Influence Of Hydrogen Addition Research Articles

Effect of hydrogen addition on the combustion and emission characteristics of methane under gas turbine relevant operating condition

The influence of hydrogen addition (0–100%) on the combustion and emission characteristics (NO and CO formation) of laminar-premixed methane flame under gas turbine relevant operating conditions was numerically studied. The PREMIX code of ANSYS CHEMKIN-PRO and the GRI-Mech 3.0 were utilized. The study of the effect of increasing hydrogen content in the methane-hydrogen mixtures on combustion and emissions at T = 298 K, P = 1 atm can provide a reference for our subsequent research on gas turbine conditions (T = 723 K, P = 16.5 atm). The LBV (laminar burning velocity) and AFT (adiabatic flame temperature) with different hydrogen contents (XH2=0–100%) and equivalence ratio (Φ = 0.6–1.4) were investigated. In addition, under gas turbine relevant lean burning conditions (Φ = 0.6, 0.8), the effect of hydrogen addition on the NO and CO emissions were investigated. The rate and sensitivity coefficients of NO/CO production were also examined. The results show that the LBV and AFT increase with the hydrogen content. Both the mole fraction of H, O and OH radicals and the flame temperature were observed to increase with the hydrogen content. Furthermore, the hydrogen addition can significantly increase the NO emissions and on the other hand suppress the CO formation. Reducing the equivalence ratio (from 1.2 to 0.6) can significantly reduce the NO emission. The addition of hydrogen can also increase the combustion stability of methane fuel under fuel-lean conditions. This is a good hint for gas turbine device to reduce NO emissions at fuel-lean side (Φ < 1).

Spark knock suppression in spark ignition engines with hydrogen addition under low and high engine speeds

The influence of hydrogen addition on spark knock characteristics is investigated under two engine speeds (2000 rpm and 4800 rpm) with experiments and chemical analyses to describe the effect of hydrogen addition on the high-speed knock as well as on the low-speed knock. The experimental results showed that the hydrogen addition of 15 HV% advances the knock limit by 3°CA at 2000 rpm, while by 1°CA at 4800 rpm, indicating that the knocking suppression effect weakens at higher engine speeds. The chemical kinetic analyses showed that hydrogen addition reduces the heat release rate under 900 K where the low temperature oxidation (LTO) appears, while it promotes the heat release rate above 900 K. These results suggest that the smaller effect of hydrogen addition at the higher engine speed is due to the smaller dependence of the LTO on the ignition process, with the shorter residence time below 900 K.

Influences of hydrogen addition from different dual‐fuel modes on engine behaviors

AbstractCompression ignition (CI) engines have good performance but more exhaust emissions. Dual fuel (DF) engines have better performance and lower emissions compared to CI mode. Also, the scarcity of fossil fuels made the researchers to find alternative fuels to power CI engines. Therefore, the present work aims to use hydrogen (H2) and honne oil biodiesel (BHO) to investigate the performance of CI engines in DF mode. Also, it aims to compare the performance of CI engines in various DF modes, namely induction, manifold injection, and port injection. First, the CI engine was fuelled completely by diesel fuel and BHO. The data were gathered when the engine ran at a constant engine speed of 1500 rpm and at 80% load. Second, the CI engine was operated in various DF modes and data were generated. CI engine operation in DF mode was smooth with biodiesel and H2. The brake thermal efficiency (BTE) of 32% and 31.1% was reported with diesel and biodiesel, respectively, for manifold injection due to low energy content and high viscosity of biodiesel. These values were higher than CI mode and other DF modes. Fuel substitution percentage for DF manifold injection was 60% and 57% with diesel and biodiesel, respectively. Smoke, hydrocarbon (HC), and carbon monoxide (CO) emissions were lower than conventional mode, but a reverse trend was observed for oxides of nitrogen (NOx) emissions. Heat release rate (HRR) and peak pressure (PP) were higher than conventional mode due to the fast combustion rate of hydrogen. The shortest ignition delay (ID) period was noticed for traditional diesel fuel, but it was longer for BHO biodiesel due to its higher viscosity and lower cetane number. On the contrary, the presence of hydrogen led to an increment in the combustion duration (CD) owing to the scarcity of oxygen in CD. Consequently, the paper clearly showed that the injection way of hydrogen plays a respectable role in the engine characteristics.

