Analysis of CRDI diesel engine characteristics operated on dual fuel mode fueled with biodiesel-hydrogen enriched producer gas under the single and multi-injection scheme

The present work aims to investigate the consequences of pilot fuel (PF) multiple injections and hydrogen manifold injection (HMI) on the combustion and tailpipe gas characteristics of a common rail direct injection (CRDI) compression ignition (CI) engine operated on dual fuel (DF) mode. The CI engine can perform on a wide variety of fuels and under high pilot fuel (PF) pressure. Pilot fuel injection (PFI) is achieved at TDC, 5, 10, and 15ºCA before the top dead center (bTDC), and divided injection consists of injecting fuel in three different magnitudes on a time basis and PF is injected into the engine cylinder at a pressure of 600 bar. In this work, the hydrogen flow rate (HFR) was fixed at 8 lpm constant and producer gas was inducted without any restriction. The investigational engine setup has the ability to deliver a PF and hydrogen (H₂) precisely in all operating circumstances using a separate electronic control unit (ECU). Results showed that diesel-hydrogen enriched producer gas (HPG) operation at maximum operating conditions provided amplified thermal efficiency by 4.01% with reduced emissions, except NOx levels, compared to biodiesel-HPG operation. Further, DiSOME with the multi-injection strategy of 60 + 20+20 and 50 + 25+25, lowered thermal efficiency by 4.8% and 9.12%, respectively compared to identical fuel combinations under a single injection scheme. However, reductions in NOx levels, cylinder pressure, and HRR were observed with a multi-injection scheme. It is concluded that multi-injection results in lower BTE, changes carbon-based emissions marginally, and decreases cylinder pressure and heat release rate than the traditional fuel injection method.     

Experimental investigations on the effect of fuel injection parameters on diesel engine fuelled with biodiesel blend in diesel with hydrogen enrichment

Fuel injection pressure and injection timing are two extensive injection parameters that affect engine performance, combustion, and emissions. This study aims to improve the performance, combustion, and emissions characteristics of a diesel engine by using karanja biodiesel with a flow rate of 10 L per minute (lpm) of enriched hydrogen. In addition, the research mainly focused on the use of biodiesel with hydrogen as an alternative to diesel fuel, which is in rapidly declining demand. The experiments were carried out at a constant speed of 1500 rpm on a single-cylinder, four-stroke, direct injection diesel engine. The experiments are carried out with variable fuel injection pressure of 220, 240, and 260 bar, and injection timings of 21, 23, and 25 °CA before top dead center (bTDC). Results show that karanja biodiesel with enriched hydrogen (KB20H10) increases BTE by 4% than diesel fuel at 240 bar injection pressure and 23° CA bTDC injection timing. For blend KB20H10, the emissions of UHC, CO, and smoke opacity are 33%, 16%, and 28.7% lower than for diesel. On the other hand NOx emissions, rises by 10.3%. The optimal injection parameters for blend KB20H10 were found to be 240 bar injection pressure and 23 °CA bTDC injection timing based on the significant improvement in performance, combustion, and reduction in exhaust emissions.     

Effect of manifold injection of hydrogen gas in producer gas and neem biodiesel fueled CRDI dual fuel engine

