Environmental Progress & Sustainable Energy最新文献

This study examines the effect of CuO and Al₂O₃ nanoparticles as heat transfer enhancers to increase the thermal performance of the chilled water refrigeration system. An experimental test rig was built that consisted of three parallel evaporator circuits that were immersed in three different water basins with CuO-water, Al₂O₃-water nanofluids and pure water as reference. The system consisted of a reciprocating compressor, air-cooled condenser, capillary expansion valve and air handling unit with copper coil heat exchanger. Nanofluids were produced by ultrasonic homogenization at mass fractions of 0.1%, 0.3% and 0.5% wt. Experimental measurements indicate that the optimal performance occurs for CuO-water nanofluid at 0.5% wt. Reasons for this are that the coefficient of performance is increased by 22%, the compressor power consumption by 31% and the heat rejection ratio by 0.8% compared to pure water. Large drops in temperature were observed at evaporator and condenser outlets. The performance improvement mechanisms are a result of the high thermal conductivity of nanofluids that increases the heat convection mechanism at the evaporator surfaces. Subcooling effects at the condenser outlet decrease the refrigerant enthalpy entering the expansion device to improve the refrigeration effect and minimize the work input of the compressor. These results prove the metal oxide nanofluids as efficient passive enhancement techniques for energy-efficient HVAC applications.

Renewable energy (RE) is fundamental in unlocking the dilemma in promoting economic goods and environmental protection. The United Nations (UN) through the “Sustainable Development Goals” (SDGs) is committed to promoting sustainable economic growth (SEG), through the utilization of clean energy. To this end, literature presents studies that examine how to improve RE development. However, there remains a gap in the literature on how research and development (R&D) and energy efficiency (EE) promote RE development in the European Union (EU). The analysis of this research utilizes the data of the EU economies for the time ranging from 1990 to 2019. The “Methods of Moments Quantile Regression (MMQR)” is adopted to overcome “cross-sectional dependence (CD)” and “heterogeneity” where longitudinal data is used. The findings show that EE and R&D are fundamental in promoting RE development in the EU economies. Inflation is also associated with improved RE development. However, the per capita Gross Domestic Product (GDP) and financial development (FD) reduce RE development in the EU region. The major policies presented in this research encourage governments to promote expenditure on R&D in order to support the development of RE resources.

A new method of hydrogen generation was developed on the nano zirconium surface by water splitting under a radiation-thermal process. The hydrogen generation process was optimized at different temperatures (373–673 K). The maximum amount of hydrogen produced was 14.0 × 10¹⁷ molecules/g.s at 673 K. The values of W_T(H₂), W_R(H₂), and W_RT(H₂) were 0.70 × 10¹⁴, 0.63 × 10¹⁴ and 1.33 × 10¹⁴ molecules/g.s at 673 K temperature. The values of G(H₂) were 2.0, 3.5, 5.7 and 8.4 molecules/100 eV at 373, 473, 573 and 673 K temperatures. The activation energy was also determined for the radiation thermal process with a 22.3 kJ/mol value. As per the mechanism, the hydrogen generation on the nano-zirconium surface is accompanied by the formation of zirconium oxide (ZrO₂). Besides, the surface analysis of zirconium was studied by FT-IR and SEM to support the mechanism. Finally, the reported method is efficient and effective and may be used for hydrogen production at an industrial scale after calibration at an industrial scale.

Agro-industrial wastes are considered a constant management challenge because they are generated in larger quantities than those the landfills are designed for, particularly, the mango pulping industries are facing a series of problems of regulatory compliance, as they generate organic wastes in quantities greater than those regulated in the applicable legislation, the present work has the objective of evaluating the technical feasibility of reincorporating mango endocarp in productive processes to obtain cellulose, using a “green” method that uses peracetic acid as a cooking liquor. The experimentation was carried out at laboratory and pilot scale, the results obtained showed that with the endocarp residues, it is possible to get high-purity cellulosic fibers with a percentage of lignin lower than 1.35%, quantities higher than 90% of hemicellulose and cellulose, whose thick cell wall structure and poorly developed lumen can be used as a platform for absorbent materials. The yield of the extraction process was higher than 50%. In conclusion, it is possible to take advantage of mango endocarp residue by selective delignification with peracetic acid to obtain high-quality cellulose.

