Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

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The present work discusses the influence of injection schedules in hydrogen diesel homogeneous charge compression ignition (HDHCCI) mode, the experiments were carried out in three distinct diesel injection schedules like single pulse, double pulse and multi-pulse at low load operation. The maximum reachable hydrogen energy shares (HES) are 27.46%, 26.97% and 39.96% for a single pulse, double pulse and multi-pulse respectively. For almost all HES levels, the single pulse and double pulse HDHCCI mode provided ultra-low NO emission when compared with hydrogen diesel dual fuel (HDDF) mode. The multi-pulse injection increased the brake thermal efficiency (BTE) compared with single pulse and double pulse injection, since the timing of injection pulse 3 (IP3) in multi-pulse significantly altered the combustion characteristics of HDHCCI mode. Locating the IP3 in the window of 30–40 °BTDC (before cool flame) enhanced the BTE and reduced the brake specific energy consumption (BSEC) of the engine. © 2020 Hydrogen Energy Publications LLC

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Department of Automotive Engineering

School of Mechanical Engineering

Vellore Campus

Fulltext

International Journal of Hydrogen Energy

Comparison of the hydrogen powered homogeneous charge compression ignition mode with multiple injection schedules and the dual fuel mode using a twin-cylinder engine

In the present study, a numerical model based on chemical kinetics was developed to investigate the effect of different parameters on characteristics of hydrogen diesel homogeneous charge compression ignition (HDHCCI) mode. The results showed that the combustion process was retarded with diminished cool flame as increasing hydrogen energy share (HES) due to reduction of H2O2, H2O and OH radicals with hydrogen addition. Thus, it increased the indicated thermal efficiency (ITE) and decreased the indicated specific energy consumption (ISEC). The levels of NOx and soot emissions were reduced by 22% and 63% at maximum HES. A spray angle of 10° decreased the total fuel impingement compared with a spray angle of 74° because of improvement in air-fuel mixing phenomena. Incomplete combustion was recovered at HES of 25% when increasing the charge temperature or adapting the twin-pulse in HDHCCI mode, consequently the ITE was improved with a decrease in ISEC. © 2021 Hydrogen Energy Publications LLC

Parametric investigation on hydrogen driven homogeneous charge compression ignition mode with advanced diesel injection using chemical kinetics based numerical model

In this research work, four different diesel injection schedules have been experimented at a BMEP of 2 bar (Low load) in hydrogen diesel dual fuel (HDDF) mode, which are namely single pulse, double pulse phase-1, double pulse phase-2 and multi-pulse. The maximum possible hydrogen energy shares (HES) for single pulse, double pulse phase-1, double pulse phase-2 and multi-pulse injection schedules were 73.99%, 48.98%, 34.46% and 24.39% respectively. Over the injection schedules, double pulse phase-2 improved the brake thermal efficiency (BTE) from 19.50% (single pulse) to 21.61% with a penalty in NO emission. On the other hand, multi-pulse moderately increased the BTE with significant reduction in NO beside rise in smoke emission. At a BMEP of 5 bar (Medium load) operation, there was a considerable reduction in NO emission at maximum range of HES level with 18.21% of EGR, moreover the engine stability was improved with minor increase in smoke emission. © 2020 Hydrogen Energy Publications LLC

Investigation on the effect of injection schedule and EGR in hydrogen energy share using common rail direct injection dual fuel engine

This research work was aimed to investigate the maximum possible utilization of hydrogen energy in CI engine with diesel fuel replacement on energy share basis in hydrogen diesel dual fuel (HDDF) mode using common rail direct injection diesel engine. In HDDF mode, experiments were performed at two load conditions such as 3 and 5 bar of brake mean effective pressures (BMEPs). At a BMEP of 3 bar, the maximum hydrogen energy share (HES) could be reached to 50.1% without erratic engine operation, the level of NO, HC, CO and CO2 emissions were decreased up to 18%, 62%, 56% and 45% as compared with neat diesel case. However, there was no significant change in brake thermal efficiency (BTE) and smoke at high HES. At a BMEP of 5 bar, the maximum possible hydrogen energy share was nearly 40%, beyond this energy share severe knocking was noticed. NO emission was raised by 48%, whereas smoke and CO2 emission were decreased up to 20% and 24%. The brake specific HC emission was increased by 42% and there was no significant variation in CO emission with HES

