Increasing Hydrogen Flow Rate Research Articles

Sustainable energy storage solutions for coal-fired power plants: A comparative study on the integration of liquid air energy storage and hydrogen energy storage systems

With the majority of the world's energy demand still reliant on fossil fuels, particularly coal, mitigating the substantial carbon dioxide (CO2) emissions from coal-fired power plants is imperative for achieving a net-zero carbon future. Energy storage technologies offer a viable solution to provide better flexibility against load fluctuations and reduce the carbon footprint of coal-fired power plants by minimizing exergy losses, thereby achieving better energy efficiency. This work focuses on developing two such energy storage technologies: Liquid Air Energy Storage (LAES) and Hydrogen Energy Storage (HES), and their integration strategies with a sub-critical coal-fired power plant. The performance of the integrated systems is analyzed based on key parameters like energy storage capacity, net unit power output during charging and discharging, round-trip efficiencies, and net unit efficiencies at different operating load conditions of the plant. Our results show that during the charging cycles, by increasing the air flow rate in LAES and the hydrogen production rate in HES, the net unit efficiency of the integrated plant decreases by 3–10% at different load conditions, while the energy-based round-trip efficiency increases with increasing liquid air and hydrogen flow rates during the discharge cycles. For the HES system, utilization of the produced hydrogen in the fuel cells gives 40–50% better roundtrip efficiencies than co-firing hydrogen in the boiler at full and minimum load and it increases with increasing hydrogen flow rates. While HES has shown a better overall net unit efficiency (41.5%, in fuel cell scenario) of the integrated unit than the LAES system (40%) for the base case operation, LAES shows superior round-trip efficiencies when operated at higher liquid air discharge flow rates (>80 kg/s). The results provide insights into the system modeling of LAES and HES integrated with a sub-critical coal power plant, contributing to the advancement of sustainable energy storage solutions.

Effect of hydrogen flow rate on microstructure and tribological properties of plasma-sprayed Cr2O3-65%TiO2 composite coatings

Atmospheric plasma spraying was used to deposit CT65 (Cr2O3-65 wt%TiO2) ceramic composite coatings on 304 stainless steel substrates. Coating structure, hardness, and compactness were evaluated by varying hydrogen flow rates (4, 6, and 8 L/min). The CT65 coating generated a slight phase change under different hydrogen flow rates, and the (Cr0.88, Ti0.12)2O3 solid solution phase was detected in the coating. The friction coefficients of these three coatings were maintained between 0.32 and 0.36. Increasing hydrogen flow rate reduced coating wear rate and transitioned wear mechanism from abrasive to adhesive. Friction film consisted of counterpart material transfer and coating solid solution. In addition, a wear behavior model diagram illustrated the friction-induced wear mechanism of CT65 composite coatings.

Engine's behaviour on magnetite nanoparticles as additive and hydrogen addition of chicken fat methyl ester fuelled DICI engine: A dual fuel approach

The present work evaluated the influence of magnetite nanoparticles in chicken fat methyl-ester blend (CFME20) and hydrogen induction in CFME20 nano-fuels combustion performance and exhaust emissions using a 1-cylinder dual DICI engine. Results revealed that CFME20 blend exhibits a significant reduction in smoke, hydrocarbon, and carbon-monoxide emissions; however, increment in oxides of nitrogen and insignificant reduction in BTE also noted. Magnetite nanoparticles mixed with CFME20 through ultrasonication to make nano-additive fuel which noticeably decreased the exhaust emissions including oxides of nitrogen and slightly enhanced the BTE as well. Performance parameters gradually enhanced with escalating nanoparticles dosage up to 100 ppm. Hydrogen induction during nano-additive pilot fuel combustion further decreased the smoke, carbon-monoxide, and hydrocarbon emissions and enhanced the BTE to an appreciable level. However, oxides of nitrogen also enhanced with increasing hydrogen flow rate, but for 10 lpm trivial increased. Hence, the results confirmed that nano-fuel (100 ppm) with hydrogen (10 lpm) addition provides optimum outcomes.

An effect of hydrogenation on the photoemission of amorphous SiCN films

The structure, chemical bonding and photoemission of amorphous hydrogenated silicon carbonitride (a-SiCN:H) films deposited by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyldisilazane as a main precursor at different hydrogen flow rates are studied. Film properties are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), absorption optical spectra and photoluminescence (PL). The photoluminescence spectra were presented by four photoemission bands centered at 441–451, 489–496, 530–535 and 577–601 (in nm). To explain structural and photoluminescence properties of the deposited films, first-principles molecular dynamics simulations of un-hydrogenated and hydrogenated silicon carbonitride samples were carried out. Based on experimental and theoretical results a possible explanation of the photoemission of the deposited films and its evolution with increasing hydrogen flow rate was done.

