Experimental evaluation of hydrogen enrichment in a dual-fueled CRDI diesel engine

The influence of hydrogen enrichment on the dieselengine fueled with diesel and palm biodiesel blend (P20) is investigated in this study. The hydrogen is injected into the intake manifold at different flow rates of 7 lpm and 10 lpm for each loading condition of 30%, 60%, 80%, 90%, and 100%, respectively. Hydrogen enrichment improves the BTE and BSEC due to its high calorific value and decreases emissions like HC, CO, and CO₂ due to its carbon-free structure. However, due to a rise in EGT, NO_x emission has increased. With the addition of hydrogen, combustion properties such as in-cylinder pressure (ICP), heat release rate (HRR), and ignition delay (ID) improve while the combustion duration (CD) drops. Compared to P20 fuel,P20 + 10H₂ has a 28% increase in BTE and a 20% decrease in BSEC at 90% load. Similarly, HC, CO, and CO₂ emissions decrease by 16%, 35%, and 12%, while NO_x emission increases by 13% compared to P20. At full load, P20 + 10H₂increasesin-cylinder pressureand heat release ratebyupto 1–5%, while CD decreases by 12.5% compared to the P20 blend.     

Investigation on combustion and emission characteristics of hydrogen-enriched dual-fuel engine operated under waste frying oil biodiesel

Using nonedible waste frying oil (WFO) as biodiesel and hydrogen in the mix composition may partly replace significant quantities of diesel fuel and help reduce fossil fuel reliance. The combination of diesel fuel, waste-fired biodiesel, and hydrogen gas can improve the performance, combustion, and emissions of single-fuel and dual-fuel diesel engines. This may lead to a novel alternative fuel mix pattern and modification for diesel engines, which is the research gap. Although there has been some research on waste-fired biodiesel and hydrogen gas-powered dual-fuel engines with the goal of partly replacing fossil fuels to a larger degree, there has been very little progress in this area. As a result, the current research effort focuses on using diesel fuel (100%, 30%, and 60%), waste-fired biodiesel (at 100%, 70%, and 40%), and hydrogen gas as fuel sources (5 and 10 liters per minute [LPM]). According to the current experiment, it was perceived in both dual-fuel and single-fuel modes. Under duel-fuel mode, the engine results for WFOB70D30 + H10 fuel blend had higher 4.2% (brake thermal efficiency [BTE]), 19.72% (oxides of nitrogen [NO_x]), and 9.09% (ignition delay [ID]) with a minimal range of (in-cylinder pressure, MFB, volumetric efficiency and heat release rate [HRR]) and a dropped rate of 4.34% (brake-specific energy consumption [BSEC]), 33.33% (carbon monoxide [CO]), 39.28% (hydrocarbons [HC]), 9.43% (smoke), and 6.97% (combustion duration [CD]) related to diesel fuel at peak load. However, single-fuel powered diesel engines provide minimal performance for the WFOB40D60 fuel blend with (11.32% lower BTE and 2.04% higher BSEC) and minimal rate of combustion (lower cylinder pressure, 2.12% minimal CD, 14.72% higher ID, minimal HRR combustion, volumetric efficiency, and MFB). Emitted fewer emissions (9.09% less CO, 4.87% less HC, 0.92% higher NO_x, and 1.69% more smoke) than diesel fuel at peak load. Therefore, it was concluded that adding 10 LPM of hydrogen gas to the biodiesel under a dual-fuel condition leads to better combustion, better performance, and less pollution than the single-fuel mode of operation.     

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.     

