Hydrogen Fueled Spark Ignition Engine Research Articles

A combined experimental and numerical study of thermal processes, performance and nitric oxide emissions in a hydrogen-fueled spark-ignition engine

This work concerns the study of a spark-ignition engine fueled with hydrogen, using both measured and numerical data at various conditions, focusing on the combustion efficiency, the heat transfer phenomena and heat loss to the cylinder walls, the performance, as well as the nitric oxide (NO) emissions formed, when the fuel/air and compression ratio are varied. For the investigation of the heat transfer mechanism, the local wall temperatures and heat flux rates were measured at three locations of the cylinder liner in a CFR engine. These fluxes can provide a reliable estimation of the total heat loss through the cylinder walls and of the hydrogen flame arrival at specific locations. Together with the experimental analysis, the numerical results obtained from a validated in-house CFD code were utilized for gaining a more complete view of the heat transfer mechanism and the hydrogen combustion efficiency for the various cases examined. The performance of the CFR engine is then identified, since the calculated cylinder pressures are compared with the measured ones, from which performance and heat release rates are calculated and discussed. Further, NO emission studies have been accomplished, with the calculated results not only being compared with the measured exhaust NO ones, but also further processed for conducting an in-depth investigation of the dependence of NO production on the spatial distribution of in-cylinder gas temperature. It is revealed that for lower fuel/air ratio the burned gas temperature is held at low level and the heat loss ratio is quite low. As the load increases and stoichiometric mixtures are used, the wall and in-cylinder gas temperatures increase substantially, together with the heat loss and the NO emissions, owing to the high hydrogen combustion velocity and the consequent high rate of temperature rise. The combustion efficiency is slightly increased, but the indicated efficiency is decreased due to higher heat loss.

Second law analysis of hydrogen–air combustion in a spark ignition engine

Besides its renewable nature and low emission advantage, hydrogen has higher exergetic efficiency of combustion compared to hydrocarbon fuels. This makes it an attractive alternative fuel for internal combustion engines. The present work concerns the estimation of irreversibilities associated with various sub-processes occurring during combustion in a hydrogen fueled spark ignition engine. A quasi-three zone phenomenological combustion model is used for predicting the pressure and temperature histories of a single cylinder, four stroke spark ignition engine operating at equivalence ratios of 0.3–0.75 in the speed range 1500–3500 rpm. For each sub-process, the history of availability destruction during combustion and the effects of operating conditions are discussed. Measures are proposed for improving the exergetic efficiency by mitigating availability destruction. It is observed that chemical reaction is the major contributor to irreversibility generation, followed by pressure equilibration and heat loss to walls. While more than 94% of the fuel supplied undergoes combustion, nearly 20–30% of the reactant availability is destroyed. Charge preheating, product mixing and piston motion are observed to have negligible effects on irreversibility generation.

Theoretical and experimental validation of hydrogen fueled spark ignition engine

In modern research, simulation has become a powerful tool as it saves time and also economical when compared to experimental study. This paper deals with a comprehensive model of a spark ignition hydrogen fueled engine. Woschni's heat transfer co-relation is used by this model for predicting the heat transfer in the engine. Two zone combustion model has been opted for simulating the combustion process. Two zone models account for the combustion chamber geometry and for the presence of burnt and unburnt gases. The results are compared with the experimental data and it is found that there was a good convergence of results. The engine efficiency and power has been slightly over predicted because dissociation has not been included in the model.

FL1-3: A Two-Zone Thermodynamic Model for Hydrogen-Fueled S.I. Engines(FL: Fuels and Lubricants,General Session Papers)

Because of significantly different physical and chemical properties of hydrogen, compared to hydrocarbons, running an engine on hydrogen or modeling the combustion of hydrogen in engines is not straightforward. This paper focuses on modeling the power cycle of a hydrogen-fueled spark-ignition engine. The authors have investigated the laminar burning velocity u_1 of hydrogen/air mixtures, with allowance for residuals, as this is a fundamental parameter in turbulent burning velocity models. The correlation for u_1 was evaluated in a quasi-dimensional engine code by a comparison to experimental data on a single cylinder hydrogen engine. A two-equation combustion model was used to allow for flame brush thickness effects. Several models for the turbulent burning velocity were used to provide values for the turbulent 'entrainment' velocity. All models were able to correctly predict the effects of varying compression ratio and ignition timing. The ability to recover the effects of changes in equivalence ratio, one of the features in which a hydrogen engine differs clearly from hydrocarbon-fueled engines, is shown to be the benchmark to distinguish between models.