The influence of hydrogen addition on the combustion characteristics of a common-rail CI engine fueled with waste cooking oil biodiesel/diesel blends

In this study, the effect of hydrogen assisted intake air on combustion characteristics of a diesel fuel-waste cooking oil biodiesel (WCOB) blend fueled CI engine has been extensively studied. While the diesel and B25 (75% diesel fuel+25% WCOB) fuels used as the main fuel were sprayed directly into the cylinder, the hydrogen, the secondary fuel was mixed with the intake air at 10, 20, 30 and 40 lpm flow rates and taken into the cylinder. The maximum in-cylinder pressure (CP) values decreased with B25 fuel compared to diesel fuel. But B25‑hydrogen dual-fuel mode operation exhibited higher maxium CP and RoPR value according to diesel fuel. It was seen that hydrogen has a more significant effect on premixed pilot fuel combustion phase compared to the diffusion combustion phase. It was observed that the combustion duration (CD) of neat B25 fuel lower than that of diesel fuel, generally. In case of B25‑hydrogen dual-fuel mode operation, CD increased depending on increasing hydrogen addition rate. It was seen that hydrogen enrichment has no adverse effect on ringing intensity (RI).

The Formation of Columnar YSZ Ceramic Layer on Graphite by PS-PVD Method for Metallurgical Applications

In the article first tests of production of YSZ ceramic coatings using PS-PVD method on graphite were presented. The influence of hydrogen addition on structure and morphology of columns was analyzed. It was shown that width of the columns increased with the increase of hydrogen content in the plasma. The presence of re-solidified oxide vapors between ceramic columns was observed. The obtained results showed the possibility of using of YSZ ceramic layer as a protective layer for metallurgical applications.

Influence of hydrogen addition on methane coupling in a moderate pressure microwave plasma

In this paper, the effect of hydrogen addition on methane coupling in a microwave moderate pressure (55 mbar and 110 mbar) plasma reactor has been studied. The use of optical emission spectroscopy allowed the determination of the rotational temperature of heavy particles and showed it to be in the range of 3000–4000 K. Due to the high temperature in the discharge the dominant product was acetylene and it was concluded that the methane coupling process is mainly through thermal decomposition with a key role of H radicals. It was revealed that the addition of hydrogen can increase both methane conversion and acetylene and ethylene yield and selectivity. With the CH4:H2 ratio of 1:1, the methane conversion increased from 31.0% to 42.1% (55 mbar) and from 34.0% to 48.6% (110 mbar), when compared to pure methane plasma. Respectively, the yield of acetylene increased from 14.4% to 25.3% (55 mbar) and from 20.1% to 34.0% (110 mbar). Moreover, the addition of hydrogen decreased the output of the problematic soot-like product. These results indicate that hydrogen addition can be a simple yet effective method of increasing selectivity to desirable products in plasma reforming of CH4.

Reactive computational fluid dynamics modelling methane–hydrogen admixtures in internal combustion engines part II: Large eddy simulation

Fuels based on admixtures of methane/natural gas and hydrogen are a promising way to reduce CO2 emissions of spark ignition engines and increase their efficiency. A lot of work was conducted experimentally, whereas only limited numerical work is available in the context of three-dimensional modelling of the full engine cycle. This work addresses this fact by proposing a reactive computational fluid dynamics modelling framework to consider the effects of hydrogen addition on the combustion process. Part I of this two-part study focuses on the modelling and crucial considerations in order to predict the mean cycle based on the G-equation combustion model using the Reynolds-averaged Navier–Stokes equations. There, the effect of increased burning speed was globally captured by increasing the flame speed coefficient A, appearing in the considered flame speed closure. The proposed simplified modelling of the early flame stage proved to be robust for the conducted hydrogen variation from 0 to 50 vol% H2 for stoichiometric and lean operation. Scope of this work, Part II, are cyclic fluctuations and the hydrogen influence thereon using large eddy simulation and the proposed modelling framework. The model is probed towards its capabilities to predict the fluctuation of the combustion process for 0 and 50 vol% H2 and correlations influencing the observed peak pressure of the individual cycle are presented. It is shown that the considered approach is capable to reproduce the cyclic fluctuations of the combustion process under the influence of hydrogen addition as well as lean operation. The importance of the early flame phase with respect to arising fluctuations is highlighted as well as the contribution of the resolved scales in terms of the flame front wrinkling.

