Effect Of Input Power Research Articles

Complete degradation of propranolol by a water falling film non-thermal plasma reactor: The effects of input power and plasma gases on transformation pathway

Propranolol, a beta-blocker, is a widely used drug for cardiovascular diseases. A synthetic sample containing propranolol (PRO) solution at native pH was recirculated up to ten times through an original coaxial non-thermal plasma reactor with a water falling film. Different discharge conditions, feed gasses, and power greatly influenced the extent of PRO degradation and the abundance of degradation products. The highest degradation rates were achieved in Ar plasma, either pure or in a mixture with O2, with over 70% of PRO degraded after only two passes through the DBD reactor. The full non-thermal plasma treatment was followed by a minimal change of pH value and conductivity. On the other hand, ambient air as the feed gas resulted in 60% of PRO degradation rate after the full treatment and contributed to a major drop in pH value and an increase in the conductivity of the treated solution. The structures of 47 degradation products in all three gases were identified and the degradation pathway is proposed, supported by DFT methodology. Scavenging experiments demonstrated that hydroxyl radical was predominant when plasma was generated using ambient air and Ar, while it had a minimal effect on the degradation in the mixture of Ar and O2. The desired level of propranolol decomposition was achieved only by the adjustment of the nonchemical parameters of the treatment, such as plasma gas composition and power. These results imply that a non-thermal plasma reactor is a highly effective method for pharmaceutical wastewater treatment, with no catalysts added.

The effects of input power and ambient temperature on the thermal performance of conical pin fin heat sink in natural convection

In the present study, thermal performance tests of horizontally oriented HSconical, HScross-cut, and HSflat with a base plate dimensions of 80*80*5 mm3 were performed in natural convection. The effects of ambient temperature (30 and 40 °C), input power (16.5 and 33 W), and conical pin fin geometry on the thermal performance of the HSs were investigated. The thermal resistance of the heat sinks decreases while the convective heat transfer coefficient, average surface temperature, and average junction temperature increase with increasing ambient temperature and input power. However, the Nusselt number increases with increasing ambient temperature for all HSs at 16.5 W, while the Nusselt number decreases with increasing ambient temperature at 33 W. The highest convective heat transfer coefficients are 32.17, 30.68, and 19.61 W/m2K for HSconical, HSflat, and HScross-cut at 33 W and 40 °C, respectively. The lowest thermal resistances are 2.75, 2.80, and 3.81 K/W for HSconical, HScross-cut, and HSflat at 33 W and 40 °C, respectively. Thermal resistances of HSconical and HScross-cut decreased by 27.78 % and 26.44 % at maximum and 27.06 % and 24.58 at minimum, respectively, compared to HSflat. The results show that the conical fins have better thermal performance in natural convection.

Comparative study of Ti-6Al-4V/ZK60A joints by fiber laser welding without filler metal

This study investigated the fiber laser welding technique for similar and dissimilar butt joints of Ti-6Al-4 V and ZK60A sheets. The effect of input power on hardness, weld depth, and width was examined. Results showed that the input power has a direct effect on weld widths and depths in such a way that by increasing laser welding power, they were increased. In dissimilar welds, magnesium islands were formed with peripheral titanium rings making the microstructure similar to a composite with magnesium islands as a matrix and titanium rings as reinforcement. Such a microstructure tended to improve mechanical properties compared to that of similar joints.

A Compact Microwave-Driven UV Lamp for Dental Light Curing

The size of current microwave-driven UV lamps limits their direct application in dental light curing. This article proposes a coaxial structure to miniaturize the UV lamp. First, the Drude model and the finite difference time domain algorithm were used to analyze the multi-physical field coupling and the complex field distribution within the lamp. Second, the dimensional parameters of the lamp were optimized, which enabled the lamp to be miniaturized and operate with high performance. Third, to analyze the sensitivity of the lamp, the effects of input power, gas pressure, and gas composition on its performance were investigated. It was found that an input power of 6 watts was enough to light the bulb with over 90% energy utilization. Finally, to verify the feasibility, an experimental system was set up. The lamp was successfully lit in the experiment, and its spectral output was tested. The results show that the microwave-driven UV lamp based on a coaxial structure is miniaturized and broad-spectrum, making it suitable for clinical dental light curing.

