Fueled HCCI Engine Research Articles

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.

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

Determination of optimum operating parameters of MWCNT-doped ethanol fueled HCCI engine for emission reduction

Carbon based metallic additives were widely researched to improve combustion charecteristics of spark ignition and compression ignition engines. It was proven that carbon nanotube additive shortens ignition delay period and improves combustion characteristics especially in diesel engines. HCCI is a lean burn combustion mode which provides high thermal efficiency and simultaneously low NOx and soot emission. However it has drawbacks such as misfire at leaner mixtures and knocking at high loads. Carbon nanotube could be used to improve combustion for HCCI engines as well. The aim of this study is to investigate the effects of multi-walled carbon nanotube addition to ethanol and n-heptane blends on HCCI engine performance, combustion and emission by experimentally and statistically. During the experiments, the mixed fuels formed with %25 ethanol, %75 n-heptane and 100, 150 and 200 ppm MWCNT additives were used. The experiment of these mixed fuels was carried out at different lambda and engine speed values. Response Surface Method was implemented to determine optimal additive amount and operation parameters of the engine. The variable parameter values to be used in the experiments were created with the central composite design, and a total of 20 experiments were performed. According to the obtained results, IMEP, ITE, BSFC, MPRR, COVimep, SOC, CA50, CO and HC response parameter values were obtained. Response parameter values were entered into the RSM environment and optimization studies were carried out depending on the response parameters targets. Among the optimum variable parameter values, the MWCNT ratio was determined as 102.16 ppm, lambda 2.7 and engine speed 1124.439 rpm. Response parameter values after optimization were determined as IMEP 4.988 bar, ITE 45.988 %, BSFC 227.846 g/kWh, MPRR 2.544 bar/CA, COVimep 1.722 %, SOC 4.445 CA, CA50 7 CA, CO 0.073 % and HC 476.452 ppm.

Predictive modelling and optimization of performance and emissions of an auto-ignited heavy naphtha/n-heptane fueled HCCI engine using RSM

In this study, the effects of engine speed and lambda input parameters of a single-cylinder HCCI engine on the performance, combustion and emissions with the use of fuels with different concentrations were investigated. As finding of the best operating point of the engine perfomance is vital, therefore, in this research work the Response Surface Method waas used to model and optimize the process. The processes of determining the experimental sets, creating the model equations of the response parameters and performing the optimization were carried out with the RSM method. The engine speed was determined as 800–1600 rpm, the lambda value was 1.8–2.6 and the naphtha ratio in the mixed fuel was 0–100 %. As a result of the study, ANOVA tables, model equations, contour graphics of response parameters were created and the effects of input parameters were examined in detail. The accuracy of the model equations created by comparing the estimated and actual response parameter values has been strengthened. After the optimization, the optimum input parameters were calculated as 75 % naphtha ratio, 1166.75 rpm engine speed and 2.12 lambda value. The response parameter values obtained depending on the optimum input parameters are effective torque 6.26 Nm, indicated thermal efficiency 33.09 %, BSFC 196.79 g/kWh, CA10 0.77 °CA, CA50 5.6 °CA, combustion duration 28.84 °CA, COVimep 1.46 %, MPRR It was determined as 6.24 bar/°CA, UHC 375.96 ppm and CO 0.05 %.

Experimental investigation on effects of equivalence ratio on combustion with knock, performance, and emission characteristics of dimethyl ether fueled CRDI compression ignition engine under homogeneous charge compression ignition mode

This study deals with the effects of different equivalence ratios on combustion with a knock, performance, emissions of a DME fueled automotive CI engine under HCCI mode. The conventional common rail direct injection (CRDI) CI engine was modified to run with DME fuel (manifold injection) under HCCI mode. The experiments were conducted on the engine at different equivalence ratios at a constant speed of 1400 rpm. Two stages of combustion (low-temperature reaction (LTR) region and high-temperature reaction (HTR) region) were observed under HCCI mode. The LTR region occurs at the temperature range from 700 to 750 K. In contrast, the HTR region was at a temperature beyond 1000 K. The cyclic variations with the coefficient of variation (COV) of maximum in-cylinder pressure, indicated mean effective pressure with knock peak pressure and knocking intensity (KI) were analyzed for assessment of combustion stability. Based on the knocking intensity, the optimum equivalence ratio with controlled auto-ignition (CAI) was found as 0.55, with peak in-cylinder pressure of 70.87 bar and peak in-cylinder temperature of 1815 K. The COV for all the parameters and KI found below the limit value (COVlimit − 5% and knocklimit − 5 MW/m2) till 0.55 equivalence ratio and beyond the equivalence ratio, the knock occurred resulting in uncontrolled auto-ignition (UAI). Ultra-Low NOx (10–15 ppm) and zero smoke emissions with a considerable reduction in CO and HC emissions were observed at a higher equivalence ratio from DME fueled HCCI mode. However, CO and HC emissions were higher at lower equivalence ratio. This study shows that the simultaneous reduction of NOx and smoke emissions could be achieved in a DME fueled HCCI engine.