A Study on the Influence of Hydrogen Addition on Combustion and Exhaust Characteristics in a Lean Burn Gas Engine for Power Generation (Second Report)

A Study on the Influence of Hydrogen Addition on Combustion and Exhaust Characteristics in a Lean Burn Gas Engine for Power Generation (Second Report)

Influence of Hydrogen Addition on Combustion and Exhaust Characteristics in a Lean-burn Gas Engine

Influence of Hydrogen Addition on Combustion and Exhaust Characteristics in a Lean-burn Gas Engine

Effect of hydrogen enrichment on combustion characteristics of methane swirling and non-swirling inverse diffusion flame

Influence of hydrogen addition on appearance of swirling and non-swirling inverse diffusion flame (IDF) along with emissions characteristics are investigated experimentally. The combustion characteristics including flame length, axial and radial temperature variation, and noise level are analysed for hydrogen addition in methane by mass basis for constant energy input and by volume basis for constant volumetric fuel flow rate. Hydrogen addition in methane IDF produces shorter flame by compressing entrainment zone, mixing zone, reaction zone, and post-combustion zone. Hydrogen addition shift these zones towards fuel and air exit from the burner. Enrichment of methane with hydrogen on a mass basis up to 6% reduces CO emission considerably and increases NOx emission moderately. Effect of H2 addition on combustion and emission characteristics is more prominent in non-swirling IDF. Combustion noise is augmented with the hydrogen addition and the magnitude of sound level depends on the hydrogen concentration.

Influence of surfactants on quaternary emulsion blend and experimental investigations on the influence of hydrogen enriched quaternary blend in DICI engine

In this research work, phase behaviour of the synthesized Schizochytrium algae biodiesel, diesel and octanol was studied with water in oil emulsions (Quaternary blend). The effects of different hydrophilic lipophilic balance were investigated by varying the ratio of Span 80 and Tween 80 (20–100%) in the quaternary blend to find an optimum HLB number. The optimum fuel blend of HLB number 12 (Span 20%: Tween 80%) showed no phase separation for 25 days. The influence of hydrogen addition in quaternary blend (QB20) and biodiesel blend (B20) under variable hydrogen flow rates (1 l/min and 2 l/min) was investigated to improve the engine parameters using dual fuel mode of operation. The dual fuel mode of operation increased the brake thermal efficiency from 29.71% for quaternary blend to 32.01% with the addition of 2 l/min hydrogen. In terms of emission, UHC was reduced by 30% and 5% for QB20 + 1 l/m H2 and QB20 + 2 l/m H2, respectively. The maximum of 11% CO emission was reduced by the hydrogen inducted QB20 + 2 l/m H2 blend.

The influence of hydrogen addition for exhaust gas emission in SI gas engine

One of the major problems in internal combustion engines is emission of pollutants with exhaust gases. Those pollutants are not only harmful for environment but also for humans. To decrease emission of pollutants many mechanical and chemical methods are used in internal combustion engines especially in exhaust system such as TWC, DPF, SCR. Alternative way for decrease in exhaust gas pollutants is use of alternative fuel as a primary energy carrier or as an additional fuel for base hydrocarbon one. In this studies the hydrogen was used as a additional fuel to methane. Both fuels were delivered to intake manifold. The share of the fuel was 100/0 methane/hydrogen and 70/30 methane/hydrogen. The addition of hydrogen to base fuel shown decrease of exhaust pollutants from engine and increase in engine operating parameters.

A Study on the Influence of Hydrogen Addition on Combustion and Exhaust Characteristics in a Lean Burn Gas Engine for Power Generation

A Study on the Influence of Hydrogen Addition on Combustion and Exhaust Characteristics in a Lean Burn Gas Engine for Power Generation

Effects of hydrogen addition on nanostructure and reactivity of carbon particles in flame–wall interactions

