Combustion Characteristics Of Engine Research Articles

Effect of Diesterol blends on the noise vibration and harshness of a Genset engine

The present investigations deal with the combined effect of Diesterol blends (B20D75E5, B20D70E10, and B20D65E15) on the performance, combustion, noise, and vibration characteristics of a compression ignition Genset engine. Studies were carried out to make the fuel blend homogeneous and stable as ethanol is immiscible in diesel/biodiesel due to its chemical structure. It is found that the Diesterol blend becomes stable when biodiesel is used as a bonding agent between ethanol and diesel. However, the higher concentration of ethanol has stronger bonding, which resulted in poor stability. The stable blends were used to study the performance characteristics of the Genset engine. The results showed that the brake thermal efficiency increased by 10.4% by adding 5% ethanol in diesel–biodiesel compared to the 15% ethanol in diesel–biodiesel blends. The brake-specific fuel consumption was found to increase by 10% due to the decrease in calorific value with the addition of ethanol. The peak value of the in-cylinder pressure gradually increases up to 10% ethanol share and further addition in the fuel blend decreases the cylinder peak pressure, which may be due to a reduction in the lower calorific value of the blended fuel when compared to conventional diesel. The water content in the blends reduced the combustion activity and caused a slight increase in vibration due to the increased instant heat release rate in 10% and 15% ethanol share. The maximum vibration reduction was observed for the 5% ethanol blend by 1.83%. On the other hand, adding 15% ethanol decreased the engine noise by 2.7% compared to the 5% ethanol blend.

Effect of Mixed Firing Ethylene Glycol on Combustion and Emission Performance of Model 4190 Diesel Engine

In order to study the influence of ethylene glycol on the combustion and emission of marine diesel engine, a combustion chamber model was established based on 4190ZLC-2 marine medium speed diesel engine by AVL-FIRE simulation software, and the accuracy of the model was verified. The effects of ethylene glycol on the combustion and emission characteristics of diesel engine under different mixing ratios were studied by simulation experiments, and the optimal mixing ratio of ethylene glycol and diesel was obtained under the premise of ensuring the diesel engine to work at full load. The results show that the average pressure in the cylinder and the maximum burst pressure in the cylinder of the dual-fuel engine mixed with ethylene glycol are decreased compared with the original engine under different mixing ratios. Under full load condition, NOx and soot emissions are decreased by increasing ethylene glycol mixing ratio, and CO emission peak is increased but not significantly increased. Through analysis, it can be concluded that when mixing ratio is 15%, final CO emission decreases by 28.6%, final NO emission decreases by 7.9%, and Soot emission decreases by 16.9%.

Investigating the Effects of Eichhornia Crassipes Biodiesel and Liquefied Petroleum Gas on the Performance and Emissions of a Dual-Fuel Engine

This study considers the effect of Eichhornia Crassipes Biodiesel (ECB) blends on the performances, combustion, and emission characteristics of a direct injection compression ignition engine operated in a dual-fuel mode (DFM) and equipped with an Exhaust gas recirculation technique (EGR). In particular, a single-cylinder, four-stroke, water-cooled diesel engine was utilized and four modes of fuel operation were considered: mode I, the engine operated with an ordinary diesel fuel; mode II, the engine operated with the addition of 2.4 L/min of liquefied petroleum gas (LPG) and 20% EGR; mode III, 20% ECB with 2.4 L/min LPG and 20% EGR; mode IV, 40% ECB with 2.4 L/min LPG and 20% EGR. The operation conditions were constant engine speed (1500 rpm), variation of load (25%, 50%, 75%, and 100%), full load, with a compression ratio of 18, and a time injection of 23° BTDC (Before top died center). With regard to engine emissions, carbon dioxide (CO₂), carbon monoxide (CO), hydrocarbons (UHC), and nitrogen oxide (NO_X) were measured using a gas analyzer. The smoke opacity was measured using an OPABOX smoke meter. By comparing the results related to the different modes with mode I at full load, the BTE (Brake thermal efficiency) increased by 20.17%, 11.45%, and 12.66% with modes II, III, and IV, respectively. In comparison to the results for mode II, the BTE decreased due to the combustion of ECB blends by 7.26% and 6.24% for mode III and mode IV, respectively, at full load. In comparison to mode II, the Brake specific energy consumption (BSEC) increased with the ECB substitution. With ECB blends, there is a noticeable decrease in the CO, CO_2, and UHC emissions at a partial load. Furthermore, the 20% ECB has no effect on CO emissions at full load. For modes II and IV, the CO₂ increased by 33.33% and 19%, respectively, while the UHC emissions were reduced by 14.49% for mode III and 26.08% for mode IV. The smoke of mode III was lower by 7.21%, but for mode IV, it was higher by 12.37%. In addition, with mode III and mode IV, the NO_x emissions increased by 30.50% and 18.80%, respectively.