Hydrogen-enriched palm biodiesel as a potential alternative fuel for diesel engines: Investigating performance and emission characteristics and mitigation strategies for air pollutants

Palm biodiesel is one of the most suitable alternative fuels due to its capability to replace traditional fossil fuel usage in IC engines. Even as palm biodiesel (POBD) reduces harmful pollutant gases, the engine performance is not on an equal scale with neat diesel. To address this shortcoming, an investigation was carried out to examine the application of palm biodiesel (PBD) and hydrogen induction through the intake air at the flow rates of 6 and 8LPM (Litre Per Minute) in the compression ignition (CI) engine. The experimental study shows that POBD has poor engine performance and moderate pollution reduction compared with neat diesel. When compared to POBD and neat diesel, the higher calorific value and other H₂ characteristics improve combustion properties, resulting in higher engine performance and lower pollutant gases (except NOx). When compared to the palm biodiesel blend (BD 30), the results of BD30+8LPM reduced the Specific fuel consumption (SFC) by 0.0885kg/kWh and improved the brake thermal efficiency (BTE) by 6.67%. The Carbon monoxide (CO), hydro carbon (HC), and smoke opacity were reduced by 0.047% volume, 29.2 ppm, and 6.52% respectively. A marginal increase in NOx was seen as 297.6 ppm.     

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.     

Investigation on a diesel engine fueled with hydrogen-compressed natural gas and Kusum seed biodiesel: Performance,combustion, and emission approach

The objective of the present study is to evaluate the performance, combustion, and emission characteristics of a compression-ignition engine using hydrogen-compressed natural gas (HCNG)-enriched Kusum seed biodiesel blend (KSOBD20). The flow rate of HCNG was set at 5, 10, and 15 liters per minute (lpm), and the injection pressure was varied in the range of 180–240 bar. Brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC) were improved when HCNG was added to the KSOBD20. Combustion characteristics, namely, cylinder pressure (CP) and net heat release rate (NHRR), were also improved. Emissions of carbon monoxide (CO), hydrocarbons (HC), and smoke were also reduced, with the exception of nitrogen oxides (NO_x). The higher injection pressure (240 bar) had a positive effect on operating characteristics. At an injection pressure of 240 bar, for KSOB20 + 15 lpm HCNG, the highest BTE and the lowest BSFC were found to be 32.09% and 0.227 kg/kWh, respectively. Also, the CP and NHRR were 69.34 bar and 66.04 J/deg. CO, HC, and smoke levels were finally reduced to 0.013%, 47 ppm, and 9%, respectively, with increased NO_x levels of 1623 ppm. For optimum results in terms of engine characteristics, the fuel combination KSOBD20 + 15 lpm HCNG at fuel injection pressure 240 bar is recommended. Thus, HCNG-enriched KSOBD20 can be used as an alternative fuel in diesel engines without requiring any modifications to increase performance and reduce emissions.     

Effect of hydrogen and ethanol addition in cashew nut shell liquid biodiesel operated direct injection (DI) diesel engine

In this experimental research, the hydrogen gas at a different flow rate (4 lpm, 8 lpm, & 12 lpm) is introduced into the intake port of a diesel engine fueled with B20 (20% CNSL (Cashew nut shell liquid) + 80% diesel) biodiesel blend to find out the best H₂ flow rate. Then, ethanol-blended (5%, 10%, and 15% by volume) B20 blend along with the best H₂ flow rate are tested in the same engine to examine the engine performance. The experimental results showed that B20 with 8 lpm H₂ flow gives the maximum brake thermal efficiency and subsequently reduces the BSFC. Furthermore, by blending ethanol with the B20 blend, the BTE of the engine is improved further. The 10% ethanol blended B20 blend with 8 lpm hydrogen flow gives the maximum BTE of 37.9% higher than diesel whose values are 33.6% at full load. Also, this fuel combination led to the maximum reduced levels of CO and HC emissions with an increase in exhaust gas temperature and NOx emissions. From the results, the 10% ethanol blended B20 blend with 8 lpm H₂ flow dual-fuel configuration is recommended as an alternative to sole diesel fuel.     