Stabilizing of Mechanical Property of Amorphous In−Zn−O Thin Films with Hydrogen Flow

Amorphous In−Zn−O thin films were deposited with various hydrogen flow rates using a magnetron sputtering system. With the addition of hydrogen, the mechanical stability of the films was dramatically improved without any degradation of electrical properties and optical transmittance. The average change in the resistance of the sample deposited at a hydrogen flow rate of 0.4% was approximately six times lower than that in the sample deposited without hydrogen. Both, the compressive residual stress and absorption coefficient of the sample, decreased with hydrogen flow, indicating similar trends with the average change in the resistance. The absorption coefficient near 3.1 eV indicated that subgap state defects also decreased with increasing hydrogen flow rates. It was confirmed that the improvement in mechanical stability was derived from the suppression of subgap defects due to the hydrogen impurity. Thus, we demonstrated that hydrogen is a promising candidate for stabilizing the mechanical properties of oxide thin films.

Value-added utilization of pyrolysis heavy distillate for the synthesis of nitrogen doped graphene with chemical vapor deposition

The synthesis of graphene and nitrogen doped graphene (NG) with inexpensive pyrolysis heavy distillate (PHD) as a carbon source and urea as a nitrogen source by chemical vapor deposition on a copper substrate under hydrogen flow has been studied. The variables in synthesis were process temperature and hydrogen flow rate. The PHD is rich in aromatic compounds. These cyclic structured molecules resemble the basic unit of graphene and there is no need to break C-C atomic bonds and allows for graphene synthesis at a lower temperature. The morphology and properties of synthesized graphene and NG were characterized by Raman spectroscopy, TEM, XRD, BET and XPS. Results indicated that the increasing hydrogen flow rate and decreasing growth temperature, increase defects in the graphene, which are favorable for the catalyst support applications. From the Raman and XRD analysis, the NG and graphene derived from these carbon sources are few layers. The average nitrogen content was 5.89% in the structure of NG with three different types of nitrogen atoms namely; pyridinic (32.03%), pyrrolic (51.70%) and graphitic (16.97%). The defects are mainly of vacancy type because pyridinic nitrogen creates vacancies in the structure of graphene. We believe that these results will play an important role in the utilization of inexpensive carbon sources to convert high value added materials.

Influence of Hydrogen Flow Rates Annealing on the Structural, Optical, and Electrical Properties of Sol-Gel Synthesized Fe doped In2O3 Films

Diluted magnetic semiconductors (DMSs) have always been of great interest to study due to their wide applications in spintronics. This research was carried out to study the influence of different hydrogen gas flow rates annealing on the physical properties of Fe doped indium oxide. In1.92Fe0.08O3 thin films were prepared by a sol-gel method and followed by a spin coating technique. Different flow rates of hydrogen gas were applied during the annealing process. All samples showed high orientation along the (222) direction and exhibit a polycrystalline structure. Grain size increased as the flow rate increased due to the stronger reduction of H2. FTIR studies showed the existence of an O-H bond in the range of 3000 - 4000 cm-1 and it was caused by the flow of H2 gas during the annealing process. The resistivity of In1.92Fe0.08O3 thin films decreased and the carrier concentration increased with increasing hydrogen flow rates. This work has significance on the size-dependent properties and the chemical bonding in Fe doped In2O3 films.

Nitrate removal and extracellular polymeric substances of autohydrogenotrophic bacteria under various pH and hydrogen flow rates

In recent years there has been an increasing interest in the use of autohydrogenotrophic bacteria to treat nitrate from wastewater. However, our knowledge about the characteristics of extracellular polymeric substances (EPS) releasing by these activities is not yet very advanced. This study aimed to investigate the change in EPS compositions under various pH values and hydrogen flow rates, taking into consideration nitrogen removal. Results showed that pH7.5 and a hydrogen flow rate of 90mL/min were the optimal operating conditions, resulting in 100% nitrogen removal after 6hr of operation. Soluble and bound polysaccharides decreased, while bound proteins increased with increasing pH. Polysaccharides increased with increasing hydrogen flow rate. No significant change of bound proteins was observed at various hydrogen flow rates.

