Higher In-cylinder Temperature Research Articles

Exploring the benefits of hydrogen-water injection technology in internal combustion engines: A rigorous experimental study

Previous hydrogen researchers have demonstrated the great potential of hydrogen as a zero-carbon fuel and its wider operational ability to directly replace the existing fossil-fuelled internal combustion engines (ICE). Hydrogen direct-injection technology can operate at stoichiometric combustion conditions, fully eliminating the intake backfire phenomena, which has the benefit of low airflow requirements and is a suitable solution for naturally aspirated ICE platforms. However, significant challenges must be addressed when operating an H2 ICE at or near stoichiometric. These include rapid pressure rise rate, high in-cylinder gas pressure and temperature and the consequential higher engine-out NOx emissions. This study provides a comprehensive experimental analysis of the effect of water injection on a light-duty H2 engine’s performance, efficiency, burn durations and NOx emission. The engine was modified to operate with hydrogen via a centrally-mounted direct H2 injector and an intake port-mounted water injection system. The study included water vapour measurements, NOx concentrations and other exhaust gases. The practical implications of these findings are significant. The results demonstrated that the NOx emissions were reduced by 79% when the water was injected at a rate of 5 kg/h at 10 bar IMEP and 2000 rpm. This reduction in emissions, coupled with the observed decrease in cylinder pressure and the rate of pressure rise, could substantially improve engine performance and efficiency. At higher load regions, the water injection extended the maximum engine load to 24 bar IMEP and increased the engine torque output by 10%. The maximum Indicated Thermal Efficiency (ITE) increased from 41% at 16.5 bar IMEP to 42.5% at 18 bar IMEP at a lower lambda, with a corresponding reduction in the intake-air-boost pressure requirement. Of particular note, the use of water injection decreased the engine-out NOx emissions under high-load conditions by more than 55%, even at richer AFR compared to pure hydrogen operation.

Numerical study of the combustion process and NOx evolution mechanism of ammonia-hydrogen compound fuel engine under different intake conditions

To explore the distinction between generation atmosphere of fuel NOx and thermal NOx in an ammonia-hydrogen compound fuel engine, a numerical calculation model was established based on a detailed ammonia-hydrogen oxidation mechanism. The combustion process and NOx evolution mechanism of the ammonia-hydrogen compound fuel engine under different intake conditions were studied. The researchresults for different equivalence ratios show that the in-cylinder hydrogen volume is the primary factor influencing the initial heat release. When the equivalence ratio is between 0.89 and 1.14, the mixture exhibits a higher combustion rate, leading to a shorter CD and an earlier CA50. At this point, the heat release process closer to TDC contributes improving engine combustion efficiency and indicated efficiency. Therefore, when the equivalence ratio is between 0.89 and 1.00, combustion efficiency is higher than 98 % and indicated efficiency is higher than 43 %, the ammonia-hydrogen compound fuel engine achieves relatively higher economy. Both over-rich and over-dilute mixtures induce an enhancement of fuel NOx, while the higher in-cylinder temperature caused by stoichiometric combustion leads to a boom of thermal NOx. Consequently, the total NOx emission from the ammonia-hydrogen compound fuel engine is higher at equivalence ratios between 0.80 and 1.00, and the NOx emission reaches its peak at an equivalence ratio of 0.89. Analysis of the evolution process of key N components in the cylinder shows that incomplete combustion plays a significant role in fuel NOx emissions, while thermal NOx emissions are mainly influenced by the distribution of in-cylinder components and combustion temperature. Specifically, thermal NOx emissions primarily depend on the in-cylinder components distribution in the narrow equivalence ratio range around stoichiometric ratio, and are significantly affected by in-cylinder temperature under other conditions. The in-cylinder oxygen concentration significantly affects fuel NOx emissions under most operating conditions. Further optimization of intake temperature shows that combustion efficiency exceeds 90 % when the intake temperature is above 280 K. When the intake temperature reaches 310 K, the combustion efficiency reaches up to 98 %, thus an intake temperature of about 310 K is sufficient to meet the need for improving the combustion efficiency of ammonia-hydrogen compound fuel engine. To achieve high efficiency and lower NOx emissions, appropriate lean combustion combined with an intake temperature slightly above room temperature is recommended.

