Ethanol Port Injection Research Articles

Optimising the Particulate Emission Characteristics of a Dual-Fuel Spark Ignition Engine by Changing the Gasoline Direct Injection Strategy

In the current global scenario, it is essential to find more effective and practical solutions to mitigate the problem of particulate emissions from vehicles. In this research, particulate emission characteristics with changing GDI pressure or applying a split GDI strategy with different second injection timings were initially explored in a Dual-Fuel Spark Ignition (DFSI) engine, which employs Ethanol Port Injection (EPI) plus Gasoline Direct Injection (GDI). The experimental results show that by increasing GDI pressure (PGDI) from 5.5 MPa to 18 MPa, ignition delay (θF) shows a small decrease of 0.68 degrees. The parameters, such as maximum in-cylinder temperature (TMI) and exhaust gas temperature (TEG), each increase by 53.75 K and 13.84 K. An apparent reduction of 59.5% and 36.26% was achieved for the concentrations of particulate number (NP) and particulate mass (MP), respectively. Particulate emissions are effectively reduced by a split GDI strategy with an appropriate range of second injection timing (tGDI2). Under tGDI2 = −260 ºCA, NP and MP concentrations exhibit a relatively lower level. However, by delaying tGDI2 from −260 ºCA to −140 ºCA, there is an increase of more than 60% in NP concentration. The research findings help offer new and valuable insights into optimising particulate number and mass emissions from DFSI engines. Moreover, the findings could contribute novel and valuable insights into the optimisation of particulate emission characteristics in DFSI engines.

Comparative study on combustion and emission of ternary-fuel combined supply SI engine with oxyhydrogen/ethanol/gasoline by different injection modes of fuel

The combination of renewable energy and multifuel combined supply is an efficient way to deal with the energetic crisis and the pollution of environment. Ethanol, gasoline and oxyhydrogen participate in combustion by means of three independent supply paths, which can improve engine power and reduce gasoline consumption and gaseous pollutant emission at the same time. However, the optimization of ternary-fuel combined supply mode is a problem that must be clarified. In this study, the engine performance at four direct injection pressure (DIP), six direct injection timing (DIT), five intake manifold absolute pressures (MAP) and four speeds is studied under the condition of equal ethanol injection ratio and gasoline injection ratio. The experimental results show that ethanol direct injection forms a mixture with a better stratified combustion state than gasoline direct injection. Moreover, oxyhydrogen negatory pressure inhalation (ONPI) can effectually increase Pmax and IMEP, reduce APmax, CA 10–90, CA 0–10, CO emission, HC emission and particulate emission, but increase NOx emission. However, ethanol direct injection (EDI) can reduce NOx emission produced by ONPI, and oxyhydrogen can attenuate the negatory effect on mixture combustion due to the excessive latent heat of vaporization of ethanol. NO emission in EDI mode is reduced by an average of 28.39 % compared to gasoline direct injection (GDI) mode under different MAPs. In conclusion, the combustion and emission characteristics of the engine in EDI + gasoline port injection (GPI) + ONPI mode are better than those in ethanol port injection (EPI) + GDI + ONPI mode. And the control strategy of "9–11 MPa DIP+250–300°CA BTDC DIT +16 L/min oxyhydrogen negative pressure inhalation volume (ONPIv)" can improve the performance of EDI + GPI + ONPI engine while reducing emission.

Study on Combustion and Emissions of a Combined Injection Spark Ignition Engine with Natural Gas Direct Injection Plus Ethanol Port Injection under Lean-Burn Conditions.

