Recently the Homogeneous charge compression ignition (HCCI) is classified as advanced lean and low-temperature combustion technique for the application of the internal combustion engines due to its potential for high engine thermal efficiency and particularly low emissions of particulate and nitrogen oxides.
HCCI has delegated another critical burning idea which is different than combustion procedure for spark ignition and diesel engine.
This sort of the ignition approach hypothetically combines the advantages of the customary engines; low exhaust emission, and high thermal efficiency.
The HCCI ignition techniques can utilize a variety of the available liquid or gaseous fuels with a little alteration in the original engine fuel system.
In all cases, the ignition process in HCCI engine is begun by many auto-ignition spots to combust the entire in-cylinder lean and homogeneous fuel-air blend all the while.
The comprehension of HCCI ignition idea is not restricted with common besides diesel and gasoline fuel only, but the extraordinary alternative fuel like biofuels, biodiesel, and hydrogen fuels can be utilized,.
The further development and upgrade for the use of the alternative fuels inside the engine cylinder with the Homogeneous Charge Compression Ignition (HCCI) burning procedures accumulate the benefits of the standard Otto cycle with diesel engine rule.
This strategy hypothetically joins the advantages of conventional engines; low crude discharges, and high mileage.
In all cases, the ignition is continuing by the auto-ignition of the lean and homogeneous fuel-air blend.
Recently, concerning examinations with HCCI engines have been discernibly increasing.
Along these lines, the HCCI engine fuel has mixed with the charged air, similar to the gasoline engine at higher air/fuel proportion.
This lean mixture will be ignited naturally because of the compression ignition principal, as in a diesel engine.
In spite of the fact that the scheduling of auto-ignition process is critical to the engine operation; the ignition events is not activated by an external occasion, for example, the beginning of the fuel injection or by the start plug timing.
Besides, the rate at which combustion heat release is not influencing by the fuel injection process, similar to the diesel engine, or by fire spread, as with spark ignition engines.
However, the partially premixed lean charge compression ignition engine can be used as an intermediate stage between the conventional and HCCI engine in order to reduce the NOx and PM emissions, simultaneously.
The essential working rule of HCCI engine at the various working condition, for example, the charge temperature, pressure proportion, and engine speed were assessed.
The outcomes demonstrate that the satisfactory operation of the HCCI engine has extremely limited by the lean charge of the air-fuel mixture and the engine operation has kept away from the stoichiometric condition.
Moreover, the homogeneity of the freshly charged mixture with the residual combusted gasses inside the engine cylinder has been studying.
The inhomogeneities of the charged mixture inside the burning chamber were discovered with the guidance of a stochastic model for the HCCI engine.
The model has been accounted with complete chemical oxidation which comprising from 53 chemical species and 590 elementary reactions.
These days the looking for the nonpetroleum fuels is the principal concern of the worldwide researcher because of the expanding worries on the lack of alternative fuel supplies and environmental contamination.
The alternative fuel, for example, biogas is showing a one of a good kind of the atomic structure.
Those natural gas is the best choice for the application of HCCI engine because of it has highest hydrogen ratio so it can produce a lower percentage of CO2 in the exhaust pipe,.
Currently, the suggested innovative technology for the use of CNG in the HCCI engine is directed toward the use of Compressed Natural Gas (CNG)-Hydrogen blends (HCNG),,.
Those, make the reactivity of fuel amid the ignition procedure is yield less middle of the road segments.
However, the higher Octane number (ON) of the natural gas fuel prescribes it to use in the HCCI engine burning.
In any case, that will guarantee the utilization of the higher compression ratio with no worry about the knock-like combustion which is the principal aim of the HCCI engine performance enhancement.
Also, the fundamental issues of utilizing CNG as a fuel in HCCI engines are the control objective of the auto-ignition timing over an extensive variety of rates and loads, constraining the heat released rate at high load operation, giving smooth operation through quick transient, accomplishing cold start, and meeting emission guidelines.
Concerning CNG issues in an HCCI engine application, a critical research movement has been completed by including DME fuel into the natural gas blend,,.