Engine's behaviour on magnetite nanoparticles as additive and hydrogen addition of chicken fat methyl ester fuelled DICI engine: A dual fuel approach

The present work evaluated the influence of magnetite nanoparticles in chicken fat methyl-ester blend (CFME20) and hydrogen induction in CFME20 nano-fuels combustion performance and exhaust emissions using a 1-cylinder dual DICI engine. Results revealed that CFME20 blend exhibits a significant reduction in smoke, hydrocarbon, and carbon-monoxide emissions; however, increment in oxides of nitrogen and insignificant reduction in BTE also noted. Magnetite nanoparticles mixed with CFME20 through ultrasonication to make nano-additive fuel which noticeably decreased the exhaust emissions including oxides of nitrogen and slightly enhanced the BTE as well. Performance parameters gradually enhanced with escalating nanoparticles dosage up to 100 ppm. Hydrogen induction during nano-additive pilot fuel combustion further decreased the smoke, carbon-monoxide, and hydrocarbon emissions and enhanced the BTE to an appreciable level. However, oxides of nitrogen also enhanced with increasing hydrogen flow rate, but for 10 lpm trivial increased. Hence, the results confirmed that nano-fuel (100 ppm) with hydrogen (10 lpm) addition provides optimum outcomes.     

Role of hydrogen in improving performance and emission characteristics of homogeneous charge compression ignition engine fueled with graphite oxide nanoparticle-added microalgae biodiesel/diesel blends

The development of low-temperature combustion models combined with the use of biofuels has been considered as an efficient strategy to reduce pollutant emissions like CO, HC. NO_x, and smoke. Indeed, Homogeneous Charge Compression Ignition (HCCI) is the new approach to drastically minimize NO_x emissions and smoke owing to the lower cylinder temperature and a higher rate of homogeneous A/F mixture as compared to compression ignition (CI) engines. The present research deal with the behavior analysis of a CI engine powered by diesel, Euglena Sanguinea (ES), and their blends (ES20D80, ES40D60, ES60D40, ES80D20). The experimental results revealed the highest brake thermal efficiency for ES20D80 although it decreased by 4.1% compared to diesel at normal mode. The average drop in HC, CO, and smoke was 2.1, 2.3, and 5.7% for ES20D80 as opposed to diesel fuel. Therefore, in the next stage, ES20D80 with various concentrations of graphite oxide (GO) nanoparticle (20, 40, 60, and 80 ppm) was chosen to carry out experiments in the HCCI mode, in which hydrogen gas was induced along with air through the intake pipe at a fixed flow rate of 3 lpm for the enrichment of the air-fuel mixture. As a result, the combination of hydrogen-enriched gas and GO-added ES20D80 in the HCCI mode showed similar performance to the CI engine but registered a major reduction of NO_x and smoke emissions, corresponding to 75.24% and 53.07% respectively, as compared to diesel fuel at normal mode.     

Effect of natural antioxidant additive on hydrogen-enriched biodiesel operated compression ignition engine

The environmental degradation and depletion of fossil fuel, urges the need of renewable fuel for IC engines. Among the renewable fuel, biodiesel are widely used as alternative fuel but for recent years hydrogen is also considered as alternative fuel because of zero emission but it possess higher auto ignition temperature. In order to reduce the self-ignition temperature of hydrogen and another liquid fuel is mixed and operated as a dual fuel mode condition in CI engine. The current investigation aims to analyse the impact of natural antioxidant additive on hydrogen-enriched biodiesel operation in a diesel engine. During the experimentation process hydrogen is admitted at the intake manifold and B20 blend of juliflora biodiesel is injected in combustion cylinder. The three test fuel samples are used for the experimentation process such as diesel, B20 and B20 with hydrogen in different flow rates such as 8, 10, 12, 16,20lpm. B20 with hydrogen shows an increment of brake thermal efficiency (BTE). Among the test fuels B20 + 16lpm and B20 + 20lpm blends have better improvement of BTE of 28.815% and 28.32%, which is higher than the conventional engine at maximum load CO, HC emission is also lower for B20 + 16lpm and B20 + 20lpm than other blends but the NO_x emission increases of 26 and 28% than diesel respectively. In order to minimize the NO_x emission, natural antioxidant additive Melia Azedarach (MA) of 1000 ppm is added to B20 + 16lpm and found that B20 + 16lpm with MA shows an improvement of BTE 2.17% higher than B20 + 16lpm without additive and the NO_x emission for B20 + 16lpm with additive is 1079 ppm, which is 21.9% lower than B20 + 16lpm without additives. Therefore B20 + 16lpm with additive is superior than other test blends.     

