Periodica Polytechnica (Budapest University of Technology and Economics)
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RETRACTED: Assessment of the Energy Efficiency of Ammonia Production by Microbubbles
Get PDFThis article has been retracted by the Editor at the request of the Authors because of the inaccuracy in a part of the research results, which also caused changes in the outcome and conclusion of the work. Please cite the corrected, revised and resubmitted version: https://doi.org/10.3311/PPch.38862
Experimental Study of Cu Nanoparticles Loading and Temperature Effects on the Thermophysical Properties of SAE10W oil: Developing a New Mathematical Correlation
Get PDFNanofluids can enhance the thermophysical properties of base fluids to increase the efficiency of thermal systems. This study is to develop a new mathematical correlation to predict the thermophysical properties of the copper/damper oil (SAE10W oil) nanofluids. Also, experiments were conducted with varying concentrations of Cu nanoparticles and different temperatures. High-Resolution Scanning Electron Microscopy (HRSEM), Energy-Dispersive X-ray spectroscopy (EDX), and X-Ray Diffractometry (XRD) are done to characterize the Cu nanoparticles. After determining the structure of Cu nanoparticles, the Cu/damper oil nanofluid is prepared through a two-step method. The density and viscosity of the nanofluids are measured according to IS 1448-32 (1992) and ASTM D445-15 standards. The specific heat of nanofluids and thermal conductivity were measured using a thermal constant analyzer. The results demonstrate that Cu nanoparticles significantly improve the thermophysical properties of pure automotive damper oil, enhancing its thermal conductivity from 15.48% to 33.28%. Furthermore, the viscosity of automotive damper oil increases by 79% and 222% with 0.050% and 0.150% volume concentrations, respectively. The density and specific heat changes are also measured and reported. Based on the experimental findings, an empirical correlation is developed through a fitting method to predict the thermophysical properties of these nanofluids. This mathematical correlation accurately calculates the properties of Cu/damper oil nanofluid, with a margin of deviation ranging from −3.7% to 7%
Metal-Coordinated Epoxy-Amine Composition with Reduced Fire Risk: Elaboration, Thermal and Ignition Resistance
Get PDFA new flame retardant-hardener for epoxy resins has been prepared. The flame retardant-hardener is a coordination compound of a chelate type, aqua-bis(ethylenediamine)-chloro-copper(II) chloride, [Cu(eda)2(H2O)(Cl)]Cl (eda – NH2C2H4NH2). The incorporation of the flame retardant curing agent, [Cu(eda)2(H2O)(Cl)]Cl, into the epoxy polymer matrix results in the production of new generation polymeric materials with reduced fire risk based. Bonding in the [hardener – flame retardant] system involve the interaction of a combustible nitrogen-containing curing agent (ethylenediamine) with a non-combustible inorganic d-metal salt (copper(II) chloride) into an aminocopper(II) chelate compound through strong Cu–N coordination bonds. The strength of bonding between the copper(II) salt and the amine hardener, as well as the participation of the resulting aminocopper(II) chelate compound in the formation of the polymer matrix framework, determine the resistance of modified epoxy-amine compositions to thermal oxidative degradation and ignition. The inclusion of the flame retardant-hardener in the epoxy resin reduces the segmental mobility of the interconnecting molecular links and leads to the creation of a denser polymer matrix. As a result, metal-coordinated epoxy-amine compositions are formed, which display good thermal resistance and self-extinguishing properties under combustion conditions
Development of Multi-Compartment Dielectric Barrier Discharge Plasma Reactor for Innovative Water Treatment
Get PDFA novel multi-compartment dielectric barrier discharge (MCDBD) plasma rector is developed and tested to produce plasma-activated water (PAW). MCDBD reactor consists of a polycarbonate container with six compartments. The top electrodes are stainless steel needles connected to AC high-voltage power supply. The bottom of each compartment is replaced with a glass slab and stainless-steel mesh electrodes. Cold plasma is generated in all compartments simultaneously to activate water. Experiments conducted by varying treatment time, power levels, gap between electrodes and water surface, and volume of water. Production of reactive oxygen and nitrogen species (ROS and RNS, respectively) in PAW is evaluated as per international standards (APHA/AWWA/IS). The application PAW greatly depends on the ROS and RNS concentration so results of MCDBD reactor are compared with conventional reactors. ROS and RNS concentration in 1800 mL water is measured 0.93 M and 0.52 M, respectively, in the MCDBD reactor. ROS and RNS concentration in 500 mL water is found to be 0.6 M and 0.44 M, respectively, in a conventional reactor. Result shows higher concentration of ROS and RNS produced in large volumes of water using MCDBD reactors. Even though the same amount of power is supplied to both conventional and multicompartment reactors, output in terms of ROS and RNS production is significantly greater in new design. Also, ROS and RNS have longer life in MCDBD reactor which is desirable to deactivate the biofilms and water decontamination. Proposed design is found to be more suitable for wastewater treatments, biomedical and agriculture applications
Experimental Analysis of Out-of-plane Behavior of Masonry Infill Walls Strengthened with Textile Reinforced Mortar and Wall Post in Autoclaved Aerated Concrete Frames
Get PDFAn experimental study was carried out to contribute to the rather limited data on the out-of-plane (OOP) behavior of masonry infills in reinforced concrete (RC) frames strengthened with the wall post and the textile-reinforced mortar (TRM). For this purpose, one unreinforced specimen served as the control, one specimen was reinforced with the wall post, and two specimens were reinforced with the TRM. They were fabricated and subjected to cyclic OOP loading until a drift ratio of 6%. Load and displacement values were recorded, and the research team discussed the failure mechanisms of the specimens. Results showed that the application of the wall post had the highest efficiency as it increased the load by about 3 times, while this value for TRM-strengthened walls was only 1.5. Strengthening modified the cracking, shifting it towards the middle parts of the wall, changing it from a brittle to a failure mode. Comparison of the envelope curves of specimens revealed significant improvements. The ultimate displacement and energy absorption capacity for the specimen reinforced with the post wall increased by 30% and 300% respectively. Similarly, for TRM-strengthened specimens, these values were 48% and 100%