Conventional ethanol spark ignition (SI) engines have poor fuel atomization and mixture formation. The objective of this paper is to improve the combustion and emission performance of ethanol SI engines under lean-burn conditions through the dual-injection mode with ethanol port injection and compressed natural gas (CNG) direct injection (CDI+EPI). This paper studies the engine performance at 1500 rpm under five CNG direct injection ratios (CDIr) and five excess air ratios (λ). The results show that as the CDIr increases under lean-burn conditions, the following occurs: the minimum advance for best torque (MBT), the coefficient of variation (CoVIMEP), and CO and HC emissions decrease; the crankshaft rotation or time with cumulative heat release rate ranging from 10% to 90% (CA 10–90) and NOx emissions first decrease and then increase; and torque, peak in-cylinder pressure (Pmax), and the λ limit first increase and then decrease. The larger the CDIr is, the less influence λ has on the MBT. When CDIr = 15%, the CoVIMEP can be effectively reduced, the engine can still work stably in all lean-burn conditions, and the λ limit will reach the maximum value of 1.73, 19.31% higher than that of the original engine (CDIr = 0). When λ = 1.1, CO emissions decrease the most and HC emissions decrease the least. At this time, CO and HC emissions decrease by 1.56 vol % and 30 ppm, respectively, on average for every 0.1 decrease in λ. For CA 10–90, torque, and Pmax, λ = 1.1, 15% CDI, and 85% EPI is the optimal combination under lean-burn conditions. When CDIr ≥ 15%, NOx emissions are at an ideal level. Under lean-burn conditions, direct-injection CNG can form a good stratified natural gas/ethanol mixture in the cylinder, effectively improving the engine’s power and stability and reducing emissions. The λ = 1.1, 15% CDI, 85% EPI combination provides a cutting-edge and outstanding solution for a natural gas/ethanol combined injection SI engine.

Experimental study on combustion and emission of an SI engine with natural gas/ethanol combined injection

Pure ethanol spark ignition (SI) engines have poor fuel atomization and mixture formation at lower load. The objective of this study is to improve the performance of ethanol SI engines through dual-injection mode with ethanol port injection plus compressed nature gas direct injection (EPI + CDI). In this paper, the performance engine at different compressed nature gas direct injection ratio (CDIr) and DIT was studied at the speed of 1500rmp. The results show that, with the increase of CDIr or the delay of direct injection timing (DIT), torque, Pmax and NOx first increases and then decreases; CA 10–90, CoVIMEP, CO and particle number (PN) first decreases and then increases; HC keeps decreasing. When CDIr = 5%, DIT = 150°CA BTDC, CA 10–90 reaches the lowest value, which is about 6.21% lower than the original engine. Besides, under this operation condition, CoVIMEP decreases to 1.13%, which is about 18.72% lower than the original engine. It is worth noting that the higher torque and Pmax at this time indicate the better combustion in the cylinder, but NOx does not increase significantly. In addition, total particle number (TPN) also reaches the minimum at this time. When CDIr = 5%, 10%, 15% and 20%, HC is reduced by 11.42%, 13.53%, 20.05% and 23.26% on average. When CDIr ≤ 10%, the overall CO is lower than the original engine. In summary, EPI + CDI can not only effectively improve combustion, but also reduce emissions. The cooperation of 5%CDIr + 95%EPI + 150°CA BTDC DIT can form an effective stratified mixture in the cylinder, providing stable and promising performance. And it is the best direct injection strategy for CDI + EPI dual-fuel combined injection SI engine.

Adjacent combustion heat release and emissions over various load ranges in a premixed direct injection diesel engine: A comparison between gasoline and ethanol port injection

In a premixed diesel engine, supplementary fuels (gasoline and ethanol) are individually premixed by port fuel injection prior to induction and combustion in the main diesel-injected combustion chamber. This study compared emissions and heat release patterns adjacent to the combustion stroke of a premixed diesel engine. A single-cylinder direct injection diesel engine was examined by varying the ratios of the supplementary fuel to diesel quantity to meet the set loads. The engine's target speed was 1600 rpm, and the brake mean effective pressures of 2, 5, and 7 bar were loads representing low-, medium-, and high-load operations, respectively. Results show that the gasoline premixture yielded higher thermal efficiency than the ethanol premixture. When the quantity of gasoline supplementary fuel increased, the thermal efficiency increased, whereas the opposite trend was observed with ethanol. The combustion phasing was delayed by increasing both supplementary fuel ratios. Quantities of nitrogen oxides, smoke, and total unburned hydrocarbon were reduced, and carbon monoxide increased with the elevated quantity of port-injected fuel. The ethanol–diesel dual fuel is advantageous regarding smoke opacity, but it suffers from nitrogen oxides trade-off.

