Introduction of Abnormal Combustion in Hydrogen Internal Combustion Engines and the Detection Method

As a clean, environmentally friendly and renewable energy source, hydrogen as an alternative engine fuel can greatly reduce atmospheric pollution and alleviate the shortage of oil resources, and is the most promising alternative fuel for vehicles among new fuels. However, due to its fast combustion rate and wide ignition limit, hydrogen often shows abnormal combustion phenomena (such as pre-ignition, backfire and knock), when it is used in the engine, thus affecting the performance and normal use of engines. In this paper, the advantages and disadvantages of hydrogen as an alternative fuel for the engine are summarized according to the characteristics of hydrogen. On this basis, the mechanism, influence factors and harm of abnormal combustion in the hydrogen internal combustion engine are analyzed and summarized, which provides a theoretical basis for solving abnormal combustion problems. Finally, several commonly used abnormal combustion detection methods are summarized.Citation: Liu, J. (2022). Introduction of Abnormal Combustion in Hydrogen Internal Combustion Engines and the Detection Method. Trends in Renewable Energy, 8, 38-48. DOI: 10.17737/tre.2022.8.1.0013

Modeling and experimental analysis of exhaust gas temperature and misfire in a converted-diesel homogeneous charge compression ignittion engine fuelled with ethanol

Homogeneous charge compression ignition (HCCI) and the exploitation of ethanol as an alternative fuel is one way to explore new frontiers of internal combustion engines with an objective towards maintaining its sustainability. Here, a 0.3 liter singlecylinder direct-injection diesel engine was converted to operate on the alternative mode with the inclusion of ethanol fuelling and intake air preheating systems. The main HCCI engines parameters such as indicated mean effective pressure, maximum in-cylinder pressure, heat release, in-cylinder temperature and combustion parameters, start of combustion, 50% of mass fuel burnt (CA50) and burn duration were acquired for 100 operating conditions. They were used to study the effect of varying input parameters such as equivalence ratio and intake air temperature on exhaust gas emission, temperature and ethanol combustion, experimentally and numerically. The study primarily focused on HCCI exhaust gas temperature and understanding and detecting misfire in an ethanol fuelled HCCI engine, thus highlighting the advantages and drawbacks of using ethanol fuelled HCCI. The analysis of experimental data was used to understand how misfire affects HCCI engine operation. A model-based misfire detection technique was developed for HCCI engines and the validity of the obtained model was then verified with experimental data for a wide range of misfire and normal operating conditions. The misfire detection is computationally efficient and it can be readily used to detect misfire in HCCI engine. The results of the misfire detection model are very promising from the viewpoints of further controlling and improving combustion in HCCI engines

Combustion, Ionization And Sporadic Pre-Ignition In A Turbocharged Gasoline Direct Injection Engine.

This research is focused on the use of ionization of combustion products in hydrocarbons-air flames to gain a better understanding of the combustion process in turbocharged gasoline direct injection engines. A GM 2.0 L Ecotec GDI-T engine is used in this investigation. The ion current is measured simultaneously by two in-cylinder combustion sensors: the spark plug and the fuel injector. The characteristics of the ion current signals produced by the two sensors are analyzed and correlated with the characteristics of the rate of heat release computed from the cylinder gas pressure. Since this is the first time for the fuel injector to be used as an ion current sensor, it was possible to determine many features of combustion in the engine which could not be determined from the spark plug signal. For example, the phase shift between the two ion current signals was used to determine the burning velocity. The results are compared with the burning velocity measured in optically accessible port injected engine in which high speed imaging techniques were used. In addition, it was possible to investigate the impact of the burning velocity on the indicated thermal efficiency and indicated mean effective pressure at different speeds and loads. Also, this research included the use of the two ion current signals for the feedback closed loop control of the engine. The engine was able to consistently operate on MBT 208 (Maximum Brake Torque) point by adjusting the ignition and injection timings. In addition, engine knock was detected and controlled by retarding ignition timing using the ion current signals. The findings from the experimental investigations are supported by a 3D gasoline cycle simulation of combustion and the ion current produced at the locations of the spark plug and the injector. The research in progress that will be documented in the dissertation will include a detailed analysis of the factors that contribute to combustion instability and cycle-to-cycle variations. Finally, combustion ionization will be used to investigate the low speed sporadic pre-ignition phenomenon (LSPI) which is currently limiting the progress toward higher power density and more efficient turbocharged gasoline engines

Evaluation of facilities performance on students’ satisfaction in Northern Nigerian Universities