This study designed and operated a calcium chloride-based solar pond (CMSP) with a 2.35 m diameter and 1.80 m depth to collect and store solar heat. The pond used CaCl₂ solutions of varying densities to establish stable thermal stratification. Hourly temperature data were recorded for a year using a 16-channel system, and a parallel COMSOL Multiphysics model was developed for validation. The study addresses the need for efficient, low-cost, long-term solar thermal energy storage to mitigate solar intermittency and fossil fuel dependence. The annual stored energy was 7040.35 MJ experimentally and 7450.19 MJ numerically, with a 5.50% deviation, confirming good model accuracy. This energy corresponds to CO₂ emission reductions of 240.22 kg (experimental) and 254.20 kg (numerical). Maximum thermal efficiencies occurred in December—49.18% experimentally and 43.32% numerically—indicating effective summer-to-winter heat utilization. Strong agreement between experimental and numerical results verified the model's predictive capability. The CMSP maintained stable stratification and demonstrated the suitability of CaCl₂ as a working salt for heat storage. Payback periods were 6.35 years (experimental) and 5.90 years (numerical), confirming both technical and economic feasibility. Overall, CaCl₂-based solar ponds provide a reliable, low-cost, and sustainable solution for seasonal thermal storage and carbon mitigation, offering strong potential for renewable heating applications.

In this study, waste tire-derived activated carbon (WTAC) was applied in dye adsorption and energy storage. The thermal decomposition temperature of WTAC was also investigated. The characterization of WTAC was analyzed through modern analytical methods of scanning electron microscopy, Raman spectroscopy, X-ray powder diffraction, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. Besides, the effects of the adsorption time, crystal violet concentration, and WTAC mass on the adsorption capacity were evaluated. As a result, WTAC showed great ability with an adsorption capacity of up to 39.2 mg/g and a specific capacitance of 311 F/g. In addition, the synthesis of aerogel from WTAC achieved a conductivity of 0.06 W/mK, which shows the potential in replacing insulation materials at the moment.

External application of serotonin (SER) was investigated to determine its effect on grapevine growth and selenium (Se) uptake under Se stress conditions. The treatment of Se (0.5 mg L⁻¹) decreased the biomass, photosynthetic pigment content, and superoxide dismutase (SOD) activity of grapevines, and increased the activities of peroxidase (POD) and catalase (CAT), suggesting a stress induction caused by Se. Under Se stress, SER treatment (150 μmol L⁻¹) increased root and shoot biomass of grapevines by 6.83% and 9.25%, respectively, compared to Se treatment. SER treatment also increased the levels of chlorophyll a and total chlorophylls by 7.15% and 4.75%, respectively, compared to Se treatment, while it did not affect the levels of chlorophyll b and carotenoid under Se stress. However, SER treatment did not affect the activities of SOD and CAT, while increasing POD activity under Se stress. Notably, SER treatment decreased root and shoot total Se contents by 9.78% and 29.34%, respectively, compared to Se treatment, and reduced Se translocation from roots to shoots. Additionally, shoot total Se content demonstrated strong correlations with POD activity, SOD activity, and root total Se content. Therefore, SER can alleviate Se stress, promote growth, and reduce Se uptake of grapevines.

Hydrogen is traditionally regarded as a cornerstone in the path to a sustainable energy economy. However, there are substantial differences in the inclusion of environmental and health effects across the hydrogen production pathways, due to different feedstocks, technologies, and byproduct emissions. This review compares the ecological footprints of renewable and non-renewable hydrogen production methods. It assesses spatial and temporal variations in greenhouse gas emissions, resource consumption, and waste generation, as well as occupational and community health risks. Comparisons are made, among other things, of emerging production technologies, such as green hydrogen via electrolysis and turquoise hydrogen derived from pyrolysis of methane, with alternatives such as steam methane reforming (SMR) and coal gasification. It suggests integrating advanced safety protocols, lifecycle assessments, and policy interventions in the technology deployment of cleaner hydrogen technologies. The importance of how hydrogen is produced, managed, and regulated is critical to the fuel's sustainability, and the study concludes that, despite its promise as a clean fuel, hydrogen holds only limited promise if it is not produced with sufficient safeguards and oversight.

Thermodynamic properties are of great significance for evaluating and optimizing hydrogen storage systems. In this work, the hydrogen storage performance of Li-modified graphene oxide and the thermodynamic properties of their hydrogen storage reaction are investigated. The calculations show that the adsorption energy of H₂ in Li-modified graphene oxide containing a single O/OH group lies within −0.19 to −0.42 eV, and the maximum hydrogen storage capacity can reach 12.6 wt%. The calculations on the adsorption state, vibration frequency, and entropy reveal that the zero-point energy correction accounts for 17%–46% of the adsorption energy, which indicates that the influence of the zero-point energy cannot be ignored. There is a good linear relationship between the entropy of adsorbed hydrogen and that of gaseous H₂. The entropy of hydrogen decreases by 10.6R to 12R after adsorption. Based on the Langmuir adsorption model, Li-modified graphene oxide can achieve maximum cyclic adsorption capacity in the operating temperature of 250 to 260 K and ∆S range of −89 to −93 J mol⁻¹ K⁻¹.