Dynamic coupling effects of injection on spray and mixture formation in an asymmetrically vibrating combustion engine

Enhanced methods of energy conversion present a viable solution for addressing energy load challenges. This study introduces a vibrating combustion engine designed to enhance energy conversion efficiency by harnessing flexible dynamics and variable asymmetric motion. However, the consideration of its unique dynamic effects has emerged as a pivotal challenge in fuel-air mixing and combustion research. This study introduces a fuel spray and mixing simulation method that facilitates the reciprocal exchange of coupling parameters between the combustion and dynamics models. It iterates the simulation outcomes of motion and combustion to predict mixture formation. Subsequently, the method is employed to explore the impact of injection position on fuel spray and mixture formation. Results show that there is an optimum injection position for the operation frequency, and retarding or advancing leads to slow compression and weak gas motion for fuel spray and mixing, although retarded injection provides high in-cylinder gas pressure and temperature. The early injection generally causes long penetration, small droplet diameter, slight impingement, and fast evaporation, unless it is too early. The results further indicate that when IAP = 6 mm, a more uniform mixture can be attained at the beginning of combustion, leading to a thermal efficiency of up to 42.9% for the engine.

Performance and sensitivity analysis of raw biogas combustion under homogenous charge compression ignition conditions

This study aims to investigate the feasibility of using raw biogas as the main fuel in homogeneous charge compression ignition (HCCI) engines and to identify the effects of different trace elements found in biogas on engine performance and emissions. This study was conducted using many models that simulate the operation of HCCI process. These models include the chemical kinetics, combustion model, and the heat transfer models. Raw biogas composition was selected based on the most available traces. The traces that were studied are Hydrogen Sulfide (H2S), Ammonia (NH3), Carbon monoxide (CO), Nitrogen (N2), Oxygen (O2), and Water vapor (H2O). Other parameters like the equivalence ratio, intake temperature, and pressure were also studied. It was found that raw biogas mixtures could produce higher power outputs in the presence of H2S and NH3. However, H2S and NH3 were found to increase the SOx and NOx percentages owing to their higher in-cylinder temperatures. Other traces such as CO and H2O can reduce the power output, but at the same time, they can reduce the engine NOx emissions but not the CO emissions. Engine performance was positively affected by increasing the intake pressure and equivalence ratio within the studied ranges. However, higher intake temperatures and reduce the engine efficiency and increase the engine emissions. On the other hand increasing the compression ratio (CR) increase the system efficiency but up to a certain limit. Considering the exhaust gas residual (EGR), this parameter reduce system performance but at the same time lower the NOx emissions significantly. A sensitivity analysis for the mentioned parameters indicates that EGR is the most effective parameter while CR are the least significant one.

Effective Utilization of Waste Cooking Oil Methyl Ester-Diesel blends in a Semi-Adiabatic CI Engine – An Experimental Approach

The utilization of energy produced in an internal combustion (IC) engine plays a key role in improving engine performance. Thermal Barrier Coating (TBC) is one of the effective engine modification methods to utilize the energy effectively in an IC engine. The alternative fuels with very poor fuel properties can be fuelled successfully in a TBC mode. In this study, an investigation was carried out in a TBC, single-cylinder, diesel engine fuelled with waste cooking oil-diesel blend. In the first phase, the waste cooking oil methyl ester (WCOME) is fuelled in the standard engine for the performance, combustion and emission characteristics. In the second phase, the WCOME blend with diesel to an appropriate percentage of 20% by volume (WCOMEB20) and tested in the standard engine for the characteristics. In the third phase, the standard engine is converted to TBC mode. The engine combustion chamber components such as piston crown, cylinder head, inlet and exhaust valve were coated with bond coat nickel, chromium, aluminium alloy (NiCrAl) thickness 100 microns and ceramic coat of 8% yttria stabilized zirconia (8%YSZ) with a thickness of 200 microns. In the fourth phase, the WCOMEB20 was fuelled in the TBC mode for the characteristics and finally, the results were compared. From the experimental result, it was come known that WCOMEB20 showed betterment in the fuel properties such as viscosity, density, and cetane index compare with the neat WCOME. The substantial improvement in the performance and exhaust emissions such as carbon monoxide (CO), unburnt hydrocarbon (UHC), and smoke opacity with WCOMEB20 compared with neat WCOME. Furthermore, the TBC mode fuelled with WCOMEB20 experienced a supreme enhancement in the performance, combustion and emission except nitric oxide (NO). This improvement was due to the betterment in the fuel properties with WCOMEB20 and high in-cylinder temperature with TBC which enhanced the combustion and reduce the unburnt charges present inside the combustion chamber. From the above finding, it was concluded that WCOMEB20 fuelled with TBC mode was an effective fuel and engine modification technique to improve the performance, combustion and emission characteristics of a diesel engine.