Numerical simulation analysis and orthogonal experiment optimization of the factors affecting plasma gasification of oil-based drilling cuttings

Plasma gasification technology is a harmless and resourceful solid waste treatment method. As a hazardous waste, studying the plasma gasification treatment of oil-based drilling cuttings has practical significance. Therefore, this paper uses Aspen Plus to establish a plasma gasification model. Based on model validation, the effects of input power, oxygen equivalence ratio, and carrier gas type on the plasma gasification process of oil-based drilling cuttings were discussed. In addition, by designing a quadratic regression orthogonal experiment, a nonlinear quadratic regression equation was established between the three factors of gasification pressure, input power, and equivalence ratio, as well as different gasification indicators, namely gas yield, lower heating value, and gasification efficiency. By solving the equation, it was found that when the gasification power is 70 kW, the gasification pressure is 10 atm, and the equivalence ratio is 0.1, the gas yield reaches its maximum of 0.74 kg/m3; When the gasification power is 15 kW, the gasification pressure is 10 atm, and the equivalence ratio is 0.1, the lower heating value of gas production reaches its maximum of 9.68 MJ/m3; When the gasification power is 15 kW, the gasification pressure is 1 atm, and the equivalence ratio is 0.1, the gasification efficiency reaches its maximum of 37.6%. At the same time, it was found that the influence of gasification pressure, input power, and equivalence ratio on gasification indicators was ranked in descending order as equivalence ratio, input power, and gasification pressure. The above research provides certain reference values for the practical operation of plasma gasification of oil-based drilling cuttings.

Coupled electromagnetic heat transfer model for cemented tailings backfill cured by microwave energy

Cemented tailings backfill (CTB) is a composite material containing binder, tailings and water, and it is commonly made available for filling mine-out areas and managing waste tailings. When backfilled, the CTB strength and its gain rate should be guaranteed for safe and efficient mining. It is acknowledged that increasing the CTB temperature is beneficial to its strength development. For this reason, microwave heating is introduced and applied to raise the CTB temperature quickly and thus accelerate its strength gain. To date, no numerical research has been conducted to investigate the electromagnetic and thermal properties of microwave cured CTB. Therefore, the present study proposes a coupled electromagnetic heat transfer model for the CTB heated by microwave energy. This proposed model considers the conversion of energy (electrical to electromagnetic and then to thermal), courses of heat conduction and convection, and relevant temperature variation. Two groups of experimental data are used to verify the prediction ability of the model simulation, and this model can accurately describe the thermal properties of the microwave heated CTB. Based on the validated model, the effects of input power, frequency and sample dimension on the distribution of heat and electromagnetic field are discussed. This study can be a contribution to the optimization of microwave parameters and sample dimension, for higher temperature development, less energy consumption and more uniform heating, in future laboratory experiments and field applications.

Experimental study of operating parameters on the performance of a novel U-type radiant tube with dual flue gas self-circulation structures

Faced with the challenges of gas-fired radiant tube performance improvement and increasingly stringent environmental requirements, we proposed a novel U-type radiant tube (N-URT) with dual flue gas self-circulation structures for heat treatment furnaces. A 1:1 scale experimental system was established to evaluate heating characteristics of the N-URT under different operating conditions. The effects of input power (P) and excess air coefficient (α) on temperature uniformity, NOx emission and thermal efficiency were analyzed and discussed in-depth. It was found that the N-URT can significantly improve the heating performance compared to conventional U-type radiant tube. As P increased from 35 to 50 kW, the maximum wall temperature difference decreased from 86.9 to 63.2 °C, the thermal efficiency dropped from 92.7% to 89.1%, and the outlet NOx emission increased from 89.6 to 103.6 mg·m−3 @8% O2. As α increased, the temperature uniformity increased, but the heat recovery and NOx reduction decreased. In addition, the effect of P on NOx emission and maximum wall temperature difference was more significant than α, indicating that the air supply strategy for a given P should be carefully considered. Accordingly, the experimental results can provide a theoretical guidance for the development and application of the radiant tube.

Trapping of Aqueous Droplets under Surface Acoustic Wave-Driven Streaming in Oil-Filled Microwells.

