Journal Articles
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Item Bio-fuel variants for use in CI engine at design and off-design regimes: An experimental analysis(2008) Bekal, S.; Ashok Babu, T.P.A.In this work an attempt has been made to study the ester based fuel variants derived from edible and inedible oil sources for identifying the most appropriate fuel variant and operating mode for running a CI engine based on performance and emission parameters. The twenty four fuel variants tested included esters obtained from the edible sunflower oil, inedible pongamia oil, and their higher and lower proportional blends with diesel. Besides, several other fuel variants obtained from the emulsification of water-in-ester (W/E) with different water proportions have been tested. Basing upon three operational variables, namely, injection timing, injection pressure, and load, comparisons are made in aspects of smoke emissions, NOX emissions, BSEC, and exhaust gas temperatures at the best injection timing. 21.5°, 23°, 24.5° and 27.5° bTDC as the four injection timings and 190, 220 and 250 bar as three injection pressures are considered for the overall study. The 264 sets of experiments conducted with these combinations, focussing on the full and partial load characteristics of the engine, show that both sunflower and pongamia oil esters exhibited similar characteristics in their engine performance, and in both the cases the best BSEC occurred with 220 bar injection pressure for most of the fuel variants, and for straight fuels the ideal injection timing found to be slightly retarded (1.5° crank angle) compared to diesel. However, 24.5° bTDC, normal for the engine, was found to be the most appropriate for the lower blends like B2 (2% ester by volume), B5 and emulsion with 10% water proportion. © 2008 Elsevier Ltd. All rights reserved.Item Synthesis of biodiesel from edible and non-edible oils and characterisation(2009) Kapilan, N.; Ashok Babu, T.P.A.; Varun, J.D.In recent years, biodiesel has been receiving increasing attention because of scarcity and increasing cost of fossil fuels and growing emissions of combustion related pollutants. In the present work, biodiesel was synthesised via the transesterification of edible and non-edible oils such as gingili and mahua, with methanol as alcohol and sodium hydroxide as catalyst. The yield percentage obtained from non-edible mahua oil was comparable to that obtained from edible gingili oil, under optimum conditions. According to American Society of Testing and Methods (ASTM), several tests were conducted to characterise the biodiesel in relation to diesel oil, in order to evaluate various physical, chemical and thermal properties such as viscosity, acid value, iodine value, flash point, fire point and calorific value. From the results, it was observed that the fuel properties of biodiesel produced from mahua oil and gingili oil were within the recommended standards of biodiesel fuel of various countries. Hence the biodiesel produced from gingili oil and mahua oil can be used as a renewable alternative fuel for the diesel engine. © 2009 Energy Institute.Item Improvement of performance of vegetable oil fuelled agricultural diesel engine(2009) Kapilan, N.; Ashok Babu, T.P.A.; Reddy, R.P.In recent years, there has been a considerable effort to develop and introduce alternative renewable fuels to replace conventional petroleum based fuels. This led to the choice of non edible Mahua Oil (MO) as one of the main alternative fuels to diesel oil in India. When MO was used as fuel in the diesel engine, it results in lower thermal efficiency and higher smoke emission due to its higher viscosity and lower volatility. Hence in the present work, Liquefied Petroleum Gas (LPG) was inducted along with the air and the LPG supply was varied from zero to the maximum value that the engine could tolerate. The engine tests were conducted on a single cylinder diesel engine, which is used in the agricultural machinery. The engine test with MO+LPG was compared with the LPG+MO biodiesel (MEMO) and Diesel+LPG. From the engine results it is observed that the MO+LPG dual fuel mode operation results in performance close to the MEMO+LPG. The MO+LPG operation results in higher brake thermal efficiency and lower smoke emission as compared to the MO operation. From the present work, it is concluded that the underutilized and non edible MO can be used as a renewable alternative fuel for the diesel engine, for the development of rural economy and for the energy security of India.Item Effect of using Mahua as an alternative fuel in diesel engine(2009) Kapilan, N.; Ashok Babu, T.P.A.; Reddy, R.P.There is an increasing interest in India, to search for suitable alternative fuels that are environment friendly. This led to the choice of non-edible Mahua Oil (MO) as one of the main alternative fuels to diesel