Study on marine engine combustion and emissions characteristics under multi-parameter coupling of ammonia-diesel stratified injection mode

In this study, the ammonia-diesel stratified injection (ADSI) is explored on a marine low-speed engine., The effect of three injection timings(ITS = −3°CA ATDC, −1°CA ATDC, and 1°CA ATDC) coupling with three diesel energy fractions (DEFS = 1%,5%, and 10%) on combustion and emission characteristics of the engine under full load is investigated. The results show that advancing IT has an obvious effect on increasing peak cylinder pressure while enhancing DEF can increase the heat release rate under ADSI mode, and the ignition delay time is less than original diesel engine. The ADSI has higher indicated thermal efficiency than original diesel engine except for IT of 1°CA ATDC coupling DEF of 1%, and its combustion efficiency can be significantly improved. Furthermore, the NOx increases with advancing IT and increasing DEF while the unburned ammonia is the opposite. The NOx emissions are all lower than original diesel engine under different IT coupling DEF. Advancing IT is an effective measure to reduce unburned ammonia. The greenhouse gas (GHG) can be greatly reduced. A priority strategy of the IT coupling DEF is proposed through comprehensive comparison under the ADSI mode, which can meet the Tier III regulations. This strategy reduces indicated specific fuel consumption and GHG around by 4% and 94% compared with the diesel engine respectively, and the combustion efficiency reaches more than 99%. The unburned ammonia is limited to less than 150 ppm.

The role of acetone for cleaner combustion in diesel engine

The effects of acetone on the combustion, performance and emission characteristics of a diesel engine were investigated. This study focused on the advantages, disadvantages and limitations of using acetone in a diesel engine. Acetone as an oxygenated additive with a carbonyl functional group was blended with diesel fuel at different concentrations. The engine was operated at a constant speed of 2000 rpm and different loads. Low concentrations of acetone reduced the coefficient of variation (COV) and slightly increased the peak pressure and the heat release rate (HRR) at most loads. The emissions of CO and NOx were reduced besides a slight enhancement in the engine performance. Relatively high concentrations significantly increased the COV at both idle and full loads and depressed the peak pressure and HRR at full load. Acetone with relatively high concentrations caused instabilities in the diesel engine operation.

Comparative Performance and Emissions of CI Engine Fuelled with Diesel and Blends of Mosambi Peel Pyro Oil, Methanol and Nano Rh2O3 with Diesel

This research article presents a comparative experimental study on the performance, exhaust emission and combustion characteristics of a CI engine fuelled with neat diesel and with three kinds of blends viz. MD10 (neat diesel with 10% mosambi peel pyro oil), MDM10 (neat diesel with 10% mosambi peel pyro oil and 10% methanol), MD10+Rh2O3 (neat diesel with 10% mosambi peel pyro oil and nano rhodium oxide fuel additive). The experiments were conducted on a direct injection single-cylinder water-cooled four-stroke diesel engine operated at a constant engine speed of 1500 rpm and under varied brake power conditions. The results showed that MD10+Rh2O3 outperformed the rest in terms of all the performance, emission and combustion characteristics. MD10+Rh2O3 was found to have achieved, 5% higher brake thermal efficiency, 18.5% reduced SFC and 8% reduced exhaust gas temperatures respectively. This fuel has also achieved 10.5%, 5.5%, 9.45%, 11% marginal drop in noxious pollutants such as CO (Carbon Monoxide), unburnt HC (Hydrocarbons), NOx and smoke respectively. Cylinder peak pressures, heat release rate, ignition delay and combustion duration of MD10+ Rh2O3 are recorded to be considerably improved. Thus, using the nanoparticle added mosambi peels pyro oil (NMPPO) blended with diesel as an alternative fuel could impart an eco-friendly, efficient and improved engine operation.