Numerical Optimization of the EGR Rate and Injection Timing with a Novel Cavitation Model in a Diesel Engine Fueled with PODE/Diesel Blends

Polyoxymethylene dimethyl ether (PODE) is one of the most promising alternative fuels for diesel engines with a high cetane number, high oxygen content, and no C-C bonds. In this paper, a new spray model with a novel cavitation sub-model is adopted in order to create a numerical model suitable for engine simulation fueled with PODE/diesel blends. The effects of the blending ratio, injection timing, and EGR rate on the combustion and emission characteristics are investigated by the simulation. The simulation results show that the self-restoring oxygen properties of PODE can efficiently improve the combustion, causing a higher in-cylinder temperature, and therefore, higher NOx emissions. Additionally, with the increase in the blending ratio, the increase in the oxidation activity of PODE/diesel blends and the improvement of atomization are conducive to reducing soot emissions. Then, the injection timing and EGR rate are optimized. The numerical results suggest that the NOx emissions decrease initially and then increase; however, soot emissions decrease monotonically with the delay of the injection timing. When the volume blending ratio is 15%, the emission performance is best when the injection timing is between 710 °CA and 715 °CA. The increase in EGR rate can effectively reduce the in-cylinder temperature and control the NOx emissions, but the excessive EGR rate leads to higher soot emissions and a deteriorated combustion process. Therefore, an EGR rate in the range of 0.0 to 0.2 has a better comprehensive emission performance from the perspective of controlling both the NOx and soot emissions.

Effect of hydrogen sulfide content on the combustion characteristics of biogas fuel in homogenous charge compression ignition engines

The use of biogas fuel in homogeneous charge compression ignition (HCCI) engines has been promoted recently due to the environmental advantages. However, hydrogen sulfide (H2S) forms a non-environment friendly content and biogas impurity that its removal is associated with high costs. In this study, the effect of using biogas fuel in the HCCI engines under different operating conditions is investigated to shed light on the best scenarios of biogas combustion, even with the presence of H2S contents. A modified reaction mechanism is introduced by considering the reactions of H2S with other species in the air-fuel mixture. The new chemical kinetics model, and a multi-zone combustion approach, have been validated against experimental data from the literature and then used to simulate the HCCI combustion of biogas fuel. It was obtained that having up to 3.8% content of H2S in the intake charge can enhance the rate of heat release and combustion pressure. However, it had no significant effect on the in-cylinder temperature profile. Higher rates of H2S contents led to produce higher rates of sulfur oxides (SOx) emissions. Increasing the equivalence ratio (up to 0.50) results in a higher in-cylinder temperature and pressure as well as a higher SOx and nitrogen oxides (NOx) emissions. Also, the HCCI combustion is influenced by the intake temperature and pressure, where increasing those parameters leads to an increase in the in-cylinder temperatures and pressures, as well as the NOx emissions. However, SOx emissions are affected only when the intake temperature reaches over 400K and the intake pressure is over 1.5bar.

Effect of the Hydrogen Injection Position on the Combustion Process of a Direct Injection X-Type Rotary Engine with a Hydrogen Blend

As a new type of power device, the X-type rotary engine (XRE) is regarded as a major revolution of the internal combustion engine with its special structure and high-efficiency hybrid cycle (HEHC). A 3D CFD model of an XRE with hydrogen–gasoline fuel is firstly built in this paper. The gasoline is premixed with air in the intake of the XRE. The hydrogen is directly injected (DI) into the cylinder with four different injection positions. The effects of the hydrogen injection position on the combustion process, engine thermodynamic performance, and unburned carbon emissions and NOx emissions are investigated. The results show that, due to the interaction between the in-cylinder main flow field and the injected hydrogen gas flow, different hydrogen concentration zones are formed at different injection positions. Furthermore, a larger hydrogen distribution area and being closer to the ignition position led to a faster in-cylinder combustion rate and a higher in-cylinder temperature and pressure. When the injection position is from the front to the back of the combustion chamber such as in position 2, the hydrogen has the widest distribution area and is closest to the ignition position, resulting in its fastest combustion speed. Meanwhile, the peak in-cylinder pressure is 3.73 MPa and the peak temperature is a maximum of 1835.16 K. Especially, the highest indicated thermal efficiency of 26.56% is found in position 2, which is 10.08% higher than that of position 4 (from right to left of the combustion chamber), which was 24.13%. At the same time, due to the best overall combustion effect, position 2 presents the lowest final unburned carbon emission of 0.36 mg, while it produces the highest NOx emission of 9.15 μg. Thus, this study provides important theoretical guidelines for the hydrogen injection strategy of the XRE using hydrogen–gasoline fuel.