Microwell arrays are ideal platforms for cell culturing, cell separation, and low-volume liquid handling. The ability to manipulate droplets in microwells could open up the opportunity for developing new biochemical assays. Here, we study the trapping of aqueous droplets in an oil-filled microwell driven by the application of nanometer amplitude vibrations called surface acoustic waves (SAW). We elucidate the dynamics of the droplet within the vortex toward the final trapping location and the physics of the trapping phenomenon using a theoretical model by considering the relevant forces. Our study revealed that the combined effect of acoustic radiation and hydrodynamic forces leads to droplet migration and trapping. We demarcate the trapping and nontrapping regimes in terms of the minimum critical input power required for the trapping of droplets of different sizes and densities. We find that the critical power varies as the square of the droplet size and is higher for a denser droplet. The effects of input power and droplet size on the trapping location and trapping time are also studied.

Acoustofluidic separation of microparticles: a numerical study

In this paper, two-dimensional simulations are performed to separate polystyrene (PS) and polymethyl methacrylate (PMMA) particles suspended in water using an acoustic field. The acoustic waves are generated by two aluminum interdigitated transducers (IDTs) over a piezoelectric substrate. The effect of input power, inlet flow rate, acoustic frequency, and distance between IDTs and channel on separation efficiency is evaluated by considering channel thickness. It is observed that the separation efficiency is enhanced by increasing acoustic frequency and input power. Also, as the inlet flow rate and distance between IDTs and channel decrease, the separation efficiency increases. The optimum values for input power, flow rate, frequency, and distance are 1.4 W, 0.2 ml/min, 5 MHz, and 75 µm, respectively, and a maximum separation of 88% is achieved.

C-dot doping for enhanced catalytic performance of TiO2/5A for toluene degradation in non-thermal plasma-catalyst system.

Non-thermal plasma (NTP) is gaining attention as a powerful tool to induce various reactions. The combination of NTP with catalysts has been successfully used to degrade volatile organic compounds (VOCs) for pollution control. In this study, a series of TiO2-C/5A catalysts, synthesized by carbon dots (C-dots) that decorate TiO2 by sol-gel and wetness impregnation methods, were incorporated with a dielectric barrier discharge (DBD) reactor in a single-stage structure to degrade toluene at atmospheric pressure and room temperature. A proton-transfer reaction mass spectrometer and a CO2 analyzer were used to monitor the concentration variations of organic by-products and CO2 online. The effects of input power, mass ratio of C-dots/TiO2 (TiO2/5A (0 wt%), TiO2-C1/5A (2.5 wt%), TiO2-C2/5A (5 wt%), TiO2-C3/5A (10 wt%)), gas flow rate, initial concentration of toluene on the toluene degradation efficiency, and CO2 selectivity were studied. The plasma-catalyst hybrid system could effectively improve the energy efficiency and reaction selectivity, attaining a maximum toluene degradation efficiency of 99.6% and CO2 selectivity of 83.0% compared to 79.5% and 37.5%, respectively, using the conventional plasma alone. Moreover, the generation of organic by-products also declined dramatically, averaging only half as much in plasma alone. The results also indicated that the appropriate amount of C-dot doping could greatly improve the catalyst efficiency in the hybrid plasma system. This is because the interaction between C-dots and TiO2 favors the formation of photoelectron holes and reduces the energy band gap and the recombination rate of photogenerated electron holes, which facilitates the generation of more active species on the catalyst surface, thereby leading to a more effective degradation reaction. These observations will provide guidance for the interaction studies between NTP and catalysts, not only for the exploration of new chemical mechanisms of aromatic compounds, but also for the screening of favorable materials for the desired reactions.

Study on Calorimetry of Excess Heat in a d/Pd Gas-Loading System

A heat-flow calorimeter was introduced into the D/Pd gas-loading system to confirm the reliability and accuracy of the results obtained by isothermal calorimetry in the previous work. The effects of input power (electrical current) and pressure on excess heat were discussed under different experimental conditions. The results showed that the heat-flow calorimetry had higher accuracy than isothermal calorimetry. Under deuterium pressure of 30 kPa, the excess heat power decreased with the decrease of the input power, and the maximum excess heat power was (6.40 ± 0.19) W with an input power of 380 W. In the experiments of discussing the relationship between pressure and excess heat, the results showed there was a maximum excess power of (10.28 ± 3.40) W when the deuterium pressure was 220 Pa. The excess heat measured in the system was far more than that in chemical reaction. The results of SEM and EDS implied that excess heat came from nuclear transmutation processes.