The high flammability of hydrogen gas gives it a steady flow without throttling in engines while operating. Such engines also include different induction/injection methods. Hydrogen fuels are encouraging fuel for applications of diesel engines in dual fuel mode operation. Engines operating with dual fuel can replace pilot injection of liquid fuel with gaseous fuels, significantly being eco-friendly. Lower particulate matter (PM) and nitrogen oxides (NO_x) emissions are the significant advantages of operating with dual fuel.Consequently, fuels used in the present work are renewable and can generate power for different applications. Hydrogen being gaseous fuel acts as an alternative and shows fascinating use along with diesel to operate the engines with lower emissions. Such engines can also be operated either by injection or induction on compression of gaseous fuels for combustion by initiating with the pilot amount of biodiesel. Present work highlights the experimental investigation conducted on dual fuel mode operation of diesel engine using Neem Oil Methyl Ester (NeOME) and producer gas with enriched hydrogen gas combination. Experiments were performed at four different manifold hydrogen gas injection timings of TDC, 5°aTDC, 10°aTDC and 15°aTDC and three injection durations of 30°CA, 60°CA, and 90°CA. Compared to baseline operation, improvement in engine performance was evaluated in combustion and its emission characteristics. Current experimental investigations revealed that the 10°aTDC hydrogen manifold injection with 60°CA injection duration showed better performance. The BTE of diesel + PG and NeOME + PG operation was found to be 28% and 23%, respectively, and the emissions level were reduced to 25.4%, 14.6%, 54.6%, and 26.8% for CO, HC, smoke, and NO_x, respectively.     

Comparitive investigation of performance and emission features of methanol,ethanol, DEE,and nanopartilces as fuel additives in diesel-biodiesel blends

The usage of biodiesel blends is restricted due to its low fuel consumption and high thermal NOx. The current study exhibits the usage of four different fuel additives methanol, ethanol, diethyl ether, and NiO nanoparticles in Neem biodiesel blend (NB25) to shore up the usage of neem oil methyl ester. Performance and emission experimentation of a compression-ignition engine fueled with NB25 having fuel additives were conducted at varying injection opening pressures (180, 210, and 240 bar) and static injection timings (19°, 23°, and 27° bTDC). The results indicate that when NiO fuel additives were doped in the NB25 blend, high peaks of NOx were found with betterment in performance features with a lower CO and HC emission.     

Effect of fuel opening injection pressure and injection timing of hydrogen enriched rice bran biodiesel fuelled in CI engine

Fuel opening injection pressure and injection timing are important injection parameters, and they have a significant influence on engine combustion, performance, and emissions. The focus of this work is to improve the performance and emissions of single-cylinder diesel engines by using injection parameters in engines running with rice bran biodiesel 10% blend (RB10+H₂) and 20% blend (RB20+H₂) with a fixed hydrogen flow rate of 7 lpm. In addition, hydrogen and biodiesel are excellent alternatives to conventional fuels, which can reduce energy consumption and strict emission standards. The investigation is conducted for three different opening injection pressure of 220, 240, 260 bar, and four different injection timings of 20°, 22°, 24°, and 26° bTDC. Results indicate that the sample ‘RB10+H₂’ provides 3.32% higher BTE and reduces the fuel consumption by 13% as diesel fuel. The blend RB10+H₂ attributes a maximum cylinder pressure of 68.7 bar and a peak HRR value of 49 J/ºCA. Further, compared to diesel, RB10+H₂ blend emits lower CO, HC, and smoke opacity by 17%, 22%, and 16%, respectively. However, an almost 12% increase of nitrogen oxides for the RB10+H₂ blend is observed. However, with advanced injection timing and higher opening injection pressure, NOx emissions is slightly increased.     

Effect of pilot fuel injection pressure and injection timing on combustion,performance and emission of hydrogen-biodiesel dual fuel engine

The present study highlights the influence of fuel injection pressure (FIP) and fuel injection timing (FIT) of Jatropha biodiesel as pilot fuel on the performance, combustion and emission of a hydrogen dual fuel engine. The hydrogen flow rates used in this study are 5lit/min, 7lit/min, and 9lit/min. The pilot fuel is injected at three FIPs (500, 1000, and 1500 bar) and at three FITs (5°, 11°, and 17?bTDC). The results showed an increase in brake thermal efficiency (B_th)from 25.02% for base diesel operation to 32.15% for hydrogen-biodiesel dual fuel operation with 9lit/min flow rate at a FIP of 1500 bar and a FITof17?bTDC. The cylinder pressure and heat release rate (HRR) are also found to be higher for higher FIPs. Advancement in FIT is found to promote superior HRR for hydrogen dual fuel operations. The unburned hydrocarbon (UHC) and soot emissions are found to reduce by 59.52% and 46.15%, respectively, for hydrogen dual fuel operation with 9lit/min flow rate at a FIP of 1500 bar and a FIT of 11?bTDC. However, it is also observed that the oxides of nitrogen (NO_X) emissions are increased by 20.61% with 9lit/min hydrogen flow rate at a FIP of 1500 bar and a FIT of 17?bTDC. Thus, this study has shown the potential of higher FIP and FIT in improving the performance, combustion and emission of a hydrogen dual fuel engine with Jatropha biodiesel as pilot fuel.     