Performance and emissions characteristics of CI engine fueled with blends of diesel and Polanga biodiesel

Globally, people are trying to counter the effects of global warming and climate change, as the burning of fossil fuels is one of the biggest challenges. Biodiesel as an alternative fuel source can help solve these problems. Since the use of edible oil would affect the food industry and leads to the increase in cost of food and fuel, hence the production of biodiesel is more beneficial when non-edible oil is used as a fuel source. Polanga oil is considered a better non-edible oil source because it contains more oil and has the highest heating value among non-edible oils. In this study, a simulation software called Diesel-RK is used to analyze the combustion, performance, and emission characteristics of a single-cylinder four-stroke diesel engine running at variable speed. Tests were conducted on a diesel engine using diesel and five different blends of Polanga biodiesel, namely 5 % (B5), 10 % (B10), 15 % (B15), 20 % (B20), and 25 % (B25), respectively. It was found that the brake-thermal efficiency initially increased up to an engine speed of 1900 rpm, where the maximum values of BTE for B5, B10, B15, B20, and B25 were 33.257 %, 33.322 %, 33.263 %, 33.24 %, and 33.121 %, respectively, while for diesel fuel, it was 33.31 % and then started to decrease on increase in the engine speed. According to the current study, increasing speed has a positive effect on NOx and PM, while BTE decreases and SO2 increases. In case of BSFC, at 1900 rpm B5 has a BSFC of 254.55 g/kWh, which is pretty good when compared to diesel fuel (253.82 g/kWh) and B25 (256.49 g/kWh). Before 1900 rpm, BTE increased slightly while BSFC and SO2 decreased slightly, but after 1900 rpm, BTE started to decrease, and BSFC and SO2 increased rapidly. In our study, we found that Polanga is promising biodiesel for future applications because the performance (B10) is similar to diesel, and the emissions are lower.

Optimization of a low heat rejection engine run on oxy‑hydrogen gas with a biodiesel-diesel blend

This experimental investigation examines the combined effects of varying compression ratio (CR) and fuel injection parameters such as fuel injection pressure (FIP) and start of injection (SOI) / injection timing on the performance of a dual-fuel low heat rejection (LHR) engine run on oxy‐hydrogen (HHO) gas with Jatropha biodiesel-diesel blend (JME20) as pilot fuel. The CR is varied from 16.5 to 18.5 in intervals of one, FIP is varied from 220 to 240 bar in intervals of 20 bar,and the SOI is varied from 24.5° to 27.5°CA bTDC in intervals of 1.5°CA. The performance, emission, and combustion characteristics of the dual-fueled LHR engine are studied, based on which the engine operating conditions are optimized. The results reveal that operating the LHR engine with 18.5 CR, 240 bar FIP, and 26°CA bTDC SOI using HHO in dual fuel operation mode with JME20 injected fuel gives better brake thermal efficiency (BTE) (6.6% higher than diesel) and combustion characteristics along with lower carbon monoxide (CO), hydrocarbon (HC), and smoke emissions. In contrast, a slight penalty in nitric oxide (NO) emissions is noticed irrespective of the engine operating conditions.

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.

Effect of piston geometry on combustion characteristics of CI engine used Sal seed oil

The effect of piston bowl geometry on reducing soot emissions, improving combustion, and in-cylinder flow movements in a direct injection diesel engine was investigated. Standard combustion chamber (SCC) and newly modified combustion chamber (MCC) geometries were compared at the same compression ratio (17.5:1). Experimental analysis of diesel engines is expensive and time consuming, and therefore the Computational Fluid Dynamics program was used to analyze the combustion, flow and emission process. AVL Fire ESE Diesel software was used in the numerical study. The numerical work was compared with the experimental results, and it was validated. In addition, 10% biodiesel mixture (10% Sal seed oil methyl ester + 90% diesel fuel) and diesel fuel were used in the analysis. These fuels and two different bowl geometries were investigated at 2000 rpm and full load conditions. Thus, the effect of the used biodiesel fuel and the developed bowl geometry were investigated. Sal seed oil methyl ester was used as biodiesel fuel. The results show that higher turbulence velocity distribution, better mixture fraction values and lower soot formation distribution are obtained by directing the MCC type fuel according to SCC type. When the pressure, temperature and heat release in the combustion chamber are examined, the highest values were obtained with B10 blended fuel used at the SCC type combustion chamber. The maximum heat release rates are 8.72, 9.38, 8.21, and 9.30 J/° for SCCD100, SCCB10, MCCD100 and MCCB10 fuels, respectively.

