India
Emissions control and performance evaluation of spark ignition engine with oxy-hydrogen blending
Mar 2018
Publication
Fast depletion of fossil fuels and their detrimental effect to the environment is demanding an urgent need of alternative fuels for meeting sustainable energy demand with minimum environmental impact. Expert studies indicate hydrogen is one of the most promising energy carriers for the future due to its superior combustion qualities and availability. The use of hydrogen in spark ignition internal combustion engine may be part of an integrated solution to the problem of depletion of fossil fuels and pollution of the environment. The broader flammability limits and fast flame propagation velocity of hydrogen ensures complete combustion of fuel and allows engine to be operated at lean ranges. Lean burn operation comparatively maintains NOx CO and HC emissions at a very low level. In the present work oxyhydrogen (HHO) gas is produced in leak proof plexiglass reactor by electrolysis of water using potassium hydroxide as electrolyte. The HHO gas generator is attached to a spark ignition engine currently operating on the road without any modifications of the engine. The HHO gas produced is then added to the air which is being drawn into the engine. Experiments were conducted on a 4-stroke single cylinder natural air cooled spark ignition engine to determine total fuel consumption specific fuel consumption air fuel ratio brake power and brake thermal efficiency and emissions CO CO2 O2 NOx HC at different loads with and without addition of HHO gas to gasoline for lower speeds ranging from 700 rpm to 1500 rpm. Also mileage tests were conducted to find the speed at which the fuel consumption is optimum.
Hydrogen Embrittlement of Steel Pipelines During Transients
May 2021
Publication
Blending hydrogen into natural gas pipelines is a recent alternative adopted for hydrogen transportation as a mixture with natural gas. In this paper hydrogen embrittlement of steel pipelines originally designed for natural gas transportation is investigated. Solubility permeation and diffusion phenomena of hydrogen molecules into the crystalline lattice structure of the pipeline material are followed up based on transient evolution of internal pressure applied on the pipeline wall. The transient regime is created through changes of gas demand depending on daily consumptions. As a result the pressure may reach excessive values that lead to the acceleration of hydrogen solubility and its diffusion through the pipeline wall. Furthermore permeation is an important parameter to determine the diffusion amount of hydrogen inside the pipeline wall resulting in the embrittlement of the material. The numerical obtained results have shown that using pipelines designed for natural gas conduction to transport hydrogen is a risky choice. Actually added to overpressure and great fluctuations during transients that may cause fatigue and damage the structure also the latter pressure evolution is likely to induce the diffusion phenomena of hydrogen molecules into the lattice of the structure leading to brittle the pipe material. The numerical simulation reposes on solving partial differential equations describing transient gas flow in pipelines coupled with the diffusion equation for mass transfer. The model is built using the finite elements based software COMSOL Multiphysics considering different cases of pipe material; API X52 (base metal and nutrided) and API X80 steels. Obtained results allowed tracking the evolution with time of hydrogen concentration through the pipeline internal wall based on the pressure variation due to transient gas flow. Such observation permits to estimate the amount of hydrogen diffused in the metal to avoid leakage of this flammable gas. Thus precautions may be taken to prevent explosive risks due to hydrogen embrittlement of steel pipelines among other effects that can lead to alter safe conditions of gas conduction.
Utilization and Recycling of End of Life Plastics for Sustainable and Clean Industrial Processes Including the Iron and Steel Industry
Aug 2019
Publication
About 400 million tonnes of plastics are produced per annum worldwide. End-of-life of plastics disposal contaminates the waterways aquifers and limits the landfill areas. Options for recycling plastic wastes include feedstock recycling mechanical /material recycling industrial energy recovery municipal solid waste incineration. Incineration of plastics containing E-Wastes releases noxious odours harmful gases dioxins HBr polybrominated diphenylethers and other hydrocarbons. This study focusses on recycling options in particular feedstock recycling of plastics in high-temperature materials processing for a sustainable solution to the plastic wastes not suitable for recycling. Of the 7% CO2 emissions attributed to the iron and steel industry worldwide ∼30% of the carbon footprint is reduced using the waste plastics compared to other carbon sources in addition to energy savings. Plastics have higher H2 content than the coal. Hydrogen evolved from the plastics acts as the reductant alongside the carbon monoxide. Hydrogen reduction of iron ore in presence of plastics increases the reaction rates due to higher diffusion of H2 compared to CO. Plastic replacement reduces the process temperature by at least 100–200 °C due to the reducing gases (hydrogen) which enhance the energy efficiency of the process. Similarly plastics greatly reduce the emissions in other high carbon footprint process such as magnesia production while contributing to energy.