柱形Pt-SDB催化剂的水–氢交换高处理量工艺

摘要：研究了基于柱形Pt-SDB催化剂的水–氢催化交换工艺, 进行了柱形Pt-SDB催化剂的流体力学性能实验并讨论了填料规格、填料催化剂装填比、反应温度、气液比、处理量等对水–氢交换传质单元高度和传质系数的影响。结果表明，催化活性较低的柱形Pt-SDB催化剂，具有液泛气速高、持液量稳定、单位床层高度压降低等优点；柱形Pt-SDB催化剂水–氢催化交换的高处理量工艺条件为θ环填料与催化剂填装比例1:1、反应温度70℃~75℃、气液比1:1、空塔气速0.3 m/s。 The process conditions are experimentally studied for H2O-H2 liquid catalytic isotopic exchange with Pt-SDB as hydrophobic cylindrical catalyst, and hydrodynamic experiments are conducted for obtaining the correlating expressions of pressure drop △P/Z, flooding gas velocity uF. The results indicate that the Pt-SDB cylindrical catalyst with little catalytic activity has a number of advantages, including low pressure drop, higher flooding gas velocity and stable liquid holdup. The height of transfer unit (HTU) is also changed to be higher with the increasing of the air velocity in empty tower and the packing dimension. The efficiency of catalytic exchange reaction is high with a packing ratio of 1:1 of hydrophilic packing and hydrophobic catalyst in separated layers. The HTU decreases with increasing operating temperature, but the trend is slowed down when the temperature is above 70˚C. The HTU increases with increasing hydrogen flow rate and decreases with increasing diluted heavy water flow rate. When the air velocity of empty tower is 0.3 m/s, the process capacity is higher.

Crystallinity of silicon films grown on carbon fibers by very high frequency plasma enhanced chemical vapor deposition

In this work, silicon films were deposited on carbon fibers using very high frequency (60MHz) plasma enhanced chemical vapor deposition (VHF-PECVD) to form Si/carbon fiber hybrid structures for the applications to the flexible solar cell. The effect of deposition conditions of VHF-PECVD such as hydrogen flow rate and R.F. power on the microstructure of Si films was investigated with Raman spectroscopy, X-ray diffraction, field emission scanning electron microscopy, and high resolution transmission electron microscopy. The crystallinity of Si films on carbon fibers showed strong dependence on the hydrogen flow rate and was changed from amorphous structure to partially crystallized structure with increasing hydrogen flow rate. Increasing R.F. power enhanced the crystallinity for amorphous Si films while deteriorated the crystallinity for partially crystallized Si films on carbon fibers. And it was observed that the crystallinity of silicon films on carbon fibers was increased drastically by thermal annealing above 500°C.

Combustion Characteristic in Growth Chamber for Preparation of Single Crystal with Hydro-Oxygen Flame Fusion Method

Combustion characteristic in growth chamber for preparation of single crystal with hydrooxygen flame fusion method was investigated. The results show that along the centerline of growth chamber a peak temperature 3504.3 K could be reached when the flow rates of oxygen and hydrogen were 6 L/min and 20 L/min respectively. With the increasing hydrogen flow rate, the temperature of the center and the diameter of the central flame increased gradually in the chamber. With the increasing oxygen flow rate, the position of the peak temperature gradually moved down, which downward moved 5 mm when the central oxygen flow rate increased for 1 L/min, while the average temperature rose ca 230℃at a distance 110 mm to the nozzle. The diameter of hydrogen distribution circle had little effect on the center and radial temperature distributions, the central oxygen impact and the ignition position of the flame. As a result, the optimal position for single crystal growth could be easily acquired for the preset flow rates of the two gases and vice versa.

From Nanoparticles to Nanowires of GaN with Different Hydrogen Gas Flow Rates by PDC-PECVD

III-V family semiconductors have received considerable attention for microelectronic and optoelectronic applications. In particular, GaN nanostructures have a huge number of applications due to its wide and direct band gap, high melting point and high electrical breakdown field. Wurtzite structure of GaN nanoparticles and nanowires were synthesized using different hydrogen gas flow rate of 0, 3 and 7sccm (standard cubic centimetres per minute) via pulsed direct current plasma enhanced chemical vapor deposition (PDC-PECVD) at low temperature, 650°C. GaN nanostructures including nanowires and nanoparticles were grown using gallium atoms and nitrogen plasma on Si (111) substrates. Characterizations of GaN nanostructures were carried out using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and field emission electron microscopy (FE-SEM). Morphology of the grown GaN nanostructures changed from nanoparticles to nanowires with increasing the hydrogen gas flow rates. XRD results demonstrate that lattice constants ratio of a/c of hexagonal structure and gallium/nitrogen ratio in the synthesized GaN nanostructures decreased with increasing hydrogen flow rates. GaN nanoparticles and nanowires were grown on Si (111) with average diameters of 45nm and 25nm, respectively. The results show that the hydrogen plasma can significantly affects on morphology and lattice parameters of GaN nanostructures by low temperature PECVD method.