Steady‐state and transient hydrothermal analyses of single‐phase natural circulation loop using water‐based tri‐hybrid nanofluids

AbstractTransient and steady‐state characteristics of the natural circulation loop are studied using various water‐based tri‐hybrid (different nature and shaped nanoparticles) nanofluids. Effects of input power, loop inclination and loop aspect ratio on the mass flow rate, effectiveness, and entropy generation rate are studied. Results disclose that tri‐hybrid nanofluids reduce the oscillation and attain steady state faster than water. Effectiveness increases and entropy generation rate decreases by using tri‐hybrid nanofluids. Nanoparticle shape has found a significant impact. Al2O3 + Cu + CNT/water shows the best performance. The mass flow rate increases with input power, loop aspect ratio, whereas, reduces with loop inclination. Effectiveness decreases and then increases with input power, whereas increases with loop inclination and decreases with loop aspect ratio. Entropy generation upsurges with input power and loop inclination, whereas decreases with loop aspect ratio. Loop aspect ratio of 1.5 to 3 is found suitable for better performance.

Hydrogen Production via Partial Oxidation Reforming of Methane with Gliding Arc Discharge Plasma

AbstractHydrogen production from partial oxidation reforming of methane in a gliding arc discharge (GAD) reactor is investigated. The effects of input power, the oxygen‐carbon molar ratio (O/C), and residence time are studied, respectively. Products such as H2, CO, CO2, and C2‐C4 hydrocarbons can be detected in the outlet gas. The experimental result shows that the input power of 36.4 W, the relitively low O/C of 0.705 and the 13.8 s residence time in this system will bring the highest H2 energy yield. Compared to the decomposition of methane, partial oxidation of methane with air can maintain a stable discharge state and no carbon deposition on electrodes is observed during the reaction process. Optical emission spectroscopy (OES) is also employed to characterize this methane‐air plasma. Based on the results of the experiment and OES, a possible mechanism of methane partial oxidation process was proposed, which points out that collisions of high‐energy electrons and excited N2 species (mainly N2(A)) with other species (such as O2, CH4) in the plasma region are two main ways for the activation of this reforming system. Hydrogen is generated principally through the H‐abstraction reaction and the H‐coupling reaction.

Effect of input microwave power and insulation on microstructure and tensile properties of cast Al 7039 alloy produced at 2.45 GHz

In the present work, microwave energy was used for casting Al 7039 alloy at 2.45 GHz in the ambient cavity environment. Effects of input power and insulation of the mould assembly during irradiation on charge melting and mould preheating were studied. Five different casts were produced at 1000 W, 1200 W, 1400 W, 1400 W with an insulated pouring basin and 1400 W with insulated mould assembly. Melting time of the charge was the least while using 1400 W with insulated mould assembly, whereas preheating of the mould was observed minimum during casting at 1400 W inside an insulated pouring basin. Cast microstructures revealed that less preheating of the mould resulted in finer grains and intermetallics, which improve tensile properties of the cast. Fractographic analyses showed the presence of coarse intermetallics in the casts produced with insulated mould assembly, which resulted in significant reduction of tensile properties.

Removal of bromoamine acid in dye wastewater by gas-liquid plasma: The role of ozone and hydroxyl radical

As a widely used anthraquinone dye intermediate, bromoamine acid (BAA) exists extensively in dye wastewater. In this study, the gas-liquid discharge non-thermal plasma technology was employed to degrade BAA. Efficient removal was achieved by the system within 15 min treatment. Besides, the effects of input power, working gas flow rate and solution pH value on BAA removal efficiency were investigated. BAA removal rate increased with higher input power and lower pH value, while too high or too low working gas flow rate could lead to the decrease of BAA removal. The existence of BAA caused significant decline of aqueous ozone concentration while enhanced the production of H2O2, indicating that the aqueous ozone participated in BAA degradation. The contributions of main active species were investigated. H2O2 and UV produced by discharges showed little effects on BAA degradation individually, however led to synergistic effect by producing OH. Over 60 % removal of BAA was attributed to OH oxidation, while direct molecular ozone contributed around 20 % degradation. The second-order rate constants of BAA reacting with ozone and OH were determined to be 1.22 × 103 M−1 s−1 and 4.06 × 109 M−1 s−1, respectively. A kinetic model was established to predict BAA degradation. 12 degradation intermediates were detected by HPLC-Q-ToF-MS, GC–MS and HPLC-UV. The degradation was mainly caused by hydroxylation, bond cleavage and addition of OH on double bonds.