oil in India. The objective of the present work is to use MO as a partial renewable alternative substitute for diesel in the agricultural diesel engine. Since the viscosity of the MO is high, it was blended with conventional diesel oil in various proportions (M5, M10, M15 and M20 on volume basis) and fuel properties of the blends were determined and compared with the diesel. Engine tests were carried out on a single cylinder diesel engine at varying loads (0%, 25%, 50%, 75% and 100%), without making any modification in the fuel injection system and the results were compared with the diesel. The M5 and M10 blends resulted in performance and emission characteristics comparable to diesel operation and also emits lower carbon monoxide, hydrocarbon and smoke emissions as compared to other blends. From the analysis, it is concluded that the MO can be partially substituted for diesel oil in the diesel engine, without making any modification in the hardware of the engine.Item Characterization of sealing ring cavitation in centrifugal pumps with water and viscous oil(Begell House Inc., 2010) Nair, K.G.; Ashok Babu, T.P.A.This research paper presents characterization of sealing ring cavitation in centrifugal pumps with water and viscous oil. The paper discusses development of theoretical formulation for sealing ring cavitation and simulation using software model along with experimental validation. The pump performance test results and its standard clearance for the sealing ring are used to simulate the theoretical model. The study is extended for pumps with SAE-30 lubricating oil. The simulation results present the variation of downstream pressure with different sealing ring dimensions in pumps. The value of downstream pressure determines the possibility of occurrence of cavitation at the clearance. The theoretical formulation developed is validated by using a venturi cavitation test set up. Clearances equivalent to various sealing ring dimensions are made at the test section using different hemispherical models. Theoretical formulation for downstream pressure at the clearance of venturi test section is derived using the test set up details and pump specification. The clearance cavitation coefficients as per K. K. Shelneves equation are obtained from theory as well as from experimentation and compared. The phenomena of cavitation damages the sealing ring which results a fall in performance of the pump. However this research work lead to the prediction of sealing ring cavitation in centrifugal pumps handling water and oil enabling the replacement of sealing ring before affecting cavitation damage. © 2010 Begell House, Inc.Item Study of variables affecting the synthesis of biodiesel from Madhuca Indica oil(2010) Kapilan, N.; Ashok Babu, T.P.A.; Reddy, R.P.Biodiesel derived from non-edible Madhuca Indica oil (MIO) seems to be a better alternative to diesel oil in India. In the present work, effects of reaction variables such as mass ratio of methanol to oil, catalyst concentration, reaction time and reaction temperature on biodiesel yield were studied. The acid value of the commercially available MIO is high, and hence a two-step process was used to produce biodiesel from MIO. In the first step, the acid value of the MIO was reduced to less than 1 mg KOH/g, using acid-catalyzed transesterification. In the second step, the pretreated MIO was converted to biodiesel using alkalinecatalyzed transesterification. From the experimental results, it is observed that the optimized conditions for biodiesel production are a 1: 4 mass ratio of methanol to oil, 55 °C reaction temperature, 120 min of reaction time, and 1% sodium hydroxide catalyst. The properties of the MIO biodiesel were found to be within the biodiesel limits of the European Union. Hence, the MIO biodiesel can be used as a substitute for diesel for the sustainable development of rural areas and as a renewable fuel. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Item Use of a CFD code in the investigation of cross corrugated heat transfer surfaces(2010) Ashok Babu, T.P.A.; Shekoor, T.M.The variation of main geometric details of cross corrugated surfaces (i.e. aspect ratio and angle of corrugation) makes it increasingly difficult to have a general design method. In the absence of adequate 'database' covering all possible configurations, it is nearly impossible to predict the highly effective configuration. Thus CFD simulation is effective, as it allows computation for various geometries, and study of the effect of various design configurations on heat transfer and flow characteristics. The present paper discusses the use of a CFD code to select the cross corrugated heat transfer surface (CC surface) with minimum core volume of a recuperator matrix. Due to difficulties Induced by geometry and computational time, simple model is used as a first step. The SS T turbulence