Effect of hydrogen addition on criteria and greenhouse gas emissions for a marine diesel engine

Abstract Hydrogen remains an attractive alternative fuel to petroleum and a number of investigators claim that adding hydrogen to the air intake manifold of a diesel engine will reduce criteria emissions and diesel fuel consumption. Such claims are appealing when trying to simultaneously reduce petroleum consumption, greenhouse gases and criteria pollutants. The goal of this research was to measure the change in criteria emissions (CO, NO x , and PM 2.5 ) and greenhouse gases such as carbon dioxide (CO 2 ), using standard test methods for a wide range of hydrogen addition rates. A two-stroke Detroit Diesel Corporation 12V-71TI marine diesel engine was mounted on an engine dynamometer and tested at three out of the four loads specified in the ISO 8178-4 E3 emission test cycle and at idle. The engine operated on CARB ultra-low sulfur #2 diesel with hydrogen added at flow rates of 0, 22 and 220 SLPM. As compared with the base case without hydrogen, measurements showed that hydrogen injection at 22 and 220 SLPM had negligible influence on the overall carbon dioxide specific emission, EF CO 2 . However, in examining data at each load the data revealed that at idle EF CO 2 was reduced by 21% at 22 SLPM (6.9% of the added fuel energy was from hydrogen) and 37.3% at 220 SLPM (103.1% of the added fuel energy was from hydrogen). At all other loads, the influence of added hydrogen was insignificant. Specific emissions for nitrogen oxides, EF NO x , and fine particulate matters, EF PM 2.5 , showed a trade-off relationship at idle. At idle, EF NO x was reduced by 28% and 41% with increasing hydrogen flow rates, whilst EF PM 2.5 increased by 41% and 86% respectively. For other engine loads, EF NO x and EF PM 2.5 did not change significantly with varying hydrogen flow rates. One of the main reasons for the greater impact of hydrogen at idle is that the contribution of hydrogen to the total fuel energy is much higher at idle as compared to the other loads. The final examination in this paper was the system energy balance when hydrogen is produced by an on-board electrolysis unit. An analysis at 75% engine load showed that hydrogen production increased the overall equivalent fuel consumption by 2.6% at 22 SLPM and 17.7% at 220 SLPM.

Tailoring of textured ZnO: Al film via hydrogen

In this present study, textured hydrogen and aluminum co-doped ZnO (HAZO) films were directly prepared on glass substrates through a pulsed DC magnetron sputtering technique. The influence of hydrogen flow rate on the morphological, optical, and electrical properties of HAZO films was investigated. With increasing hydrogen flow rate, surface morphology changed from pyramid-like to crater-like, feature size increased, and light trapping ability improved. The change in micro-structure of the HAZO films showed that hydrogen suppresses the more complex peaks and optimizes the dominant (002) and (004) peaks. In our experiment, optimal HAZO film properties were achieved at a hydrogen flow rate of 8 sccm, showing higher light trapping ability than commercial textured SnO2: F (FTO).

Deposition of Titanium Layer on Steel Substrate Using PECVD Method: A Parametric Study

Metallic titanium film was deposited on H-13 steel substrate at 470°C - 530°C using plasma enhanced chemical vapor deposition (PECVD) method. In this paper, the effects of manufacturing parameters were investigated on deposited titanium coating characteristics. XRD, FESEM, XPS and AFM were used in order to study coating characteristics. Increasing hydrogen flow rate from 200 to 360 sccm, resulted in a 72% decrease in oxygen content and 38% decrease in chlorine content of the film. Applied plasma voltage has a severe effect on nanohardness of coating. Pressure of the deposition chamber has a negative effect on titanium characteristics.