Experimental investigation of various ethanol blends impact on combustion and emissions characteristics of diesel ignited dual fuel HCCI engine

Purpose Homogeneous charge compression ignition (HCCI) engine is an advanced combustion method to use alternate fuel with higher fuel economy and, reduce NOX and soot emissions. This paper aims to investigate the influence of ethanol fraction (ethanol plus gasoline) on dual fuel HCCI engine performance. Design/methodology/approach In this study, the existing CI engine is modified into dual fuel HCCI engine by attaching the carburetor to the inlet manifold for the supply of ethanol blend (E40/E60/E80/E100). The mixture of ethanol blend and the air is ignited by diesel through a fuel injector into the combustion chamber at the end of the compression stroke. The experiments are conducted for high load conditions on the engine i.e. 2.8 kW and 3.5 kW maximum output power for 1,500 constant rpm. Findings It is noticed from the experimental results that, with an increase of ethanol in the blends, ignition delay (ID) increases and the start of combustion is retarded. It is noticed that E100 shows the highest ID and low in-cylinder pressure; however, E40 shows the lowest ID compared to higher fractions of ethanol blends. An increase in ethanol proportion reduces NOX and smoke opacity but, HC and CO emissions increase compared to pure diesel mode engine. E100 plus diesel dual-fuel HCCI engine shows the highest brake thermal efficiency compared to remaining ethanol blends and baseline diesel engine. Originality/value This experimental study concluded that E100 plus diesel and E80 plus diesel gave optimum dual fuel HCCI engine performance for 2.8 kW and 3.5 kW rated power, respectively.

Numerical comparison of combustion characteristics and cost between hydrogen, oxygen and their combinations addition on natural gas fueled HCCI engine

Hydrogen, oxygen, and their combinations as effective species in the production of radical OH, which plays an effective role in the HCCI combustion enhancement, are considered to study their effect on combustion characteristics and resolving the challenges facing natural gas HCCI engines numerically. There are five items were considered for adding oxygen, hydrogen and their compounds, including 1%, 2%,3%, 4% and 5% of the fuel mixture for hydrogen, 10%, 20%, 30%, 40% and 50% for the extra oxygen in oxidizer and add up half of each respectively, including 0.5% H2 + 5%O2, 1% H2 + 10%O2, 1.5% H2 + 15%O2, 2% H2 + 20%O2, and 2.5% H2 + 25%O2. Adding hydrogen to some extent improves the engine efficiency, lowers combustion duration, and brings the engine cycle closer to the ideal Otto cycle and reduces CO and UHC emissions, but it can only increase engine operating range by as much as 4.2% at low load, increases NO emission, and increases the combustion noise. Hydrogen addition results in faster methane combustion, shortens the fuel combustion duration and increases the OH radical concentration. Up to 30%, added oxygen can extend the engine working range up to 48% at low loads, making the engine run smoother and shortening the combustion duration, although IMEP and efficiency decrease, CO and UHC emissions increase. By using hydrogen and oxygen compounds obtained their both benefits simultaneously, the engine operating range expands by 40.19% at low loads, the emissions would be less than the Euro 6 standard limitation and the maximum difference in efficiency is only 2.38% less than hydrogen addition. By adding these additives, ignition delay decreases and SOC advances. Using hydrogen and oxygen to improve engine performance at low loads is an appropriate and affordable solution, which does not cost much.

