scispace - formally typeset
Search or ask a question
Author

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
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the performance, combustion and emission characteristics of dual-fuel engines which use natural gas, biogas, producer gas, methane, liquefied petroleum gas, propane, etc. as gaseous fuel.
Abstract: Petroleum resources are finite and, therefore, search for their alternative non-petroleum fuels for internal combustion engines is continuing all over the world. Moreover gases emitted by petroleum fuel driven vehicles have an adverse effect on the environment and human health. There is universal acceptance of the need to reduce such emissions. Towards this, scientists have proposed various solutions for diesel engines, one of which is the use of gaseous fuels as a supplement for liquid diesel fuel. These engines, which use conventional diesel fuel and gaseous fuel, are referred to as ‘dual-fuel engines’. Natural gas and bio-derived gas appear more attractive alternative fuels for dual-fuel engines in view of their friendly environmental nature. In the gas-fumigated dual-fuel engine, the primary fuel is mixed outside the cylinder before it is inducted into the cylinder. A pilot quantity of liquid fuel is injected towards the end of the compression stroke to initiate combustion. When considering a gaseous fuel for use in existing diesel engines, a number of issues which include, the effects of engine operating and design parameters, and type of gaseous fuel, on the performance of the dual-fuel engines, are important. This paper reviews the research on above issues carried out by various scientists in different diesel engines. This paper touches upon performance, combustion and emission characteristics of dual-fuel engines which use natural gas, biogas, producer gas, methane, liquefied petroleum gas, propane, etc. as gaseous fuel. It reveals that ‘dual-fuel concept’ is a promising technique for controlling both NOx and soot emissions even on existing diesel engine. But, HC, CO emissions and ‘bsfc’ are higher for part load gas diesel engine operations. Thermal efficiency of dual-fuel engines improve either with increased engine speed, or with advanced injection timings, or with increased amount of pilot fuel. The ignition characteristics of the gaseous fuels need more research for a long-term use in a dual-fuel engine. It is found that, the selection of engine operating and design parameters play a vital role in minimizing the performance divergences between an existing diesel engine and a ‘gas diesel engine’.

513 citations

Journal ArticleDOI
TL;DR: In this article, wind tunnel tests were conducted to assess the aerodynamic performance of single-, two-and three-stage Savonius rotor systems with both semicircular and twisted blades.

337 citations

Journal ArticleDOI
TL;DR: In this paper, a three-bladed rotor system has been tested in a low speed wind tunnel, and its performance has been compared with conventional semicircular blades (with twist angle of 0°) on the basis of starting characteristics, static torque and rotational speed.

248 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of compression ratio on the performance, combustion and emission characteristics of a dual fuel diesel engine run on raw biogas was investigated, where a 3.5-kW single cylinder, direct injection, water cooled, variable compression ratio diesel engine is converted into a biogAS run dual-fuel diesel engine by connecting a venturi gas mixer at the manifold.

226 citations

Journal ArticleDOI
TL;DR: In this article, a two-bladed turbine is tested in an open type test section and its performance is assessed in terms of power and torque coefficients, and the effects of Reynolds number on the dynamic and static characteristics are also discussed.

209 citations


Cited by
More filters
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