 Our aim is to develop a catalytic combustion chamber in order to make the combustion of lean mixture faster. By increasing the fast rate of burning it will results in increased in efficiency and lower exhaust emissions.  And we planned to investigate the combustion characteristics of lean mixtures with minimum modifications at a lower cost.

INTRODUCTION:  Due to the increasing cost and undertrained supply of petroleum in recent years, there have been strenuous effects to make spark ignition and compression engines more efficient.  The concept of internal combustion engine is one, where oxidation of fuel is brought with the aid of a catalyst in the combustion chamber walls offers the advantages of a stratified charge engine without its disadvantages.  The catalyst are used in the form of coating on the walls or in any form to initiate combustion and make it burn faster, then the advantage improved efficiency can be obtained in addition to lower exhaust emissions.

CONCEPT OF CATALYTIC COMBUSTION: THE CATALYST:  First of all, the catalyst must be capable of withstanding continues and cyclic operation at very high temperatures, ideally as high as 1600’C, without degradation of either catalyst or physical properties.  This requires the use of high melting point materials with good thermal shock properties.  With the discovery that heterogeneous catalyst can be used to promote stable ultra lean thermal combustion at heat release comparable to those of conventional combustors.

NICKEL AND SILVER METAL CATALYST IN THE COMBUSTION CHAMBER:

The various surface properties that can be enhanced by the proper selection of coating materials are,  Mechanical properties,  Thermo chemical properties,  Electrochemical properties,  Optical properties,  Electrical properties. Etc., COATING DETAILS: selection of coating materials

 The base metal on which the coating applied was alloy aluminium, a preconditioning of the surface was necessary and it was done by a process called zinc coating to remove oxide layer to enable the coating to have good bonding with base metal. after conditioning of piston and cylinder head, electroplate coating was done. SETUP FOR ELECTROPLATING OF CATALYST ON THE PISTON CROWN ELECTROPLATING COATING TECHNIQUES:

MODIFICATIONS IN THE ENGINE:  The cylinder heads and pistons were nickel and silver coated  A pressure transducer for measuring the pressure was mounted on the cylinder head.  A modified carburettor for varying air fuel ratio is mounted to engine.  A crank angle degree marker (CDM) is coupled to the engine crankshaft to measure the crank angle.  An air box to find the air fuel ratio.  Modems to interface the engine and the computer.  A fuel flow meter to measure the fuel flow rate.

SPECIAL EQUIPMENTS:  The list of various special equipment used in this steady are,  Pressure Transducer.  Crank degree marker (CDM).  Eddy current dynamometer.  Digital tachometer.  Exhaust gas analyzer.  Automatic fuel flow meter.  Avl indimeter software.

 The engine used is a BAJAJ 150CC engine, which is mounted on a concrete bed to withstand the dynamic forces and vibrations produced.  Air is admitted into the engine by means of an indigenously designed air- box, also known as air- damper. It is used to measure the volume of air consumed by the engine and as a pressure damper. The air-box houses an orifice plate.  The fuel flow measurement in the fuel reservoir has two photoelectric cells, which are used to measure the time taken for consumption.  Loading of the engine is done by means of an eddy current dynamometer. The dynamometer shaft is directly coupled to the engine gearbox shaft and thus the engine can be loaded in constant torque, constant speed and constant current modes.

SECTIONAL VIEW OF EXPERIMENTAL SETUP

 One more highlight of this setup is the crank degree marker. It is an accurate device, which is directly coupled to the engine crankshaft and is used for measuring the crank angle at which maximum pressure occurs.  The CDM also measures the heat release at various crank angles. The setup also has provisions for measuring the exhaust emissions.  The exhaust gas from the engine is fed into a moisture separator, which separates the moisture from the exhaust and then feeds into the exhaust gas analyzer.  The EGA measures the CO emissions in % of volume and HC emissions in ppm.

 Brake thermal efficiency as improved in both nickel and silver coatings by nearly 10% to 30%.  The benefits of using lean mixtures in S.I. engines are obvious.  Better fuel utilization and lower exhaust emissions are achieved.  The result indicates reduction of about 70% to 90% of CO and 10% to 20% of HC and 15% to 25% of fuel consumption. CONCLUSIONS:

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