Experimental investigation of propanol dual fuel HCCI engine performance: Optimization of propanol mass flow rate, impact of butanol blends (B10/B20/B30) as fuel substitute for diesel

Propanol diesel (P100 + D) dual fuel HCCI (DF-HCCI) engine was used to overcome HCCI engine challenges. In the present study, propanol was supplied along with intake air through the carburetor and diesel/butanol blend was injected into the engine cylinder through fuel injector. MFR of propanol was varied using different fuel jets (jet 40, jet 60, jet 70, jet 80, and jet 90) in carburetor. Additionally, the influence of different butanol blends (B10/B20/B30) on the engine performance was examined as a substitute for diesel fuel. Results revealed that increase in MFR of propanol, increases ignition delay (ID) leading to reduce combustion duration (CD) and pressure rise rate (PRR), which assist to reduce NOX emissions and smoke opacity compared to baseline diesel engine. From the optimization, it was concluded that jet 60 and jet 70 were appropriate for 20% and 40% load respectively, although jet 90 was appropriate for 60%, 80%, and 100% load conditions. On average 67.64% diesel can be replaced by propanol in optimized P100 + D DF-HCCI engine. Further, in place of diesel fuel, butanol blends (B10/B20/B30) are supplied through injector to ignite propanol DF-HCCI engine. The results showed that NOX and CO emissions are reduced compared to P100 + D DF-HCCI engine.

Effect of advanced intake valve closing on the thermo-chemical characteristics of the homogeneous combustion in a DME fueled HCCI engine

This numerical study was performed to analyze the thermo-chemical characteristics of homogeneous combustion on the effect of advanced intake valve closing timing in a DME fueled HCCI engine. To achieve this, the engine simulation was performed using the detailed chemical kinetic mechanism, including 453 reactions for dimethyl ether (CH3OCH3), and the modified NOX mechanism was applied to analyze the NOX reaction pathway of the DME combustion. The experimental study was performed to validate the engine analysis using a single cylinder CI engine with the injection timing of BTDC 40 degree and IVC timing of BTDC 128 degree. The injection quantity and pressure were set to 8 mg and 50 MPa at 1500 RPM, respectively. The results of engine performance such as cylinder pressure, cylinder temperature, heat release rate, and IMEP were decreased and the ISFC and ignition delay were increased when the IVC timing was advanced since the overall rates of a chemical reaction and the reaction rate of OH radicals are reduced. Especially, the reduction of CH2OCH2O2H radicals was a very important factor it affects the ignition delay in the low temperature reaction. Consequently, it influences the LTC and HTC reactions and makes a difference in the fuel oxidation rate and combustion reaction. Furthermore, the OH radicals also had the greatest effect to the CO oxidation and NOX production. The CO and NOX emissions were primarily occurred by the forward reactions of HCO + O2 → CO + HO2 and HO2 + NO → NO2 + OH during the combustion period, respectively. The chemical reactivity and CO oxidation reaction were reduced as the fuel mass fraction increased in the low combustion temperature. In addition, the reaction path of NOX emission related to the thermal NOX reaction did not occur due to the low combustion temperature. Thus, the thermo-chemical characteristics of the DME homogeneous combustion of this work suggest that the chemical reaction of fuel oxidation and exhaust emissions are limited as the effect of chemical oxidation rate, reaction rate, and the OH radical depending on the IVC timing changes.

Experimental Investigations of Performance, Combustion and Emission Characteristics of Ethanol Fueled HCCI Engine