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.     

Comparative performance analysis of diesel engine fuelled with hydrogen enriched edible and non-edible biodiesel

In the present study, a comparative analysis of enrichment of hydrogen alongside diesel fuel and two different sources of biodiesel namely rice bran oil is an edible oil, and karanja oil being non-edible is tested. Hydrogen at a fixed flow rate of 7 lpm is inducted through the intake manifold. A total of six fuel samples are considered: diesel (D), hydrogen-enriched diesel (D + H₂), hydrogen-enriched 10, and 20% rice bran biodiesel blend (RB10 + H₂ and RB20 + H₂), and hydrogen-enriched 10 and 20% karanja biodiesel blend (KB10 + H₂ and KB20 + H₂). Results indicate that enrichment of hydrogen improves combustion and results in 2.5% and 1.6% increase in the brake thermal efficiency of diesel fuel and rice bran biodiesel, respectively. For karanja biodiesel the increment is negligible. Fuel consumption of the D + H? is 6.35% lower and for RB10 + H? and KB10 + H? it is decreased by 2.9% and 1.3%, respectively. The Presence of hydrogen shows the 4–38% lower CO emissions and 6–14% lower UHC emission due to better combustion. The blends RB10 + H? and KB10 + H? produce up to 6–13% higher NOx emission and that for the blends RB20 + H? and KB20 + H? it goes up to 25%. Overall rice bran oil is found to provide better performance than karanja biodiesel.     

Effect of hydrogen enrichment in the intake air of diesel engine fuelled with honge biodiesel blend and diesel

In the current investigation, the enrichment of hydrogen with the honge biodiesel blend and diesel is used in a compression ignition engine. The biodiesel is derived from the honge oil and mixed with diesel fuel by 20% (v/v). Thereafter, hydrogen at different volume flow rates (10 and 13 lpm) is introduced into the intake manifold. The outcomes by enrichment of hydrogen on the performance, combustion and emission characteristics are investigated by examining the brake thermal efficiency, fuel consumption, HC, CO, CO₂, NOₓ emissions, in-cylinder pressure, combustion duration, and rate of heat release. The engine fuelled with honge biodiesel blend is found to enhance the thermal efficiency, combustion characteristics. Compare to diesel, the BTE increased by 2.2% and 6% less fuel consumption for the HB20 + 13H₂ blend. Further, reduction in the emission of exhausts gases like CO and HC by 21% and 24%, respectively, are obtained. This is due to carbon-free structure in hydrogen. Moreover, due to high pressure in the cylinder, there is a slight increase in oxides of nitrogen emission compare to diesel. The combustion characteristics such as rate of heat release, combustion duration, and maximum ₂rate of pressure rise and in-cylinder pressure are high due to hydrogen.     

A study on the effect of hydrogen enriched intake air on the characteristics of a diesel engine fueled with ethanol blended diesel

