HCCI Engine Research Articles

Enhancement of combustion characteristics of waste alcohol using n-heptane through RSM in an HCCI engine

Enhancement of combustion characteristics of waste alcohol using n-heptane through RSM in an HCCI engine

An experimental evaluation of TiO2 nanoadditive for HCCI engines running on ABE fuel

An experimental evaluation of TiO2 nanoadditive for HCCI engines running on ABE fuel

Exploring Fuel Characteristics and Performance in HCCI Engines with Alternative Fuels

Exploring Fuel Characteristics and Performance in HCCI Engines with Alternative Fuels

Attaining improved control over the start of combustion in dual-fuel HCCI engine through the influence of EGR

Attaining improved control over the start of combustion in dual-fuel HCCI engine through the influence of EGR

Computational investigation of combustion and emission characteristics of HCCI engine fueled with Carbon-Free NH3 –H2O2 blend

A computational investigation is provided of the utilization of blends of NH3 and H2O2 as carbonless fuels for HCCI combustion. A Computational Fluid Dynamics (CFD) model is developed and validated to assess the engine’s performance under varying proportions of NH3 and H2O2, equivalence ratios, and inlet temperatures. The heat release rate profiles demonstrated dual peaks, which were rationalized as an initial fuel decomposition followed by a slow thermal explosion and then a fast depletion of the fuel after the generation of a pool of OH radicals through decomposition of H2O2. Findings suggest that an increase in mole fraction of H2O2 advances combustion. Increasing the H2O2 volume fraction also decreases combustion duration, while increasing the IMEP. In-cylinder peak pressure and Maximum Pressure Rise Rate (MPRR) increase with H2O2 mole fraction, leading to reduced thermal efficiency, particularly at higher equivalence ratios, and an increased danger of uncontrolled combustion (knocking). Additionally, higher inlet mixture temperatures were shown to result in an advancement in the start of combustion and a reduction in combustion duration, with a corresponding increase in peak pressure. This points to the possibility of potentially controlling the notoriously difficult-to-control HCCI combustion through intake temperature for NH3/H2O2 fuel blends. However, increased NOx emissions are observed for increased intake temperature and in any case the NOx emissions are orders of magnitude above current regulatory limits, which means that practical engine operation will only be possible with an aftertreatment scheme based on the de-NOx activity of NH3.

Experimental studies on the exhaust emissions of a n-butanol/diesel dual-fuel HCCI engine under different intake temperature

Abstract To improve the exhaust emissions of n-butanol/diesel blends fueled HCCI engines, the influence of intake temperature (Tin) on the HC, CO, and NO x emissions was studied by bench tests on λ of 2.5, engine speed of 1000 r/min under the conditions with the blending ratio of B50 and B90. Experimental results show that the HC and CO decline as Tin rises. At the same Tin, the CO and HC of B90 are lower than B50. When the intake temperature is lower than 150°C, the NO x emissions are almost zero.

Comparative Experimental Analysis and Performance Optimization of Single-Cylinder DI and HCCI Engine with Series Catalytic Converters

The stringent norms imposed by the government to reduce emissions to the environment have forced all engine manufacturers to reduce engine emissions. Carbon monoxide and NOx emissions from diesel engines are topics of significant consideration. This causes climate change and natural calamities. The current paper focuses on the comparative performance optimization of single-cylinder engines in DI and HCCI mode fitted with custom-designed catalytic converters in Series configuration using Taguchi regression Analysis based on experimental results obtained for series combination. The present work tested a diesel engine in both DI and HCCI modes with catalytic converters in series configurations with various monolith lengths and compression ratios. The test results are then analyzed using the Taguchi method and regression analysis. Overall, BTE is higher for HCCI mode than DI mode with the series arrangement of catalytic converters in the 24% to 35% range. Meanwhile, BSFC is lower for HCCI mode, in the 20% to 64% range. Hydrocarbon emission is higher, starting from 15% to 48%. The NOx emissions are lower for lower load, but on full load, they are more than those in DI Mode. CO emissions are also Higher for HCCI mode in the 12% to 30% range.

Effect of direct water injection timing and quantity on combustion, performance, and emission characteristics of a homogeneous charge compression ignition engine − A CFD analysis