A Review on Recent Advances in Hydrogen Energy, Fuel Cell, Biofuel and Fuel Refining via Ultrasound Process Intensification
Mar 2021
Publication
Hydrogen energy is one of the most suitable green substitutes for harmful fossil fuels and has been investigated widely. This review extensively compiles and compares various methodologies used in the production storage and usage of hydrogen. Sonochemistry is an emerging synthesis process and intensification technique adapted for the synthesis of novel materials. It manifests acoustic cavitation phenomena caused by ultrasound where higher rates of reactions occur locally. The review discusses the effectiveness of sonochemical routes in developing fuel cell catalysts fuel refining biofuel production chemical processes for hydrogen production and the physical chemical and electrochemical hydrogen storage techniques. The operational parameters and environmental conditions used during ultrasonication also influence the production rates which have been elucidated in detail. Hence this review's major focus addresses sonochemical methods that can contribute to the technical challenges involved in hydrogen usage for energy.
Production of Advanced Fuels Through Integration of Biological, Thermo-Chemical and Power to Gas Technologies in a Circular Cascading Bio-Based System
Sep 2020
Publication
In the transition to a climate neutral future the transportation sector needs to be sustainably decarbonized. Producing advanced fuels (such as biomethane) and bio-based valorised products (such as pyrochar) may offer a solution to significantly reduce greenhouse gas (GHG) emissions associated with energy and agricultural circular economy systems. Biological and thermochemical bioenergy technologies together with power to gas (P2G) systems can generate green renewable gas which is essential to reduce the GHG footprint of industry. However each technology faces challenges with respect to sustainability and conversion efficiency. Here this study identifies an optimal pathway leading to a sustainable bioenergy system where the carbon released in the fuel is offset by the GHG savings of the circular bio-based system. It provides a state-of-the-art review of individual technologies and proposes a bespoke circular cascading bio-based system with anaerobic digestion as the key platform integrating electro-fuels via P2G systems and value-added pyrochar via pyrolysis of solid digestate. The mass and energy analysis suggests that a reduction of 11% in digestate mass flow with the production of pyrochar bio-oil and syngas and an increase of 70% in biomethane production with the utilization of curtailed or constrained electricity can be achieved in the proposed bio-based system enabling a 70% increase in net energy output as compared with a conventional biomethane system. However the carbon footprint of the electricity from which the hydrogen is sourced is shown to be a critical parameter in assessing the GHG balance of the bespoke system.
Indentation and Hydride Orientation in Zr-2.5%Nb Pressure Tube Material
Jun 2019
Publication
In this study indentations were made on Zr-2.5%Nb pressure tube material to induce multi-axial stress field. An I-shaped punch mark was indented on the Pressure tube material with predefined punch load. Later material was charged with 50 wppm of hydrogen. The samples near the punch mark were metallographically examined for hydrides orientation. It was observed that hydrides exhibited preferentially circumferential orientation far away from the indent to mixed orientation containing both circumferential and radial hydrides near the indent. This is probably as a result of stress field generated by indentation. Extent of radial hydride formation was observed to be varying with indentation load.
Insights into Renewable Hydrogen Energy: Recent Advances and Prospects
Jan 2020
Publication
Presently the fulfilment of world’s energy demand highly relies on the fossil fuel i.e. coal oil and natural gas. Fossil fuels pose threat to environment and biological systems on the earth. Usage of these fuels leads to an increase in the CO2 content in the atmosphere that causes global warming and undesirable climatic changes. Additionally these are limited sources of energy those will eventually dwindle. There is huge urge of identifying and utilizing the renewable energy resources to replace these fossil fuels in the near future as it is expected to have no impact on environment and thus would enable one to provide energy security. Hydrogen is one of the most desirable fuel capable of replacing vanishing hydrocarbons. In this review we present the status of energy demands recent advances in renewable energy and the prospects of hydrogen as a future fuel are highlighted. It gives a broad overview of different energy systems and mainly focuses on different technologies and their reliability for the production of hydrogen in present and future.