The engine can work easily over various loads if a little parcel of the DME fuel is included into the CNG HCCI engine,.
However, by finding the ideal measurement of the DME fuel as an added substance to the CNG fuel, the NOx outflow will be decreased in the case of lean air/fuel blend burning.
Furthermore, the best method may use to enhance and control the ignition practices of using CNG in HCCI engine was utilizing hydrogen added substances into the CNG/air blend.
Likewise, other procedures proposed to conquer the snags concerning CNG in HCCI engines.
In which, the exhaust gas fuel changing and Ozone added substances to the natural gas fuel can utilize additionally to enhance and develop the ignition zone of CNG/HCCI engines.
This paper talks about the likelihood of using the alternative gaseous fuels in HCCI engine combustion, utilizing a tri-fuel operation technique.
The issue of using alternative fuels such as CNG, Dimethyl ether, and hydrogen fuels for HCCI engines has developed during the last decades.
This is not associated only with the diminishing petroleum product assets, as well as with the developing worry for the exhaust emission regulations and the battle against an Earth-wide temperature boost.
Also is associated with increasing the possibility of the trigger the charge auto-ignition and controlling the HCCI engine combustion phasing problems.
However, the point of the present work is to explore the impact of a few potential added substances, such as Hydrogen and the Dimethyl ether (DME), on the ignition behaviors of a Natural Gas HCCI engine.
This was done by utilizing hydrogen gas and DME fuel added substances in CNG/HCCI engines to control the start of combustion timing, avoidance of knock, and extension of the working area in such engines.
In our proposed system, hydrogen will expand the working scope of CNG HCCI engine and diminish the regulated emissions significantly, while DME will assume a noteworthy part in controlling the auto-ignition timing of the HCCI ignition, particularly at low admission air temperature.
Finally, the engine operating a range of CNG HCCI engine will be presented as a function of each fuel dose precisely.
By mixing Dimethyl ether (DME) and hydrogen (H2) fuels with Compressed Natural Gas (CNG) it was probably to attain a stable operation of the HCCI engine at different load condition.
By applying a different amount of the Dimethyl ether and hydrogen fuels into the inlet air, it was possible to adjust the engine combustion phasing to avoid the knock-like combustion phenomenon.
By this method, it was achievable to study the connection between the Dimethyl ether and hydrogen fuel additive percentage, the inlet air/fuel quantity and the CNG needed to get auto-ignition close to Top Dead Center (TDC).
Different fuel mixture ratios of CNG, Dimethyl ether and hydrogen fuel have also tested in the same manner.
All examinations were approved at different air/fuel equivalence ratio from 0.15 to 0.50.
The impact of DME and hydrogen fuel added substances into CNG fuel in HCCI engines have predicted numerically and experimentally.
A chemical kinetic mechanism merged with a Zero-Dimensional model have been utilized to calculate the auto-ignition and combustion of CNG/DME fuel blends with the impact of 10 and 20 % of hydrogen mole portion.
The obtained results elucidated that by adding hydrogen into the blends of CNG/DME fuel the engine operation region will be expanding from the knock limit side.
However, if the mixture of CNG/DME fuel containing a small amount of hydrogen the ignition will be retarding rather than that without hydrogen.
As engine load increases, the required CNG amount in the mixture blends to meet the necessity of knocking and misfire restrictions will be expanded.
Besides, any increments of CNG stream rate requests more stream rate of DME fuel and this amount will be fundamentally varying the amount of hydrogen dose in the whole fuel blends.
However, the predicted results support our planned method to develop the working engine region, particularly at high load conditions.
Furthermore, the DME fuel is capable of igniting the charged blends whether H2 additives substances has employed to smooth the blend reactivity and retarding the ignition to happen after the cylinder TDC.
Moreover, there is a reasonable agreement between both of the engine experimental results and engine test prediction of the in-chamber pressure illustration data.
Reference: H.A.E.D. Bastawissi, M. Elkelawy, H. Panchal, K. Kumar Sadasivuni, Optimization of the multi-carburant dose as an energy source for the application of the HCCI engine, Fuel. (2019) 15–24. doi:10.1016/j.fuel.2019.04.167.