Dual fuel ethanol port injection in a compression ignition diesel engine: Technical analysis, environmental behavior, and economic viability

The increase in prices, dependence on fossil fuels, and concerns about greenhouse gas emissions, and strict emissions regulations have motivated researchers to look for low carbon renewable fuels for internal combustion engines. Ethanol is one of these fuels due to its presence in the energy matrix of several countries. Among the methods applied to use ethanol in compression ignition engines, the primary technique currently studied is port fuel injection (PFI). This research studies the feasibility of using ethanol as a partial fuel in a generator set analyzed beyond the technical and environmental parameters and the economic aspect. The experiments were conducted in a diesel single-cylinder engine, with its original diesel fuel direct injection system, and added an auxiliary PFI system for the ethanol supply. The research gap is based on the lack of studies that include, in addition to the analysis of performance parameters and gaseous emissions, the economic viability assessment for the studied engine, which is also a fundamental factor in an actual application. The engine was tested under different conditions of six progressive replacements of diesel fuel by ethanol, starting only with diesel fuel (baseline test) and increasing ethanol mass fraction up to 0.634. The measured data showed that ethanol effectively increased ignition delay and reduced combustion duration, which did not lead to increased efficiency and reduced fuel consumption. The maximum in-cylinder pressure was 71.3 bar in the baseline test and dropped progressively to 51.6 bar when in the most significant substitution. The rate of heat release increased by about 92.5% with ethanol concerning the baseline test. When ethanol was used, the CO emissions decreased by up to 43%, resulting in about 2.4 g/kWh, while NOx emissions reduced by up to 20% compared to the baseline test, achieving 0.69 g/kWh. The economic analysis made it clear that the operational cost increased when the engine worked with ethanol replacing partially diesel fuel. However, with a slight increase in operational cost, especially in São Paulo (SP) state, it is possible to reduce pollutant emissions. For the baseline test, the operating cost was 0.354 U$/kWh. The specific fuel cost reaches a maximum of 0.441 U$/kWh, 25% higher than the respective baseline test, increasing ethanol fraction.

Effects of ethanol port injection timing and delivery rate on combustion characteristic of a heavy-duty V-12 diesel engine

Using biobased fuels in Diesel engines is an effective solution reduce the generation of toxic components in the exhaust gas. One of them, alcohol, is the potential fuel to reduce emissions and dependence on fossil fuels. So, this study is aimed to investigate the effects of ethanol port injection timing and delivery rate on the combustion characteristic of a heavy-duty V-12 Diesel engine when ethanol substitution percentage is 30% to reach the original diesel quantity at full load. The combustion characteristic analysis indicates that the variation in cylinder gas pressure and temperature decreases when retarded ethanol injection timing and decreased ethanol delivery rate, the engine works more smoothly due to the maximum rate of pressure rise decreases. However, the changes are greater when changing the ethanol injection timing as compared to ethanol delivery rate case.

Improvement of combustion and emission by combined combustion of ethanol premix and gasoline direct injection in SI engine

In this paper, a test platform for ethanol port injection plus gasoline direct injection was built to explore the effects of different ethanol-gasoline ratios (Re), direct injection timing (DIT) and ignition timing (IT) on the combustion and emissions of a SI engine. Results clearly show that when the total fuel contains more ethanol, the ignition timing corresponding to the maximum torque is smaller than the ignition timing when the total fuel contains more gasoline. Compared with the sole ethanol port injection (EPI) mode and gasoline direct injection (GDI) mode, G25 with EPI + GDI is the best mode for high-efficiency combustion and G25 with IT = 20°CA BTDC and DIT = 120°CA BTDC can be regarded as the optimal operating condition for highest torque output, braking thermal efficiency and lowest BSFC. As for exhaust emissions, CO and HC reach the lowest at G25 while NOx has an opposite trend. Delayed ignition within the range of 10-30°CA BTDC reduces HC and NOx emissions. As for particle number emissions, the size of peak particle number gradually decreases from G100 to G0, the accumulation particle number (APN) is further oxidized and shows a significant downward trend with the increase of ethanol. The lowest TPN was obtained at G25 in which the TPN has dropped by 9% and 85% respectively compared with sole EPI and GDI mode. When Re ≥ 50%, the nucleation mode particle number (NPN) in the total particle distribution is higher than the accumulation mode particle number, while there is an opposite result when Re＜50%. Overall, the findings of this paper make contributions to the development of high-efficiency and low-pollution combined engines and further promote the application of clean alternative fuels.

