Hydrogen Direct Injection Research Articles

Time-averaged heat transfer correlation for direct injection hydrogen fueled engine

This paper presents the development of an empirical correlation for the prediction of time-averaged heat transfer for a direct-injection hydrogen fueled engine. Computer simulation based on one-dimensional gas dynamics approach was used to perform the time-averaged analysis for the in-cylinder heat transfer. Simulation was performed for 1800 ≤ rpm ≤ 5000, 0.2 ≤ φ ≤ 1.2 and 130 deg before top dead center (BTDC) ≤ SOI ≤ 70 deg BTDC. Experimental measurements were used to verify the developed model, during which the engine performance could be determined to a reasonable accuracy of 10%. The equivalence ratio (φ) was considered as a governing variable, through the new correlation for the time-averaged heat transfer. A nonlinear regression approach was used to develop the new correlations. In the case of all the simulation data, the proposed correlations have a satisfactory performance with the determination coefficient (R2) of about 0.99. A relative error of 10% was found in more than 95% of the simulation data. However, the relative error was reduced to about 50% in the newly developed correlations, which increased its reliability to more than the Taylor's correlation for representing the actual data. Due to the general form, hydrocarbon fuel is suitable for the newly developed correlations that are theoretically made.

Jet-guided combustion characteristics and local fuel concentration measurements in a hydrogen direct-injection spark-ignition engine

Spark-ignition (SI) hydrogen engines based on direct injection (DI) promise significant advantages in terms of thermal efficiency and power output, and present a means of overcoming problems related to knocking, backfiring, and preignition. A better understanding of the effects of hydrogen jets on the fuel concentration distribution and mixing process in a DISI engine should provide new and useful insights into combustion optimization. The objective of the present work was to gain a deeper comprehension of the characteristics of late-injection hydrogen combustion. An experimental combustion setup was applied to a fired, jet-guided DISI engine operated at 600rpm in stratified mode. GDI injector with the jet directed toward the spark plug was used to develop the stratified combustion concept. A high-speed camera synchronized with the spark was focused on a 52mm-diameter field of view through a window at the bottom of the piston crown. A series of single-shot images captured at different intervals was used to study the time evolution of the flame distribution. Variations in the fuel injection timing relative ignition timing were found to impact the development of the early flame, as well as the flame propagation. This research also employed spark-induced breakdown spectroscopy (SIBS) to measure the local fuel–air concentration in the spark gap at the time of ignition under stratified-charge conditions.

A Hydrogen Direct Injection Engine Concept that Exceeds U.S. DOE Light-Duty Efficiency Targets

A Hydrogen Direct Injection Engine Concept that Exceeds U.S. DOE Light-Duty Efficiency Targets

Three-dimensional computational fluid dynamics simulation of hydrogen engines using a turbulent flame speed closure combustion model

The mixture formation and combustion process of a hydrogen direct-injection internal combustion engine is computed using a modified version of a commercial three-dimensional computational fluid dynamics code. The aim of the work is the evaluation of hydrogen laminar flame speed correlations and turbulent flame speed closures with respect to combustion of premixed and stratified mixtures at various levels of air-to-fuel equivalence ratio. Heat-release rates derived from in-cylinder pressure traces are used for the validation of the combustion simulations. A turbulent combustion model with closures for a turbulent flame speed is investigated. The value of the computed heat-release rates mainly depends on the quality of laminar burning velocities and standard of turbulence quantities provided to the combustion model. Combustion simulations performed with experimentally derived laminar flame speed data give better results than those using laminar flame speeds obtained from a kinetic scheme. However, experimental data of hydrogen laminar flame speeds found in the literature are limited regarding the range of pressures, temperatures and air-to-fuel equivalence ratios, and do not comply with the demand of high-pressure engine-relevant conditions.

Controlled autoignition of hydrogen in a direct-injection optical engine

Research into novel internal combustion engines requires consideration of the diversity in future fuels in an attempt to reduce drastically CO2 emissions from vehicles and promote energy sustainability. Hydrogen has been proposed as a possible fuel for future internal combustion engines and can be produced from renewable sources. Hydrogen’s wide flammability range allows higher engine efficiency than conventional fuels with both reduced toxic emissions and no CO2 gases. Most previous work on hydrogen engines has focused on spark-ignition operation. The current paper presents results from an optical study of controlled autoignition (or homogeneous charge compression ignition) of hydrogen in an engine of latest spark-ignition pentroof combustion chamber geometry with direct injection of hydrogen (100bar). This was achieved by a combination of inlet air preheating in the range 200–400°C and residual gas recirculated internally by negative valve overlap. Hydrogen fuelling was set to various values of equivalence ratio, typically in the range ϕ=0.40–0.63. Crank-angle resolved flame chemiluminescence images were acquired for a series of consecutive cycles at 1000RPM in order to calculate in-cylinder rates of flame expansion and motion. Planar Laser Induced Fluorescence (LIF) of OH was also applied to record more detailed features of the autoignition pattern. Single and double (i.e. ‘split’ per cycle) hydrogen injection strategies were employed in order to identify the effect of mixture preparation on autoignition’s timing and spatial development. An attempt was also made to review relevant in-cylinder phenomena from the limited literature on hydrogen-fuelled spark-ignition optical engines and make comparisons were appropriate.