Direct water injection in an HCCI engine is a promising strategy to extend the operating load limit. The advantage of water injection depends on the percentage of water evaporated inside the cylinder, which further depends on the time available for the evaporation and the interaction of water spray plumes with the in-cylinder air-flow field. Here, CFD investigations are done to find the effect of water injection timing (WIT) and quantity on the load limit and performance and emission characteristics of the HCCI engine. Various WITs are considered for the study, varying from 100° CA before TDC to 20° CA before TDC. The water-to-fuel ratio is varied from 0 to 1 in steps of 0.2. A three-dimensional computational fluid dynamics model is used for the study, and CFD models used are validated from the available experimental data in the literature. The results show that WITs before 650° CA and after 670° CA are inappropriate for the HCCI engine, as heat release rate and MRPR are high in these cases. Also, the evaporation rate of water increases when the water injection is done in the region where the direction of the air-flow field is opposite to the direction of water injection. At the WIT of 60°, the HRR and MRPR are minimal, and the water vapor distribution is good compared to other cases. Also, it is seen that a water-to-fuel ratio of 0.8 gives more scope for extending the upper load limit with a marginal penalty of the IMEP; hence, a WIT of 60° with the water-to-fuel ratio of 0.8 is considered optimum. With the optimum case, it is feasible to increase the ER from 0.74 to 0.95, resulting in an increase of IMEP from 3.23 bar to 4.92 bar, which is 52.3 % more than without a water injection case at the ER of 0.74. Also, it showed minimum NOx emissions in all the water injection cases. Hence, these results address the primary challenges associated with HCCI engines, demonstrating that direct water injection can substantially improve the combustion controllability and operational range of HCCI engines.

Analysis of combustion characteristics of ammonia/hydrogen mixed fuel in HCCI engine

Abstract A zero-dimensional HCCI combustion model for ammonia/hydrogen mixed gases was established to study the influence of hydrogen on the combustion characteristics of ammonia fuel. The effects of compression ratio, intake temperature, and hydrogen ratio on the combustion performance of ammonia were analyzed. The results suggest that due to the high ignition point of ammonia, the intake temperature must reach 523 K when the compression ratio is 18 for ammonia fuel to be compression ignited. At the same time, it was found that under this condition, ammonia fuel can burn under lean conditions (ϕ=0.2). The study also found that when the intake temperature is 523 K, the minimum-to-compression ratio during ammonia compression ignition decreases from 18 to 10 as the hydrogen doping ratio increases from 0 to 0.2.

Controllability of Pre-Chamber Induced Homogeneous Charge Compression Ignition and Performance Comparison with Pre-Chamber Spark Ignition and Homogeneous Charge Compression Ignition

This paper presents an experimental and numerical evaluation of the pre-chamber induced HCCI combustion concept (PC-HCCI) in terms of engine performance, emissions, and controllability. In this concept, a spark-initiated combustion in the pre-chamber is utilized to trigger the kinetically controlled combustion of an ultra-lean mixture in the main combustion chamber. The experimental measurements were performed on a single-cylinder engine with a custom-made active pre-chamber. A high compression ratio of 17.5 was used, which limits the maximum achievable engine load due to high knocking tendency but enables both standard PCSI combustion (flame propagation) at very high dilution levels and HCCI combustion at reasonable intake temperatures. The analysis of combustion characteristics and the resulting performance is performed at indicated mean effective pressures (IMEPs) of 3.5 and 3.0 bars, and three different intake temperatures of 80 °C, 90 °C, and 100 °C. The variation in engine load was achieved by adjusting the excess air ratio in the main chamber. On each combination of intake temperature and engine load, a spark sweep and an injected PC fuel mass sweep were performed to obtain the highest indicated efficiency while satisfying the restrictions in terms of combustion stability and knock intensity. It was shown that, unlike in a conventional HCCI engine, the combustion phasing can be directly and reliably controlled by adjusting either spark timing or the reactivity of the pre-chamber mixture, ensuring adequate combustion stability and eliminating potential misfires. A similar indicated efficiency as with conventional HCCI combustion was obtained, while the NOx emissions, although slightly elevated, are still insignificant. Compared to PCSI combustion at the same engine load, a 4-percentage-point increase in indicated efficiency and two times lower NOx emissions were achieved. Compared to the most efficient PCSI operating point, it was 1 percentage point lower, indicating that efficiency was achieved, but the specific NOx emissions are reduced by approximately 70%. Most importantly, very similar performance was obtained with significant variations in intake temperature, proving the reliability and adaptability of this combustion concept.

Syngas application in various engines

Current engines are not designed to use syngas as fuel, which presents challenges such as differences in air-to-fuel ratio and fuel properties compared to traditional fuels like gasoline and diesel. This research recommends applying dual combustion, regulating pressure rate, using catalysts and employing EGR (exhaust gas recirculation), in order to improve engine efficiencies while reducing emissions. This study concludes that syngas is more effectively utilized in diesel and HCCI engines (homogeneous charge compression ignition) than in gasoline engines due to the cycle variations impacting efficiency. With technological advancements, syngas and other alternative fuels can be developed to reduce emissions and production cost, justifying their implementation.

Comprehensive Comparison of Traditional Engines and Emerging Alternatives

As the natural environment deteriorates, electric vehicles will gradually replace internal combustion engines that use traditional fossil fuels. This paper compares traditional engines to alternatives regarding efficiency, emissions, price, and market share. In brief, alternative engines have advantages over traditional internal combustion engines in terms of efficiency, emissions, and long-term overhead, as evidenced by rising market share. In 2022, the share of electric vehicles in global sales has reached 14%. Compared to traditional internal combustion engine vehicles, electric vehicles have a higher well-to-wheel efficiency, up to more than twice of internal combustion engine vehicles. From a price perspective, electric vehicles have a higher original cost. However, lower maintenance costs allow electric vehicles to achieve the same cost as equivalent combustion engines in 5-8 years. Electric vehicles typically have low well-to-wheel and fuel emissions and are more sustainable. In the future, more research and development are needed for electric vehicles to make them suitable for most cities worldwide. At the same time, research into the traditional internal combustion engine should be addressed, as cleaner, more efficient engines such as the HCCI engines are already available for civilian use.