Numerical Modelling of Unconfined and Confined Hydrogen Explosion
Sep 2019
Publication
Numerical studies were conducted with the objective of gaining a better understanding of the consequences of potential explosion that could be associated with release of hydrogen in a confined and unconfined environment. This paper describes the work done by us in modelling explosion of accidental releases of hydrogen using our Fire Explosion Release Dispersion (FRED) software. CAM and SCOPE models in FRED is used for validation of congested/uncongested unconfined and congested/uncongested confined vapour cloud explosion respectively. In the first step CAM is validated against experiments of varying gas cloud size blockage ratio equivalence ratio of the mixture and blockage configuration. The model predictions of explosion overpressure are in good agreement with experiments. The results obtained from FRED i.e. overpressure as a function of distance match well in comparison to the experiments. In the second step SCOPE is validated against vented explosion experiments available in open literature. In general SCOPE reproduces the maximum overpressure within the factor of 2. Moreover it well predicts the trends of increase in overpressure with change in type of the fuel increase in number of obstacles blockage ratio and decrease in the vent size.
Plasmonic Nickel Nanoparticles Decorated on to LaFeO3 Photocathode for Enhanced Solar Hydrogen Generation
Nov 2018
Publication
Plasmonic Ni nanoparticles were incorporated into LaFeO3 photocathode (LFO-Ni) to excite the surface plasmon resonances (SPR) for enhanced light harvesting for enhancing the photoelectrochemical (PEC) hydrogen evolution reaction. The nanostructured LFO photocathode was prepared by spray pyrolysis method and Ni nanoparticles were incorporated on to the photocathode by spin coating technique. The LFO-Ni photocathode demonstrated strong optical absorption and higher current density where the untreated LFO film exhibited a maximum photocurrent of 0.036 mA/cm2 at 0.6 V vs RHE and when incorporating 2.84 mmol Ni nanoparticles the photocurrent density reached a maximum of 0.066 mA/cm2 at 0.6 V vs RHE due to the SPR effect. This subsequently led to enhanced hydrogen production where more than double (2.64 times) the amount of hydrogen was generated compared to the untreated LFO photocathode. Ni nanoparticles were modelled using Finite Difference Time Domain (FDTD) analysis and the results showed optimal particle size in the range of 70–100 nm for Surface Plasmon Resonance (SPR) enhancement.
Recent Advances in Biomass Pretreatment Technologies for Biohydrogen Production
Jan 2022
Publication
Hydrogen is an economical source of clean energy that has been utilized by industry for decades. In recent years demand for hydrogen has risen significantly. Hydrogen sources include water electrolysis hydrocarbon steam reforming and fossil fuels which emit hazardous greenhouse gases and therefore have a negative impact on global warming. The increasing worldwide population has created much pressure on natural fuels with a growing gap between demand for renewable energy and its insufficient supply. As a result the environment has suffered from alarming increases in pollution levels. Biohydrogen is a sustainable energy form and a preferable substitute for fossil fuel. Anaerobic fermentation photo fermentation microbial and enzymatic photolysis or combinations of such techniques are new approaches for producing biohydrogen. For cost-effective biohydrogen production the substrate should be cheap and renewable. Substrates including algal biomass agriculture residue and wastewaters are readily available. Moreover substrates rich in starch and cellulose such as plant stalks or agricultural waste or food industry waste such as cheese whey are reported to support dark- and photo-fermentation. However their direct utilization as a substrate is not recommended due to their complex nature. Therefore they must be pretreated before use to release fermentable sugars. Various pretreatment technologies have been established and are still being developed. This article focuses on pretreatment techniques for biohydrogen production and discusses their efficiency and suitability including hybrid-treatment technology
Numerical Modelling of Hazards of Hydrogen Storage
Sep 2017
Publication
