IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Due to its renewable nature, emission advantage and easy adaptation, biodiesel is emerging as an alternative to fossil diesel. There are however concerns on biodiesel storage stability aspect due to the presence of unsaturated content in its composition. This paper discusses on studying the effect of long term storage stability of Karanja derived biodiesel (KME) on the performance, combustion and emission characteristics of a turbo-charged, multicylinder, direct injection diesel engine. For aged karanja derived biodiesel (A-KME) stored in a mild steel container for 500 days, both the fuel properties and the engine performance are found to change. It is observed that the aged fuel as compared to the fresh karanja derived biodiesel (F-KME) showed i) an increase in the acid value and kinematic viscosity from 0.374 mg KOH/g to 0.89 mg KOH/g and 5.6 to 5.7 cSt respectively, ii) a slight decrease in ignition delay and maximum rate of pressure rise, iii) a maximum increase in peak cylinder pressure of about 10% and duration of combustion of 8 deg. CA, iv) a decrease in brake thermal efficiency to an extent of over 4%, v) an increase in un burnt hydrocarbon emissions particularly at low loads, and, vi) a significant increase in exhaust nitric oxide (∼30%) and the smoke emissions (∼78%) at higher loads.

Department of Mechanical Engineering

World University root node

ICEF

Effect of Long Storage Stability of Karanja (Pongamia) Derived Biodiesel Fuel on the Performance, Combustion and Emission Characteristics of a Multi-Cylinder Turbo-Charged Direct Injection Diesel Engine

Due to concerns regarding energy security, fuel cost, and the environment, straight and processed vegetable oils are being considered as part or full replacement of diesel fuel in compression ignition engines. The lower heating value of a candidate fuel is an important characteristic used in energy release estimation. In this work, a convenient method of estimating the heating values of straight and processed vegetable oils based on the bond energies of their fatty acid/methyl ester constituents is proposed. The estimated lower heating values of 17 different straight vegetable oils are on the order of 37 MJ/kg and for 15 different processed fuels on the order of 38 MJ/kg. The accuracy of estimations when compared with the available experimental data is observed to be within 3%. © 2009 American Chemical Society.

Energy and Fuels

Estimation of a lower heating value of vegetable oil and biodiesel fuel

Suitability of vegetable oil as an alternative to diesel fuel in compression ignition engines has become attractive, and research in this area has gained momentum because of concerns on energy security, high oil prices, and increased emphasis on clean environment. The experimental work reported here has been carried out on a turbocharged direct-injection multicylinder truck diesel engine using diesel fuel and jatropha methyl ester (JME)-diesel blends. The results of the experimental investigation indicate that an increase in JME quantity in the blend slightly advances the dynamic fuel injection timing and lowers the ignition delay compared with the diesel fuel. A maximum rise in peak pressure limited to 6.5 per cent is observed for fuel blends up to 40 per cent JME for part-load (up to about 50 per cent load) operations. However, for a higher-JME blend, the peak pressures decrease at higher loads remained within 4.5 per cent. With increasing proportion of JME in the blend, the peak pressure occurrence slightly advances and the maximum rate of pressure rise, combustion duration, and exhaust gas temperature decrease by 9 per cent, 15 per cent and 17 per cent respectively. Although the changes in brake thermal efficiencies for 20 per cent and 40 per cent JME blends compared with diesel fuel remain insignificant, the 60 per cent JME blend showed about 2.7 per cent improvement in the brake thermal efficiency. In general, it is observed that the overall performance and combustion characteristics of the engine do not alter significantly for 20 per cent and 40 per cent JME blends but show an improvement over diesel performance when fuelled with 60 per cent JME blend. © IMechE 2008.

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering

Experimental investigations on combustion of jatropha methyl ester in a turbocharged direct-injection diesel engine

Nano-aluminum particles were produced by the electrical wire explosion method at this laboratory. &nbsp;The size and shape of the particles were measured using a transmission electron microscope (TEM). &nbsp;Aluminum wires are exploded by application of high voltage, to yield particles of size around 40 nm. &nbsp;The X-ray diffraction (XRD) results also confirm that the powder formed by the above process as aluminum with an average size of 42 nm. &nbsp;Previous studies on ultrafine-aluminum applied to solid propellants have tested a particle size not less than about 100 nm. &nbsp;The thermal characteristics were analyzed using thermo gravimetric and differential thermal analyses (TG-DTA). &nbsp;The composition of the material was characterized by energy dispersive angle X-ray (EDAX) analysis. &nbsp;The low pressure deflagration limit (LPDL) tests were carried out for dry-pressed pellets of the nano-aluminum or normal aluminum with ammonium perchlorate (AP). &nbsp;Sandwich burning tests of the nano-aluminum and normal aluminum added to the middle lamina of binder were also carried out. &nbsp;It showed that the addition of nano-aluminum marginally increased the burning rate at elevated pressures and higher lamina thicknesses. &nbsp;Composite propellant formulations were developed out with a bimodal size distribution of AP particles, with the baseline non-aluminized formulations exhibiting plateau burning rate trends. &nbsp;Burning rate studies of the non-aluminized, nano-aluminized, and normal aluminized propellants were carried out. &nbsp;It was found that the burning rate of the nano-aluminized propellants increased by 100% compared to normal aluminized propellants. &nbsp;In the nano-aluminized propellants, the plateau effects in the burning rate of the corresponding non-aluminized propellants in the intermediate pressure range were removed, but significantly low pressure-exponents were observed at elevated pressures. &nbsp;The results point out that the nearly complete combustion of nano-aluminum near the propellant burning surface actually controls the propellant burning rate. &nbsp;The nano-aluminum combustion is diffusion-limited at elevated pressures, and hence, results in significantly low pressure-exponents of burning rate in that pressure range.

Department of Aerospace Engineering

Department Of Biotechnology

Department of Electrical Engineering

Production and Characterization of Nano-Aluminum and its Effect in Solid Propellant Combustion

Advanced low temperature combustion (LTC) modes are most promising to reduce green house gas emissions owing to fuel economy benefits apart from simultaneously reducing oxides of nitrogen (NOx) and particulate matter (PM) emissions from diesel engines. Various LTC strategies have been proposed so far and each of these LTC strategies have their own advantages and limitations interms of precise ignition control, achievable load range and higher unburned emissions. In the present work, a small single cylinder diesel engine is initially operated under conventional combustion mode at rated speed, varying load conditions to establish the base line reference data. Then, the engine is modified to operate under different LTC strategies including Homogenous Charge Compression Ignition (HCCI), Premixed Charge Compression Ignition (PCCI) and Reactivity Controlled Compression Ignition (RCCI). The modifications done in the existing engine include a newly designed cylinder head to accommodate a high pressure, fully flexible electronically controlled direct diesel fuel injection system, a low pressure gasoline port fuel injection system, an intake air pre heater and a fuel vaporizer for external mixture preparation. Using a National Instruments (NI) controller, the engine operating parameters interms of direct injected diesel fuel timings, injection pressures, port injected gasoline fuel timings, intake air temperatures, fuel vaporizer temperatures and gasoline to diesel fuel ratio depending upon the type of LTC modes are optimized so as to achieve maximum brake thermal efficiencies. All the three LTC strategies with optimized operating parameters are compared among themselves and also with that of conventional combustion mode at a lower load, rated speed condition. The obtained results show that among all other LTC strategies, RCCI exhibit 8% higher brake thermal efficiency along with near zero NOx and smoke emissions and a lower pressure rise rate.