Effects of hydrogen in the cooling step of chemical vapor deposition of graphene

We investigated the effects of hydrogen gas flow rate in the cooling step of CVD on graphene film. We discovered that hydrogen gas in the cooling step influences the quality of graphene. The D peak (defects of graphene) intensity of the Raman spectrum tends to increase with an increasing hydrogen flow rate. Whether methane gas as a hydrocarbon source is maintained during the cooling step or not, the hydrogen flow rate during the cooling step strongly affects the quality of CVD-grown graphene.

Reduction and characterizations of iron particles: influence of reduction parameters

Iron particles have some applications as electromagnetic devices in magnetic recording and data storage technology due to their small sizes and high data storage capacity. The devices can be advanced by improving the properties of existing materials according to the production parameters. Thus, the influences of reduction parameters on the properties of iron particles were studied. The iron particles were reduced from superparamagnetic iron oxide nanoparticles by altering reduction parameters under hydrogen atmosphere at high (400 °C) temperature. The structural analysis of the films was carried out using the X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) techniques. The XRD data revealed that the crystal textures changed for the particles reduced at each parameter. And, the crystal structure turns from the cubic spinel structure of magnetite and body centered cubic (bcc) structure of iron to the bcc iron as the reduction time increases from 15 to 240 min. Then, the similar structure change can be seen for the samples reduced at increasing hydrogen flow rates. The HRTEM studies revealed that the surface morphology of the films strongly depend on the flow rate. Finally, magnetite peaks weaken and then disappear as the precursor mass decreases to the lowest value. The average crystallite sizes were found to be consistent with changing crystal structure. Furthermore, the magnetic characteristics studied by a vibrating sample magnetometer were observed to be affected by the parameters. Besides, magnetic differences may arise from the variation of crystal structure and crystal sizes caused by individual reduction parameters of reduction time, hydrogen flow rate and precursor mass.

Electrical Properties of Atmospheric Plasma-Sprayed La10(SiO4)6O3 Electrolyte Coatings

In this present work, La10(SiO4)6O3 as a promising electrolyte candidate for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been synthesized and its electrical property was investigated as a function of temperature. In order to improve the density and oxide ion conductivity of La10(SiO4)6O3, the feedstock powder was prepared by sintering the oxide mixture powders at proper sintering temperatures and times. The hexagonal apatite-type ceramic coatings with a typical composition of La10(SiO4)6O3 were deposited by atmospheric plasma spraying (APS) with different hydrogen flow rates. With increasing hydrogen flow rate oxide ion conductivity successively decreases. The highest ionic conductivity of the dense composite electrolyte coatings reaches a value of 2.4 mS/cm at 900 °C in air, which is comparable to other apatite-type lanthanum silicate (ATLS) conductors.

Influence of hydrogen-doped MgO thin films on the discharge characteristics in plasma display panels

In order to improve the discharge characteristics of Magnesium Oxide (MgO) thin films, hydrogen was doped to MgO thin films using an ion plating technique. Changes in the surface morphology, crystal orientation, optical properties, secondary electron emission coefficient, and defect states were studied with increasing hydrogen flow rates during the growth using field emission scanning electron microscope, X-ray diffraction, ellipsometry, γ-focused ion beam, and photoluminescence analysis. The change in firing voltage and delay time in plasma display panels (PDP) with the hydrogen-doped MgO thin films were also investigated. The results indicated that optimal hydrogen doping conditions can affect the surface structure and defect states: resulting in a significant reduction in the firing voltage and delay time of the PDP.

Improvement of crystal quality of AlN grown on sapphire substrate by MOCVD

AbstractThe crystalline quality of aluminum nitride (AlN) epilayers grown on sapphire substrates by MOCVD was improved by increasing hydrogen flow rate during the high temperature growth process. The AlN epilayer exhibited a root mean square (rms) of roughness was 1.944 nm from the 2×2 µm2 size atomic force microscopy (AFM) images. Full widths at half maximum (FWHMs) of (002) and (102) rocking curves of triple‐axis high resolution X‐ray diffraction (HRXRD) measurements were as narrow as 28.8 arc sec and 868 arc sec, respectively. The optical transmittance spectra showed a sharp absorption edge at a wavelength of 200 nm and strong Fabry‐Perot (FP) oscillations. It is proposed that the improvement in crystalline quality is due to the surface in the low‐temperature aluminum nitride (LT‐AlN) buffer layer is promoted to be stable Al‐polarity by the conditions of increasing hydrogen flow rate and ramping up the growth temperature. Addtionally, the parasitic reactions are effectively suppressed by increasing the hydrogen flow rate during the growth process of high temperature. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)