Influence of 1-pentanol as the renewable fuel blended with hydrogen on the diesel engine characteristics and trade-off study with variable injection timing

Biofuels are considered as one of the best viable and inexhaustible alternatives to conventional diesel fuel. Alcohols have become very important and popular in the present scenario due to their characteristic fuel properties and production nature. This study examines the influence of 1-pentanol and hydrogen on various performance characteristics of CRDI diesel engines. The experiment was carried out with a load range of 25%–100% in 25% percent increments, at 1500 rpm constant engine speed. The influence of injection-timing at 9°, 12°and 15°bTDC was first investigated using 30% 1-pentanol as fuel to observe the effect on engine parameters in comparison with base fluid. Compared to conventional and retarded injection timings, 1-pentanol displayed better emission and performance characteristics at higher injection timings. Additionally, at 15°bTDC, 30% 1-pentanol was used with 12 LPM hydrogen in a dual fuel mode. Compared to plain diesel, the hydrogen-enriched fuel resulted in a 1.50% lower HRR (heat release rate) and 6.77% higher cylinder pressure at 75% load. Thus, it is evident that hydrogen enrichment at 75% load effectively reduces hydrocarbon and nitrogen oxide emissions by 6.66% and 10%, respectively, and improves thermal efficiency by 5%. The experiment revealed that 1-pentanol performs effectively at higher injection timings and that hydrogen improved the performance even further. Furthermore, the long-term viability of hydrogen and 1-pentanol as an energy source is well demonstrated in future scenarios.     

Investigating the effects of injection and induction modes of hydrogen addition in a CRDI pilot diesel-fuel engine with exhaust gas recirculation

This work compares the outcomes of different flow rates of hydrogen added by induction and injection methods in three different flow rates (3, 9, and 15 LPM) through the intake manifold of a constant speed CRDI diesel engine operated at 1500 rpm. The premixed air and hydrogen mixture was ignited by injecting diesel fuel at 23? bTDC. Hydrogen addition reduced CO, HC, and smoke in both the techniques, but efficiency was decreased at a higher percentage of hydrogen induction, whereas it increased with the injection technique. The higher calorific value and flame velocity helped proper combustion and improved brake thermal efficiency by 7%, and the brake-specific energy consumption was reduced by 10.7%. In addition, CO, UHC, and Smoke were decreased by 15.8, 29.7, and 15% compared with neat diesel at full BMEP. Nitrogen oxides decreased by 5.6% for 15 LPM of hydrogen injection compared to the induction method with the same flow rate but higher than diesel fuel by 35.9%. Three different EGR percentages (5, 7.5, and 10%) were used to reduce the higher NOx emission. Though the injection process was complex compared to the induction method, the injection process can provide promising results even at higher hydrogen flow rates.     

Direct injection of hydrogen main fuel and diesel pilot fuel in a retrofitted single-cylinder compression ignition engine