Hydrogen fueled spark ignition engine with electronically controlled manifold injection: An experimental study

In this work, a single cylinder conventional spark ignition engine was converted to operate with hydrogen using the timed manifold fuel injection technique. A solenoid operated gas injector was used to inject hydrogen into the inlet manifold at the specified time. A dedicated electronic circuit developed for this work was used to control the injection timing and duration. The spark timing was set to minimum advance for best torque (MBT). The engine was operated at the wide-open throttle condition. For comparison of results, the same engine was also run on gasoline. The performance and emission characteristics with hydrogen and gasoline are compared. From the results, it is found that there is a reduction of about 20% in the peak power output of the engine when operating with hydrogen. The brake thermal efficiency with hydrogen is about 2% greater than that of gasoline. A lean limit equivalence ratio of about 0.3 could be attained with hydrogen as compared to 0.83 with gasoline. CO, CO 2 and HC emissions were negligible with hydrogen operation. However, for hydrogen operation, NO x emission was four times higher than that of gasoline at full load power. The best ignition timing for hydrogen was much retarded when compared to gasoline. The effect of hydrogen injection pressure was also studied and no specific changes were observed. The effect of operating speed was also studied.

Intake charge dilution effects on control of nitric oxide emission in a hydrogen fueled SI engine

Though hydrogen fueled spark ignition engine can operate at high thermal efficiency with almost zero emission of HC and CO, the high level of NO x poses problems. The high combustion temperature and lean mixtures used are the reasons. In this work, the effect of N 2 , CO 2 and hot EGR gas as diluents in the intake charge to suppress NO emission in a manifold injected hydrogen fueled SI engine was studied. Nitrogen as a diluent is not so effective at low loads while inducting smaller amounts, but very effective at higher loads where the mixture becomes richer and the dilution effect (oxygen depletion) is significant. On other hand, carbon dioxide is a good diluent with relatively better thermal effect and diluent effect and effectively controls NO emission at all output regions. However this is at the expense of thermal efficiency. Recirculating hot exhaust gas which contains both N 2 and steam comes in between N 2 and CO 2 in terms of its effectiveness. On the whole N 2 is the most effective as it has minimum impact on thermal efficiency for a given level of permissible NO emission. Thus it is felt that cold EGR could be a good option. In all cases, a good control system is necessary to supply correct quantity of diluent.

An experimental study on performance and emission characteristics of a hydrogen fuelled spark ignition engine

In the present paper, the performance and emission characteristics of a conventional four cylinder spark ignition (SI) engine operated on hydrogen and gasoline are investigated experimentally. The compressed hydrogen at 20 MPa has been introduced to the engine adopted to operate on gaseous hydrogen by external mixing. Two regulators have been used to drop the pressure first to 300 kPa, then to atmospheric pressure. The variations of torque, power, brake thermal efficiency, brake mean effective pressure, exhaust gas temperature, and emissions of NO x , CO, CO 2 , HC, and O 2 versus engine speed are compared for a carbureted SI engine operating on gasoline and hydrogen. Energy analysis also has studied for comparison purpose. The test results have been demonstrated that power loss occurs at low speed hydrogen operation whereas high speed characteristics compete well with gasoline operation. Fast burning characteristics of hydrogen have permitted high speed engine operation. Less heat loss has occurred for hydrogen than gasoline. NO x emission of hydrogen fuelled engine is about 10 times lower than gasoline fuelled engine. Finally, both first and second law efficiencies have improved with hydrogen fuelled engine compared to gasoline engine. It has been proved that hydrogen is a very good candidate as an engine fuel. The obtained data are also very useful for operational changes needed to optimize the hydrogen fueled SI engine design.

Development of a pre-ignition submodel for hydrogen engines

In hydrogen-fuelled spark ignition engine applications, the onset of pre-ignition remains one of the prime limitations that needs to be addressed to avoid its incidence and achieve superior performance. This paper describes a new pre-ignition submodel for engine modelling codes. The effects of changes in key operating variables, such as compression ratio, spark timing, intake pressure, and temperature on pre-ignition limiting equivalence ratios are established both analytically and experimentally. With the established pre-ignition model, it is possible not only to investigate whether pre-ignition is observed with changing operating and design parameters, but also to evaluate those parameters' effects on the maximum possible pre-ignition intensity.

Thermophysical Properties of Working Fluid and Heat Transfer in a Hydrogen Combustion Engine

A larger burning velocity and a shorter quenching distance for hydrogen as compared with hydrocarbons bring a higher degree of constant volume and a larger cooling loss from burning gas to the combustion chamber wall in internal combustion engines. Because of the large cooling loss, the reduction of the cooling loss are crucial for improving the thermal efficiency in hydrogen combustion engines. Empirical correlation for total heat transfer from burning gas to the combustion chamber walls are often used to calculate the cooling loss. However, previous research by the authors has shown that the widely used heat transfer correlation reported by Woschni cannot be properly applied to the hydrogen combustion. For this background, this research analyzes the relationship between characteristics of thermophysical properties of working fluid and heat transfer to the wall in a hydrogen-fueled spark-ignition engine.