Bu çalışmada dört zamanlı, tek silindirli, port enjeksiyonlu bir benzinli motordan (SI) homojen dolgulu sıkıştırma ile ateşlemeli motora (HCCI) dönüşümü yapılmış Ricardo Hydra test motoru kullanılmıştır. Referans heptan ve heptan/etil alkol karışımlarının (E15 ve E25) yanma, motor performansı ve egzoz emisyonlarına etkisi deneysel olarak incelenmiştir. Emme havası giriş sıcaklığı 60℃’de sabitlenmiş ve motor hızı 800 rpm olarak belirlenmiştir. Farklı hava fazlalık katsayısı (HFK) değerlerinde silindir içi basınç, ısı dağılımı, yanma başlangıcı, CA50, yanma süresi, indike termik verim, indike ortalama efektif basınç (IMEP) ve egzoz emisyon sonuçları incelenmiştir. Heptan yakıtına etil alkol ilavesi yanmanın gecikmeye alınarak uzamasına neden olmuştur. Ayrıca yanmanın yavaşlatılması sağlanmıştır. Buna bağlı olarak basınç artış oranı azalarak HCCI yanma kontrol altına alınmıştır. En yüksek indike termik verim E15 yakıtı kullanımında HFK’nın 2 olduğu şartlarda %49 olarak belirlenmiştir. En yüksek IMEP E25 yakıtı kullanımında HFK’nın 1,3 olduğu şartlarda 6,1 bar olarak tespit edilmiştir. CO ve HC emisyonları ise heptan yakıtına etil alkol ilave edilmesi ile eş zamanlı olarak artış göstermiştir. Karışım yakıtları kullanımında silindir içi gaz sıcaklıklarının heptana göre düşük olması, yüksek emisyon değerlerinin temel nedeni olduğu ifade edilebilir. E15 yakıtının uygun çalışma şartlardında ideal yakıt olduğu bu çalışma ile ifade edilebilir.

3D CFD simulation of a natural gas fueled HCCI engine with employing a reduced mechanism

In the present study, the implementation of a previously proposed reduced mechanism is examined through a CFD model by means of modified Kiva3V coupled with Chemkin II in a CFR natural gas fueled HCCI engine. Firstly, to investigate the accuracy of the reduced mechanism, its applicability was examined with experimental data. The model results with the reduced mechanism are in good agreement with experimental data. Then, after validation of the model, to further examine the validity of the reduced mechanism, 7 sets of different operating conditions were investigated. The in-cylinder pressure, peak pressure (Pmax), gross indicated mean effective pressure (gross IMEP), cumulative heat release (CHR), emissions, and the crank angle when 50% of heat is released (CA50) have been selected as representative parameters for evaluating the performance of the reduced mechanism. The results of the model demonstrated that the calculated representative parameters using the reduced mechanism are in good agreement with the detailed mechanism. Results reveal that the present reduced mechanism gives reliable performance for combustion, performance and emissions characteristics prediction, as well as computational time improvement for multidimensional CFD simulations from about 480min to average 189min for all cases on quad core 4 Intel CPU and 4 Gigabyte RAM personal computer. The reduced mechanism has 26 species and 63 reactions.

Modelling and Simulation of Methanol and Diesel Fuelled HCCI Engine for Improved Performance and Emission Characteristics

Modelling and Simulation of Methanol and Diesel Fuelled HCCI Engine for Improved Performance and Emission Characteristics

Numerical investigation of ethanol fuelled HCCI engine using stochastic reactor model. Part 2: Parametric study of performance and emissions characteristics using new reduced ethanol oxidation mechanism

Ethanol fuelled homogenous charge compression ignition engine offers a better alternative to tackle the problems of achieving higher engine efficiency and lower emissions using renewable fuel. Present study computationally investigates the HCCI operating range of ethanol at different compression ratios by varying inlet air temperature and engine speed using stochastic reactor model. A newly developed reduced ethanol oxidation mechanism with NOx having 47 species and 272 reactions is used for simulation. HCCI operating range for compression ratios 17, 19 and 21 are investigated and found to be increasing with compression ratio. Simulations are conducted for engine speeds ranging from 1000 to 3000rpm at different intake temperatures (range 365–465K). Parametric study of combustion and emission characteristics is conducted and engine maps are developed at most efficient inlet temperatures. HCCI operating range is defined using combustion efficiency (>85%) and maximum pressure rise rate (<5MPa/ms). In HCCI operating range, higher efficiency is found at higher engine loads and lower engine speeds. Emission characteristics of species (NOx, N2O, CO, CH4, C2H4, C2H6, CH3CHO, and HCHO) found in significant amount is also analysed for ethanol fulled HCCI engine. Emission maps for different species are presented and discussed for wide range of speed and load conditions. Some of unregulated species such as aldehydes are emitted in significantly higher quantities from ethanol fuelled HCCI engine at higher load and speed conditions.