Experimental investigation on the performance of the prototype of aircraft Opposed-Piston engine with various values of intake pressure

Over the last few decades, we have observed significant changes in the automotive and aviation sector regarding emission reduction and performance improvement. It is said that electrification is the main direction for the automotive industry, especially for short distances; thus, car manufacturers provide their vehicles with fully electric or hybrid engines. However, such an objective is difficult for the aviation industry, where flight endurance plays a key role, especially for small aircraft. For this reason, turbocharged internal combustion and small turbine engines are still widely used in such aircraft.This paper presents the experimental investigation of the intake pressure influence on the axial-opposed piston engine's performance, which might be used for aviation purposes. The experimental results were conducted on a prototype, axial opposed-piston engine PAMAR 4 equipped with the two-stage turbocharging system. Thanks to its variable systems, such an engine provided a wide range of intake pressure values. The tests were performed for intake pressure values up to 453 kPa. The experimental tests proved that the engine efficiency increased with the intake pressure. However, the engine's durability and reliability might be significantly affected due to the high in-cylinder pressure and temperature.

Influence of Simarouba Glauca (Laxmi taru) biodiesel on engine performance and emissions of conventional compression ignition engine

The present paper reports the performance and emission studies for a four stroke single cylinder CI-DI unmodified engine using laxmi taru biodiesel as fuel. Laxmi taru biodiesel has 80% potential of extracting oil from the seeds as compared to other biofuels. The properties of laxmi taru biodiesel fuel nearly match the properties of diesel fuel. In this paper performance and emission tests are conducted for different blends such as S0 (0% laxmi taru + 100% diesel), S5, S10, S20, S40 by volume. At full load conditions (4.9 kW) brake thermal efficiency (BTE) decreased for S5, S10, S20 and S40 blends by 3.26%, 4.53%, 3.16% and 5.54% respectively as compared to diesel fuel operation because of poor heating value of laxmi taru biodiesel. Presence of oxygen content in the fuel and better combustion leads to decreased carbon monoxide (CO) emission for S5, S10, S20 and S40 blends by 4%, 8%, 12% and 28% as that of diesel. Similarly hydrocarbon (HC) emission reduced by 16.21%, 24.32% and 29.7% in S10, S20 and S40 blends respectively. Oxides of Nitrogen (NOx) emission increased by 27.19%, 30.57%, 15.2% and 19.3% for S5, S10, S20 and S40 blends respectively in comparison with diesel fuel, under full load conditions due to high incylinder temperature. Usage of laxmi taru biodiesel in CI engines resulting in drastic reduction in carbon based (CO, HC) emissions without altering the performance of the engine. Therefore laxmi taru biodiesel is better alternate fuel for CI engines.

Colorless distributed combustion (CDC) effects on a converted spark-ignition natural gas engine

This study examines combustion and emission characteristics of a converted-engine, which suggests that a diesel engine with high compression ratio is transformed to a spark-ignition engine through natural gas addition coming from the intake port. The pollutant emissions such as NOX for the converted-engine pollutant is generally higher than that of a diesel-engine along with higher in-cylinder temperature. Those challenges can be overcome through new and novel combustion methods such as colorless distributed combustion (CDC). Colorless distributed combustion is a method that provides ultra-low pollutant emissions, a more uniform thermal field and reduced combustion noise along with mitigated flame instability. CDC is basically achieved by reducing oxygen concentration in the oxidizer. That decrease can be provided with recirculation of hot combustion products into the oxidizer. In order to achieve CDC, N2 as the diluent was entrained into the fuel-oxidizer mixture from 23 % to 13 % O2 concentrations by mass. The converted-engine representing a tractor engine operated at 2300 rpm and full load was investigated numerically to obtain its performance, combustion and emission characteristics under CDC conditions through ANSYS Forte 3-Dimensional analysis program. G-equation combustion model with methane chemical kinetic mechanism consisting of 29 species and 171 equations, and RANS k-e turbulence model were selected for all modelings. According to the results predicted, it is demonstrated that for the converted engine there has been an improvement of up to 29% in terms of performance. In addition, it is concluded that a 97.66% decrease in NOX emission has been achieved without reducing the combustion performance of the converted engine under CDC.