model was preferred over other flow models for simulations. This simple model, comprised of three corrugated plates having their crest nearly in contact, with hot and cold fluids flow alternately through passage created between the plates. Some selected cross corrugated heat transfer surfaces are used for the analysis. The results for the simplified model, presented in terms of outlet temperatures, heat transfer coefficients and skin friction coefficients, is encouraging to undertake extensive work in CFD simulation and create more 'database' on various configurations. Design calculations of a recuperator matrix for a 10 kW micro turbine have been carried out for the selected surfaces. The relation between the minimum core volume of the matrix from design calculation and average skin friction coefficient from CFD analysis is established to use CFD analysis for selection of heat transfer surfaces with minimum recuperator matrix core volume. The analysis is carried out with air and nitrogen as heat transfer fluids.Item An analysis of cycle-by-cycle fluctuation in combustion parameter in CI engine operation for various bio-fuels(2011) Bekal, S.; Ashok Babu, T.P.A.The cycle-by-cycle fluctuations in peak pressure of combustion in a CI engine were studied for lower and higher blends of diesel and ester, and water-in-ester emulsions, at four injection timings and three injection pressures using coefficient of variation. The sunflower ester-diesel blends are found to have lower cycle-by-cycle fluctuations than pongemia ester-diesel blends. The fluctuations are found to be higher than that of diesel for higher blend proportions of ester. The water-in-ester emulsion show higher cycle-by-cycle fluctuations than that of ester-diesel blends. In most cases, the Brake specific energy consumption is also found to be higher where the coefficient of variation has higher values. Copyright © Taylor & Francis Group, LLC.Item Performance characteristics of a dual fuel engine operatedwith mahua biodiesel and liquefied petroleum gas(2011) Kapilan, N.; Ashok Babu, T.P.A.; Reddy, R.P.Fuel crisis because of dramatic increase in vehicular population and environmental concerns have renewed the interest of the scientific community to look for alternative fuels of bio-origin such as vegetable oils and ethanol. India is looking at biodiesel derived from Mahua oil (MO), as one of the renewable alternative fuels for compression ignition (CI) engine. Although MO biodiesel (MOB) has several advantages over fossil diesel, in the present scenario, the use of biodiesel is restricted due to its high cost. In India, liquefied petroleum gas (LPG) is easily available and is one of the cheapest gaseous fuels. Hence, use of LPG to fuel a CI engine along with MOB seems to be an option for substitution of fossil diesel. In the present work, LPG, which was fumigated along with the air and biodiesel was admitted into the engine cylinder through conventional fueling device as an igniter. A single cylinder CI engine was modified to work in dual fuel mode and engine tests were carried out at rated speed under variable load conditions. The performance of the engine in dual fuel mode was compared with the diesel. The dual fuel operation results in thermal efficiency close to the diesel and also reduces the NOx and smoke emissions significantly. From the experimental results, we concluded that biodiesel in dual fuel mode with cheaper gaseous fuel induction is an option for reducing the operating cost of the biodiesel fuelled CI engine. Copyright © 2011 by ASTM International.Item Experimental investigation in pool boiling heat transfer of ammonia/water mixture and heat transfer correlations(2011) Sathyabhama, A.; Ashok Babu, T.P.A.The nucleate pool boiling heat transfer coefficient of ammonia/water mixture was investigated on a cylindrical heated surface at low pressure of 4-8bar and at low mass fraction of 0NH3<0.3 and at different heat flux. The effect of mass fraction, heat flux and pressure on boiling heat transfer coefficient was studied. The results indicate that the heat transfer coefficient in the mixture decreases with increase in ammonia mass fraction, increases with increase in heat flux and pressure in the investigated range. The measured heat transfer coefficient was compared with existing correlations. The experimental data were predicted with an accuracy of ±20% by the correlation of Calus&Rice, correlation of Stephan-Koorner and Inoue-Monde correlation for ammonia/water mixture in the investigated range of low ammonia mass fraction. The empirical constant of the first two correlations is modified by fitting the correlation to the present experimental data. The modified Calus&Rice correlation predicts the present experimental data with an accuracy of ±18% and the modified Stephan-Koorner correlation with an accuracy of ±16%. © 2011 Elsevier Inc.