Effects of operating parameters on combustion and soot emissions in a pilot ignited HPDI natural gas engine for different combustion modes

In this paper, a comprehensive numerical study of the combustion and emission characteristics of a direct injection natural gas engine operating at the high load condition was presented. First, two combustion modes, natural gas mixing-limited combustion (NMLC) and natural gas slightly premixed combustion (NSPC), were defined separately. Subsequently, the potential of combustion chamber type, spray angle of natural gas (SAN), diesel injection pressure (DIP), and natural gas injection pressure (NIP) to achieve high thermal efficiency and low soot emissions are evaluated in both NMLC and NSPC modes. The results showed that in both NMLC and NSPC modes, the straight-sided combustion chamber (SSCC) has more potential to improve the indicated thermal efficiency (ITE) and reduce soot emissions. In NMLC mode, an appropriate increase in SAN can promote the development of vortex at the bowl bottom and improve the stratification state of concentration gradient, thus enhancing ITE, inhibiting the production of pyrene (A4) and acetylene (C2H2), and reducing soot emissions. However, an excessive increase in SAN will lead to fuel accumulation, thus deteriorating soot emissions. In NSPC mode, when SAN increases to 15°, ITE reaches the maximum. Meanwhile, the production of soot precursors (A4 and C2H2) reduces, thus soot emissions reach an extremely low level. However, when SAN exceeds 15°, soot emissions increase rapidly along with the rising SAN. In both combustion modes, when NIP is low, increasing DIP can significantly reduce soot emissions. In NMLC mode, the increase of NIP is more effective in enhancing ITE and inhibiting soot formation. In NSPC mode, when NIP reaches 30 MPa, the maximum pressure rise rate (MPRR) exceeds the limit (1.5 MPa/°CA). When NIP exceeds 30 MPa, ITE begins to decrease. Therefore, NIP should be controlled within 30 MPa for NSPC mode.

Combustion and Emission Characteristics of CNG-Diesel Dual Fuel Engine with Variation of Air Fuel Ratio

Compressed natural gas (CNG) is a popular alternative fuel because of its more environmentally friendly properties than fossil fuels , including applications in diesel engines. However, supplying too much compressed natural gas fuel causes poor engine performance and emissions due to a decrease in the air-fuel ratio on the dual-fuel engine. The addition of air using electric superchargers was done to return the air-fuel ratio to ideal conditions. Lambda value (λ) was variation under low load (1.52 to 2.71), medium load (1.18 to 2.17), and high load (0.94 to 2.17) on a CNG-diesel dual fuel engine. The addition of pure air in each load can increase combustion stability in certain lambda, which was indicated by an increase in thermal efficiency, heat release rate, and a decrease in ignition delay, combustion duration, hydrocarbon, and carbon monoxide emissions.

Assessment of the exergy, emissions, and combustion characteristics of a diesel engine operating on low-glyceride biodiesel blended with diesel fuel

The behavior of biofuels depends on glyceride content, water content, viscosity, density, and other properties that produce different effects on emissions and fuel performance. Therefore, this work performs an experimental evaluation of the performance of low glyceride palm oil biodiesel blended with diesel fuel operating in a compression ignition engine based on an analysis of exergy, emissions, and combustion characteristics. 90 tests were carried out, operating the engine with diesel/biodiesel 90/10% (B10), 80/20% (B20) and 50/50% (B50) fuel blends, under two load conditions at engine speeds of 1500, 1800, 2100, 2400 and 2700 rpm. Among the main results were a higher concentration of carbon monoxide (CO) and carbon dioxide (CO2) was obtained for B10, and lower concentration of nitrogen oxides (NOx) compared with fuels B20 and B50. Moreover, the increase in the fuel blend, allows better burning in premixed phase and reducing burning in the diffuse phase, improving the combustion process of the engine, mainly due to less delay in fuel injection associated with the low content of glycerides in the blend. Concluding that the decrease of glycerides in biodiesel provides adequate performance, a considerable decrease in emissions and homogeneous combustion when blended with conventional diesel.