CFD-guided optimization of the injector and injection parameters for light-duty GCI engine

In this study, computational fluid dynamics (CFD) and machine learning (ML) were used to investigate the effects of and optimize the injector design parameters for light-duty gasoline compression ignition (GCI) engine. This study was performed at part- (6 bar) and high-load (22 bar) indicated mean effective pressure (IMEP) conditions. The effects of number of nozzles (nNoz), spray angle (SA) and plume angle (PA) while maintaining total nozzle area (TNA) and start of injection (SOI) were first investigated. The increased nNoz and PA enhanced fuel/air mixing, especially in the bowl region, by even spray distribution at part-load condition, but the effects are negligible at high-load mixing-driven combustion due to high in-cylinder temperature and pressure at the time of main injection. On the other hand, SA had significant effect on the air utilization and hence engine performance and emissions at both part- and high-load conditions. The best design from this manual parametric study produced a balanced air utilization between piston bowl and squish region resulting from the fuel spray targeting the upper lip of the bowl. The second phase of this study focused on the optimization of the injector and injection parameters including nNoz, SA, nozzle hole diameters (dNoz) and SOI using design of experiment (DoE) approach. 32 DoE cases were generated and best design was selected at each load point. It was found that the SA and SOI are the most influential injection parameters. Specifically, two optimum SOI regimes at part-load conditions have been identified. These are a) early injection resulting in retarded combustion and low pressure rise rate and b) late injection yielding high combustion efficiency and low hydrocarbon emission. At high-load condition, SOI right before top dead center (TDC) is most preferable and early injection should be avoided to minimize pressure rise rate. The narrow SA (90 degrees (deg) in this study) as well as wide SA were found to produce optimum performance. Subsequently, ML algorithm was used to further optimize the injector and injection parameters. As a result of this optimization study, 10.7% reduction of fuel consumption at part-load and 7.5% reduction at high-load were achieved.

Evaluation of composition and carbon atoms distribution of the exhaust hydrocarbons by varying post-injection parameters in DI diesel engine

This study was aimed to explore the effects of different post-injection parameters on the cracking, formation mechanism, composition, and carbon atoms distribution of exhaust hydrocarbon (HC) compounds of the diesel engine. The influence of three post-injection fuel masses (PIM) and six dwell duration with different start of injection (SOI) timings were assessed with an operating speed of 1000 rpm and a basic engine load of 0.5 MPa. Post-injection strategy greatly influenced the composition and carbon atoms distribution of exhaust gases emissions. It was noted that the formation of light HC species was lowered during early post-injection at SOI 20-40° crank angle (CA) due to the high in-cylinder temperature and more oxidation but increased as the SOI delayed due to more cracking of diesel fuel. An increase in the PIM also increased the formation of HC species at all SOI. Peak values of C1 (one carbon), C2 (two carbon), and C3 (three-carbon) compounds were recorded at SOI 60°CA with 15 mg PIM respectively, and the maximum value of 2700 ppm was observed for non-methane hydrocarbon (NMHC) at SOI 80°CA. While higher HC (C8) compounds achieved a peak of 275 ppm at SOI 80°CA with 15 mg PIM. At early SOI 20-40°CA, lighter HCs compounds concentration fractions were accounted for about 50–80% of THC emissions with 5–15 mg PIM. While at later SOI 80-120°CA C8 concentration fractions were dominant over all other HC fractions occupying a concentration fraction of more than 50% with 5, 10, and 15 mg PIM.