Performance evaluation of academic facilities of HEIs is very critical to educational effectiveness. Presently, there is limited or no research/data in Nigeria to assess how extensively the use of or lack of academic facilities benchmarking practices. The aim of this research was to develop a facilities performance framework for HEIs academic facilities in order to serve as a reference model for policy makers while designing HEIs facilities standard targeted towards improving facilities performance for enhanced student satisfaction. Quantitative research approach using survey design was adopted. Data was collected using closed-ended questionnaires distributed to a sample of 1000 student randomly selected from three universities in the northern Nigeria out of which 735 were considered valid for the analysis. Research questions were answered by testing the proposed research hypothesis which were developed for the research. The descriptive analyses were conducted using the Statistical Package for Social Science Software (SPSS version 23) while the inferential statistics were analyzed using a Partial Least Squares Structural Equation Modelling software (SmartPLS version 3.0). Overall, the result found that facilities performance significantly influenced student satisfaction. The R-square value indicated that performance of the HEIs component facilities explained 63 percent of the variance in students’ satisfaction. Furthermore, it was found that 66.7 percent of the performance of HEIs components facilities was explained by the performance of both physical and non-physical facilities that constitutes the HEIs academic facilities. The implication of this results points to the importance of including students’ feedback in the facilities management aspect of HEIs. This is for the fact that students’satisfaction was shown to be significantly related to the condition of the university facilities. It is recommended that future research should focus on identifying students satisfaction with academic facilities in the HEIs using experience as a measure of facilities performance to promote the concept of best practices benchmarking for the institutions to esterblished quality facilities in their institutions

A study of mixture formation in a lean burn research engine using laser fluorescence imaging

Lean burn in spark-ignition engines offers a significant efficiency advantage compared with stoichiometric operation. The lean operation is restricted by increasing cyclic fluctuation in torque. In order to make use of the efficiency advantage and meet the mandatory emission standards the lean operation limit has to be further extended. This requires particular control of the mixing of fuel and air. To study the effect of mixture formation on cyclic variability and to provide quantitative information on the mixing of air and fuel planar laser-induced fluorescence (PLIF) was developed and applied to an operating SI engine. The method is based on imaging the fluorescence of a fluorescent marker (3-pentanone) mixed with the fuel (iso-octane). 3-pentanone was found to have similar vaporisation characteristics to those of iso-octane as well as low absorption and suitable spectral properties. The technique was applied to an one-cylinder SI engine with a cylinder head configuration based on the Honda VTEC-E lean burn system. The mixture formation process during the inlet and compression stroke could be described by measuring the average fuel concentration in four planes, between 0.7 and 15.2 mm below the spark plug, in a section of the cylinder orthogonal to the cylinder axis. The results showed that for 4-valve pent-roof cylinder head systems with swirl inlet flows, fuel impinging on the cylinder wall opposite to the inlet valves has a major influence on the mixture formation process. In order to quantify the cyclic variability in the mixture formation process and its contribution to cyclic variability in combustion the fuel concentration in a plane near the spark plug was measured on a large number of cycles. It could be shown, that the fuel concentration in a small region close to the spark plug has a dominating effect on the subsequent pressure development for lean mixtures. Variations in the mixture concentration in the vicinity of the spark plug contribute significantly to cyclic variations in combustion. In order to address the issue of nonuniformity in residual gas concentration prior to ignition a laser induced fluorescence method was developed to measure nitric oxide (NO) concentrations in the unburned charge in the same one-cylinder research engine. Measurements of average and instantaneous NO concentrations revealed, that the residual gas is not homogeneously mixed with the air and that significant cyclic variations in the local residual gas concentration exist

Monitoring of the piston ring-pack and cylinder liner interface in diesel engines through acoustic emission measurements

Investigation of novel condition monitoring systems for diesel engines has received much recent attention due to the increasing demands placed upon engine components and the limitations of conventional techniques. This thesis documents experimental research conducted to assess the monitoring capabilities of Acoustic Emission (AE) analysis. In particular it focuses on the possibility of monitoring the piston ring-pack and cylinder liner interface, a critical engine sub-system for which there are currently few practical monitoring options. A series of experiments were performed on large, two-stroke and small, four-stroke diesel engines. Tests under normal operating conditions developed a detailed understanding of typical AE generation in terms of both the source mechanisms and the characteristics of the resulting activity. This was supplemented by specific tests to investigate possible AE generation at the ring-pack/liner interface. For instance, for the small engines measures were taken to remove known AE sources in order to accentuate any activity originating at the interface whilst for the large engines the interfacial conditions were purposely deteriorated through the removal of the lubricating oil supply to one cylinder. Interpretation of the results was based mainly upon comparisons with published work encompassing both the expected ring-pack behaviour and AE generation from tribological processes. This provided a strong indication that the source of the ring-pack/liner AE activity was the boundary frictional losses. The ability to monitor this process may be of significant benefit to engine operators as it enhances the diagnostic information currently available and may be incorporated into predictive maintenance strategies. A further diagnostic technique considered was the possibility of using AE parameters combined with information of crankshaft speed fluctuations to evaluate engine balance and identify underperforming cylinders.EU Competitive and Sustainable Growth Programme, Project no: GRD2-2001-5001

Experimental assessment of a methodology for the indirect in-cylinder pressure evaluation in four-stroke internal combustion engines