DEVELOPMENT OF HYDROGEN POWER PLANT OF A NEW GENERATION

The article considers the possibility of usage of alternative fuels based on hydrogen. The authors performed the analysis of the advantages and problems of hydrogen fuel usage, and considered the concept of an engine with direct injection of hydrogen into the cylinder, efficiency and environmental friendliness.

Effect of hydrogen enriched air on the performance and emissions of mahua oil fuelled diesel engine

Neat vegetable oils as fuels for diesel engines give rise to engine performance and durability problems due to the differences in some of the properties between vegetable oils and diesel. The objective of the present work was to improve the performance of mahua oil fuelled diesel engine using hydrogen enriched air. Mahua oil was used as the main fuel in a direct injection diesel engine and hydrogen enriched air was supplied at different flow rates through a gas carburetor. The performance and emission parameters of the dual fuel engine were studied at different loads and compared with corresponding base line diesel and mahua oil fuelled operating conditions. Mahua oil combustion with varying quantities of hydrogen (10 lpm, 20 lpm, 30 lpm, 40 lpm and 50 lpm) enriched air resulted in improvement in brake thermal efficiency and reduction in smoke density. The maximum thermal efficiency was recorded at 40 lpm hydrogen enrichment. Hydrogen enrichment was found to increase the combustion rate of mahua oil. The NO X concentration was higher for mahua oil operation with hydrogen enrichment; but lower than diesel.

Optimization of Hydrogen Jet Configuration by Single Hole Nozzle and High Speed Laser Shadowgraphy in High Pressure Direct Injection Hydrogen Engines

Optimization of Hydrogen Jet Configuration by Single Hole Nozzle and High Speed Laser Shadowgraphy in High Pressure Direct Injection Hydrogen Engines

過濃混合気塊点火燃焼による高圧筒内直接噴射水素エンジンのNOx生成低減に関する研究

過濃混合気塊点火燃焼による高圧筒内直接噴射水素エンジンのNOx生成低減に関する研究

A Study on Hydrogen Jet Configuration and Flame Propagation by Shadowgraphic Visualization in High Pressure Direct Injection Hydrogen Engines

A Study on Hydrogen Jet Configuration and Flame Propagation by Shadowgraphic Visualization in High Pressure Direct Injection Hydrogen Engines

Mixture Formation in Direct Injection Hydrogen Engines: CFD and Optical Analysis of Single- and Multi-Hole Nozzles

Mixture Formation in Direct Injection Hydrogen Engines: CFD and Optical Analysis of Single- and Multi-Hole Nozzles

Influence of injection strategy in a high-efficiency hydrogen direct injection engine

Influence of injection strategy in a high-efficiency hydrogen direct injection engine

High-Pressure Hydrogen Jet and Combustion Characteristics in a Direct-Injection Hydrogen Engine

High-Pressure Hydrogen Jet and Combustion Characteristics in a Direct-Injection Hydrogen Engine

Degradation of Silicon Nitride Glow Plugs in Various Environments. Part 2: Gas Burner Rig

In the development of advanced natural gas and hydrogen direct injection combustion engines, a challenge is providing reliable hot‐surface (glow plug, GP) ignition systems; most promising are GPs with silicon nitride‐based heaters. This paper presents experimental results of accelerated degradation tests of the GPs on natural gas‐burning rig, continuing previously published results on GP degradation in air. Degradation, ultimately leading to GP failure, occurs through the synergistic effects of electric field and chemical reactions in the combustion environment. The resulting microstructural modifications of the ceramic heater, studied by SEM/EDS, are a combination of sintering additive ions migration and surface oxidation.