Fuel suitability for homogeneous charge compression ignition combustion

The main focus of this paper is to investigate the impact of fuel type on HCCI combustion under different engine loads. A coupled chemical kinetics-computational fluid dynamic (CFD) model is developed to investigate the combustion performance and emissions characteristics of a HCCI engine with pre-combustion chamber fueled with natural gas, natural gas/10% dimethyl ether (DME) mixtures, or methanol. The simulation results indicate that the probability of partial combustion increases when using natural gas under low engine load. However, methanol and natural gas/DME experience complete combustion under low engine load. In contrast, for both methanol and natural gas/DME the rate of pressure rise and heat release at high engine load is very high which induces engine knock. At leaner mixtures (ER<0.26), natural gas/DME attains the highest indicated mean effective pressure (IMEP) compared to that of methanol and natural gas. However, natural gas fueled HCCI engine has the highest IMEP under rich mixture conditions (ER>0.26). NOx emissions of natural gas fueled HCCI engine are much lower than that of methanol and natural gas/DME, especially at high engine loads. However, natural gas/DME and methanol offer superior combustion control and NOx, carbon monoxide (CO), and unburned hydrocarbon (UHC) emissions under low to moderate engine loads. However, the use of natural gas in HCCI combustion is suitable for moderate to high engine loads.

Exergetic examination of a hydrogen enriched compressed natural gas fuelled homogeneous charge compression ignition engine

A second-law based exergetic study is undertaken for a parametric examination of CNG fuelled HCCI engine. The effects of change in equivalence ratio, turbocharger pressure ratio, ambient temperature, and hydrogen enrichment on the engine performance are investigated through energy and exergy efficiencies.

Study on the phase relation between ion current signal and combustion phase in an HCCI combustion engine

Ion sensing is a promising approach for cycle resolved combustion phasing in HCCI engines. This paper investigates the fundamental processes affecting the phase difference (Pdelta) between ion current signal phase Ion50 and combustion phase CA50 based on 2 numerical models. One model is used to explore fluid dynamic effects on an HCCI engine. The other model, a 10-zone model, is used to primarily explore the affecting mechanism on Pdelta. Both numerical analysis and experimental results of the ionization process indicate that Pdelta is affected by both flame ionization and fuel heat release process. For fuels with similar octane number (ON), such as gasoline (ON=97) and ethanol (ON=107), both the combustion phase CA50 and the ion current signal phase Ion50 retard when the equivalence ratio Φ decreases. However, the CA50 for ethanol fuel retards moderately compared with the gasoline case since the CA50 for ethanol fuel is more sensitive to intake temperature Tin rather than Φ. Then larger Pdelta values can be seen in ethanol fueled HCCI engine under lower Φ conditions. For the fuels with different widely octane number, such as gasoline and diesel (ON=0), their combustion boundary conditions are different in HCCI engines, they produce ions at a different ratio. For diesel fuel, the ion production rate is much lower due to the lower intake temperature and higher compression ratio. Under low Φ conditions, the ion current signal cannot be observed at the beginning of ion concentration increase in diesel fueled HCCI engines, and the Ion50 appears much later compared with the gasoline fueled HCCI engine. As a result, the values of Pdelta increase significantly in the diesel fueled HCCI engine.

Particulate Morphology and Toxicity of an Alcohol Fuelled HCCI Engine

Particulate Morphology and Toxicity of an Alcohol Fuelled HCCI Engine

Recent Trends in Internal Combustion Engines

This special issue is devoted to the recent trends in internal combustion engines. Recent trends in internal combustion engines aim to reduce fuel consumption and also lower exhaust gas emissions.The aim of this special issue is to bring all topics and all the scientific/technological approaches in recent trends in internal combustion engines. We, as editorial team, received several contributions as original research articles and review articles that will stimulate the continuing efforts to understand new technologies in internal combustion engines (ICEs). The papers are “Design and implementation of the control system of an internal combustion engine test unit” by T. Koc et al., “Trends of syngas as a fuel in internal combustion engines” by F. Y. Hagos et al., “Simulation analysis of combustion parameters and emission characteristics of CNG fueled HCCI engine” by P. M. Diaz et al., “Calibration and validation of a mean value model for turbocharged diesel engine” by R. Li et al., “Fuzzy sets method of reliability prediction and its application to a turbocharger of diesel engines” by Y.-F. Li and H.-Z. Huang.

Effect of Start of Injection on the Particulate Emission from Methanol Fuelled HCCI Engine

Effect of Start of Injection on the Particulate Emission from Methanol Fuelled HCCI Engine