For the general public to use hydrogen as a vehicle fuel they must be able to handle hydrogen with the same degree of confidence as conventional liquid and gaseous fuels. The hazards associated with jet releases from accidental leaks in a vehicle-refuelling environment must be considered if hydrogen is stored and used as a high-pressure gas since a jet release can result in a fire or explosion. This paper describes the work done by us in modelling some of the consequences of accidental releases of hydrogen implemented in our Fire Explosion Release Dispersion (FRED) software. The new dispersion model is validated against experimental data available in the open literature. The model predictions of hydrogen gas concentration as a function of distance are in good agreement with experiments. In addition FRED has been used to model the consequence of the bursting of a vessel containing compressed hydrogen. The results obtained from FRED i.e. overpressure as a function of distance match well in comparison to experiments. Overall it is concluded that FRED can model the consequences of an accidental release of hydrogen and the blast waves generated from bursting of vessel containing compressed hydrogen
Experimental Investigation on Helium Jet Release and Distribution in a Vented Cylindrical Enclosure – Effect of Wall Temperature Conditions
Oct 2015
Publication
Hydrogen generated during core meltdown accidents in nuclear reactors can cause serious threat to the structural integrity of the containment and safe operation of nuclear power plants. The study of hydrogen release and mixing within the containments is an important area of safety research as hydrogen released during such accidents in nuclear power plants can lead to hydrogen explosions and catastrophic consequences. A small scale experimental setup called the AERB-IIT Madras Hydrogen Mixing Studies (AIHMS) facility is setup at IIT Madras to study the distribution of hydrogen subsequent to release as a jet followed by its response to various wall thermal conditions. The present paper gives details of the design fabrication and instrumentation of the AIHMS facility and a comparison of features of the facility with respect to other facilities existing for hydrogen mitigation studies. Then it gives details of the experiments conducted and the results of the preliminary experiments on concentration build-up as a result of injection of gases (air and helium) and effect of thermally induced natural convection on gas mixing performed in this experimental facility.
Single Step Compact Steam Methane Reforming Process for Hydrogen-Cng (H-Cng) Production from Natural Gas
Sep 2011
Publication
Compressed natural gas (CNG) is being increasingly used as a clean transportation fuel. However for further reduction in emissions particularly NOx H-CNG mixture with ~ 20 % hydrogen is recommended. Presently most of the H-CNG mixture is produced by blending hydrogen with CNG. For hydrogen production Steam Methane Reforming (SMR) is a major process accounting for more than 90% of hydrogen production by various industries. In this process natural gas is first reformed to syn gas under severe operating conditions (Pressure 20-30 bar temperature 850-950 deg C) followed by conversion of CO to hydrogen in the shift reactor. Other method of hydrogen production such as electrolysis of water is more expensive. Further there are issues of safety with handling of hydrogen its storage and transportation for blending. In order to overcome these problems a single step compact process for the production of H-CNG gaseous mixture through low severity steam methane reforming of natural gas has been developed. It employs a catalyst containing nickel nickel oxide magnesium oxide and silica and has the capability of producing H-CNG mixture in the desired proportion containing 15-20 vol % hydrogen with nil CO production. The process is flexible and rugged allowing H-CNG production as per the demand. The gaseous H-CNG product mixture can directly be used as automobile fuel after compression. The process can help as important step in safe transition towards hydrogen economy. A demonstration unit is being set up at IOC R&D Centre.
Parametric Studies on LaNi4.7Al0.3 Based Hydrogen Storage Reactor with Embedded Cooling Tubes
Mar 2019
Publication
This study reports the investigative conclusions of parametric studies conducted to understand the effect of operating parameters on absorption and desorption characteristics of LaNi4.7Al0.3 metal hydride system for thermal management applications. Reactor with improved design containing 55 embedded cooling tubes is fabricated and filled with 4 kg of metal hydride alloy. Using water as heat transfer fluid (HTF) effects of supply pressure HTF temperature and HTF flow rate on absorption and desorption characteristics of the reactor are analyzed. Increasing supply pressure leads to prominent improvement in absorption capacity while the increase in HTF temperature enhanced desorption performance. At 20 bar and 20 °C 46.2877 g of hydrogen (1.16 wt%) was absorbed resulting in total energy output of 707.3 kJ for 300 s. During desorption at 80 °C with water flow rate of 8 lpm heat input of 608.1 kJ for 300 s resulted in 28.5259 g of hydrogen desorption.