Effect of port injection of ethanol on engine performance, exhaust emissions and environmental factors in a dual-fuel diesel engine

This paper investigates the effect of ethanol addition and hot exhaust gas recirculation (EGR) on engine performance, exhaust emissions, and air-pollution damage-cost in a dual-fuel diesel engine. The ethanol is injected at low pressure into the intake manifold using a port-fuel injector while diesel fuel is injected directly into the cylinder. Only the duration of the ethanol injection is changed in the dual-fuel injection system while the diesel injection parameters are not changed. Ethanol fuel is added by port injection in such amounts as to provide additional heat energy in the range of 0–40% to the heat energy of the diesel fuel taken to the engine for any engine operating conditions. Moreover, 5%, 10%, and 15% rates exhaust gas recirculation (hot EGR) for each engine operating conditions are applied. The engine is operated at 1400, 1600, 1800 and 2000 rpm engine speeds at full load (≈40 Nm). In this paper, the highest improvement in engine performance and environmental factors is obtained with ethanol addition of 40% without the hot EGR at 1400 rpm. Under these conditions, the brake engine power ( BEP) and brake engine torque ( BET) increase of 6.9% and 8.1% while NOx emission and air-pollution damage-cost decreased of 32% and 23.9%, respectively. However, CO, HC, and smoke ( FSN number) emissions increased significantly. On the other hand, the brake thermal efficiency ( BTE) and brake specific energy consumption ( BSEC) are negatively affected by the ethanol addition and hot EGR.

Investigation of combustion and emissions of an SI engine with ethanol port injection and gasoline direct injection under lean burn conditions

In order to reach the goal of energy conservation and pollution emissions reduction, the combustion and emissions of a combined injection engine with ethanol port injection and gasoline direct injection under lean burn conditions are investigated in this paper. The experiments are carried out by using different direct injection timing (DIT), gasoline addition ratio (αgasoline) and excess air ratios (λ). The results indicate that Tmax declines after gasoline addition at λ = 1, 1.2, while increases after gasoline addition at λ = 1.4. The IMEP reaches the maximum value at DIT = 90 or 105 °CA BTDC and 0%, 10% and 30% gasoline addition bring the highest IMEP at λ = 1, 1.2 and 1.4, respectively. The COVIMEP decreases continuously with the increase of αgasoline and the EPI+GDI mode has great advantages in improving the combustion stability under λ = 1.4 condition. As for gaseous emissions, from λ = 1 to λ = 1.4, HC emissions change from increasing trend to the decreasing trend with the increase of αgasoline, while the NOx emissions show the opposite. As for particle number, at λ = 1 and 1.2, the total particle number (TPN) shows an upward trend with the increase of αgasoline. When λ = 1.4, TPN decreases with the increase of αgasoline.

Co-effects of fuel research octane number and ethanol injection ratio on dual-fuel spark-ignition engine

The combustion and emission characteristics of a dual-fuel spark-ignition engine with direct injection of gasoline surrogates and port injection of ethanol were studied. Toluene reference fuel with different research octane number namely TRF#1, TRF#2, TRF#3, TRF#4 and TRF#5 were employed as gasoline surrogates, in which TRF#1 with high octane number was to simulate commercial gasoline under direct-injection spark-ignition mode as comparison. For dual-fuel spark-ignition mode, the ethanol port-injection ratios were 21%, 25%, 29%, 32% and 35%, respectively. The results demonstrated that with the increase of the ethanol ratio, the knock-limited spark timing was advanced gradually. The emissions of hydrocarbon, ethane, propylene, isopentane, cyclohexane and aromatic hydrocarbons reduced while CO, NOx, ethylene, acetaldehyde and ethanol increased. Compared to TRF#1 in direct-injection spark-ignition mode, the indicated thermal efficiencies of dual-fuel spark-ignition mode were slightly lower under most test conditions. When direct injection of TRF#3, TRF#4, TRF#5 and the ethanol ratio was higher than 29%, some of the indicated thermal efficiencies of the engine were consistent with or higher than that of TRF#1 in direct-injection spark-ignition mode. Based on dual-fuel spark-ignition mode and with the assistance of port injection of ethanol, the indicated thermal efficiency of low research octane number fuels was comparable to that of TRF#1 in direct-injection spark-ignition mode.

