A.P. Sathiyagnanam

Bio: A.P. Sathiyagnanam is an academic researcher from Annamalai University. The author has contributed to research in topics: Diesel engine & Diesel fuel. The author has an hindex of 17, co-authored 29 publications receiving 781 citations.

Combined influence of injection timing and EGR on combustion, performance and emissions of DI diesel engine fueled with neat waste plastic oil

Abstract: Disposal of waste plastic accumulated in landfills is critical from the environmental perspective. The energy embodied in waste plastic could be recovered by catalytic pyrolysis as waste plastic oil (WPO) and could be recycled as a fuel for diesel engines. This method presents a sustainable solution for waste plastic management as the gap between global plastic production and waste plastic generation keeps widening. The present study investigates the combined influence of EGR and injection timing on the combustion, performance and emission characteristics of a DI diesel engine fueled with neat WPO. Experiments were conducted at three injection timings (21°, 23° and 25°CA bTDC) and EGR rates (10, 20 and 30%) at the engine’s rated power output. When compared to diesel, the combustion event occurred closer to the TDC when the injection timing is delayed from 25°CA bTDC to 21°CA bTDC. The peak in-cylinder pressures and HRRs dropped gradually as the injection timing was delayed from 25°CA bTDC to 21°CA bTDC at all EGR rates. The engine delivered diesel-like fuel consumption with 5.1% higher brake thermal efficiency. NOx decreased up to 52.4% under 30% EGR when WPO was injected lately 21°CA bTDC. Smoke density remained lower by 46% and 9.5% for 10% and 20% EGR rates respectively for WPO only at early injection timing of 25°CA bTDC. HC and CO emissions stayed lower at early injection timing of 25°CA bTDC under 10% EGR. WPO injected at the advanced injection timing of 25°CA bTDC and low EGR rate of 10% was found to simultaneously reduce smoke and NOx by 46% and 38% respectively.

1-Hexanol as a sustainable biofuel in DI diesel engines and its effect on combustion and emissions under the influence of injection timing and exhaust gas recirculation (EGR)

Abstract: 1-Hexanol is a high-carbon bio-alcohol with higher cetane number and higher energy density than the popularly researched 1-butanol that makes it an attractive fuel for diesel engines. Studies are rapidly emerging on high-yield bio-synthesis of 1-hexanol from glucose and ligno-cellulosic biomass feedstock using engineered micro-organisms like E. coli and Clostridium species. Despite its favorable properties and promising prospects for production in bio-refineries, 1-hexanol has been barely investigated in engines. This study utilized three blends of 1-hexanol viz., HEX10, HEX20 and HEX30 obtained by mixing 10, 20 and 30% by vol. as blend component with diesel respectively. Engine tests were carried out at all loads to study the effects of 1-hexanol addition on combustion and emission characteristics of a direct injection diesel engine. Results indicated that addition of 1-hexanol to fossil diesel resulted in longer ignition delays with enhanced premixed combustion phase characterized by higher peaks of pressures and heat release rates (HRR) at the engines standard injection timing without exhaust gas recirculation (EGR). NOx emissions increased at high loads while smoke density reduced at all loads with increasing 1-hexanol content in the blends. Later tests were extended to investigate the effects of injection timing (21°, 23° and 25° CA bTDC) and EGR rates (10, 20 and 30%) on engine characteristics for all blends at high engine loads. HEX30 injected at 25°CA bTDC under 30% EGR presented the longest ignition delay with ≈2% increase in peak pressure and peak HRRs when compared to baseline diesel operation. HEX30 at similar conditions was also beneficial in terms of reduced smoke density by 35.9% with a slight penalty in NOx emissions by ≈3%. Biomass-derived 1-hexanol could be a promising and viable biofuel for existing diesel engines with some modifications.