Up to 90% hydrogen energy fraction was achieved in a hydrogen diesel dual-fuel direct injection (H2DDI) light-duty single-cylinder compression ignition engine. An automotive-size inline single-cylinder diesel engine was modified to install an additional hydrogen direct injector. The engine was operated at a constant speed of 2000 revolutions per minute and fixed combustion phasing of ?10 crank angle degrees before top dead centre (°CA bTDC) while evaluating the power output, efficiency, combustion and engine-out emissions. A parametric study was conducted at an intermediate load with 20–90% hydrogen energy fraction and 180-0 °CA bTDC injection timing. High indicated mean effective pressure (IMEP) of up to 943 kPa and 57.2% indicated efficiency was achieved at 90% hydrogen energy fraction, at the expense of NO_x emissions. The hydrogen injection timing directly controls the mixture condition and combustion mode. Early hydrogen injection timings exhibited premixed combustion behaviour while late injection timings produced mixing-controlled combustion, with an intermediate point reached at 40 °CA bTDC hydrogen injection timing. At 90% hydrogen energy fraction, the earlier injection timing leads to higher IMEP/efficiency but the NO_x increase is inevitable due to enhanced premixed combustion. To keep the NO_x increase minimal and achieve the same combustion phasing of a diesel baseline, the 40 °CA bTDC hydrogen injection timing shows the best performance at which 85.9% CO₂ reduction and 13.3% IMEP/efficiency increase are achieved.     

CFD analysis of hydrogen injection pressure and valve profile law effects on backfire and pre-ignition phenomena in hydrogen-diesel dual fuel engine

This paper focuses on optimizing the hydrogen TMI (timed manifold injection) system through valve lift law and hydrogen injection parameters (pressure, injection inclination and timing) in order to prevent backfire phenomena and improve the volumetric efficiency and mixture formation quality of a dual fuel diesel engine operating at high load and high hydrogen energy share. This was achieved through a numerical simulation using CFD code ANSYS Fluent, developed for a single cylinder hydrogen-diesel dual fuel engine, at constant engine speed of 1500 rpm, 90% of load and 42.5% hydrogen energy share. The developed tool was validated using experimental data. As a results, the operating conditions of maximum valve lift = 10.60 mm and inlet valve closing = 30 °CA ABDC (MVL10 IVC30) prevent the engine from backfire and pre-ignition, and ensure a high volumetric efficiency. Moreover, a hydrogen start of injection of 60 °CA ATDC (HSOI60) is appropriate to provide a pre-cooling effect and thus, reduce the pre-ignition sources and helps to quench any hot residual combustion products. While, the hydrogen injection pressure of 2.7 bar and an inclination of 60°, stimulate a better quality of hydrogen-air mixture. Afterwards, a comparison between combustion characteristics of the optimized hydrogen-diesel dual fuel mode and the baseline (diesel mode) was conducted. The result was, under dual fuel mode there is an increase in combustion characteristics and NOx emissions as well as a decrease in CO2 emissions. For further improvement of dual fuel mode, retarding diesel start of injection (DSOI) strategy was used.     

Performance and emission characteristics of CIE using hydrogen,biodiesel, and massive EGR

Hydrogen is considered as an excellent energy carrier and can be used in diesel engines that operate in dual fuel mode. Many studies have shown that biodiesel, which is sustainable, clean, and safe, a good alternative to fossil fuel. However, tests have confirmed that using biodiesel or hydrogen as a fuel or added fuel in compression ignition engines increases NOx concentrations. Cooled or hot exhaust gas recirculation (EGR) effectively controls the NOx outflows of diesel engines. However, this technique is restricted by high particulate matter PM emissions and the low thermal efficiency of diesel engines.In this study, gaseous hydrogen was added to the intake manifold of a diesel engine that uses biodiesel fuel as pilot fuel. The investigation was conducted under heavy-EGR conditions. An EGR system was modified to achieve the highest possible control on the EGR ratio and temperature. Hot EGR was recirculated directly from the engine exhaust to the intake manifold. A heat exchanger was utilized to maintain the temperature of the cooled EGR at 25 °C.The supplied hydrogen increased NOx concentrations in the exhaust gas emissions and high EGR rates reduced the brake thermal efficiency. The reduction in NOx emissions depended on the added hydrogen and the EGR ratios when compared with pure diesel combustion. Adding hydrogen to significant amounts of recycled exhaust gas reduced the CO, PM, and unburned hydrocarbon (HC) emissions significantly. Results showed that using hydrogen and biodiesel increases engine noise, which is reduced by adding high levels of EGR.     