Recent innovations in engine control and diagnostics are providing room for development of innovative combustion approaches (e.g., low-temperature combustion) able to minimize the creation of pollutants. To ensure the constant fulfillment of the prescribed thermodynamic conditions, however, a fast real-time monitoring of the in-cylinder pressure is needed. To this end, dynamic pressure sensors, flush-mounted on the cylinder head, are commonly used. With this approach, the measurement accuracy is high, but the durability is limited by the harsh working conditions. The installation on the cylinder head is also complex. The development of robust and effective indirect measurement systems could then represent the enabler of a further development of this technology. In the present study, an innovative methodology to measure the in-cylinder pressure has been conceived and extensively tested on a four-stroke single-cylinder engine. The proposed approach is based on the analysis of the mechanical stress on the engine studs by means of a piezoelectric strain washer. This solution allows the user for a rapid and cost-effective sensor installation, described in the paper along with the signal post-processing techniques. Results showed good accuracy and robustness of the methodology, making the results of practical use for engine control

Diagnostics Methods and Their Application in Automotive Engine

Import 15/01/2013Gasoline engine is a complex power generating machines and used widely in automotive industry, which the failure rate is high. Carrying out the gasoline engine fault diagnostic methods have been studied and still a lasting topic for scientists. Crankshaft instantaneous angular acceleration contains information for fault diagnostic. It can directly reflect the state of applying work and current pressure in each cylinder. By means of analyzing the angular acceleration signal, the instantaneous engine running state and a lot of related faults can be discovered. Under the normal working conditions, the motive force performance of each cylinder is unanimous basically, the gasoline engine operates steadily. Its angular acceleration always fluctuates in a normal range and presents certain regularity. The operation when a certain cylinder is working abnormally, the consistency of motive force is destroyed, the engine becomes bad to the stationary of operation, and the angular acceleration signal will be out of shape. By observing its fluctuation, the working process in each cylinder can be evaluated. In this thesis, the instantaneous angular acceleration is evaluated by phase modulation method using the Hilbert Transform technique. To verify the signal analysis technique, the engine model created originally by Weeks, RW & Moskwa, J.J. is extended by modeling of the non-uniform driving torque in contrast to the original model assuming uniform driving torque to produce fluctuation of the crankshaft angular acceleration. Many subsystems of the engine are also modeled by the simulation program Matlab/Simulink. Torque of engine at some spark advances was simulated to compare and found out the best angle to obtain the maximum brake torque, as well.Zážehový motor je široce používán v dopravních prostředcích. Jako u každého stroje, i u zážehového motoru mohou vznikat poruchy, které je třeba diagnostikovat. Provedení benzínového motoru a metody diagnosticky poruch byly studovány a jsou stále tématem pro výzkum. Okamžité úhlové zrychlení klikového hřídele poskytuje diagnostické informace o poruchách spalovacího procesu. To se může přímo odrážet na výkonu motoru daném aktuálním spalovacím tlakem v každém válci. Prostřednictvím analýzy signálu úhlového zrychlení, ve stavu kdy motor běží, může být objevena spousta chyb. Za normálních pracovních podmínek jsou hnací síly každého válce v podstatě shodné, zážehový motor pracuje v ustáleném režimu. Jeho úhlové zrychlení vždy kolísá v normálním rozsahu a představuje určitou pravidelnost. Když za provozu některý válec pracuje nepravidelně, je narušen časový průběh krouticího momentu, motor se stane nestabilní ve stacionárním provozu a úhlové zrychlení signálu bude vykazovat odchylky. Tím, že sledujeme kolísání okamžitého úhlového zrychlení, může být vyhodnocen spalovací a kompresní proces individuálně v každém válci zvlášť. V této práci, je hodnoceno okamžité úhlové zrychlení klikového hřídele metodou fázové modulace. Nástrojem k demodulaci je analytický signál, jehož imaginární část je vypočtena pomocí Hilbertovy transformace. Chceme-li ověřit metodu zpracování impulsního signálu pro ECU, použijeme simulační model motoru. První dynamický model vytvořili Week, R.W. a Moskwa, J.J.. Tento model průběžně počítal krouticí moment jako konstantu pro všechny fáze práce motoru. K testování výpočtu okamžitého úhlového zrychlení klikového hřídele bylo třeba modelovat vznik nerovnoměrnosti krouticího momentu při hoření paliva ve válci a kompresi směsi, jako příčiny periodického zrychlování a zpomalování při otáčení kliky na požadovaných otáčkách. Model motoru je rozdělen na subsystémy, které jsou modelovány simulačním programem Matlab / Simulink. Krouticí moment motoru při některých zapalovacích postupech byl pro porovnání simulován a byl hledán nejlepší úhel předstihu zapalování pro dosažení maximálního hnacího momentu.Prezenční352 - Katedra automatizační techniky a řízenívyhově