Engine performance and octane on demand studies of a dual fuel spark ignition engine with ethanol/gasoline surrogates as fuel

For gasoline preparation, it is necessary to control the fuel’s octane number, which often affects production costs. Ethanol is widely used as gasoline alternative fuel with high octane number. In this paper, based on a modified dual fuel spark ignition engine, studies of port injection of ethanol and direct injection of gasoline surrogates (toluene reference fuel) were conducted. The results revealed that when direct injection of toluene reference fuel with research octane number of 90, with the increase of ethanol injection ratio, the flame development duration and rapid combustion duration were prolonged (about 2°CA and 3°CA, respectively). Meanwhile, nitrogen oxide emissions, total hydrocarbon emissions, ethane, isopentane, cyclohexane, olefins and aromatics gradually decreased. For direct injection of fuels with different research octane number and port injection ratio of ethanol fixed at 21%, even when the research octane number of gasoline surrogates was as low as 75, the combustion history and engine efficiency were close to those of fuel with research octane number of 95. In particular, the indicated thermal efficiency of dual fuel spark ignition mode with direct injection of fuel with research octane number of 75 combined with 35% ethanol ratio was similar to that of direct injected spark ignition mode fueled with research octane number of 95 under respective knock limited spark timings.

Experimental investigation on combustion characteristics in dual-fuel dual-injection engine

Dual-injection strategy combined with dual-fuel can provide flexible and instantaneous blend ratios according to engine demands under different operating conditions. Furthermore, ethanol direct injection has the potentials to increase the engine compression ratio and thermal efficiency by taking advantages of ethanol fuel such as the high octane number and latent heat. Therefore, in order to maximize the charge cooling effect, a dual-fuel (gasoline and ethanol) dual-direct injection system is proposed and investigated in this paper. In current work, different injection modes in terms of knock suppression and combustion performance are compared and studied on a single-cylinder SI engine with stoichiometric air/fuel ratios. The results show that the new injection strategy of dual-fuel dual-direct injection mode can significantly expand engine load compared with conventional modes of gasoline direct injection plus ethanol port injection and ethanol direct injection plus gasoline port injection. Direct injection ethanol mode can reduce knocking tendency. However, with higher brake mean effective pressure, dual-fuel dual-injection mode shows higher knock tendency. Dual-fuel dual-injection mode can increase brake mean effective pressure and thermal efficiency simultaneously. However, the brake thermal efficiency behavior is non-linear when increasing brake mean effective pressure and direct injection ethanol mass fraction. The equivalent heat value brake specific fuel consumption decreases with the increase of direct injection ethanol ratio, and dual-fuel dual-injection mode has superior fuel conversion efficiency. Relatively high maximum pressure can be found in dual-fuel dual-injection mode. With the increase of ethanol ratio, the combustion phasing is further advanced, resulting in better combustion, which contributes to higher thermal efficiency.

Experimental investigation on the effects of nozzle-hole number on combustion and emission characteristics of ethanol/diesel dual-fuel engine

Since fuel reactivity stratification greatly influences the combustion process of dual-fuel engines and nozzle geometry directly affects the distribution of direct injected fuel, experiments were carried out to investigate the effects of nozzle-hole number on the combustion and emissions of dual-fuel engine. The experiments were performed on a single-cylinder diesel engine with port injection of ethanol and direct injection of diesel. There are four diesel injectors with 4, 5, 6 and 8 nozzle holes studied in this paper, while the total orifice areas and included spray angles of the injectors are kept the same. With reduced nozzle holes, the experimental results showed that both the in-cylinder peak pressure and PPRR (peak pressure rise rate) of ethanol/diesel dual-fuel combustion were decreased while with extended combustion durations. This is mainly because the number of high fuel reactivity regions was reduced with fewer diesel sprays, then the combustion of premixed ethanol was slowed down which consequently decreased the heat release rate. With reduced nozzle holes, the engine-out NOx emissions were decreased, and soot emissions were slightly increased while still maintained at quite low level. The UHC and CO emissions were slightly increased with reduced nozzle holes which resulted in lower combustion efficiency. However, the influences of nozzle-hole number on dual-fuel combustion were gradually decreased with advanced injection, which was mainly because of the enhanced diesel/air mixing. The experimental results indicated that dual-fuel combustion with reduced nozzle holes could achieve moderate heat release with lower PPRR.

