Akhilendra Pratap Singh

An Experimental Investigation of Combustion, Emissions and Performance of a Diesel Fuelled HCCI Engine

Homogeneous charge compression ignition (HCCI) is an advanced combustion concept that is developed as an alternative to diesel engines with higher thermal efficiency along with ultralow NOx and PM emissions. To study the performance of this novel technique, experiments were performed in a two cylinder engine, in which one cylinder is modified to operate in HCCI mode while other cylinder operates in conventional CI mode. The quality of homogeneous mixture of air and fuel is the key feature of HCCI combustion. Low volatility of diesel is a major hurdle in achieving HCCI combustion because it is difficult to make a homogeneous mixture of air and fuel. This problem is resolved by external mixture preparation technique in uses a dedicated diesel vaporizer with an electronic control system . All the injection parameters such as fuel quantity, fuel injection timing, injection delay etc., are controlled by the injection driver circuit. To study the effect of exhaust gas recirculation on combustion and emission behavior, two different EGR conditions (0% and 15%) are investigated. Results show superior emission characteristics of HCCI combustion as compared to conventional CI combustion and gives up to 80% and 50% reduction in NOx and smoke respectively. However HC and CO emissions are slightly higher as compared to conventional combustion. Application of EGR controls the combustion rate significantly and improves emission behavior at a cost of slightly inferior performance.

Evaluation of Fuel Injection Strategies for Biodiesel Fueled CRDI Engine Development and Particulate Studies

In this study, a state-of-the-art single cylinder research engine was used to investigate the effects of fuel injection parameters on combustion, performance, emission characteristics, and particulates and their morphology. The experiments were carried out at three FIPs (400, 700 and 1000 bar) and four SoMI timings (4°, 6°, 8° and 10° bTDC) for biodiesel blends [B20 (20% v/v biodiesel blend) and B40 (40% v/v biodiesel blend)] compared to baseline biodiesel at a constant engine speed (1500 rpm), without pilot injection and exhaust gas recirculation (EGR). The experimental results showed that FIP and SoMI timings affected the in-cylinder pressure and the heat release rate (HRR), significantly. At higher FIPs, the biodiesel blends resulted in slightly higher rate of pressure rise (RoPR) and combustion noise compared to baseline mineral diesel. All the test fuels showed relatively shorter combustion duration at higher FIPs and advanced SoMI timings. The biodiesel blends showed slightly higher NOx and smoke opacity compared to baseline mineral diesel. Lower particulate number concentration at higher FIPs was observed for all the test fuels. However, the biodiesel blends showed relatively higher particulate numbers compared to baseline mineral diesel. Significantly lower trace metals in the particulates emitted from biodiesel blend fueled engine was an important finding of this study. The particulate morphology showed relatively smaller number of primary particles in particulate clusters from biodiesel exhaust, which resulted in relatively lower toxicity, thus rendering biodiesel more environmentally benign.

Experimental evaluation of sensitivity of low-temperature combustion to intake charge temperature and fuel properties

Main challenge for mineral diesel in achieving low-temperature combustion is its poor volatility characteristics, which results in relatively inferior fuel–air mixtures. In this experimental study, feasibility of mineral diesel–fueled premixed homogeneous charge compression ignition (PHCCI) combustion was explored by employing an external charge preparation technique. An external mixing device called “fuel vaporizer” was developed for improving the fuel–air mixing. To investigate the effect of fuel properties on PHCCI combustion, this study was carried out using a variety of additives blended with mineral diesel, which included low-quality high-volatile fuel (kerosene), low-cetane high-volatile fuels (ethanol and gasoline) and high-cetane low-volatile fuel (biodiesel). To investigate the effects of intake charge temperature (Ti), experiments were performed at three Tis (160, 180 and 200 °C) and six different relative air–fuel ratios (λ = 1.5–5.25). In all experiments, exhaust gas recirculation (EGR) rate was maintained constant at 10%. Experimental results showed that combustion phasing was significantly affected by the fuel properties and Ti. At lower engine loads, volatile additives improved start of combustion, combustion phasing and heat release rate; however, excessive knocking was seen at higher engine loads. Diesoline (15% v/v gasoline with mineral diesel) and diesosene (15% v/v kerosene with mineral diesel) showed significant improvement in engine performance characteristics, while B20 (20% v/v soybean biodiesel with mineral diesel) delivered relatively higher indicated specific fuel consumption (ISFC). Increasing Ti affected fuel–air mixing, which resulted in slightly lower carbon monoxide (CO) and hydrocarbon (HC) emissions, but higher Ti led to excessive knocking and resulted in slightly higher oxides of nitrogen (NOx) emissions. Addition of volatiles reduced particulate emissions; however, increasing Ti led to slightly higher particulate emissions. Presence of significant number of nanoparticles during combustion of B20 was another important finding of this study. Overall, it was concluded that addition of volatile additives such as gasoline, alcohols and kerosene, in addition to optimized Ti can improve mineral diesel–fueled PHCCI combustion and can lead to potentially expanded operating window.