Thermo-hydrodynamic analytical model, numerical solution and experimental validation of a radial heat pipe with internally finned condenser applied for building heat recovery units

Heat pipes have been extensively applied in the domain of energy conversion and heat recovery application. A novel radial heat pipe with internally finned condenser has been proposed to recover waste heat from air conditioning units. Full mathematical description and computational fluid dynamics model were developed to predict the loop flow and thermal performance in a single radial heat pipe, respectively. The research focuses mainly on the effects of input power, filling ratio, pipe diameter, and velocity of the cooling water on the thermal performance and entropy generation rate of this novel heat pipe. Numerical results illustrate that average reductions in total thermal resistance with utilization of fins approximately achieved 8.69% and 14.78% for fins nf = 4 and nf = 8, respectively. Similarly, entropy generation rate shows an average decrease of 19.4% and 37.5% for identical operations. Additionally, the effect of internally finned condenser on the multiphase fluid flow has been comprehensively analyzed, including the break of the condensed film, generation of bubbles and nucleation boiling. The results further indicate that incorporation of internal fins has a significant influence on enhancing thermal homogenization and waste thermal recovery efficiency of a radial heat pipe. Case results agreed well with experimental data within average deviation being no more than 10%.

Synthesis of few-layer graphene flakes by magnetically rotating arc plasma: effects of input power and feedstock injection position

A magnetically rotating arc plasma system is used for the synthesis of graphene flakes by methane decomposition. Effects of input power and feedstock injection position on product microstructures are investigated. The morphology and composition of the products are characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction, etc. Results show amorphous spherical particles with a diameter in the range of 10–40 nm and graphene flakes with 1–20 layers are generated in the plasma process. The graphene flakes are produced under a high gas temperature and long thermal history, while the spherical particles are favored by the opposite conditions. As the gas temperature increases, the products change from spherical particles to graphene flakes; moreover, the graphene flakes have larger size, fewer layers, straighter graphitic layers and better crystalline structure under a higher gas temperature. Emission spectral analysis indicates there exist lots of H atoms when the feedstock gas has a long thermal history in the plasma, revealing the importance of H atoms in the graphene flake formation. It is suggested that a high temperature and rich H environment can suppress the formation of curved or closed structures, leading to the production of graphene flakes with high crystallinity.

Experimental analysis of flow and convective heat transfer in the water-cooled packed pebble bed nuclear reactor core

A randomly packed pebble bed test facility is set up to study the flow and convective heat transfer in the water-cooled pebble-bed type nuclear reactor core. Water is used as the test fluid. The electrical induction heating system provides internal heat source for the packed pebble bed. The effects of input power, porosity, fluid velocity and inlet temperature are studied on the flow resistance and convective heat transfer coefficients. A new correlation is proposed to predict the pressure drop in the random packed pebble bed. The correlations given by Wakao et al. and KTA agree well with the experimental convective heat transfer coefficients in the high-velocity and low-velocity conditions respectively. A new correlation is presented based on the trend similarity between the Colburn j factor and friction factor, to predict the pebble bed convective heat transfer characteristics, with a discrepancy no more than 10%.

Input Power effect on Shock Wave Acceleration Phenomena due to Interaction with Discharge Field

Input Power effect on Shock Wave Acceleration Phenomena due to Interaction with Discharge Field

Input power effect on microstructure and mechanical properties of Mo[sbnd]Si[sbnd]N multilayer coatings

The MoSiN single layer and multilayer films were fabricated by a reactive radio frequency, r.f., magnetron sputtering system with pure Mo and Si targets. The Ar/N2 flow ratio was fixed at 12/8, while r.f. input powers for Mo and Si were 135 W and 0 to 150 W, respectively. The corresponding Si contents in the coating ranged from 0 to approximately 20 at.%. The microstructure of the MoSiN single layers evolved from Mo2N (111) crystalline to amorphous feature with input powers and related Si doping amounts. The MoSiN multilayer coatings were fabricated with crystalline MoN, crystalline and amorphous MoSiN layers with sequential stacking of any two building layers. The multilayer film made of MoN and crystalline MoSiN layers showed an obvious crystalline microstructure, while the amorphous MoSiN layer incorporated multilayer MoSiN systems effectively suppressed the continuity of the columnar growth. The correlation between mechanical properties, including hardness, Young's modulus, indentation cracking, and scratch behavior, were investigated and discussed in terms of film microstructure evolution.