Extraction and characterization of waste plastic oil (WPO) with the effect of n-butanol addition on the performance and emissions of a DI diesel engine fueled with WPO/diesel blends

Abstract: With growing global energy demands, recovering energy from waste plastic presents an attractive avenue to explore as it promotes recycling. Oil synthesized from waste plastic can be excellent fuel for diesel engines but yields higher carcinogenic smoke emissions and poor performance than fossil diesel (D). This study demonstrates the extraction and characterization of waste plastic oil (WPO) obtained by pyrolysis in a laboratory scale batch reactor and later sets out to investigate the effects of adding a renewable oxygenated component in the form of n -butanol (B), a naturally occurring biofuel. Three ternary blends, D50-WPO40-B10, D50-WPO30-B20 and D50-WCO20-B30 were strategically prepared to utilize both a recycled component (WPO by up to 40%) and a renewable component ( n -butanol by up to 30%). The performance and emissions of DI diesel engine when fueled with these blends was then analyzed in comparison with both neat WPO and diesel operation. Results indicated that n -butanol addition presented lower smoke emissions and higher HC emissions when compared to diesel. Addition of 10% n -butanol by vol . to WPO/ULSD blend reduced NO x emissions favorably when compared to both WPO and diesel. However NO x emissions were higher than the corresponding WPO case for higher volume n -butanol blends. Brake thermal efficiency (BTE) of the engine increased with increasing n -butanol fraction in the blends when compared to WPO. Fuel consumption of ternary blends was found to be better than WPO. D50-WPO40-B10 blend presented less NO x and smoke emissions with improvement in engine performance when compared to diesel. Study revealed that n -butanol could be a viable additive for diesel engines operating with WPO extracted from mixed waste plastic.

Effective utilization of waste plastic oil in a direct injection diesel engine using high carbon alcohols as oxygenated additives for cleaner emissions

Abstract: Waste plastic in municipal solid wastes degrade very slowly over several years and poses a serious challenge for sustainable environment. Hydrocarbons embodied in waste plastic could be converted into liquid fuel. Recycling waste plastic oil (WPO) in diesel engines offers a sustainable solution for ecological safety and energy security. However WPO produces carcinogenic smoke emissions in diesel engines that have to be controlled. This study attempts to minimize these emissions with the aid of oxygenated three high-carbon alcohols and also provides a comparative analysis on the effects of their addition to WPO individually on emissions and performance of a single cylinder diesel engine. A response surface methodology (RSM) based optimization using a 3-factor × 3-level full factorial experimental design was employed to find the optimum combination of exhaust gas recirculation (EGR), injection timing and alcohol with an objective to minimize NOx and smoke emissions with minimum BSFC. Three injection timings (21°, 23° and 25°CA bTDC) and three EGR rates (10, 20 and 30%) were used. Multiple regression models developed using RSM for NOx, smoke density and BSFC were found to be statistically significant. Interactive effects between injection timing and EGR on responses for all blends were compared. From desirability approach, WPO70P30 injected at 21° CA bTDC with 10% EGR delivered optimum emission and performance characteristics with a maximum desirability of 0.968. Pentanol was found to be the best among n-hexanol and n-octanol for this purpose. Confirmatory tests validated the models to be adequate with an error in prediction within 6%. With reference to diesel, n-pentanol with WPO injected at 21° CA bTDC with 10% EGR reduced smoke emissions by 76.8% and increased NOx emissions by 32% with an improvement in BSFC by 17.8%. With respect to neat WPO, the same blend reduced smoke emissions by 74.2% and increased NOx emissions by 9.7% with an improvement in BSFC by 3.2%.

Prediction of emissions and performance of a diesel engine fueled with n-octanol/diesel blends using response surface methodology

Abstract: n-Octanol (C8H17OH) is an advanced biofuel derived from ligno-cellulosic biomass that is suitable for compression ignition technology with several properties closer to fossil diesel. This study analyses the performance and emissions of a direct-injection (DI) diesel engine fueled with n-octanol/diesel blends containing 10% (OCT10), 20% (OCT20) and 30%(OCT30) by volume of n-octanol using a 3 × 3 full-factorial experimental design matrix that considers blend composition of n-octanol in diesel, exhaust gas recirculation (EGR) rates of 10%, 15% and 20% and injection timings of 19°, 21° and 23° crank angle (CA) before top dead centre (bTDC) as factors. Models for oxides of nitrogen (NOx), smoke, brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) were developed using response surface methodology (RSM) and were found to be significant statistically. The variation of EGR had a considerable effect on both BTE and BSFC of the engine followed by blend composition and injection timing. Best performance (BTE = 37.06%, BSFC = 0.23kg/kWh) was delivered by OCT10 at 10% EGR and 23°CA while the lowest performance (BTE = 30.95%, BSFC = 0.28kg/kWh) was by OCT30 at 20% EGR and 19°CA. Injection timing was found to have the highest effect on NOx emissions while EGR affected smoke opacity to the maximum. NOx was found to decrease from 1790 ppm (for OCT10 at 10% EGR and 23°CA) to as low as 410 ppm (for OCT30 at 20% EGR and 19°CA). Smoke opacity was found to decrease from 94.2% (for OCT10 at 20% EGR and 19°CA) to as low as 43% (for OCT30 at 10% EGR and 23°CA). Desirability approach was used to determine the best combination of blend composition of n-octanol, EGR and injection timing for minimising smoke, NOx and BSFC simultaneously. 17% by volume of n-octanol/diesel blend injected at 20° CA bTDC and 10% EGR was predicted to be optimum which delivered a simultaneous reduction of NOx (−47.4%), smoke (−21.08%) and BSFC (−8%) during confirmatory tests with a reasonable accuracy of within 4%. This method is robust and could be employed to other small engines for developing models that can predict engine characteristics with reasonable accuracy.