Introduction to Air Pollution and Its Control

Air pollution prevention is an economic burden to a person and to a nation on a global scale. Air pollution is a threat to human and environment; therefore, it is extremely important to understand fundamental sources, causes, health effects associated with air pollution. This monograph gives an overview about air pollution and suggests the suitable preventive measures to reduce air pollution. This monograph includes air pollution from IC engines, primary organic aerosols (POAs), effect of volatile organic compounds (VOCs) on health and some advanced topics such as numerical simulation of airflow in hospital. This monograph also includes various engine technologies such as multipoint port fuel injection (MPFI), common rail direct injection (CRDI), indirect injection engine (IDI) and gasoline direct injection (GDI) techniques to reduce air pollution from road transport sector. Nuclear pollution, which is another threat for human life and environment is discussed towards end of this monograph.

Toxicity and mutagenicity of exhaust from compressed natural gas: Could this be a clean solution for megacities with mixed-traffic conditions?

Despite intensive research carried out on particulates, correlation between engine-out particulate emissions and adverse health effects is not well understood yet. Particulate emissions hold enormous significance for mega-cities like Delhi that have immense traffic diversity. Entire public transportation system involving taxis, three-wheelers, and buses has been switched from conventional liquid fuels to compressed natural gas (CNG) in the Mega-city of Delhi. In this study, the particulate characterization was carried out on variety of engines including three diesel engines complying with Euro-II, Euro-III and Euro-IV emission norms, one Euro-II gasoline engine and one Euro-IV CNG engine. Physical, chemical and biological characterizations of particulates were performed to assess the particulate toxicity. The mutagenic potential of particulate samples was investigated at different concentrations using two different Salmonella strains, TA98 and TA100 in presence and absence of liver S9 metabolic enzyme fraction. Particulates emitted from diesel and gasoline engines showed higher mutagenicity, while those from CNG engine showed negligible mutagenicity compared to other test fuels and engine configurations. Polycyclic aromatic hydrocarbons (PAHs) adsorbed onto CNG engine particulates were also relatively fewer compared to those from equivalent diesel and gasoline engines. Taken together, our findings indicate that CNG is comparatively safer fuel compared to diesel and gasoline and can offer a cleaner transport energy solution for mega-cities with mixed-traffic conditions, especially in developing countries.

Future Mobility Solutions of Indian Automotive Industry: BS-VI, Hybrid, and Electric Vehicles

Worldwide scientists and researchers are concerned about climate change and global warming. Automotive vehicles are a major source for emission of greenhouse gases (GHG) and particulate matter (PM). Complying with strict BS-VI emission norms require improvised engine calibration, complex after-treatment (DOC, SCR, and DPF) system calibration, infrastructure development and engine validation. BS-VI will significantly reduce GHG and atmospheric PM, but with long-term perspective, an alternate solution is required to develop zero-emission vehicles. Recently, government planned to debar gasoline and diesel vehicles by 2030. In this scenario, Indian automotive industry has to be future-ready. The future disruptions in Indian automotive would include implementation of hybrid, electric, and fuel-cell vehicles. Government has started working in infrastructure development of hybrid and electric vehicles such as charging units, battery development, charging infrastructure development. However, currently hybrid and electric vehicles are significantly costlier and are required to be economically feasible. It can be assumed that conventional gasoline engines will be used in hybrid vehicles. Diesel engines would also be difficult to be phased out since implementation of hybrid/electric vehicles in long-haul vehicles and high-tonnage vehicles would remain challenging, where diesel engines are currently used virtually unchallenged by any other technology options.