Combustion Analysis in a Hydrogen-Fueled Engine with Indicator Diagram.

Hydrogen has higher burning velocity and shorter quenching distance than hydrocarbons, and combustion characteristics of hydrogen in internal combustion engines are different from hydrocarbons. Authors have reported influencing factors to thermal efficiency in a hydrogen fueled spark ignition engine, and shown that heat release rate is very important in the thermal efficiency analysis. Error factors in calculation of heat release rate were analyzed in this research. Results show that hydrogen combustion with higher burning velocity than hydrocarbons has faster change in specific heat during combustion period, and it is better to include the term of dk/dθ especially in evaluation of cooling loss ratio. Influences of coolant temperature and engine speed on thermal efficiency were also analyzed in this research.

Performance evaluation of a hydrogen-fuelled spark ignition engine using electronically controlled solenoid-actuated injection system

This paper discusses the development of an electronically controlled gas injection system for a hydrogen-fuelled spark ignition engine. In view of its typical combustion characteristics the mode of fuelling plays a critical role for practical operation of a hydrogen engine. The system developed should have adequate flexibility to provide the appropriate mixture into the engine at the appropriate point in the engine cycle operation. The present work describes in detail the design considerations of an electronically controlled solenoid actuated injection system. Conditions leading to smooth operation of the engine could be achieved without any problem of backfire, knocking or rapid rate of pressure rise. The performance and emission characteristics of the engine were determined under various operating conditions.

A computer simulation of hydrogen fueled spark ignition engine

The work reported here pertains to some of the computer simulation models developed for hydrogen fueled spark ignition (SI) engines. The engine combustion process is modeled by using a semi-empirical turbulent flame speed expression. This combustion model has been employed to account for the hydrogen-air combustion process over a wide range of stoichiometric variables for the Varimax engine operating at various speeds and compression ratios. Based on the computed results, graphs showing the variation of combustion crank angle and flame speed with fuel-air equivalence ratio, engine speed, compression ratio etc., have been plotted.

Performance and emission characteristics of hydrogen fueled spark ignition engine

A study of alternate fuels leads to hydrogen as a candidate fuel for the future. Its remarkable properties provide the potential of high thermal efficiency at part load by operating the engine unthrottled with lean mixtures. The problems of pre-ignition and backfiring could be overcome at a wide range of operation by providing a cold spark plug with a narrow gap and by keeping combustion chamber walls clean. Hydrogen operation of spark-ignited engines has been found to be very profitable at low equivalence ratios both from the point of view of increased thermal efficiency and reduced nitrogen oxides emissions.

Lean limit emissions of hydrogen-fueled engines

The use of quality governing to regulate the power output of hydrogen-fueled spark ignition engines provides a significant efficiency advantage over conventional throttled engines for operation at light loads. In many cases, it is even possible to have an engine idle without throttling by operating with a very lean mixture. However, as the lean limit of combustion is approached, incomplete combustion results in the emission of hydrogen peroxide and unburned hydrogen. These emissions are undesirable since unburned hydrogen is simply wasted fuel and hydrogen peroxide released into the atmosphere is a source of hydroxyl radicals which catalyze the production of photochemical smog. Unburned hydrogen and hydrogen peroxide emissions have been measured as a function of equivalence ratio for a four-cylinder hydrogen-fueled engine. The results indicate that the engine should not be operated with an equivalence ratio below about 0.4 to minimize these emissions. Thus, some throttling will be required at idle and very low power outputs. It was also determined that hydrogen peroxide emissions were drastically reduced by passage through a complete standard exhaust system, most likely by decomposition on the metal walls. Thus, for reasonably small values of hydrogen peroxide emissions, appropriate exhaust system design could reduce these emissions to negligible levels.

Performance and NOxEmissions of Spark Ignited Combustion Engines Using Alternative Fuels—Quasi One-Dimensional Modeling I. Hydrogen Fueled Engines

Abstract Hydrogen and methanol have been suggested as potential non-petroleum derived substitutes for current reciprocating engine fuels. The present paper reports the results of a computer simulation of the performance and NOx emissions of hydrogen fueled spark ignition engines. The engine combustion process is modeled by employing a semi-empirical turbulent flame speed expression. The NOx emissions are determined by integrating the chemical rate equations resulting from the extended Zeldovich mechanism over the boundary conditions determined by the cycle analysis. Hydrogen exhibits very rapid burning rates and the resulting high pressures and temperatures lead to fast NO formation and destruction rates. Maximum NO emissions are predicted for lean mixtures near φ = 0.8 in agreement with experimental observations. For richer mixtures rapid decomposition of NO during the expansion stroke lowers exhaust emissions. NOx control by exhaust gas recirculation is much more effective in lean mixtures than in stoic...