Journal Articles
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Item Technical aspects of biodiesel and its oxidation stability(2009) Kapilan, N.; Ashok Babu, T.P.; Reddy, R.P.Biodiesel is a clean burning alternative renewable fuel made from natural renewable sources. It is defined as mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, which conform to ASTM specifications for use in diesel engines. Biodiesel present a very promising alternative fuel to diesel oil and properties of this oil offer the advantage of immediate substitution in existing diesel engines with little or no modifications at all. But one of the major technical problems associated with the biodiesel is its susceptibility to oxidation, which can cause the fuel to become acidic and to form insoluble gums and sediments that can plug fuel filters. This is due to the unsaturated fatty acid chains and the presence of the double bond in the molecule, which produce a high level of reactivity with the oxygen, especially when it placed in contact with air. The oxidation of fatty acid chains is a complex process that proceeds by a variety of mechanisms. The various other factors influence the oxidation process of biodiesel includes light, temperature, extraneous materials, peroxides, size of the surface area between biodiesel and air. One of the methods of improving biodiesel oxidative stability includes the deliberate addition of antioxidants or modification of the fatty ester profile. This article discusses the technical aspects of biodiesel and its oxidation stability.Item A comprehensive review on evaporative cooling systems(Elsevier B.V., 2023) Kapilan, N.; Isloor, A.M.; Karinka, S.The evaporative cooling system (ECS) is one of the cheapest and oldest cooling technologies. The conventional single stage ECS is most widely used in domestic application, particularly in hot and dry regions. However, in this system, the temperature of the air cannot be reduced below the wet bulb temperature of the air. The multistage ECS system helps to overcome this problem. The combination of direct and indirect ECS helps to reduce the temperature of the air below its wet bulb temperature. The further reduction in air temperature may be achieved with the help of the cooling coil driven by vapour compression system. The energy consumed by the ECS is lower as compared to vapour compression refrigeration system. The ECS can be driven with the help of solar power. The conventional cooling pad used in ECS can be replaced with locally available natural fibers to reduce initial cost and to reduce dependence on import of cooling pads. The performance of the ECS can be improved with the help of heat pipe. Various techniques are used to enhance ECS's performance. The performance of the vapour compression refrigeration system can be improved with the help of ECS. This paper discusses basics and types of ECS, methods used to increase the performance of ECS, types of natural fiber cooling pad material, process variables affecting ECS, recent technical advancements, challenges and opportunities. © 2023 The AuthorsItem Methyl esters of Mahua oil as an ecofriendly fuel in heavy duty vehicles(Chemical Publishing Co., 2008) Kapilan, N.; Krishna; Reddy, R.P.In this investigation, Mahua oil methyl ester (MOME) was prepared by transesterfication using potassium hydroxide. According to the ASTM procedure, several tests were conducted to characterize mahua oil in relation to diesel oil. Various physical, chemical and thermal properties such as viscosity, flash point, fire point and calorific value were evaluated. From the analysis, it was observed that the properties of mahua oil methyl ester are close to diesel oil. To evaluate the mahua oil methyl ester as a fuel for diesel engine and dual engine, it was used as a fuel in a single cylinder, four stroke, direct injection, constant speed, compression ignition diesel engine and dual fuel engine. From the experimental results, it was observed that the mahua oil methyl ester result in performance and emissions close to diesel operation.Item Evaluation of methyl esters of mahua oil (mahua indica) as diesel fuel(2008) Kapilan, N.; Reddy, R.P.There is increasing interest in India for suitable alternative fuels that are environment friendly. This search has led to mahua oil (MO) as one alternative for diesel fuel in India. Mahua oil methyl esters (MOME) were prepared by transesterification using potassium hydroxide (KOH) as catalyst and nuclear magnetic resonance (NMR) testing was done to determine the conversion of vegetable oil to biodiesel (MOME). The properties of MOME were close to those of diesel oil. Engine testing was conducted using a single-cylinder 