An experimental study was performed to investigate the influence of hydrogen addition on carbon particles (soot) characteristics in flame–wall interactions through the ethylene jet diffusion impinging flames. Different soot rings were formed on the plate surface when the impinging flames propagated along the plate surface. The nanostructure, oxidation reactivity and other internal properties of inner and outer ring soot were comparably analyzed with the help of high-resolution transmission electron spectroscopy (HRTEM), thermogravimetric analyzer (TGA) and X-ray diffraction (XRD). The results showed that the inner ring soot was the liquid-like material with the amorphous structure. The outer ring soot was composed of primary spherical particles with classic core-shell structures. The increasing addition of hydrogen promoted the disordered extent of inner ring soot with the decrease of fringe length and the increase of fringe tortuosity. It was potentially attributed to the reduction of nucleation rates and the less condensation of PAHs on the particle surface. The degree of graphitization for outer ring soot increased and the opposite trends of fringe length and tortuosity variations were observed when part of ethylene was substituted by hydrogen. It might be due to the higher flame temperature of the post-impingement region which led by the decrease of flame domain contacted to the plate and the enhancement of soot oxidation by increased OH radicals. The oxidation reactivity increased for the inner ring soot and decreased for the outer ring soot with the increasing addition of hydrogen. It also verified the correlation between soot nanostructure and oxidation reactivity that soot with the higher graphitization degree of nanostructure presented the lower oxidation reactivity.

Numerical investigation on adding/substituting hydrogen in the CDC and RCCI combustion in a heavy duty engine

In this paper, the influence of hydrogen addition or substitution on Conventional Diesel Combustion (CDC) and Reactivity Controlled Compression Ignition (RCCI) combustion at 1208 and 1300 rpm on medium load, without exhaust gas recirculation (EGR) in Caterpillar 3401 heavy-duty diesel engine is numerically investigated. Different parameters of the ringing intensity, heat efficiency, heat release, cylinder pressure variations, CO, soot, UHC, NOx and CO2 emissions are studied and compared with and without hydrogen combustion. It results that in CDC at 1208 rpm, if hydrogen is substituted to 40.2% of diesel input energy, the emission of CO, soot, UHC, NOx and CO2 greenhouse will decrease to 98%, 27%, 99%, 13% and 38%, respectively; however, indicated work suffers 1% reduction. On the other hand, in all states of hydrogen addition in CDC at 1208 rpm, all pollutant emissions increase, but, this addition leads to increasing of output work. In the best case when hydrogen is added to diesel by 55% of input energy, work increases by 43%; however, when hydrogen is added over than 55% of input energy, knocking will happen. In RCCI combustion, when hydrogen is added or substituted, instead of methane and diesel respectively, methane combustion will improve and emissions except NOx, will reduce. Hydrogen addition in RCCI combustion at 1300 rpm causes the increment of chamber reactivity, which leading to advance the ignition and hasten the rate of temperature and pressure rise in the chamber. The important result is that the hydrogen substitution more than 11% of input energy for methane, and hydrogen addition more than 60% of input energy for diesel cause knocking phenomenon in RCCI engine. In the final, to make a comprehensive comparison the performance and pollutions of gasoline-diesel, methane-diesel, methane-diesel-hydrogen and diesel-hydrogen combustions in this engine are compared among several studies.

Hydrogen-induced amorphization of Zr-Cu-Ni-Al alloy

Arc melting was utilized in this study to produce Zr55Cu30Ni5Al10 alloys under mixed atmospheres with various ratios of high-purity hydrogen to argon. The influences of hydrogen addition on the solidification structure and glass-forming ability of Zr55Cu30Ni5Al10 alloy were determined by examining microstructures in different parts of the cast ingots. The results showed that different degrees of crystallization structures were obtained in the ascast button ingots after arc melting in high-purity Ar, and the cross-sectional solidification morphology of arcmelted ingots was found to consist of crystals with varying from the bottom up. By contrast, there were completely amorphous structures in the middle and upper areas of the as-cast button ingots fabricated by adding 10% H2 to the high-purity Ar atmosphere. A clear solidification interface was found between the crystal and glass in the ascast button ingots, which indicates that hydrogen addition can enhance the Zr55Cu30Ni5Al10 alloy’s glass-forming ability. The precise mechanism responsible for this was also investigated.