Statistics, Lessons Learned and Recommendations from Analysis of HIAD 2.0 Database
Mar 2022
Publication
The manuscript firstly describes the data collection and validation process for the European Hydrogen Incidents and Accidents Database (HIAD 2.0) a public repository tool collecting systematic data on hydrogen-related incidents and near-misses. This is followed by an overview of HIAD 2.0 which currently contains 706 events. Subsequently the approaches and procedures followed by the authors to derive lessons learned and formulate recommendations from the events are described. The lessons learned have been divided into four categories including system design; system manufacturing installation and modification; human factors and emergency response. An overarching lesson learned is that minor events which occurred simultaneously could still result in serious consequences echoing James Reason's Swiss Cheese theory. Recommendations were formulated in relation to the established safety principles adapted for hydrogen by the European Hydrogen Safety Panel considering operational modes industrial sectors and human factors. This work provide an important contribution to the safety of systems involving hydrogen benefitting technical safety engineers emergency responders and emergency services. The lesson learned and the discussion derived from the statistics can also be used in training and risk assessment studies being of equal importance to promote and assist the development of sound safety culture in organisations.
Numerical Investigation of Hydrogen-air Deflagrations in a Repeated Pipe Congestion
Sep 2019
Publication
Emerging hydrogen energy technologies are creating new avenues for bring hydrogen fuel usage into larger public domain. Identification of possible accidental scenarios and measures to mitigate associated hazards should be well understood for establishing best practice guidelines. Accidentally released hydrogen forms flammable mixtures in a very short time. Ignition of such a mixture in congestion and confinements can lead to greater magnitudes of overpressure catastrophic for both structure and people around. Hence understanding of the permissible level of confinements and congestion around the hydrogen fuel handling and storage unit is essential for process safety. In the present study numerical simulations have been performed for the hydrogen-air turbulent deflagration in a well-defined congestion of repeated pipe rig experimentally studied by [1]. Large Eddy Simulations (LES) have been performed using the in-house modified version of the OpenFOAM code. The Flame Surface Wrinkling Model in the LES context is used for modelling deflagrations. Numerical predictions concerning the effects of hydrogen concentration and congestion on turbulent deflagration overpressure are compared with the measurements [1] to provide validation of the code. Further insight about the flame propagation and trends of the generated overpressures over the range of concentrations are discussed.
In-situ Study of the Effect of Hydrogen on Fatigue Crack Initiation in Polycrystalline Nickel
Aug 2019
Publication
Correlating hydrogen embrittlement phenomenon with the metallic microstructural features holds the key for developing metals resistant to hydrogen-based failures. In case of fatigue failure of hydrogen charged metals in addition to the hydrogen-based failure mechanisms associated with monotonic loading such as HELP HEDE etc. microstructural features such as grain size type of grain boundary (special/random) fraction of special grain boundaries; their network and triple junctions can play a complex role. The probable sites for fatigue crack initiation in such metals can be identified as the sites of highest hydrogen concentration or accumulated plastic strain. To this end we have developed an experimental framework based on in-situ fatigue crack initiation and propagation studies under scanning electron microscope (SEM) to identify the weakest link in the metallic microstructure leading to failure. In-situ fatigue experiments are performed on carefully designed polycrystalline nickel (99.95% pure) specimens (miniaturised shallow-notched & electro-polished) using a 10 kN fatigue stage inside the SEM. Electron Back Scattering Diffraction (EBSD) map of the notched region surface helps identify the distribution of special/random grain boundaries triple junctions and grain orientation. The specimen surface in the shallow notched region for both the hydrogen charged and un-charged specimens are then carefully studied to correlate the microstructural feature associated with fatigue crack initiation sites. Such correlation of the fatigue crack initiation site and microstructural feature is further corroborated with the knowledge of hydrogen trapping and grain’s elastic anisotropicity to be either the site of high hydrogen concentration accumulated plastic slip or both.