Utilization of unattended Putranjiva roxburghii non-edible oil as fuel in diesel engine

The search for alternative sources of energy has been driven by the increased cost and depletion of supply of fossil fuels. The alternatives are mainly vegetable oils. Putranjiva roxburghii, a non-edible vegetable oil can be used in diesel engine for its fuel properties which are comparable with diesel. Blends (10%, 20%, 30%, and 40% v/v) of pure Putranjiva oil and diesel are used in Ricardo Variable Compression Diesel Engine to study the performance and emission characteristics at various brake power. Putranjiva oil blends yield better performance at 45° CA bTDC injection timing in comparison to 40° CA bTDC timing for diesel. Maximum 30% blend of Putranjiva oil with diesel can be used as an alternative fuel in diesel engine for it differs very little from diesel in performance and is better than diesel with regard to emissions.     

Numerical and experimental investigation of hydrogen enrichment in a dual-fueled CI engine: A detailed combustion,performance, and emission discussion

An effort has been made to simulation a compression ignition engine using hydrogen-diesel, hydrogen-diethyl ether, hydrogen-n-butanol and base diesel fuel as alternatives. The engine measured for the simulation is a single cylinder, four stroke, direct injection, diesel engine. During the simulation the injection timing and engine speed are kept constant at 23°bTDC and 1500 rpm. Diesel-RK, a piece of commercial software employed for this project, can forecast an engine emission, performance and combustion characteristics. The examination of the anticipated outcomes reveals that adding hydrogen to diesel leads in a small increase in efficiency and fuel consumption. With the usage of hydrogen-blend fuels, the majority of dangerous pollutants in exhaust are greatly decreased. The shortest ignition delay was consistently given by 5H295DEE. The lowest CO₂ (578.61 g/kWh) was given by 5H295nB at CR 19.5. Hydrogen blends increase NOx emissions more than base diesel fuel. In the case of smoke and particulate matter emission, the reduce tendency was seen.     

Hydrogen effects on NOx emissions and brake thermal efficiency in a diesel engine under low-temperature and heavy-EGR conditions

Cooled and heavy exhaust gas recirculation (EGR) has been used to control NOx emissions from diesel engines, but its application has been limited by low thermal efficiency or high unburned hydrocarbon emissions. In this study, hydrogen was added into the intake manifold of a diesel engine to investigate its effect on NOx emissions and thermal efficiency under low-temperature and heavy-EGR conditions. The energy content of the introduced hydrogen was varied from an equivalent of 2-10% of the total fuel’s lower heating value. A test engine was operated at a constant diesel fuel injection rate and engine speed to maintain the same engine control unit (ECU) parameters, such as injection time, while observing changes in the carbon dioxide produced due to variations in the hydrogen supply. Additionally, the EGR system was modified to control the EGR ratio. The temperature of the intake gas manifold was controlled by both the EGR cooler and the inter-cooling devices to maintain a temperature of 25 °C. Exhaust NOx emissions were measured for different hydrogen flow rates at a constant EGR ratio. The test results demonstrated that the supplied hydrogen reduced the specific NOx emissions at a given EGR ratio while increasing the brake thermal efficiency. This behavior was observed over constant EGR ratios of 2, 16, and 31%. The rate of NOx reduction due to hydrogen addition increased at higher EGR ratios compared with pure diesel combustion at the same EGR ratio. At an EGR ratio of 31%, when the hydrogen equivalent to 10% of the total fuel’s lower heating value was supplied, the specific NOx was lowered by 25%, and there was a slight increase in the brake thermal efficiency. This behavior was investigated by measuring and analyzing changes in the exhaust gas composition, including oxygen, carbon dioxide, and water vapor.     