Department of Electrical Engineering

School of Electrical Engineering

International Journal of Engineering and Advanced Technology Regular Issue

Effect of Hydrogen Energy Share on a Hydrogen Diesel Dual Fuel Mode using a Common Rail Direct Injection System

In today's scenario, both in gasoline and diesel engines, it is important to reduce power consumed by the auxiliary devices causing parasitic loss. Oil pump is one such device, used for lubrication purpose, which consumes higher power developed by the engine causing parasitic loss. Conventionally gerotor construction pumps are predominantly used in majority of engines, owing to its simpler construction, lower NVH and cost. However, this type being a positive displacement pump, consumes higher power with increase in speed. Hence, variable displacement oil pumps are gaining importance as the oil flow rate can be varied over the entire engine operating range. In this work, basic design elements of variable displacement oil pump are identified followed by building of mathematical model to calculate the critical design parameters. The basic mathematical model built can calculate oil flow rate, leakage losses and power consumption at different speed and load conditions. Proto samples were also built and tested at steady state conditions at different speed and load conditions. Results obtained shows that the mathematical model can predict the performance with in an accuracy of 5%. Hence, the developed mathematical model can be used as a tool for optimizing the design to achieve the target flow requirement with least power consumption. © 2019 SAE International. All Rights Reserved.

SAE Technical Papers

Mathematical Modelling and Analysis of Vane Type Variable Displacement Oil Pump

This numerical investigation aimed at studying the effects of varying biogas composition, equivalence ratio and intake charge temperature on combustion phasing of a biogas powered homogeneous charge compression ignition (HCCI) engine. Initially, the numerical model is validated against the experimental results. The present numerical investigations on a biogas powered HCCI engine indicates that the combustion phasing is advanced with increase in the methane concentration present in biogas. While, higher concentration of carbon dioxide is resulted in delayed onset of combustion. It was noticed that above 50% of biogas composition shows significant improvement in combustion phasing. Low concentration of methane helps in avoiding the knock combustion and it needs high intake charge temperature of 475 K to sustain the combustion. With increase in methane concentration, the combustion phasing was advanced for a constant equivalence ratio of 0.2 and 0.3 respectively. Combustion noise was attenuated at high concentration of carbon dioxide for a fixed value of equivalence ratio. © IAEME Publication

International Journal of Mechanical Engineering and Technology

Numerical investigations on a biogas powered homogeneous charge compression ignition engine