Honge Oil Biodiesel as a Promising feedstock – An Experimental Investigation

The performance, combustion and emission characteristics of a vertical air-cooled single-cylinder four-stroke diesel engine fueled with karanja (honge) and diesel oil blends with B20 (20% biodiesel and 80% diesel), B50 (50% biodiesel and 50% diesel) and B100 were experimental tested (100% biodiesel). The bio-oil was extracted using soxhlet extractor and mechanical pressing in the presence of n-hexane. The transesterification process was accomplished through two stage process with NaOH and methanol. Performance parameters evaluated include Thermal Braking Efficiency (BTE), Specific Fuel Consumption (SFC), Total Fuel Consumption (TFC) and Braking Performance (BP). Heat Release Rate (HRR) and pressure-crank angle diagram are two of the combustion properties evaluated. Carbon dioxide (CO2), carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and oxygen (O2) are among the emission characteristics examined. These parameters were determined under constant load conditions of 0%, 25%, 50%, 75% and 100% at the rated speed of 1500 rpm and the results for each karanja oil blend (B20, B50, B100) were compared to diesel. As a result, it is concluded that B20 blend offers superior performance, combustion and emission characteristics compared to other test fuel blends.

Effects of hydrogen mixture ratio and scavenging air temperature on combustion and emission characteristics of a 2-stroke marine engine

A numerical study was conducted to investigate the effects of hydrogen and scavenging air temperature (SAT) on the combustion and emission characteristics of a 2-stroke heavy-duty dual-fuel (DF) marine engine at full load. The engine had a 700 mm bore fuelled with hydrogen–methane (H2-CH4) mixtures. Three-dimensional simulations of the combustion and emission formation inside the engine cylinder with various H2 contents in the H2-CH4 mixture were performed. ANSYS FLUENT simulation software was used to analyse the engine performance, in-cylinder pressure, temperature, and emission characteristics. The CFD models were validated against the measured data recorded from the engine experiments. The results showed that an increase in the in-cylinder peak pressure increased the engine power when the H2 content in the H2-CH4 mixture increased. Notably, CO2 and soot emissions decreased (up to more than 65%) when the H2 content in the gaseous mixture increased to 50%. Specific NO emissions in the DF modes were lower than that of the diesel mode, when the H2 content in the gaseous mixture was lower than 40%. However, they increased compared to the diesel mode when the H2 content continued to increase. This limits the H2 amount that should be used in a gaseous mixture creating NO emissions. The results also showed that the SAT cooling method can further reduce emission problems while enhancing engine power. In particular, reducing the SAT to 28 °C in the gaseous mixture with 10% H2 ensured that the DF mode emitted the lowest NO emissions compared to the diesel mode. This reduced NO emissions by 37.92% compared to the measured NO emissions of the research engine (a Tier II marine engine). This study successfully analysed the benefits of using an H2-CH4 mixture as the primary fuel and the SAT cooling method in a 2-stroke ME-GI heavy-duty marine engine.

Effect of Cetane-Coupled Pilot Injection Parameters on Diesel Engine Combustion and Emissions.

The effects of cetane number (CN) coupled with pilot injection ratio and pilot injection timing on the combustion and emission characteristics of a four-cylinder diesel engine were investigated. The results showed that as the pilot injection ratio increases, the peak cylinder gas pressure (CGP) increases, and the peak of heat release rate (HRR) increases accordingly; the coupled CN increases, the brake specific fuel consumption (BSFC) decreases, and the brake thermal efficiency (BTE) increases; CO and HC emissions increase; and NO x emissions increase. In addition, the number concentration and total mass of particulate matter (PM) decrease with the increasing pilot injection ratio. Only when the pilot injection ratio reaches 20% does the fuel produce pilot injection heat release. The ignition delay time (ID) and combustion duration (CD) are redefined for the pilot injection heat release operating conditions. With the delay of the pilot injection timing, the peak CGP increases, the coupled CN increases, the BTE increases, the BSFC decreases, CO and HC emissions increase, and NO x emissions decrease. With the delay of the pilot injection timing, the number concentration and total mass of PM decrease. In addition, no pilot injection heat release was generated for any of the five fuels at pilot injection timings from 30°CA BTDC to 45°CA BTDC.