Influence of hydrogen injection timing and duration on the combustion and emission characteristics of a diesel engine operating on dual fuel mode using biodiesel of dairy scum oil and producer gas

The main aim of the present work is to investigate the influence of hydrogen injection timing and injection duration on the combustion and emissions of a CI engine functioning on dual fuel (DF) mode by employing diesel/dairy scum oil methyl ester (DiSOME)/Waste frying oil methyl ester (WFOME) - producer gas (PG) combination. Hydrogen flow rate was maintained constant (8 lpm) and injected in air-producer gas (PG) mixture an inlet manifold using a gas injector. In this current work, injection timing was varied from TDC to 15 deg., aTDC in steps of 5. Similarly, injection duration was adopted from 30 deg., CA to 90 deg., CA and differed in steps of 30. From the outcome of work, it is noticed that the best possible injection timing and injection duration were found to be 10 deg., aTDC and 60 deg., CA respectively. Results showed that, at optimum injection parameters, diesel-PG combination with hydrogen resulted in augmented BTE by 6.7% and 12.4%, decreased smoke by 26.04% and 36.4%, decreased HC by 16.6% and 22.4%, decreased CO by 23.5% and 29.6% and increased NOx by 12.4% and 22.1%, compared to DiSOME and WFOME supported DF operation. Investigation with DiSOME-hydrogen enriched PG combustion showed satisfactory operation.     

Using renewable n-octanol in a non-road diesel engine with some modifications

n-Octanol is a promising biofuel synthesized from biomass with several properties closer to diesel than the more popularly researched n-butanol. This study investigates the effects of injection timing (2°CA advance & retard), EGR (up to 30%) and Oct30 (30% by vol. of n-octanol in diesel) on combustion, performance, and emissions of a DI diesel engine. Results in comparison with diesel indicated Oct30 blend presented an enhanced premixed combustion phasing with higher peaks of pressure and HRR. BSFC was found to be slightly higher for Oct30 blend at all EGR rates. Further, when the injection timing is advanced, the blend produced better BSFC. Oct30 delivered better BTE at all injection timings. NOx and smoke emissions are lower for Oct30 at all conditions. Oct30 could overcome the trade-off between smoke and NOx emissions at a combination of certain EGR and injection timings. It was found that at advanced injection, the reduction in NOx and smoke density was 19.02% and 57.14%, respectively, while BTE increased by 4.6% and BSFC increased by 1.3%. At late injection, a reduction of 50.87% in NOx emissions and 15.87% in smoke density was achieved with a slight drop in BTE by 3.5% and an increase in BSFC by 9.7%.     

Control of backfire and NOx emission reduction in a hydrogen fueled multi-cylinder spark ignition engine using cooled EGR and water injection strategies

The experimental study was carried out on a constant speed multi-cylinder spark ignition engine fueled with hydrogen. Exhaust gas recirculation (EGR) and water injection techniques were adopted to control combustion anomalies (backfire and knocking) and reduce NOx emission at source level. The experimental tests were conducted on the engine with varied EGR rate (0%–28% by volume) and water to hydrogen ratio (WHR) (0–9.25) at 15 kW load. It was observed from the experiments that both the strategies can control backfire effectively, but water injection can effectively control backfire compared to EGR. The water injection and EGR reduce the probability of backfire occurrence and its propagation due to the increase in the requirement of minimum ignition energy (MIE) of the charge, caused mainly due to charge dilution effect, and reduction in flame speed respectively. The NOx emission was continuously reduced with increase in EGR rate and WHR, but at higher rates (of EGR and WHR), there was an issue of stability of engine operation. It was found from the experimental results that at 25% EGR, there was 57% reduction in NOx emission without drop in brake thermal efficiency whereas, with WHR of 7.5, the NOx emission was reduced by 97% without affecting the efficiency. The salient point emerging from the study is that water injection technique can control backfire with ultra-low (near zero) NOx emission without compromising the performance of the hydrogen fueled spark ignition engine.     

