electric vehicle batteries could be more profitable in the industrial sector due to the realistic tariff. In addition to the operation cost, government saving is analyzed from the initial cost aspect. Results illustrated that utilization of repurposed battery packs can reduce construction costs of new on-peak thermal power plants by 72.5% and 82% in the residential and industrial sectors, respectively. Finally, the effect of using repurposed lithium-ion battery packs on the emission rates of greenhouse gases and other air pollutants are surveyed. The reused batteries can be employed to achieve sustainable development.
关键词： Load leveling,Secondary use,Lithium-ion battery,Environmental analysis,Electric vehicle,Economic analysis
更新于2025-09-16 10:30:52
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Fluorometric determination of aflatoxin B1 using a labeled aptamer and gold nanoparticles modified with a complementary sequence acting as a quencher
摘要： A fluorometric aptamer based assay is described for rapid and sensitive detection of aflatoxin B1 (AFB1). It is making use of a fluorescein (FAM) labeled anti-AFB1 aptamer and complementary DNA-modified gold nanoparticles (GNPs). In the absence of AFB1, the FAM-labeled aptamers hybridize with complementary DNA strands that were covalently immobilized on GNPs. This results in quenching of the green fluorescence (with excitation/emission peaks at 485/525 nm). In the presence of AFB1, the aptamer probe binds AFB1 and is released from the GNPs. Hence, fluorescence is restored. Under optimized conditions, AFB1 in the concentration range from 61 pM to 4.0 μM can be detected, and the detection limit is 61 pM. This assay is highly selective for AFB1. It was applied to the determination of AFB1 spiked into 50-fold diluted wine and 20-fold diluted beer.
关键词： Mycotoxin,Food safety,Environmental analysis,Fluorescence quenching,Fluorophore,Fluorescent probe,Nanomaterials,Nanoprobe
更新于2025-09-11 14:15:04
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Environmental impact analysis applied to solar pasteurization systems
摘要： In many under-developed regions of the world, most people live in rural villages, where the electrical grid is often not available and traditional potabilization systems would be too expensive and technologically too complex to be implemented. Thus every year, millions of people in the world die due to diseases related to water contamination. Solar Pasteurization Systems represents a promising alternative to address such problems, as they can thermally disinfect water employing solar energy alone, without using fossil fuels or electrical grid connection. Evaluating the cradle-to-grave environmental footprint of Solar Pasteurization Systems, and in general of technologies aimed at producing safe drinking water, represents an issue of major importance. This is relevant because an effective solution has to be, at the same time, environmentally and locally sustainable for a given geographical context. In this work, a complete Life Cycle Assessment and Exergo-environmental analysis are performed in order to calculate and compare the eco-profiles of two Solar Pasteurization technologies: a Natural Circulation and a Thermostatic Valve System. Results show that Natural Circulations Systems are generally more environmentally sustainable (0.30 mPt/l) than the Thermostatic Valve System (0.83 mPt/l) thanks to the higher productivity of treated water. A sensitivity analysis is performed to investigate the dependency of the model systems from different operational and environmental conditions, at different installation sites, i.e. Somalia, Brazil and Italy. The main difference is represented by the productivity of the systems. In all cases the solar collector array is the main item responsible for environmental burdens, impacting for almost 45% of the total score. The analysis also shows that the use of solar energy in Pasteurization is important to avoid direct emissions and to lower the global environmental impact connected with thermal energy production compared to the eco-profiles of other widely diffused pasteurization technologies based on the combustion of fossil fuels or biomass that can be used to provide the same function (in general higher than 1.2 mPt/l). Moreover, with the aim of qualitatively assessing the benefit associated with the potential implementation of solar pasteurization systems, an improvement of the sanitary conditions is envisioned, especially in under-developed countries where, definitively, a large scale diffusion would be recommended.
关键词： Solar Pasteurization,Solar Energy,Life Cycle Assessment,Exergo-environmental analysis,Water Disinfection,Water Treatment
更新于2025-09-09 09:28:46