This work aims to replace conventional diesel fuel with low and no carbon fuels like ethanol and hydrogen to reduce the harmful emission that causes environmental degradation. Pursuant to this objective, this study investigated the performance, combustion, and emission characteristics of the diesel engine operated on dual fuel mode by ethanol-diesel blends with H₂ enriched intake air at different engine loads with a constant engine speed of 1500 rpm. The results were compared to sole diesel operation with and without H₂ enrichment. The ethanol/diesel was blended in v/v ratios of 5, 10, and 15% and tested in a diesel engine along with a 9 lpm H₂ flow rate at the intake manifold. The results revealed that 10% ethanol with 9 lpm H₂ combination gives the maximum brake thermal efficiency, which is 1% and 4.8% higher than diesel with and without H₂ enrichment, respectively. The brake specific fuel consumption of the diesel-ethanol blends with H₂ flow increased with increasing ethanol ratio in the blend. When the ethanol ratio increased from 5 to 10%, in-cylinder pressure and heat release rate were increased, whereas HC, CO, and NO_x emissions were decreased. At maximum load, the CO and HC emission of 10% ethanol blend with 9 lpm H₂ case decreased by about 50% and 28.7% compared to sole diesel. However, NO_x emission of the same blend was 11.4% higher than diesel. From the results, the study concludes that 10% ethanol blended diesel with a 9 lpm H₂ flow rate at the intake port is the best dual-fuel mode combination that gives the best engine characteristics with maximum diesel replacement.     

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.     

Strategy to reduce carbon emissions by adopting ammonia–Algal biodiesel in RCCI engine and optimize the fuel concoction using RSM methodology

Search for carbon free and carbon neutral fuels to tackle GHG emission and global warming has envisioned interest on ammonia, biodiesels, and technologies for their effective combustion. The RCCI mode of combustion, a LTC technology presents an alternate to conventional CI combustion. The low reactive Ammonia at 20%, 30%, 40% and 50% by energy is injected in the manifold along with direct injection of high reactive algal biodiesel for achieving RCCI. Using RSM approach, considering the effects of various factors and their impact on performance and emission an Ammonia Energy Faction (AEF) of 44% was optimized for RCCI mode of operation. This was validated by experimental findings. BTE of 35.13% and BSEC of 10.84 MJ/kWh were realized. HC, CO, CO₂, NOx and smoke emissions were significantly reduced by 44%, 32%, 48%, 55%, and 66%, when compared to conventional neat biodiesel combustion.     

Utilization of pyrolytic oil and hydrogen enriched syngas from single feedstock (delonix regia) through pyrolysis process and its influence on performance and emission characteristics in CI engine

The main objective of the present investigation is to conduct the performance, combustion and emission analysis of CI engine operated using hydrogen enriched syngas (pyrolytic gas) and biodiesel (pyrolytic oil) as dual fuel mode condition. Both the pyrolytic oil and syngas is obtained from single feedstock delonix regia fruit pod through pyrolysis process and then pyrolytic oil is converted into biodiesel through esterification. Initially biomass is subjected to thermal degradation at various pyrolysis temperature ranges like 350–600 °C. During the pyrolysis process syngas, pyrolytic oil and char are produced. The syngas is directly used in the CI engine and pyrolytic oil is converted into biodiesel and then used in the CI engine. The pyrolytic oil and syngas is subjected to FTIR and GC/TCD analysis respectively. The syngas analysis confirms the presence of various gases like H₂, CH₄, CO₂, CO and C₂H₄ in different proportions. The various proportions of the syngas is mainly depending upon the reactor temperature and moisture content in the biomass. The syngas composition varies with increase in the temperature and at 400 °C, higher amount of hydrogen is present and its composition are H₂ 28.2%, CO is 21.9%, CH₄ is 39.1% and other gases in smaller amounts. The biodiesel of B20 and syngas of 8lpm produced from the same feedstock are considered as test sample fuels in the CI engine under dual fuel mode operation to study the performance and emission characteristics. The study reveals that BTE has slight increase than diesel of 1.5% at maximum load. On the another hand emission like CO, HC and smoke are reduced by 15%,25% and 32% respectively at full load condition, whereas NO_x emission is increased at all loads in the range of 10–15%. Therefore B20+syngas of 8lpm can be used as an alternative fuel in CI engine without any modification and major products from pyrolysis process with waste biomass is fully used as fuel in the CI engine.     