Genotoxicity of Diesel Particulate Matter Emitted by Port-Injection of Hydrous Ethanol and n-Butanol

This work evaluated the genotoxic potential of the soluble organic material (SOM) extracted from the particulate matter (PM) emitted by an automotive diesel engine. The engine was modified to operate with a home-made multipoint-port injection system to substitute 10% of ultralow-sulfur diesel (ULSD) fuel in energy basis by hydrous ethanol (h-Et) or n-butanol (n-Bu) injected into the manifold during the intake stroke. A low engine load mode named M4 (43 N·m at 2410 min−1) and a medium-load mode M2 (95 N·m at 2410 min−1) were selected from the vehicle homologation cycle. PM was collected with a stainless steel filter located 1.5 m downstream the exhaust manifold. The SOM of the PM was extracted to evaluate the genotoxic activity on human lymphocytes using the comet assay. Results indicated that independently of the mode, the SOM coming from alcohols led more genotoxicity than ULSD, following the order h-Et > n-Bu > ULSD. The low engine load operation exhibited much more deoxyribonucleic acid (DNA) damage than mode M2, especially the PM produced by hydrous ethanol port-injection. Although further research is still necessary, these findings suggest that the biology activity of the SOM coming from alcohols PM could be a barrier for the implementation of alcohol port-injection technology.

Combustion, performance and emissions of a diesel power generator with direct injection of B7 and port injection of ethanol

This work investigates a diesel engine operating with diesel oil containing 7% biodiesel (B7) and hydrous ethanol with concentrations varying from 5 to 30%. The experiments were conducted in a 49-kW diesel power generator, equipped with an electronic ethanol injection unit installed in the intake manifold and without any modifications in the diesel oil injection system. The results showed a decrease of in-cylinder pressure and net heat release rate with the use of ethanol at low loads and an increase at high loads, in comparison with B7. Increasing ethanol injection caused increased ignition delay and decreased combustion duration. Fuel conversion efficiency was raised up to 13% with the use of ethanol. The use of 30% ethanol in the fuel caused a reduction of carbon dioxide (CO2) emissions up to 12% and nitric oxide up to 53%. Carbon monoxide, total hydrocarbons and oxides of nitrogen (NOX) emissions increased with ethanol addition. The replacement of 20% of diesel fuel by ethanol showed the lowest penalties on NOX emissions.

Experimental and numerical investigations on the cyclic variability of an ethanol/diesel dual-fuel engine

Experiments and simulations were used to explore the cyclic variability of an ethanol/diesel dual-fuel engine. The experiments were conducted on a light-duty diesel engine fueled with port injection of ethanol and direct injection of diesel. The influences of engine load, ethanol proportion and diesel injection timing on the cyclic variability were investigated. In-cylinder pressure traces of 150 consecutive cycles were acquired at each test condition. Consequently, cyclic variations of ignition timing (CA5), combustion phasing (CA50), accumulated heat release (Qf) and indicated mean effective pressure (IMEP) were used to quantify the cyclic variability. The experimental results showed that the fluctuations of CA5 and CA50 were very small throughout the premixed ratio sweep for both the light and high loads. However, the cyclic variation of IMEP was increased with the increasing ethanol ratio at both load conditions. And the cyclic variation of IMEP was reduced at the high load. The variations of IMEP and Qf showed similar magnitudes and trends at the test conditions, indicating that the cyclic variation of IMEP was mainly caused by the variation of Qf. Simulations confirmed that the combustion of premixed ethanol showed larger variations to initial in-cylinder temperature fluctuations at the light load, and consequently resulted in higher cyclic variation of Qf. At the high load, the increased combustion temperature enhanced the oxidation of ethanol, which contributed to stabilizing the combustion and reducing the cyclic variations. The cyclic variations increased with retarded diesel injection timing, which was mainly due to the reduced combustion temperature.