Failure Analysis of Cooling Duct of Top Engine Cowl Panel of Fighter Aircraft
Jun 2019
Publication
Present work describes the failure analysis of cooling duct of a fighter aircraft. The analyzed chemical composition of cooling duct indicates that it is manufactured from Al-based alloy (AA 3003 or its equivalent). Microstructure of cooling duct displays the presence of two phases namely matrix and insoluble particles. The hardness values at different locations within damaged area of cooling duct reflect nearly same and consistent. The fracture surface of the cooling duct exhibits transgranular features and cracks with little branching. The analyzed hydrogen content in cooling duct is significantly higher (∼ 12 ppm) than the specified one (< 1 ppm). However the alloy used to fabricate cooling duct is not susceptible to typical hydrogen embrittlement. This shows hydrogen pick up during operation. The presence of cracks with branching does reflect features of hydrogen embrittlement. In addition striations indicative of fatigue features are also observed. It thus appears that the cooling duct has failed due to pick up of large amount of hydrogen as well as vibrational fatigue.
Modelling of Fatigue Crack Initiation in Hydrogen Charged Polycrystalline Nickel
Jun 2019
Publication
Hydrogen Embrittlement (HE) leads to deterioration of the fracto-mechanical properties of metals. In spite of vast literature it is still not clearly understood and demands significant research on this topic. For better understanding of the hydrogen effect on fatigue behaviour of metals present work focuses on developing a computational framework for fatigue crack initiation studies in metals in the presence of hydrogen. The developed framework consists of a nonlocal crystal plasticity model coupled with hydrogen transport model to study the fatigue behaviour of hydrogen charged metals. The nonlocal crystal plasticity model accounts for the statistically stored dislocations (SSDs) and geometrically necessary dislocations (GNDs) in polycrytalline metal. Hydrogen transport model on the other hand accounts for diffusion and trapping behavior of hydrogen due to concentration gradient pressure gradient plastic strain-rate with dislocations as the only trapping sites along the slip systems. A polycrystalline representative volume element (RVE) with periodic boundary conditions is used in this study. Fatigue crack initiation criterion is proposed for the simulated RVE with controlled microstructure by considering a critical value of the fatigue indicator parameter (FIP). FIP is formulated based on the experimental observations of several crack initiation sites along the grain boundaries their normal direction with respect to loading direction and the accumulated plastic strain in nickel polycrystalline samples. Developed simulation framework correctly accounts cyclic stress-strain behavior and multiple fatigue crack initiation sites observed experimentally in the presence of hydrogen.
Energy, Exergy, and Environmental Analyses of Renewable Hydrogen Production Through Plasma Gasification of Microalgal Biomass
Feb 2021
Publication
In this study an energy exergy and environmental (3E) analyses of a plasma-assisted hydrogen production process from microalgae is investigated. Four different microalgal biomass fuels namely raw microalgae (RM) and three torrefied microalgal fuels (TM200 TM250 and TM300) are used as the feedstock for steam plasma gasification to generate syngas and hydrogen. The effects of steam-tobiomass (S/B) ratio on the syngas and hydrogen yields and energy and exergy efficiencies of plasma gasification (hEn;PG hEx;PG) and hydrogen production(hEn;H2 hEx;H2 ) are taken into account. Results show that the optimal S/B ratios of RM TM200 TM250 and TM300 are 0.354 0.443 0.593 and 0.760 respectively occurring at the carbon boundary points (CBPs) where the maximum values of hEn;PG hEx;PG hEn;H2 and hEx;H2 are also achieved. At CBPs torrefied microalgae as feedstock lower thehEn;PG hEx;PG hEn;H2 and hEx;H2 because of their improved calorific value after undergoing torrefaction and the increased plasma energy demand compared to the RM. However beyond CBPs the torrefied feedstock displays better performance. A comparative life cycle analysis indicates that TM300 exhibits the highest greenhouse gases (GHG) emissions and the lowest net energy ratio (NER) due to the indirect emissions associated with electricity consumption.
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