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Author: search.filters.author.Verma, SaketSubject: search.filters.subject.Hydrogen

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    Experimental analysis on the effect of hydrogen supply systems in a diesel dual fuel engine
    (ISEES, 2019) Verma, Saket
    An experimental investigation on dual fuel (DF) operation of a diesel engine with hydrogen as the main fuel and diesel as the pilot fuel has been performed. The focus has been made on gaseous fuel delivery system for performance enhancement during DF operations. Two techniques of hydrogen delivery namely, manifold port induction and manifold port injection are compared in the DF engine. In the case of manifold induction, the gas is introduced with the help of a gas mixture in the intake manifold, whereas in the case of manifold injection, the gas is introduced with the help of an injector. The injector is located close to the intake valve and its timing is controlled through an electronic control unit. It was found that hydrogen manifold injection improves the diesel substitution and thermal efficiency of the DF engine as compared to manifold induction technique. The diesel substitution was improved by 2.3% and 1.5% at low and high loads respectively. Similarly, the brake thermal efficiency was improved by 0.4% and 0.5% at low and high loads respectively.
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    Exergy Analysis of Hydrogen-Fueled Spark Ignition Engine Based on Numerical Investigations
    (Springer, 2017-02) Verma, Saket
    Hydrogen fuelled IC engines (H2ICEs) have been considered as one of the most promising systems for pollution free transportations and their performance and combustion merits have been extensively discussed in the literature. However, studies related to these discussions have largely been linked to first-law analysis. On other hand, second-law of thermodynamics coupled with first-law, also known as exergy analysis, can give better insight into the engine performances. Bearing it in mind, this work presents second-law quantification of hydrogen engine processes and sub-processes, which helps to understand its true potential to deliver the output and simultaneously estimates various losses. This study quantifies different process inefficiencies in terms of irreversibilities thereby identifying the gaps to be addressed for further improvements. A computational fluid dynamics model has been prepared to simulate hydrogen-fueled spark-ignition engine (H2SIE) operations and second-law equations have been coupled to ascertain different exergy terms. Present study shows that combustion process is the biggest source of irreversibility in IC engines. It has also been found that the level of irreversibility for a hydrogen-operated engine is substantially lesser as compared to that with gasoline engine under identical ranges of operating conditions. Combustion irreversibilities for H2SIE and gasoline engine were found to be 15% and 23.6% of the total input fuel exergy respectively. Moreover, significant increase in second-law efficiency for H2SIE as 44.4% compared to 36.8% that for gasoline engines has been found. Another important conclusion from this work includes exergy distribution for H2SIE, which is considerably diverse from gasoline engine operation. It indicates that optimization and improvements of different H2SIE processes require specific attentions; nevertheless, show much better ability to deliver.
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    Analysis of metal hydride storage on the basis of thermophysical properties and its application in microgrid
    (Elsevier, 2020-10) Verma, Saket
    Present study focuses on the analysis of metal hydride hydrogen storage in renewable power generators-based microgrid (µG) system. The design of metal hydride storage unit requires parametric analysis on the basis of its thermophysical properties such as activation/deactivation energy, enthalpy of formation, equilibrium pressure, reaction kinetics and external thermal management system. This parametric analysis helps to assess suitability of the hydride storage with hydrogen generation (electrolyzer) and utilization (fuel cell) units in µG. Application of metal hydride in the µG creates a sophisticated system which requires careful analysis and operating strategy for achieving manifold benefits such as higher efficiency, durability of the components and self-sufficiency. In the present study, different hydrides are selected namely, LaNi5, TiCr1.6Mn0.2, hydroalloy C5 graphite and MgH2 for performance analysis on the basis of their thermophysical properties. The performance is evaluated in different operating modes aiming for higher efficiency, components durability and system self-sufficiency (minimum grid-dependency). A detailed mathematical modelling is performed in the MATLAB simulation tool for performance evaluation of overall µG system, which consists of 5 kW photovoltaic (PV), 1 kW fuel cell (FC), 5 L hydride storage and 0.6 kW electrolyzer. It was observed that the hydrogen charging and discharging processes in the hydride storage unit strongly depend on its thermophysical properties and hence require certain specific operating conditions for efficient working. Considering suitable discharging characteristics at low temperature and pressure, LaNi5 and C5 hydroalloy can be suitable for transient operation with proton exchange membrane fuel cell application. Overall energy efficiency of up to ≈ 95.49% is achieved in such type of storage-based µG. Grid-dependency ratio (load demand met by grid power/total load demand) was found between 0.26 and 5.83% in different operating modes.
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    A renewable pathway towards increased utilization of hydrogen in diesel engines
    (Elsevier, 2020-02) Verma, Saket
    In the present work, dual fuel operation of a diesel engine has been experimentally investigated using biodiesel and hydrogen as the test fuels. Jatropha Curcas biodiesel is used as the pilot fuel, which is directly injected in the combustion chamber using conventional diesel injector. The main fuel (hydrogen) is injected in the intake manifold using a hydrogen injector and electronic control unit. In dual fuel mode, engine operations are studied at varying engine loads at the maximum pilot fuel substitution conditions. The engine performance parameters such as maximum pilot fuel substitution, brake thermal efficiency and brake specific energy consumption are investigated. On emission side, oxides of nitrogen, hydrocarbon, carbon monoxide and smoke emissions are analysed. Based on the results, it is found that biodiesel-hydrogen dual fuel engine could utilize up to 80.7% and 24.5% hydrogen (by energy share) at low and high loads respectively along with improved brake thermal efficiency. Furthermore, hydrocarbon, carbon monoxide and smoke emissions are significantly reduced compared to single fuel diesel engine operation. Exhaust gas recirculation (EGR) has also been studied with biodiesel-hydrogen dual fuel engine operations. It is found that EGR could improve the utilization of hydrogen in dual fuel engine, especially at the high loads. The effect of EGR is also found to reduce high nitrogen oxide emissions from the dual fuel engine and brake thermal efficiency is not significantly affected.
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    An experimental investigation of exergetic performance and emission characteristics of hydrogen supplemented biogas-diesel dual fuel engi
    (Elsevier, 2018-01) Verma, Saket
    An experimental investigation of a conventional diesel engine with diesel, biogas and hydrogen as fuels has been carried out, while the engine is modified to operate in dual fuel mode using diesel as the pilot fuel and biogas as the main fuel respectively. In order to improve the biogas-diesel dual fuel engine performance and emission characteristics, small percentages of hydrogen supplementations, viz. 5%, 10%, 15% and 20%, in biogas were studied and the comparison was also made to that with the neat biogas-diesel dual fuel operation. Engine performance characterization has been done with exergy based approach, and major sources of irreversibilities in various engine processes are also investigated and compared for the above mentioned cases. The results show that hydrogen supplementations in biogas have lesser effect on the combustion characteristics at low load, while, at high load, the combustion patterns change significantly with higher heat release rates and peak combustion pressures. Furthermore, performance and emission characteristics are found nearly unaffected with 5% of hydrogen addition both at low and high loads. Nevertheless, further addition of hydrogen in biogas causes improvements in performance and emission characteristics of the dual fuel engine