The influence of residual gas on ozone-assisted combustion in an HCCI reciprocating engine

This work is an investigation on the influence of both residual gas and ozone on the combustion process in an HCCI engine fuelled with iso-octane/air/ozone mixtures and on how ozone reacts with residual gases. It is well known that ozone releases oxygen atoms mainly through the O3+M⇄O2+O+M reaction and this may lead to an improvement of the engine combustion. Nevertheless, the chemical interaction between ozone and the species in the residual gas has not yet been investigated in the literature. CFD simulations of a closed-valve engine cycle have been carried out by using an axisymmetric domain. The model has been validated against experimental data and a parametric analysis has been carried out to assess different compositions and amounts of residual gases on the engine performance. The results show that during compression ozone enables Low-Temperature Combustion, with a small amount of heat released before the occurrence of auto-ignition. The combustion is faster and advanced with a reduction of UHCs and an increase of NOx. The results show that the influence of ozone is more effective as the mass of residual gases increases. With an ozone concentration of 35 ppm at IVC the gross work per cycle increases by 2.52 %, 3.58 % and 5.7 %, compared to the case without ozone, with 0 %, 5 % and 10 % by mass of residual gases, respectively. It can be concluded that ozone is more beneficial for cases where combustion is slower due to the higher amount of residual gases.

Investigate the effect of EGR stratergies on the HCCI engine's performance with N-heptane fuel injection

In this study, the effect of EGR strategies on the HCCI engine's performance is studied. A program was established to control the injection fuel and amount of exhaust gas recirculation on the HCCI engine. The results of the research show that when the EGR rate is greater than 30%, the engine operates stably according to the HCCI combustion characteristic at speeds lower than 2400 rpm. But when engine speeds are higher than 2400 rpm, the HCCI combustion characteristic is unstable; the torque and the indicator efficiency decrease rapidly. When the HCCI engine increases the EGR rate, the start of combustion is gradually later, the coefficient gradually decreases to close to the black smoke characteristic curve, the CO, HC, and CO2 emissions increase. The NOx emissions tend to increase when the EGR ratio increases from 0–25%, but the NOx decreases when the EGR rate is greater than 25%.

HCCI Engine: Advancements in Combustion Control and Potential Innovation in Power Configuration for Vehicles

HCCI Engine: Advancements in Combustion Control and Potential Innovation in Power Configuration for Vehicles

Huge Potential of HCCI Engine in Rarefied Air Environments

Huge Potential of HCCI Engine in Rarefied Air Environments

Combustion Process and Performance of HCCI Engines under Different Fuels

Combustion Process and Performance of HCCI Engines under Different Fuels

System development for production and onsite use of hydrogen in wet-ethanol fueled HCCI engine for cogeneration of power and cooling

The main goal of this study is to look at how the development and investigation of on-site production and end-use of green hydrogen as a blended fuel in wet-ethanol operated homogeneous charge compression ignition (HCCI) engine bottoming with ORC and ERC affects engine's energetic and exergetic performances. The exhaust of HCCI engine is utilized to run an ORC turbine which drives the electrolyzer employed for hydrogen production, and the heat rejected from ORC condenser is further utilized to operate an ERC for producing the desired cooling energy. Innovative design and integration increase the engine's thermo-environmental performance and lower hydrogen transport and storage costs. Energy-exergy analyses model is applied to examine the system performance with (0–20%) hydrogen-wet-ethanol mixtures. EES professional software with REFPROP toolbox library data simulated the equation. Adding hydrogen from 5 to 20% improved HCCI engine energy and exergy efficiencies from 41.56% to 44.01% and 37.23%–38.73%, respectively. Using R134a, system efficiencies rise from 42.7% to 48.77% and 37.94%–55.12%. ORC and ERC. The injection of hydrogen from 0 to 20% decreases exergy destruction in HCCI engines from 90.09% to 89% and increases it in catalytic converters from 4.08% to 5.73%.

Development and Investigation of a Hydrogen Enriched Natural Gas Fuelled HCCI Engine for Combined Generation of Power, Heating, and Cooling

Development and Investigation of a Hydrogen Enriched Natural Gas Fuelled HCCI Engine for Combined Generation of Power, Heating, and Cooling

Development and investigation of a hydrogen enriched natural gas fuelled HCCI engine for combined generation of power, heating, and cooling

Development and investigation of a hydrogen enriched natural gas fuelled HCCI engine for combined generation of power, heating, and cooling