An experimental study on emission characteristics in compression ignition engine with silver and zinc coated catalytic converter

Effect of harmful emission like oxides of nitrogen (NOx) and smoke (or) particulate matter (PM) from automobile vehicles to the environment become an addressable topic nowadays. In general NOx and smoke levels are slightly higher in diesel engine compared to petrol engine due to excess Oxygen (O2) supply, high in-cylinder temperature & improper mixing (Heterogeneous mixture) of fuel & air. These emissions are normally controlling by either combustion or by after treatment process. To control these emissions in after treatment process, three-way catalytic converter coated with noble materials like platinum, palladium & rhodium is used in diesel as well as petrol engines. In this present work, various emission characteristics were studied in single cylinder, water cooled, four stroke direct injection diesel engine with and without silver & zinc coated catalytic converter. Experimental results shown that diesel engine with silver (Ag) & zinc (Zn) coated catalytic converter provide 70% of reduction in NOx, 60% of reduction in CO, 55% of reduction in HC and 40% of reduction in CO2 emissions respectively at the exhaust pipe in full load condition compared with conventional diesel engine.

Exploring the Effects of the Key Multi-Injection Parameters on Combustion and Emissions in Intelligent Charge Compression Ignition (ICCI) Mode

<div class="section abstract"><div class="htmlview paragraph">Developing advanced combustion mode has been the active area for high efficiency and ultra-low emissions of the next-generation internal combustion engines. In this paper, a series of experiments were conducted in a modified single-cylinder compression ignition engine for operating a brand-new combustion mode denoted as intelligent charge compression ignition (ICCI) mode. By using two common-rail systems, commercial gasoline and diesel were alternately directly injected into the cylinder through multi-injection strategies in the injection timing range of 50~320 °CA BTDC. Thus, the in-cylinder stratified condition can be flexibly and accurately adjusted in this unique combustion mode. The key injection parameters, such as gasoline injection timing and diesel split ratio, were investigated to explore their effects on engine combustion, emissions, and fuel consumption. The results showed that the diesel split ratio mainly affected combustion phasing, while the gasoline injection timing had significant effects on the peak value of in-cylinder pressure and pressure rising rate. Higher diesel split ratio in early injection caused earlier combustion phasing and higher in-cylinder temperature, leading to higher NOx emissions, but the accumulation mode particle was decreased. Besides, when more gasoline was injected in compression stroke to form more homogeneous cylinder condition, lower NOx emissions of 0.1 g/kWh were reached, meeting EURO VI standard. Furthermore, lower CO emissions and fuel consumption can be obtained simultaneously, while the accumulation mode particle decreased along with nucleation mode increasing. However, peak pressure and peak pressure rising rate were increased because of more concentrated heat release. HC emissions of all the experimental cases had few vary in the experiment.</div></div>

Experimental investigation on lean burn spark ignition engine using alcohol-gasoline blends

This study discusses the effects of addition of small amount of alcohols on performance and emission behaviour of a gasoline fuelled lean burn SI engine. Experiments were carried out in a single cylinder diesel engine, which is made to operate as SI engine on lean condition with gasoline as a fuel. The engine was operated at wide open throttle at a compression ratio of 10.5:1 and 1,500 rpm at diverse equivalent ratios by injecting the fuel into manifold. The test outcomes stipulate that use of ethanol-gasoline blend (10% by volume) was better compared with methanol-gasoline blend (10% by volume) and pure gasoline. The test results also revealed that there was 2.5% and 7.5% improvement in brake thermal efficiency with M10 and E10 blends and apparent extension in the lean limit of operation with alcohol-gasoline blends. In emission front, reduction in hydrocarbon and carbon monoxide emissions were observed. However, carbon dioxide and nitric oxide emissions were increased due to better combustion and high in-cylinder temperature. On the whole it is concluded that small alcohol addition to gasoline improves performance and reduce emissions for lean operating SI engine.

Experimental based comparative exergy analysis of a multi-cylinder spark ignition engine fuelled with different gaseous (CNG, HCNG, and hydrogen) fuels

The experimental investigation was carried out on a multi-cylinder spark ignition (SI) engine fuelled with compressed natural gas (CNG), hydrogen blended CNG (HCNG) and hydrogen with varying load at 1500 rpm in order to perform comparative exergy analysis. The exergy analysis indicates that work exergy, heat transfer exergy and exhaust exergy were the highest with hydrogen at all loads due to its high flame temperature, low quenching distance, and high flame speed. The engine's exergy efficiency was the highest with hydrogen (34.23%), and it was about 24.23% and 24.08% with CNG and HCNG respectively at high load (20.25 kW). This indicates a higher potential of hydrogen to convert chemical energy input of fuel into heat and then power output. The exergy destruction was observed minimum with hydrogen at all loads, and it was drastically reduced at high loads. The combustion irreversibility which was calculated using species present during combustion, was the main contributor to exergy destruction, and it decreased with hydrogen. The minimum combustion irreversibility was 11.75% with hydrogen, followed by HCNG and CNG with 16.46% and 18.88% respectively at high load. The high quality of heat due to high in-cylinder temperature and low entropy generation during combustion caused by less number of chemical species in hydrogen combustion are the main reasons for lower combustion irreversibility with hydrogen.