Kinetic analysis of ethanol and dimethyl ether flames with hydrogen addition

The influences of hydrogen addition on laminar premixed ethanol/O2/Ar and DME (dimethyl ether)/O2/Ar flames under fuel-lean (Ф = 0.8) and fuel-rich (Ф = 1.7) conditions at 1.0 atm are studied by the detailed kinetic analysis. The comparisons are conducted to illustrate the characteristics of these two isomers affected by H2 addition. The chemical effects of H2 addition on ethanol and dimethyl ether flames are distinguished and separated from its dilution and thermal effects respectively. The results show that the mole fractions of CH4, C2H6 and CH2O in DME flames are larger than those in ethanol flames. The influences of hydrogen addition on CH4, C2H6 and CH2O in ethanol flames are weakly. The chemical effects of H2 addition promote the production of CH4, C2H6 and CH2O and shift the profiles to the upstream side in DME flames. The dilution and thermal effects which decrease the mole fractions of these species and shift profiles to the downstream side are more dominant for DME flames. Meanwhile, the mole fractions of C2H2, C2H4 and CH3CHO in DME flames are less than those in ethanol flames. The H2 chemical effects which mainly promote the formation of C2H2 and C2H4 in ethanol flames suppress the production of these species in DME flames slightly for the fuel-rich condition. The dilution and thermal effects of hydrogen on these species are more dominant in ethanol flames than those in DME flames.

Experimental investigations of the hydrogen addition effects on diesel engine performance

In the global content regarding the impact on the environmental of the gases emissions resulted from the fossil fuels combustion, an interest aspect discussed on the 21st Session of the Conference of the Parties from the 2015 Paris Climate Conference and the gradual diminution of the worldwide oil reserves contribute to the necessity of searching of alternative energy from durable and renewable resources. At the use of hydrogen as addition in air to diesel engine, the level of CO, HC and smoke from the exhaust gases will decrease due to the improvement of the combustion process. At low and medium partial loads and low hydrogen energetic ratios used the NOX emission level can decrease comparative to classic diesel engine. The hydrogen use as fuel for diesel engine leads to the improving of the energetic and emissions performance of the engine due to combustion improvement and reduction of carbon content. The paper presents, in a comparative way, results of the experimental researches carried on a truck compression ignition engine fuelled with diesel fuel and with hydrogen diesel fuel and hydrogen as addition in air at different engine operation regimes. The results obtained during experimental investigations show better energetic and pollution performance of the engine fuelled with hydrogen as addition in air comparative to classic engine. The influences of hydrogen addition on engine operation are shown.

On the effects of hydrogen addition in premixed formaldehyde flames

The influences of hydrogen addition on laminar premixed fuel-rich formaldehyde flames at the atmospheric pressure are studied by the detailed kinetic analysis. The chemical effects of hydrogen addition on flame structures, mole fractions of major species and free radicals are distinguished clearly from the dilution and thermal effects. The results show that the H2 chemical effects can promote the oxidation of formaldehyde and make the mole fraction profile of formaldehyde move toward the upstream side. The increase of H radical concentration is mainly due to the chemical effects of hydrogen addition. The reaction OH + H2 = H + H2O plays a major role in the productions of H and OH radicals. The productions of O, HCO and HO2 radicals are enhanced by the H2 chemical effects. However, the hydrogen dilution and thermal effects on decreasing these radicals' concentrations are more dominant. The mole fractions of CO and CO2 decrease with H2 addition. The H2 chemical effects facilitate the formation of CO, but suppress the production of CO2.

Combustion characteristics of primary reference fuels with hydrogen addition

The influences of hydrogen addition on laminar premixed fuel-rich primary reference fuels flames at atmospheric pressure are studied by the detailed kinetic analysis. The chemical effects of hydrogen addition on important intermediate species including radicals are distinguished clearly from the dilution and thermal effects. The results show that the increase of the percent of iso-octane in primary reference fuels makes the mole fractions of CH2O and C2H2 reduce but facilitates the production of C3H3. The dilution and thermal effects of hydrogen can suppress the formation of H, O, and OH radicals and CH2O, C2H2 and C3H3 species, and make the profiles shift to the downstream side. The hydrogen chemical effects can promote the formations of these radicals and intermediate species. The H2 chemical effects on H radical are larger than those on O and OH radicals. The dilution and thermal effects are dominant and the overall mole fractions of H, O, and OH radicals, and CH2O, C2H2 and C3H3 species decrease with the hydrogen addition. Finally, the detailed consumption pathways of primary reference fuels combustion with various levels of hydrogen additions are analyzed.