Use of higher alcohol biofuels in diesel engines: A review

Abstract: Biofuels have grabbed the attention of engine researchers ever since the oil-crisis and escalating costs of petro-chemicals cropped up in the ׳70s. Ethanol and methanol were the most widely researched alcohols in IC engines. However, the last decade has witnessed significant amount of research in higher alcohols due to the development of modern fermentation processes using engineered micro-organisms that improved yield. Higher alcohols are attractive second/third generation biofuels that can be produced from sugary, starchy and ligno-cellulosic biomass feedstocks using sustainable pathways. The present work reviews the current literature concerning the effects of using higher alcohols ranging from 3-carbon propanol to 20-carbon phytol on combustion, performance and emission characteristics of a wide range of diesel engines under various test conditions. The literature is abound with evidence that higher alcohols reduce carcinogenic particulate emissions that are prevalent in diesel engines. NOx emissions either increased or decreased based on the domination of either cetane number or heat of evaporation. Brake specific fuel consumption (BSFC) of the engine usually suffered due to low energy content of alcohols. A notable feature is that the combination of higher alcohols (like butanol or pentanol), high exhaust gas recirculation (EGR) rates and late injection timing enabled low temperature combustion (LTC) in diesel engines that can simultaneously reduce smoke and NOx emissions with improved engine efficiency. It can be concluded that higher alcohols reduce smoke emissions with their fuel-borne oxygen; enhance air/fuel mixing by offering long ignition delay and eventually replace fossil diesel (partially or wholly) to enable a clean and efficient combustion in compression-ignition engines. The chief thrust areas include developing mutant strains with higher yield, higher tolerance to toxic inhibition and low-cost substrates for fermentation. Further work is required in stipulating optimum blend-fuel characteristics and ensuring the long-term durability of the engines using these fuels.

Evolution, challenges and path forward for low temperature combustion engines

Abstract: Universal concerns about degradation in ambient environment, stringent emission legislations, depletion of petroleum reserves, security of fuel supply and global warming have motivated research and development of engines operating on alternative combustion concepts, which also have capability of using renewable as well as conventional fuels. Low temperature combustion (LTC) is an advanced combustion concept for internal combustion (IC) engines, which has attracted global attention in recent years. LTC concept is different from the conventional spark ignition (SI) combustion as well as compression ignition (CI) diffusion combustion concepts. LTC technology offers prominent benefits in terms of simultaneous reduction of both oxides of nitrogen (NO x ) and particulate matter (PM), in addition to reduction in specific fuel consumption (SFC). However, controlling ignition timing and combustion rate are primary challenges to be tackled before LTC technology can be implemented in automotive engines commercially. This review covers fundamental aspects of development of LTC engines and its evolution, historical background and origin of LTC concept, encompassing LTC principle, its advantages, challenges and prospects. Detailed insights into preparation of homogeneous charge by external and internal measures for mineral diesel and gasoline like fuels are covered. Fuel requirements and fuel induction system design aspect for LTC engines are also discussed. Combustion characteristics of LTC engines including combustion chemistry, heat release rate (HRR), combustion duration, knock characteristics, high load limit, fuel conversion efficiencies and combustion instability are summarized. Emission characteristics are reviewed along with insights into PM and NO x emissions from LTC engines. Finally, different strategies for controlling combustion rate and combustion timings for gasoline and mineral diesel like fuels are discussed, showing the way forward for this technology in future towards its commercialization.