Hydrogen is a suitable alternate fuel as it can be produced from renewable sources, and also it does not emit carbon monoxide, hydrocarbons, particulates, and carbon dioxide (CO2). The homogeneous charge compression ignition (HCCI) mode is a relatively new engine combustion concept wherein a lean premixed air-fuel mixture is admitted and ignition occurs at multiple points throughout the combustion chamber by compression. The main merits of HCCI are extremely low levels of nitric oxide (NO) and smoke emissions with the potential to develop high thermal efficiency. In this work, experiments were performed on a stationary engine in three different modes of operation, namely, hydrogen-fueled HCCI (HHCCI), hydrogen diesel HCCI (HDHCCI), and neat diesel compression ignition (CI). In the HHCCI mode, thermal efficiency was better than the conventional diesel mode, and emission of NO was very low. The charge temperature had to be held at the lowest level to avoid misfire as this resulted in the best combustion phasing and thermal efficiency. When very early in-cylinder injection of diesel was also employed along with hydrogen diesel HCCI, i.e., HDHCCI mode, intake charge heating was not needed as diesel aided the ignition process. Operation in the neat diesel HCCI mode led to advanced combustion and low thermal efficiency. However, the additional use of hydrogen led to high thermal efficiencies because of proper combustion phasing (combustion occurring close to top dead center). The operating range in the HDHCCI mode was 2–4 bar of brake mean effective pressure (BMEP). Induction of hydrogen also lowered the concentration of NO, smoke, carbon monoxide (CO), and hydrocarbon (HC) emissions as compared to the diesel-based HCCI mode. On the whole, the HHCCI mode is promising in terms of thermal efficiency and low emissions. The HDHCCI operation with common rail injection enables proper combustion phasing and has potential for high thermal efficiency with low emissions. The results indicate that the engine can be operated in the CI mode at low outputs and switch over to HCCI operation with neat hydrogen along with charge heating in the low BMEP range (0.5–2.2 bar). Beyond this output, operation can be in the hydrogen diesel HCCI mode which is viable without heating the intake charge till a BMEP of 4 bar. At higher BMEPs, the engine can only be operated in the neat diesel CI mode. © 2018, Springer International Publishing AG, part of Springer Nature.

Green Energy and Technology

Experimental analysis of hydrogen-fueled homogeneous charge compression ignition (HCCI) engine

Objectives: This paper focuses on the influence of delay time parameterson the consequence parameter of downtime per unit time. Methods/Analysis: DTA data sets needed for various systems are synthesized in line with the Taguchi method of design of experiments. Main effects of plot for the parameters are arrived for individual parameters. Interaction effect among parameters also had been considered for analysis. Findings: Main effects of plot for means clearly reveals the parameters having most influence on the consequence variable of downtime per unit time. Also the inspection time is found not influence much. Attempt also has been made in this article to find out the interaction between certain key parameters. The interaction plot reveals the clear opposite interaction between some parameters and the maintenance inspection time. Application/Improvements: The information on the factors that affect the down time the most can best be utilized by maintenance managers and other stake holders to give focused attention to particular parameters associated in breakdown failure reduction techniques, during the post-DTA implementation period.

VIT Unitversity

Indian Journal of Science and Technology

Analyzing the Influence of Parameters of Delay Time Analysis on Down Time using Taguchi Method

A single-zone zero dimensional model was developed to study the effect of intake charge temperature (ICT) and equivalence ratio on start of combustion (SOC) of homogeneous charge compression ignition engine, which used hydrogen as a fuel. Considering that when 99.99% of hydrogen is burned then it is said to be auto ignited the intake charge temperature range was chosen from 360-400K. For this range of temperature the equivalence ratio was varied from 0.1-1.0, and the results were plotted. It was observed from the results that there was no ignition at ICT of 361 K at equivalence ratio of 1 but the combustion initiated when the ICT was increased by 1K. It was seen from the results that as ICT increases, the combustion advances well before top dead centre (TDC) but the indicated mean effective pressure (IMEP) is reduced due to lesser utilization of heat from the fuel. The SOC combustion did not varied significantly at different equivalence ratios. Thus the SOC of combustion was more sensitive to the ICT as compared to the equivalence ratio. A single-zone model helps to predict this auto ignition point, although the estimated peak and mean effective pressures are over estimated by this model because of the assumptions of total homogeneity of the inducted charge. © 2016, Sphinx Knowledge House. All rights reserved.