4-stroke direct-injection, constant-speed compression-ignition diesel engine using MO, MOME and B20 as fuels. The engine ran smoothly with MOME and B20, but heavy smoke emissions were observed when MO was used as fuel. © 2007 AOCS.Item Experimental investigation of esters of mahua oil as an alternative fuel for dual fuel engine(2008) Reddy, P.B.; Kapilan, N.; Reddy, R.P.In the present work, an attempt was made to use methyl ester of mahua oil (MEMO) as substitute for dieselin dual fuel engine. A four stroke single cylinder engine was modified to work in dual fuel mode. From the test results, it was observed that the MEMO could be used as pilot fuel in dual fuel engine. At lower loads, diesel gave higher brake thermal efficiency. But at higher loads, biodiesel resulted in brake thermal efficiency comparable with diesel and lower smoke and oxides of nitrogen emissions. From the test results, it was concluded that MEMO could be used as a substitute for diesel in dual fuel engine.Item Evaluation of properties and storage stability of Madhuca indica biodiesel(Japan Oil Chemists Society yukagaku@jocs-office.or.jp, 2009) Kapilan, N.; Ashok Babu, T.P.; Reddy, R.P.Mahua Oil (MO) is an underutilized non-edible vegetable oil, which is available in large quantities in India. In the present work, biodiesel was derived from the MO by the transesterification process. The fuel properties of the MO biodiesel were found to be within the limits of biodiesel specifications of many countries. The chemical nature of biodiesel makes it more susceptible to oxidation during long-term storage which leads to degradation of fuel properties that can compromise fuel quality. The effect of long storage condition on the stability of the MO biodiesel was studied in the present work. The biodiesel samples were stored in plastic containers at room temperature. The study was conducted for a period of 12 months and the test sample was kept in the darkness. From the experimental results, it was observed that the acid value and viscosity increases with the storage time, but the iodine value decreased with increasing storage time. This is due to the presence of the double bond in the molecule of the biodiesel which produce a high level of reactivity. This high level reactivity produces formation of hydroperoxides, soluble polymers and other secondary products. From the experimental results, a slight difference in the acid value, iodine value and viscosity of the MO biodiesel stored for a period of 30 days was observed. But after this period, the differences were significant. © 2009 by Japan Oil Chemists' Society.Item Studies on exhaust emissions of mahua oil operated compression ignition engine(2009) Kapilan, N.; Reddy, R.P.The world is confronted with fossil fuel depletion and environmental degradation. The energy demand and pollution problems lead to research for an alternative renewable energy sources. Vegetable oils and biodiesel present a very promising alternative fuel to diesel. In this work, an experimental work was carried out to study the feasibility of using raw mahua oil (MO) as a substitute for diesel in dual fuel engine. A single cylinder diesel engine was modified to work in dual fuel mode and liquefied petroleum gas (LPG) was used as primary fuel and mahua oil was used as pilot fuel. The results show that the performance of the dual fuel engine at the injector opening pressure of 220 bar and the advanced injection timing of 30°bTDC results in performance close to diesel base line (DBL) operation and lower smoke and oxides of nitrogen emission.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 Characterization and effect of using Mahua oil biodiesel as fuel in compression ignition engine(2009) Kapilan, N.; Ashok Babu, T.P.; 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 Mahua Oil (MO) as one of the main alternative fuels to diesel. In this investigation, Mahua Oil Biodiesel (MOB) and its blend with diesel were used as fuel in a single cylinder, direct injection and compression ignition engine. The MOB was prepared from MO by transesterification using methanol and potassium hydroxide. The fuel properties of MOB are close to the diesel and confirm to the ASTM standards. From the engine test analysis, it was observed that the MOB, B5 and B20 blend results in lower CO, HC and smoke emissions as compared to diesel. But the B5 and B20 blends results in higher efficiency as compared to MOB. Hence MOB or blends of MOB and diesel (B5 or B20) can be used as a substitute for diesel in diesel engines used in transportation as well as in the agriculture sector. © 2009 Science Press, Institute of Engineering Thermophysics, CAS and Springer Berlin Heidelberg.