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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.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the hydrodynamic and heat transfer characteristics at four different % mixing of biomass in sand (2.5, 7.5%, 12.5% and 20%) have been investigated in a pressurized circulating fluidized bed.

26 citations

Journal ArticleDOI
01 May 2011
TL;DR: In this article, the unsteady free-surface velocities during the surge motion of a liquid tank are determined through experimental investigation, and a new experimental approach has been discussed for cap...
Abstract: In this work, the unsteady free-surface velocities during the surge motion of a liquid tank are determined through experimental investigation. A new experimental approach has been discussed for cap...

25 citations

Proceedings ArticleDOI
15 Nov 2013
TL;DR: In this paper, a computational study has been performed to simulate the air-flow over different blade profiles using shear stress transport (SST) k-ω turbulence model and the results obtained are validated with the available experimental data.
Abstract: Rapid depletion rate of fossil fuels with an increasing energy demand and their high emission are imposing the evolution activities in the arena of renewable energy To meet the future demands of renewable energy sources, wind energy is a very promising concept In this feature, the drag based vertical axis wind turbines (VAWTs) are suitable for small scale wind energy generation for decentralized locations However, these turbines have low power and torque coefficients as compared to other wind turbines Numerous blade shapes have been proposed till now to improve the performance of these turbines In the present paper, a computational study has been performed to simulate the air-flow over different blade profiles using shear stress transport (SST) k–ω turbulence model The results obtained are validated with the available experimental data In the dynamic simulations, the power and torque coefficients are calculated considering the blade arc angle as the variable shape parameter The effects of drag and lift forces on the variable blade shapes are also studied in static simulations at various angular positions The present paper tries to demonstrate an effective computational methodology to predict the flow behavior around a drag based VAWT Through this study, it has been found possible to select an optimal blade shape from the point of its aerodynamic performanceCopyright © 2013 by ASME

23 citations

Journal Article
TL;DR: In this article, the specific composition of diesel and hydrogen for maximum brake thermal efficiency at five loading conditions (20, 40, 60, 80% and 100% of full load) individually on the basis of the maximum diesel substitution rate according to the literature is investigated.
Abstract: In this twenty first century, the most emerging gaseous fuel is the hydrogen. This is because, it contains huge amount of energy potential and environment friendly. In this paper, experiments are performed in a compression ignition diesel engine with dual fuel mode. Diesel and hydrogen are used as pilot liquid and primary gaseous fuels, respectively. The objective of this study is to find out the specific composition of diesel and hydrogen for maximum brake thermal efficiency at five loading conditions (20%, 40%, 60%, 80% and 100% of full load) individually on the basis of the maximum diesel substitution rate according to the literature. At the same time, the effects on brake specific fuel consumption, brake specific energy consumption, volumetric efficiency and exhaust gas temperature are also observed at various liquid gaseous fuel compositions for all five loadings. The experimental study is further extended to second law analysis to optimize the dual fuel engine run. It is seen that a diesel engine can be run in hydrogen-diesel dual fuel mode efficiently if the diesel to hydrogen ratio is maintained within 40% to 60%.

23 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the importance of urban physics related to the grand societal challenges is described, after which the spatial and temporal scales in urban physics and the associated model categories are outlined.

627 citations

Journal ArticleDOI
TL;DR: In this article, a dual-fuel engine with high-cetane fuel and natural gas injection is used to provide a source of ignition for the charge of a spark-ignition (SI) engine.

595 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide a perspective on the past, present and future of Computational Wind Engineering (CWE) and provide a more detailed view on CFD simulation of pedestrian-level wind conditions around buildings.

570 citations

01 Jan 2002
TL;DR: In this article, the aerodynamic design and performance of VAWTs based on the Darrieus concept is discussed, as well as future trends in design and the inherent socioeconomic and environmental friendly aspects of wind energy as an alternate source of energy.
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.

549 citations

Journal ArticleDOI
TL;DR: 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 and indicates that fuzzy based models provide realistic estimates.
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.

411 citations