International Journal of ChemTech Research

Simulation analysis of hydrogen fuelled homogeneous charge compression ignition (HCCI) engine

The biogas diesel PPCCI (predominantly premixed charge compression ignition) mode where in biogas was inducted with air and diesel was injected into the cylinder using a common rail system was investigated. The injection timing of diesel which was in the range 55-70 °BTDC was found to be very influential as it affected combustion rate and phasing significantly. Though the best intake charge temperatures needed were in the range of 50-90 °C for best performance, operation even without charge heating was possible. For best performance about 80% of the total energy had to be supplied by biogas. At the best condition the thermal efficiency of the biogas diesel PPCCI mode was better than the biogas diesel DF (dual fuel) mode. HC (hydrocarbon) and NOx (nitric oxides) levels were in general significantly lower than the DF mode. The limited range of BMEPs (brake mean effective pressures) (2-4 bar) can be extended by combining the PPCCI mode with the normal diesel mode at low BMEPs and with the DF mode at high BMEPs. Thus PPCCI mode is an option for operating a diesel engine using biogas as the main fuel with low exhaust emissions. © 2015 Elsevier Ltd.

Energy

Comparison of the predominantly premixed charge compression ignition and the dual fuel modes of operation with biogas and diesel as fuels

This work was aimed at improving the performance and extending the load range of hydrogen fueled homogeneous charge compression ignition (HCCI) engine through charge temperature regulation and addition of carbon dioxide in order to control the combustion phasing. Intake charge temperature and equivalence ratio were varied from 130 °C to 80 °C and 0.19 to 0.3 respectively. In the neat hydrogen mode it was possible to operate the engine only until a brake mean effective pressure (BMEP) of 2.2 bar. Higher charge temperatures lead to knocking and advanced combustion. At any equivalence ratio the lowest possible charge temperature is the one that leads to the highest thermal efficiency. Addition of carbon dioxide retarded the combustion process and improved the thermal efficiency and also extended the load range to a BMEP of 3.1 bar. Efficiencies of hydrogen HCCI mode were higher than the conventional diesel mode with negligible level of NO emissions. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Investigations on the effects of intake temperature and charge dilution in a hydrogen fueled HCCI engine

In this experimental study, hydrogen was inducted along with air and diesel was injected into the cylinder using a high pressure common rail system, in a single cylinder homogeneous charge compression ignition engine. An electronic controller was used to set the required injection timing of diesel for best thermal efficiency. The influences of hydrogen to diesel energy ratio, output of the engine and exhaust gas recirculation (EGR) on performance, emissions and combustion were studied in detail. An increase in the amount of hydrogen improved the thermal efficiency by retarding the combustion process. It also lowered the exhaust emissions. Large amounts of hydrogen and EGR were needed at high outputs for suppressing knock. The range of operation was brake mean effective pressures of 2-4 bar. The levels of HC and CO emitted were not significantly influenced by the amount of hydrogen that was used.

Experimental investigations on a hydrogen diesel homogeneous charge compression ignition engine with exhaust gas recirculation

The present investigation was to study the performance, combustion and emission characteristics of homogeneous charge compression ignition (HCCI) combustion of diesel fuel with external mixture formation technique. A stationary four stroke, single cylinder, direct injection diesel engine capable of developing 4.4 kW at 1500 rpm was modified to operate in HCCI mode. To achieve homogeneous mixture, diesel fuel was inducted in vapour form by using a diesel fuel vaporizer. The fuel vaporizer was mounted in the intake system to provide diesel vapour, which is mixed with air and inducted into the cylinder. To control the early ignition of diesel vapour-air mixture, cooled EGR technique was adopted. Experiments were conducted with diesel vapour induction without EGR and diesel vapour induction with 10% EGR and results are compared with conventional diesel fuel operation (DI @ 23 deg bTDC and 200 bar injection pressure). From the experimental results, it is found that, the ignition delay is reduced considerably for diesel vapour induction due to better mixture preparation and results in low emissions. A reduction of about 55% and 80% in NOx emissions and 20% and 30% reduction in smoke emissions are obtained for diesel vapour induction without EGR and Diesel vapour induction with 10% EGR compared to conventional mode of operation. © 2008 Elsevier Ltd. All rights reserved.

Fuel

Study of performance, combustion and emission characteristics of diesel homogeneous charge compression ignition (HCCI) combustion with external mixture formation