The effect of EGR and hydrogen addition to natural gas on performance and exhaust emissions in a diesel engine by AVL fire multi-domain simulation,GPR model,and multi-objective genetic algorithm

In this study, the effect of adding hydrogen to natural gas and EGR ratio was conducted on a diesel engine to investigate the engine performance and exhaust gases by AVL Fire multi-domain simulation software.For this investigation, a mixture of hydrogen fuel and natural gas replaced diesel fuel. The percentage of hydrogen in blend fuel changed from 0% to 40%. The compression ratio converted from 17:1 to 15:1. The EGR ratios were in three steps of 5%, 10%, and 15%, with different engine speeds from 1000 to 1800 RPM. The Gaussian process regression (GPR) was developed to model engine performance and exhaust emissions. The optimal values of EGR and the percentage of hydrogen in the blend of HCNG were extracted using a multi-objective genetic algorithm (MOGA).The results showed that by increasing EGR, thermal efficiency, the engine power, and specific fuel consumption decreased due to prolongation of combustion length while cumulative heat release increased but, its effect on cylinder pressure is insignificant. Adding hydrogen to natural gas increased the combustion temperature and, consequently NOx. While the amount of CO and HC decreased. The results of GPR and MOGA illustrated that at different engine speeds, the optimum values of EGR and HCNG were 6.35% and 31%, respectively.     

Realizing low emissions on a hydrogen-fueled spark ignition engine at the cold start period under rich combustion through ignition timing control

This paper analyzed low emissions on a hydrogen-fueled spark ignition (SI) engine at the cold start period under rich combustion through ignition timing (IT) control. Cold start characteristics of hydrogen-fueled engine were investigated experimentally. The study was performed under different IT. The results demonstrated that when excess air ratio (λ) was 0.7 and IT varied from 25 °CA BTDC to 10 °CA ATDC, the peak cylinder pressure of the first cycle and the successful start time (SST) of hydrogen engine first increased and then decreased with the retard of IT. At 15 °CA BTDC, the hydrogen engine gained the shortest SST and the highest cylinder pressure in the first cycle. Flame development period (CA0-10) first shortened and then lengthened, and flame propagation period (CA10-90) prolonged when IT gradually retarded. The average NOx emissions efficiently reduced by 90.2%, HC and CO emissions caused by the evaporated lubricant oil reduced individually by 33.8% and 19.7% in the first 6 s during the cold start process with the retard of IT. Especially when IT delayed from 25 °CA BTDC to 15 °CA BTDC, the effect of IT on HC emissions was significant.     

Statistical and experimental investigation of the influence of fuel injection strategies on CRDI engine assisted CNG dual fuel diesel engine

With an alarming enlargement in vehicular density, there is a threat to the environment due to toxic emissions and depleting fossil fuel reserves across the globe. This has led to the perpetual exploration of clean energy resources to establish sustainable transportation. Researchers are continuously looking for the fuels with clean emission without compromising much on vehicular performance characteristics which has already been set by efficient diesel engines. In this study, the combustion, performance and emission characteristics of CRDI diesel engine assisted CNG dual fuel research engine operated at constant speed of 1500 rpm with variable engine load (16, 20 and 24 NM) to analyses the influence of fuel injection timings (7.5, 12.5 and 17.5 SOI) and fuel injection pressure (500, 750 and 1000 bar) under reactivity-controlled compression ignition (RCCI) mode. In the case of a fuel injection pressure of 1000 bar, the maximum brake specific fuel consumption of 0.42 kg/kWh is registered with a brake mean effective pressure of 3.2 bar. Response surface methodology has been used in this analysis for predicting the optimal input parameters (engine load, fuel injection timing, and fuel injection pressure), which results in an optimal combination of performance (BP, BTHE, and BSFC) and emission (HC, NOx, and CO) parameters. A variety of optimal solutions based on the desirability method is obtained from the model, and optimal input parameters is suggested as load 20(Nm), injection pressure 750(Bar), and injection timing (BTDC) 12.5. Additionally, to obtain a ‘regression model’ a statistically significant test (ANOVA) is developed. Results have shown that the suggested ‘Regression Model’ is best fitted to 0.095 standard deviations, 0.972 corrected R², and 18.482 acceptable accuracy.