Study of methane enrichment in a biogas fuelled HCCI engine

Biogas has been a promising alternative fuel for IC engines. However, its CO₂ content reduces calorific value and ignitability. The CO₂ fraction of raw biogas can be separated out by various techniques, which are collectively called methane enrichment. The present study explores the effect of methane enrichment on the output parameters of a Homogeneous Charge Compression Ignition (HCCI) engine. A single cylinder CI engine is altered for this purpose. Biogas (CH₄ + CO₂) is supplied along with air. Diethyl Ether (DEE) is used as the secondary fuel to initiate auto-ignition. The effects of injecting DEE at the inlet port and upstream in the intake manifold are also compared. Performance, emission and combustion characteristics such as brake thermal efficiency, equivalence ratio, HC, CO, CO₂, NO_x and smoke emissions, start and duration of combustion, in-cylinder pressure and maximum heat release rate are compared for operation with raw biogas (50% methane) and methane enriched biogas (100% methane) for various biogas flow rates and engine torques. Results show that methane enrichment enhances brake thermal efficiency by up to 2% compared to raw biogas. Methane enrichment advances and speeds up combustion. HC, CO and CO₂ emissions, maximum cylinder pressure and maximum heat release rate are also improved with methane enrichment. Ultra-low NO_x and smoke emissions can be obtained using raw biogas as well as methane enriched biogas. Low biogas flow rates provide better brake thermal efficiency and HC emissions. Manifold injection of DEE enhances brake thermal efficiency by up to 2% compared to port injection by virtue of greater mixture homogeneity.     

Exploration of engine characteristics in a CRDI diesel engine enriched with hydrogen in dual fuel mode using toroidal combustion chamber

The impact of dual fuel (diesel/hydrogen) on different performance aspects of CRDI diesel engines is investigated in this study. Amongst the fuel alternatives for IC (internal combustion) engines, the research described in this study recommended hydrogen as the least polluting and renewable in the long term. A CNG-LPG injector feeds hydrogen into the intake manifold, while diesel injectors pump pilot diesel to a DI engine adapted to hydrogen and diesel (dual-fuel mode). By maintaining 5.2 KW of consistent IP (Indicated Power) and engine speed at 1500 ± 10 rotations per minute (RPM), the hydrogen energy was varied in the dual fuel at 0% (100% diesel), 6%, 12%, 18% and 24%. With the increase in H₂ energy proportion, a decrease (5.2% decrease at 24% HES) in the BSEC (brake specific energy consumption) and the engine's BTE (brake thermal efficiency) is improved (7.85% increase at 24% HES). When emissions are considered, indicated NO_x increased (3.42%) while indicated CO₂ (3.61%), CO (2.84%), and smoke (4.85%) decreased with an increase in the proportion of hydrogen. Along with this, it was noted that the peak HRR (heat release rate) of 69.8 J/deg and in-cylinder pressure of 80.8 bar which increased significantly with the increase in hydrogen rate.     

Experimental studies on homogeneous charge CI engine fueled with LPG using DEE as an ignition enhancer

Producing and using renewable fuels for transportation is one approach for sustainable energy future for the world. A renewable fuel contributes lesser global climate change. The present work reports on the utilization of liquified petroleum gas (LPG) as a primary fuel with diethyl ether (DEE) as an ignition enhancer in a direct injection diesel engine. LPG has a simpler hydrocarbon structure than conventional fuels. DEE is recently reported as a renewable fuel and to be a low-emission high-quality diesel fuel replacement. A single cylinder, four-stroke, water-cooled naturally aspirated DI diesel engine having rated output of 3.7 kW at 1500 rpm was used for the experiments. Measurements were made to study the performance, combustion and emissions characteristics. From the results, it is observed that, the brake thermal efficiency lower by about 23% at full load with a reduction of about 65% NO emission than the diesel operation. The maximum reduction in smoke and particulate emissions is observed to be about 85% and 89%, respectively, when compared to that of diesel operation, however an increase in CO and HC emissions was observed.