Direct injection of hydrogen, oxygen and water in a novel two stroke engine

This short communication proposes novel two stroke engine burning hydrogen in oxygen in presence of large amounts of steam as residual gases. This engine has a bowl-in-piston combustion chamber, exhaust valves only and it uses direct injection of hydrogen, oxygen and water. Diesel-like compression ignition combustion is achieved by injecting the oxygen and the hydrogen in the surrounding steam close to a continuously operated glow plug. The operation of the engine is simulated by commercial softwares. The water injection enables acceptable metal temperatures and reduced heat losses. First computational results show brake efficiencies above 55% achieved with mass of water injected about twice the mass of oxygen and hydrogen mixture and operation with a significant amount of exhaust gas recirculation. It seems reasonable to guess efficiencies of the fully optimised and developed engine approaching the 60% mark, 20% higher than those of the state-of-the-art H 2ICEs designed for operation with air using the spark-ignition engine concept as well as of those projected for Diesel engines operating with exhaust energy recovery. Worth of mention is also the much higher power density following the two stroke operation.

Degradation of Silicon Nitride Glow Plugs in Various Environments Part 1: dc Electric Field in Ambient Air

All-ceramic glow plugs (GP) based on sintered-silicon nitride are evaluated as hot surface ignition systems for natural gas and hydrogen direct injection combustion engines. This paper presents experimental results of the accelerated degradation tests of the GPs in air, wherein GP is heated solely by dc electricity. The complex degradation process has been linked mostly to the redistribution of the sintering additives in Si3N4/Yb2O3 system under an influence of dc electric field and temperatures over 1300°C, as experienced by GP in-service. Ytterbium ions migration varies with time, temperature, and voltage. The microstructural damage was studied primarily by SEM microscopy.

Fundamental Characteristics of Ignition-Combustion of Rich Mixture Plume in High Pressure Direct Injection Hydrogen Engines

Fundamental Characteristics of Ignition-Combustion of Rich Mixture Plume in High Pressure Direct Injection Hydrogen Engines

Performance comparison between hydrogen and gasoline fuelled S.I. engine

Due to its combustion properties, the hydrogen has a great potential in energetic improvement and emission performance of spark ignition (SI) engine. In this respect, the paper presents comparative results of the experimental researches carried on SI single cylinder engine fuelled with gasoline or only hydrogen, at some engine speeds and full load. Direct injection hydrogen fuelled engine power is greater with almost 30% comparative to gasoline engine due to cycle heat release increasing. The hydrogen direct injection method in the engine cylinder at the beginning of the compression stroke after the intake valve closed has been chosen to avoid reducing the power output per litre. Using this fuelling method was possible to avoid the uncontrolled burning process for all engine operating regimes. Hydrogen supply system used is original and offers great flexibility in operation to establish the adjustments. The obtained results show that the engine fuelled with hydrogen offers the possibility of qualitative load adjustment using for the engine performance improvement especially at partial loads. The paper presents a strategy for combining qualitative and quantitative setting adjustment in order to optimize engine operation at all regimens.

High-pressure hydrogen materials compatibility of piezoelectric films

Hydrogen is well known for materials compatibility issues, including blistering and embrittlement in metals, which are challenges for its use as the next-generation “green” fuel. Beyond metals, hydrogen also degrades piezoelectric materials used as actuators used in direct injection hydrogen internal combustion engines. We present the materials compatibility studies of piezoelectric films in high-pressure hydrogen environments. Absorption of high-pressure hydrogen and composition changes were studied with an elastic recoil detection analysis and Rutherford back-scattering spectrometry in lead zirconate titanate and barium titanate thin films. Hydrogen surface degradation in the form of blistering and Pb mixing was also observed.

Engine performance and optimum injection timing for 4-cylinder direct injection hydrogen fueled engine

This paper presents the engine performance and optimum injection timing for 4-cylinder direct injection hydrogen fueled engine. The 4-cylinder direct injection hydrogen engine model was developed utilizing the GT-Power commercial software. This model employed one dimensional gas dynamics to represent the flow and heat transfer in the components of engine model. Sequential pulse injectors are adopted to inject hydrogen gas fuel within the compression stroke. Injection timing was varied from 110° before top dead center (BTDC) until top dead center (TDC) timing. Engine speed was varied from 2000 rpm to 6000 rpm, while the equivalence ratio was varied from 0.2 to 1.0. The validation was performed with the existing previous experimental results. The negative effects of the interaction between ignition timing and injection duration was highlighted and clarified. The results showed that optimum injection timing and engine performance are related strongly to the air fuel ratio and engine speed. The acquired results show that the air fuel ratio and engine speed are strongly influence on the optimum injection timing and engine performance. It can be seen that the indicated efficiency increases with increases of AFR while decreases of engine speed. The power and torque increases with the decreases of AFR and engine speed. The indicated specific fuel consumption (ISFC) decreases with increases of AFR from rich conditions to lean while decreases of engine speed. The injection timing of 60° BTDC was the overall optimum injection timing with a compromise.