Showing papers by "Ujjwal K. Saha published in 2018"

Impact of Intake Charge Preheating on a Biogas Run Dual Fuel Diesel Engine Using Ternary Blends of Diesel-Biodiesel-Ethanol

Abstract: In the pursuit of minimizing a considerable amount of imported fossil diesel and greenhouse gas (GHG) emissions, green fuels like biodiesel, ethanol, and biogas can be used efficiently unde...

Performance estimation of Savonius wind and Savonius hydrokinetic turbines under identical power input

Abstract: In the context of energy crisis, extensive depletion of fossil fuel, and climate change, the vertical-axis Savonius-type wind or hydrokinetic turbines appear to be promising candidates to extract energy from wind or free-flowing water because of their superior self-starting capability and design simplicity. The present investigation focuses on comparative analysis between Savonius wind turbines (SWTs) and Savonius hydrokinetic turbines (SHTs) at the same input power. To accomplish this, two configurations are considered, viz., 2-bladed and 3-bladed turbine designs having semicircular blade profiles. Experimental studies revealed that the SWTs operate in a slightly wider range of tip-speed ratios than the SHTs. It is also observed that, like SHTs, 2-bladed SWTs result in an improved (47%) peak power coefficient (CPmax) than 3-bladed SWTs. In line with this, the computational studies, conducted to complement the experimental analysis, showed the superiority of 2-bladed SWTs over the 3-bladed SWTs. Both experimental and computational analyses reveal that the SHTs and SWTs show identical drag and lift characteristics for given kinetic energy of the inlet fluid stream.

Supplementing the Energy Need of Diesel Engines in Indian Transport and Power Sectors

Abstract: The progress and prosperity of a nation like India depends largely upon the fossil fuel-based power production sectors. However, the use of these fuels leads to detrimental effects on the ecosystem because of various pollutants emitted from combustion of fossil fuel. Being the second largest populist country in the globe, India is heavily dependent on imported fossil fuels, thereby making it the major source of global warming and pollutant emission. The fossil energy in India is primarily used in transport and stationary power production sectors. Another problem with these fossil fuels is that it is located in the certain part of the globe which makes oil-deficient countries to depend on them. Therefore, an alternative arrangement is necessitated to reduce these dependencies and oil imports. Alternative renewable energy sources in the form of vegetable oil, biodiesel, biogas, producer gas, and alcohols have good prospects to replace or supplement fossil fuel. Oils derived from vegetables show the most promising fuel for diesel engines. However, vegetable oils have the lower calorific values along with the high viscosity and density as compared to diesel, which are not suitable properties to run the engine. Hence, these properties are improvised through blending, preheating, transesterifications, and emulsifications. Transesterification of vegetable oil yields biodiesel which is the most prominent and popular among the processes. Gaseous fuels such as biogas and producer gas have also been successfully implemented in diesel engine through the dual fuel mode. Stressing the importance of alternative fuel sources for diesel engines, the present study focuses on the effects of these arrangements on engine performance and emission characteristics.

Performance Characteristics of Vertical-Axis Off-Shore Savonius Wind and Savonius Hydrokinetic Turbines

Abstract: The rise in energy demand, climate change and depletion of fossil fuel, encourages the researchers to find a solution to the scarcity of clean energy. Therefore, the extraction of energy from renewable energy sources has become a topic of interest in the past few decades across the globe. Thus, harvesting the offshore wind and hydro energy and converting it to electrical power using various electromechanical devices has been a challenge. In this context, the vertical-axis Savonius wind and Savonius hydrokinetic turbines appear to be promising concept for energy conversion because of their good self-starting capability and simplicity in design. The present study attempts to characterize the performances of a Savonius wind turbine (SWT) and a Savonius hydrokinetic turbine (SHT) under identical input flow conditions. In order to characterize their performances, the SWT is tested in a low-speed wind tunnel with closed test section whereas the SHT is tested in an open channel flume. In each case, the torque and power coefficients are estimated at different mechanical loading conditions. It is observed that the SWT and SHT demonstrate peak power coefficients of 0.25 and 0.28 respectively for the same input power. However, the SWT is found to operate over a slightly wider range of tip-speed ratios than the SHT before the onset of stall. Finally, the computational study using ANSYS 14.5 has been carried out to evaluate the flow physics of the turbine at various azimuthal positions.