Showing papers by "Ujjwal K. Saha published in 2012"

Effect of hydrogen-diesel quantity variation on brake thermal efficiency of a dual fuelled diesel engine

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%.

Diagnosing the effects of pilot fuel quality on exergy terms in a biogas run dual fuel diesel engine

Abstract: This work presents the exergy balances of biogas dual fuel combustion modes using two different pilot fuels in a single–cylinder diesel engine. The main focus is on the use of biodiesel (BD) as a pilot in place of fossil diesel fuel. The results reveal that the important exergy loss recovery sources are the exhaust gas and cooling water exergy. By accessing these losses, there is an increase of 28–30% in work exergy for dual fuel modes as compared to diesel mode. Use of BD, in place of diesel as a pilot, reduces the maximum exergy efficiency roughly by 2%.

An Experimental Investigation of Hydrodynamics and Heat Transfer Characteristics of Biomass Blending in a Pressurized Circulating Fluidized Bed

Abstract: In the present investigation, the effects of blending of biomass in sand, superficial velocity and operating pressure on bed hydrodynamics and heat transfer in a pressurized circulating fluidized bed have been studied. Experiments have been conducted at four different percentage blending of biomass such as 2.5%, 7.5%, 15% and 20% in sand and with two different weight composition ratios. All the above studies have been made at two different superficial velocities of 5 and 7 m/s and at three different operating pressures such as 1, 3 and 5 bar. The sand and biomass particle sizes used for the study are 309 µm and 407 µm, respectively. Results show that, with the increase in operating pressure , t he bed voidage decreases . The axial heat transfer coefficient increases from the bottom to the top of heat transfer probe with the increase in operating pressure. The radial variation of heat transfer coefficient decreases from the wall to the core of the heat transfer probe. The heat transfer coefficient is also found to be increasing with the increase in % blending of sawdust in sand. The overall uncertainty in calculating heat transfer coefficient is found to be 3.90%.

Experimental Analysis of Emulsified Palm Oil Methyl Ester Towards Alternative Diesel Fuel

Abstract: Palm oil methyl ester (POME) produced from crude palm oil have some excellent properties which makes it a feasible alternative to diesel fuel. However, its higher oxygen content makes it nitrogen oxide emission prone when burned in diesel engines. This problem can be resolved by emulsifying POME with distilled water in the presence of suitable surfactant. Two phase water in oil emulsion is prepared by using ultrasonic bath sonication. SPAN 80, a lipophilic surfactant is used for 1% by volume to prepare the emulsion. Water quantity in the emulsion is varied by 5% and 10% by volume and stability study is performed. It is found that emulsion with 5% water is more stable. Thereafter, POME emulsion samples are prepared with 5% water and tested in a variable compression ratio diesel engine. The performance and emission characteristics are investigated for a set of loads and compression ratios (CR). The experimental observations show that 5% water in POME produce 3.5% lower brake thermal efficiency and 11% higher brake specific fuel consumption as compared to baseline diesel. Furthermore, the exhaust gas temperature and other emissions like oxides of carbon, oxides of nitrogen and hydrocarbon for the emulsified POME are found to be lower than the baseline diesel.Copyright © 2012 by ASME

Finite Difference Based Sigma - Transformation Approach For Liquid Sloshing In A Rectangular Tank

Abstract: In this paper, a fully non-linear finite difference model has been developed based on the inviscid flow equations, and a simple mapping function was used to remove the time-dependence of the free surface in the fluid domain The time-varying fluid surface is mapped onto a rectangular domain by the sigma- transformation This method is a simple way to simulate non-breaking waves quickly and accurately especially that has a low steepness The fluid motion is solved in a unit square mesh in the transformed flow domain (ie, computational domain) Difference between the peaks and troughs of waves are discussed for three different cases of horizontal (surge), vertical (sway) and combined excitations of off and at resonance frequency of the tank The spectrum analysis of horizontally excited tank is presented The stability and instability regions associated with vertical and combined excitations conditions are discussed with the plots of free surface elevation, phase-plane diagram and free surface profile

Unsteady Simulation of a Vertical Axis Wind Turbine

Abstract: In the present study, an unsteady computational investigation has been carried out in order to analyze the performance of a single-stage vertical axis wind turbine using ANSYS Fluent 6.3 software package and the results obtained are validated with the experimental data. A Realizable k-e turbulence model with enhanced wall functions has been used to analyze a three dimensional model of this turbine. The data and boundary conditions for this analysis have been taken from the experimental observations. The experiments have been carried out under various load conditions to find the power and torque coefficients. The outcomes of numerical simulation and experiments are compared, analyzed and are found analogous with the data available in open literature.