Ujjwal K. Saha

Bio: Ujjwal K. Saha is an academic researcher from Indian Institute of Technology Guwahati. The author has contributed to research in topics: Diesel engine & Diesel fuel. The author has an hindex of 28, co-authored 120 publications receiving 3565 citations. Previous affiliations of Ujjwal K. Saha include Indian Institute of Technology Bombay.

Assessment of Dual Fuel Diesel Engine Performance by Modulating Biogas Flowrate and Intake Charge Preheating

Abstract: In this experimental study, the performance, combustion and emission of a diesel engine both in pure diesel mode (PDM) and in dual fuel mode (DFM) have been assessed and compared. The bioga...

A Simple Yet Robust Mechanism for the Improvement of Phase-Locked-Loop System and its Verification with Grid Side Converter Control

Abstract: The increasing number of nonlinear loads and the integration of renewable energy sources into the grid make the conventional SRF-PLL less accurate for estimating the phase and frequency of the grid voltage. A variety of enhanced filtering-based PLLs have been reported in the literature to solve this issue. However, these techniques are computationally more complex. For this reason, a method has been proposed to improve the performance of low pass filter (LPF)-based SRF-PLL, which is easy to implement and is computationally less expensive. In this paper, two in-loop second-order notch filters have been used with an LPF to nullify the effect of dominant lower order harmonics. The dynamic performance of the proposed technique is improved by implementing a PID type loop filter. The proposed scheme is compared with the other methods, like MRF-PLL, conventional and LPF-based SRF-PLL. The response of the proposed PLL is found to be encouraging under different grid disturbances. The efficacy of the proposed PLL has been verified by implementing the current controller to control the active and reactive grid current for the grid side converter in the hardware setup.

Hybrid Double-Divergent Nozzle as a Novel Alternative for Future Rocket Engines

Abstract: The efficiency of a rocket engine is dependent on altitude adaptability of its nozzle. In this context, double-divergent nozzles (DDNs) have drawn immense interest. The DDNs explored till now compr...

Effect of Load Level on Performance and Emission Characteristics of a Biogas Run Dual Fuel Diesel Engine

Abstract: Energy consumption has increased steadily due to industrialization and rise in population of the world. Fossil fuel, especially crude oil, is the predominant energy source around the globe. However, the reserves of fossil fuel are limited and will be depleted in near future. Therefore, there is a great interest in exploring alternative renewable energy. Biogas, a renewable fuel, can be used in internal combustion engines for power generation. The utilization of biogas in diesel engines in dual fuel mode has colossal prospective if explored to the fullest. The current investigation unravels the influence of load level on the performance and emission characteristics of a biogas powered dual fuel diesel engine at different compression ratios. Results revealed that the performance and emission of a biogas powered dual fuel diesel engine improves at high load level. However, CO, CO2, HC, NOX emission and cylinder pressure increases at high load level.

Experimental Probe Into a Biogas Run Dual Fuel Diesel Engine Using Oxygenated Ternary Blends at Optimum Equivalence Ratio and Under the Effect of Intake Charge Preheating

Abstract: The key challenge of dual fuel mode (DFM) of a compression ignition (CI) diesel engine is to improve the engine overall performance, and to reduce the carbon monoxide (CO) and unburnt hydrocarbon (HC) emissions. The gaining popularity of DFM lies with its inherent ability to curb harmful pollutants nitrogen oxides (NOx) and smoke, besides offering operational flexibility to use gaseous and liquids fuels simultaneously. In addition, the use of renewable fuels in DFM is found to be the highly suitable to achieve the optimum engine overall performance. In this DFM study, biogas as the primary gaseous fuel is used in a diesel engine in conjunction with ternary blends of diesel-biodiesel-ethanol (TB-E), diesel-biodiesel-butanol (TB-BT) and diesel-biodiesel-diethyl ether (TB-DEE) as the renewable pilot fuels. For each combination, the experiments are conducted at the optimum global fuel-air equivalence ratio (?global) and with intake charge preheating to analyze the performance, combustion and emission characteristics of the engine. The important parameters such as brake thermal efficiency, actual diesel replacement, coefficient of variation of indicated mean effective pressure, relative cycle efficiency, cylinder mean gas temperature, ignition delay, combustion duration are investigated. The study demonstrates the optimum performance of the DFM engine with TB-DEE.

Wind turbine design with emphasis on Darrieus concept Ion Paraschivoiu

Abstract: Wind energy is the fastest growing alternate source of energy in the world since its purely economic potential is complemented by its great positive environmental impact. The wind turbine, whether it may be a Horizontal-Axis Wind Turbine (HAWT) or a Vertical-Axis Wind Turbine (VAWT), offers a practical way to convert the wind energy into electrical or mechanical energy. Although this book focuses on the aerodynamic design and performance of VAWTs based on the Darrieus concept, it also discusses the comparison between HAWTs and VAWTs, future trends in design and the inherent socio-economic and environmental friendly aspects of wind energy as an alternate source of energy.

Applications of fuzzy logic in renewable energy systems – A review

Abstract: In recent years, with the advent of globalization, the world is witnessing a steep rise in its energy consumption. The world is transforming itself into an industrial and knowledge society from an agricultural one which in turn makes the growth, energy intensive resulting in emissions. Energy modeling and energy planning is vital for the future economic prosperity and environmental security. Soft computing techniques such as fuzzy logic, neural networks, genetic algorithms are being adopted in energy modeling to precisely map the energy systems. In this paper, an attempt has been made to review the applications of fuzzy logic based models in renewable energy systems namely solar, wind, bio-energy, micro-grid and hybrid applications. It is found that fuzzy based models are extensively used in recent years for site assessment, for installing of photovoltaic/wind farms, power point tracking in solar photovoltaic/wind, optimization among conflicting criteria. The review indicates that fuzzy based models provide realistic estimates.