Effect of changing injection pressure on mahua oil‐based biodiesel combustion with blended Al2O3 nanoparticles on CI engine performance and emission parameters

AbstractAlternative fuels have drawn a lot of interest as oil and gas sources have depleted and environmental concerns have grown. An alternative fuel being researched as a potential replacement for fossil fuels is biodiesel. A 5.2 KW, 4‐stroke, single‐cylinder diesel engine's Performance, combustion, and emission characteristics were evaluated in this study at 1500 rpm with various fuel injection pressures (180, 200, 220, and 240 bar). B20 (80 percent diesel and 20 percent mahua biodiesel) was created by blending mahua oil‐based biodiesel with plain diesel at a 20/80 ratio. Al2O3 nanoparticles were then added at four different quantities, including 25, 50, 75, and 100 ppm. It is found that BTE was improved by 6.1% and BSFC was reduced by 2.5% for B20A25over diesel at the FIP of 220 bar. In‐cylinder pressure was higher and HRR was raised by 7.2% for B20A25compared to diesel at 180 bar. CO emission was reduced by 39% in B20A25 when compared to biodiesel blend at 180 bar. When compared to diesel at 180 bar, B20A25's HC and CO2 emissions were reduced by 7.5% and 4.5%, respectively. Smoke for B20A25 at 240 bar was 3.6 percent lower than diesel. Maximum NOx emissions reduction was seen when Al2O3 nanoparticles were added to the blend at 220 bar FIP.

The effects of nanoparticles as a biodiesel ingredient on the performance of a VCR diesel engine

The combustion, efficiency, and emission properties of a single-cylinder variable compression ratio diesel engine were examined in this research (B100A30C30). To create a homogeneous solution, the ultrasonicator was used in conjunction with a 30 ppm concentration of silicon carbide and carbon nanotubes, two common nanoparticles found in fuel combinations. The increased mixing and chemical reactivity offered by nanoparticles' greater surface area to volume ratio during combustion improved the combustion, performance, and emission characteristics of diesel engines. The engine with nanoparticles (B20A30C30) had a thermal efficiency of braking that is 20% higher than the engine with regular particles (B100). Following that, nitrogen oxide emissions reduced by 38%, carbon monoxide emissions by 68%, hydrocarbon emissions by 52%, and smoke emissions by 48%.

Performance, emissions and exergy analyses of adding CNTs to various biodiesel feedstocks

Extraction of biodiesel from waste cooking oil, jatropha, and corn oils is done by transesterification. Diesel and biodiesel were blended at 20% volume ratio to make methyl ester. At doses of 25, 50, and 100 mg/l, carbon nanotubes (CNTs) was mixed with biodiesel blend. The objective of the present research is to examine experimentally a diesel engine performance, combustion characteristics, exergy and emissions analyses with inclusion of nano additive to various methyl ester feedstocks. Methyl ester blend is enriched with CNTs as JB20C100, WB20C100 and CB20C100 where the improvements in thermal efficiency are raised about biodiesel mixture by 9%, 13% and 15%, respectively. Addition of 100 ppm of CNTs to biodiesel blends achieves the greatest reductions in CO (14%, 22% and 30%), HC (16%, 20% and 25%), and smoke emissions (15%, 19% and 23%) for JB20C100, WB20C100 and CB20C100, respectively. By comparing with B20, blending 100 ppm CNTs with JB20, CB20, and WB20 obtained the highest increases in cylinder pressure of 3%, 5%, and 10%, as well as the highest increases in heat release of 4%, 7%, and 11%, respectively. The downside of CNTs addition achieves a rise in NOx emissions by 10%, 17%, and 22% for JB20C100, WB20C100, and CB20C100, respectively. Exergetic efficiency increases by 8%, 19%, and 24% for B20T100, B20A100, and B20C100, respectively. Sustainability index improvements achieve 1.5%, 5% and 6.5%, for B20T100, B20A100, and B20C100, respectively. WB20 with CNTs of 100 ppm is highly recommended for improving engine performance, combustion, and exergy characteristics with considerable emissions reduction.

Combustion characteristics of a lean-burned CBM engine with hydrogen direction injection

A 3D model of a CBM engine was established, and the combustion modes under different injection parameters and ignition matching conditions were studied by using methane PFI+ hydrogen DI injection method. Flame propagation, flame structure and engine indication thermal efficiency under the three combustion modes were analyzed. The results show that when the interval between injection and ignition is less than 10°CA, the flame structure of plume ignition will be formed; when the interval between injection and ignition is greater than 10°CA and less than 16°CA, the flame form of concentration stratification will be formed; when the interval is greater than 16°CA, the homogeneous flame structure will be formed. The flame propagation speed of plume ignition is significantly higher than that of the other two combustion modes. Under the three combustion modes, the injection and ignition schemes are adjusted several times. When the injection time is -8°CA ATDC and the ignition time is -2°CA ATDC, the flame structure is the plume ignition structure. The indicated thermal efficiency is higher than the other two combustion modes, and the indicated thermal efficiency of the engine is up to 52.8%.