Low-Temperature Combustion: An Advanced Technology for Internal Combustion Engines

Universal concerns about degradation of ambient environmental conditions, stringent emission legislations, depletion of petroleum reserves, security of fuel supply, and global warming have motivated R&D of engines operating on alternative combustion concepts, which have the capability of using renewable fuels. Low-temperature combustion (LTC) is an advanced combustion concept for internal combustion (IC) engines, which has attracted global attention in recent years. LTC is radically different from conventional spark ignition (SI) combustion and compression ignition (CI) diffusion combustion concepts. LTC technology offers prominent benefits in terms of simultaneous reduction of both oxides of nitrogen (NOx) and particulate matter (PM) in addition to reducing specific fuel consumption. However, controlling ignition timing and heat release rate (HRR) are primary challenges to be tackled before LTC technology can be implemented in automotive engines commercially. This chapter reviews fundamental aspects of development of LTC engines and their evolution, historical background, and origin of LTC concept and its future prospects. Detailed insights into preparation of homogeneous charge by external and internal measures for diesel like fuels are discussed. Combustion characteristics of LTC engines including combustion chemistry, HRR, and knock characteristics are also touched upon in this chapter. Emission characteristics are also reviewed along with insights into PM and NOx emissions from LTC engines.

Utilization of Alternative Fuels in Advanced Combustion Technologies

In the past few decades, rapid technological advancements have resulted in significantly fast depletion of petroleum resources. Extensive utilization of gasoline and mineral diesel in automobiles sector has led to an increase in the worldwide fuel consumption. Today compression ignition (CI) engines are being widely used in light-duty and heavy-duty vehicles, mainly because of their higher efficiency, greater reliability, and superior fuel economy compared to gasoline engines. However, CI engines experience major drawbacks of very high emissions of oxides of nitrogen (NOx) and particulate matter (PM). Although several after-treatment devices such as lean NOx trap (LNT), diesel particulate filters (DPFs), diesel oxidation catalysts (DOCs) are being used to meet stringent emission norms, however, high initial cost, operational issues, and system complexity put serious limitations on their usage. Therefore, researchers have been actively working to explore and develop new combustion strategies such as low-temperature combustion (LTC) in order to control harmful exhaust emissions. Utilization of alternative fuels in these advanced combustion concepts has given a new direction to IC engine research through which issues such as rapid petroleum consumption rate and engine exhaust emissions can be resolved simultaneously. This chapter describes various derivatives of LTC technique and methodology for utilization of various alternative fuels.

Introduction of Alternative Fuels

Energy is a basic requirement for economic development. Growing energy consumption has resulted in world becoming increasingly dependent on fossil fuels such as coal, oil and gas; therefore, it becomes necessary to develop a sustainable path of energy. Gaseous fuels and biofuels seem to have the potential to contribute significantly to India’s energy security. This monograph shows the current status of different alternative fuels and describes some advanced techniques to improve the quality of alternative fuels. Utilization of these alternative fuels in existing vehicles is another important aspect, which has been covered in this monograph.

Evolving Energy Scenario: Role and Scope for Alternative Fuels in Transport Sector

Due to rapidly increasing energy consumption rate, access to clean, affordable and sustainable energy has become one of the important factors for economic development of any country. Depletion of petroleum reserves and associated issues related to their utilization in internal combustion (IC) engines motivated researchers to explore such alternative energy resources. In this quest, researchers have developed various solar-based and water-based energy generation methodologies; however, these techniques are not mature enough to fulfil the current energy requirements of transport sector. Therefore, appropriate alternatives to liquid fossil fuels (mineral diesel and gasoline) have been explored, in which gaseous fuels (compressed natural gas (CNG), liquefied petroleum gas (LPG), dimethyl ether (DME), Hydrogen, HCNG, etc.), biofuels [alcohols, biodiesel, straight vegetable oil (SVO)], synthetic fuels, etc., are the important ones. Utilization of microbes to produce biofuels has also gained significant attention of researchers. This chapter provides a snapshot of the current energy landscape, available options and discusses the path forward, which can be used for the development of sustainable and secure energy options for our nation.