Impacts of additives on performance and emission characteristics of diesel engines during steady state operation

Abstract: Depletion of fossil fuel resources and stringent emission mandates has spurred the search for improved diesel engines performance and cleaner combustion. One of the best approaches to solve these issues is to use biodiesel/diesel additives. The effects of biodiesel/diesel additives on the performance and emissions of diesel engines were comprehensively reviewed throughout this article. The additives reviewed herein were classified into five categories, i.e., oxygenated additives, metallic and non-metallic based additives, water, antioxidants, and polymeric-based additives. The effects of each category on the engine performance (i.e., brake specific fuel consumption (bsfc) and brake thermal efficiency (bte)) and emissions (i.e., CO, NO x , HC, and PM) were exclusively summarized and discussed. Furthermore, various strategies used for adding water like water-diesel emulsion, direct water injection, and adding water into the inlet manifold were illustrated and their pros and cons were completely scrutinized. Finally, opportunities and limitations of each additive considering both engine performance and combustion benignity were outlined to guide future research and development in the domain.

Effect of different technologies on combustion and emissions of the diesel engine fueled with biodiesel: A review

Abstract: Due to the shortage of the conventional fossil fuels and air pollution from combustion, new, sustainable and cleaner fuel resources are urgently required. Biodiesel has been introduced as a potential and alternative fuel for years. Biodiesel can be produced from different sources such as vegetable oils, animal fat, waste oil, etc. All of them are renewable and do not affect the food security. When biodiesel is used as a fuel resource for diesel engines, the performance and emission characteristics such as brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and brake power are almost maintained while hydrocarbons (HC), carbon monoxide (CO), and particulate matter (PM) is decreased significantly. However, higher NOx concentration is observed. This disadvantage of using biodiesel or biofuels in general is improved in recent years. The purpose of this work is to do a comprehensive investigation of different approaches applying to biodiesel fueled engine like biodiesel additives, exhaust gas recirculation (EGR), water injection (WI), emulsion technology (ET), injection strategy modification, simultaneous technologies (ST), combustion chamber geometry modification and low temperature combustion (LTC) mode. By the way, the impacts of these technologies on engine performance and emission characteristics are summarized. Upon the comparison, using LTC mode is more efficient and feasible than the others. It can reduce both NOx and PM emissions simultaneously by up to 95% and 98%, respectively, while engine performance is slightly reduced. Looking inside the LTC mode, the most efficient model is the reactivity controlled compression ignition (RCCI) combustion system. Applying RCCI combustion model might lead to the increase of CO and HC emissions, but this issue can be easily solved by using some available technologies.

A comprehensive review on the environmental impacts of diesel/biodiesel additives

Abstract: Biodiesel, in its neat or blended form with petrodiesel, is widely accepted alternative fuel for diesel engines. Although biodiesel is presumably associated with lower CO2, HC, and PMs emissions, it suffers from its own drawbacks including higher viscosity, lower volatility, lower heating value, and higher NOx emissions. In order to address these shortcomings and to meet stringent emission norms, diesel/biodiesel additives have attracted more attention recently owing to their ability to improve engine performance and mitigate hazardous emissions. While discrete emissions analysis could provide useful information on environmental impacts associated with various fuel additives, decision-making on such basis would be very difficult or even impossible since different fuel additives may have different positive/negative effects on pollutants generated during combustion process. This issue becomes even more serious in multi-objective optimization studies due to the fact that considering all emission indices for finding a global optimal point would be very complex as a result of conflicting objectives. Moreover, exhaust gas emission analysis does not consider environmental impacts caused in fuel production process. Discrete emissions analysis also lacks weighting in decision-making procedure since the level and degree of harmfulness of pollutants may not be comparable. Life cycle assessment (LCA) has been recognized as a valuable tool to address these challenges through systematical evaluation of potential environmental impacts of fuel additives. Accordingly, this paper was aimed at comprehensively reviewing and mechanistically discussing the effects of various diesel/biodiesel additives including metal-based, oxygenated, antioxidant, cold flow improver, lubricity improver, and cetane number improver additives as well as engine operating parameters like engine load, engine speed, EGR, and injection timing on both regulated and non-regulated emissions. Moreover, the environmental impacts of various diesel/biodiesel additives by incorporating an LCA approach was also critically discussed.