Experimental studies on combustion and emissions of RCCI (reactivity controlled compression ignition) with gasoline/n-heptane and ethanol/n-heptane as fuels

This paper presents an experimental study on the combustion and emissions characteristics of RCCI (reactivity controlled compression ignition) combustion in which in-cylinder direct injection of n-heptane combined with port injection of ethanol and gasoline, respectively, are used with a single-cylinder engine. Results show that, when the system is fueled with ethanol/n-heptane at a specific overall lower heating value per-cycle, the ignition delay of RCCI combustion increases greatly but the in-cylinder temperature and pressure drop severely for a larger premixed ratio. NOx and soot emissions are significantly improved for RCCI combustion under conditions of increased premixed ratio. At different premixed ratios, the HC (hydrocarbon) emission of gasoline/n-heptane is lower than that of ethanol/n-heptane, but the NOx and soot emissions are higher than those obtained with ethanol/n-heptane. When the premixed ratio is approximately 0.57, the indicated thermal efficiencies of both gasoline/n-heptane and ethanol/n-heptane reach their maximum values. When fueled with ethanol/n-heptane along with the increase in engine load, CO, NOx and soot emissions are lower than fueled with gasoline/n-heptane, but the HC emissions are higher. When IMEP (indicated mean effective pressure) is higher than 6 bar, the indicated thermal efficiency of ethanol/n-heptane is higher than that of gasoline/n-heptane. Ethanol is a good candidate to replace gasoline as port injected fuel in RCCI mode at heavy loads.

A study on the combustion and emission characteristics of an SI engine under full load conditions with ethanol port injection and gasoline direct injection

Abstract Ethanol has the potential to improve engine efficiency and reduce harmful emissions when used as fuel in a spark-ignited engine. Ethanol is mostly supplied in a splash-blended form with gasoline or in a pure form; however, this is not an optimal way of using ethanol because the use of ethanol leads to increased brake specific fuel consumption. To fully utilize the merits of ethanol, on-demand control of ethanol and gasoline is required so that the fuel-blending ratio can be altered according to the engine operating conditions. This study investigated the effect of ethanol port fuel injection and gasoline direct injection systems on engine combustion and emission characteristics under full load conditions. The experiment was conducted using two different compression ratios and various ethanol injection timings. Knock occurrence decreased as the ethanol injection timing was held while intake valves were open. Minor reductions in carbon monoxide, total hydrocarbon, and particulate emissions were observed under a compression ratio of 9.5, while the reduction in emissions became significant under a compression ratio of 13.3 as the amount of ethanol injection increased.

Study of Cylinder Charge Control for Enabling Low Temperature Combustion in Diesel Engines

Suitable cylinder charge preparation is deemed critical for the attainment of a highly homogeneous, diluted, and lean cylinder charge, which is shown to lower the flame temperature. The resultant low temperature combustion (LTC) can simultaneously reduce the NOx and soot emissions from diesel engines. This requires sophisticated coordination of multiple control systems for controlling the intake boost, exhaust gas recirculation (EGR), and fueling events. Additionally, the cylinder charge modulation becomes more complicated in the novel combustion concepts that apply port injection of low reactivity alcohol fuels to replace the diesel fuel partially or entirely. In this work, experiments have been conducted on a single cylinder research engine with diesel and ethanol fuels. The test platform is capable of independently controlling the intake boost, EGR rates, and fueling events. Effects of these control variables are evaluated with diesel direct injection and a combination of diesel direct injection and ethanol port injection. Data analyses are performed to establish the control requirements for stable operation at different engine load levels with the use of one or two fuels. The sensitivity of the combustion modes is thereby analyzed with regard to the boost, EGR, fuel types, and fueling strategies. Zero-dimensional cycle simulations have been conducted in parallel with the experiments to evaluate the operating requirements and operation zones of the LTC combustion modes. Correlations are generated between air–fuel ratio (λ), EGR rate, boost level, in-cylinder oxygen concentration, and load level using the experimental data and simulation results. Development of a real-time boost-EGR set-point determination to sustain the LTC mode at the varying engine load levels and fueling strategies is proposed.