Experimental investigations on direct injection diesel engines using grape seed oil methyl ester with different bowl geometries

ABSTRACTIn this paper, the performance of direct injection diesel engine was experimentally investigated under the influence of two different pistons’s geometry deep bowl combustion chamber (DBCC) and toroidal combustion chamber (TCC) compared with standard piston combustion chamber (SPCC) geometry. The experiments were carried out standard atmospheric conditions of 1.01325 bar and 30 ± 2 °C. The piston bowl was designed and developed without modifying the compression ratio of the engine. The investigations were carried out with B25 (25% GOME + 75% diesel), B50 (50% GOME + 50% diesel), B75 (75% GOME +25% diesel) and B100 (100% GOME) by volume blends for three different bowl geometries. The thermogravimetric analysis (TGA) was given the importance of higher in-cylinder temperature for the mass change of GOME leads to a more premixed phase of combustion. The results showed that DBCC has better combustion characteristics when compared with SPCC and TCC for all the blends. The B25 and B50 blends showed good combustion characteristics with DBCC and SPCC individually. While TCC showed average engine characteristics for all the blends categorically, the brake thermal efficiency for B25 blend confirmed a 4.7% higher than SPCC-diesel with DBCC piston, and the smoke, CO (Carbon monoxide), and HC (Hydrocarbon) are reduced by 9.2%, 30.7%, and 4.6%, respectively. Thus, the B25 blend in a DBCC piston engine was observed to be the distinction than other configurations. The results confirmed that the DBCC is a good option for B25 blend.

Investigations on effects of ethanol blending on performance and combustion characteristics of gasoline fuelled lean burn SI engine

This study discusses the effects of addition of small amount of ethanol on performance and emission behaviour of a gasoline fuelled lean burn SI engine. Experiments were carried out in a single cylinder diesel engine which is made to operate as SI engine on lean condition with gasoline as a fuel. The engine was operated at wide open throttle at a compression ratio of 10.5:1 and 1500 rpm at diverse equivalent ratios by injecting the fuel into manifold. The test outcomes stipulated that use of ethanol-gasoline blend (10% by volume) was better compared with pure gasoline. The test results also revealed that there was an accountable increase in brake power output, brake thermal efficiency and an apparent extension in the lean limit of operation with ethanol-gasoline blend. In emission front, reduction in hydrocarbon and carbon monoxide emissions were observed. There was an increase in carbon dioxide and NO emissions due to better combustion and high in-cylinder temperature. On the whole it is concluded that small ethanol addition to gasoline improves performance and reduces emission for lean operating SI engine.

Improved mixture quality by advanced dual-nozzle, included-angle split injection in HSDI engine: Exergetic exploration

A Ford 1.8 l high-speed diesel engine (HSDI) is utilized for a thorough investigation of split dual injection with two included-angle nozzles. The system is equipped with variable-geometry turbocharging (VGT) and high-pressure common-rail (HPCR) technologies which lets multi-injections per cycle. The share of fuel between pulses is divided into three portions of 70-30, 80-20, and 90-10 with included angles of 10, 20, and 30 while the dwell time between pulses are 5CA, 10CA, 15CA, and 20CA. The results demonstrate that the optimum option is 70 (5) 30-30deg “split injection with 70-30% of mass share, dwell of 5CA and with 30° of nozzle divergence” with the best homogeneity of mixture (UI = 0.9742) and peak temperature (Tmax = 2011.58 K) that yield maximum thermo-mechanical exergy amounting to 439 J. In addition, the highest amount of accumulative irreversibility happens for 90 (10) 10–20 deg. It is found that there is a relation between mixture uniformity and accumulative work/heat exergy, whereas a high rate of pressure rise (RPR) contribute to irreversibility rate or exergy destruction in diesel engine, i.e. RPR (80-20) = 904.67 kPa/deg. More, the results are in agreement with literature reporting that higher in-cylinder temperature (Tmax (70 (5) 30-30deg) = 2011.58 K)) can possibly decrease the accumulative irreversibility.