Report - DETERMINATION OF THE PERFORMANCE AND HEAT BALANCE...

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DETERMINATION OF THE PERFORMANCE AND HEAT BALANCE CHARACTERISTIC OF A DIESEL ENGINE Introduction The practical engine characteristics of interest are power ( P e ), torque ( T e ), and specific fuel consumption ( bsfc ). The relative importance of these parameters varies over an engine’s operating speed and load range. The maximum brake power and the break mean effective pressure ( BMEP ) define an engine’s full potential (Figure 1). The maximum brake torque and BMEP , over the full speed range, indicates the ability of the designer to obtain a high air flow through the engine over the full speed range (volumetric efficiency η v ) and use that air effectively (relative air/fuel ratio λ and heat balance). Then, over the complete operating range, and most especially those parts of that range including partial load where the engine will operate for long periods of time, engine fuel consumption and engine emissions are important (Figure 1). Internal combustion engine tests are usually carried out by an engine dynamometer. The test engine is mounted on a test bed and the output shaft of the engine is connected to the dynamometer rotor. Figure 2 illustrates the operating principle of such dynamometer. The rotor 1
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may be coupled electromagnetically, hydraulically, or by mechanical friction to a stator, which is supported on low friction bearings (Figure 3). The stator is balanced by the rotor stationary. The torque is exerted on the stator with the rotor rotation is measured over lever arm by balancing the stator with weights, springs, or pneumatic means. 2
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The Objectives of the Experiment 1) Determinations of the engine’s effective torque ( T e ), break mean effective pressure (BMEP) , power ( P e ) and break specific fuel consumption ( bsfc ) characteristics at full and partial load conditions. 2) Determination of the engine’s volumetric efficiency (η v ) and relative air/fuel ratio (λ) at full and partial load conditions. 3) Determination of the engine’s heat balance i.e. heat for power ( e Q . ), heat rejected to cooling ( water Q . ), heat rejected to exhaust ( exh Q . ) and heat rejected to overall friction ( friction Q . ). Experimental Setup Engine Specifications Model: TZDK-Basak diesel engine Type: Direct injection diesel engine, four stroke Cylinder: 4 Bore diameter: 100 mm Stroke: 100 mm Displacement: 3,14 liter Compression ratio (ε): 16,8 Dynamometer The engine that will be used for this experiment is coupled with an Eddy-current dynamometer. The load and speed of the engine is controlled by a fuel pump injection rate and dynamometer resistance. Fuel injection rate is controlled by the adjustment of the fuel pump. Dynamometer resistance is controlled by the adjustment of electromagnetic field density. The power of the engine will be converted to heat in the dynamometer and rejected from the dynamometer with the help of cooling water. The torque on the engine crankshaft is transmitted to the dynamometer by a coupling and acts on
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This note was uploaded on 12/03/2010 for the course MECHANICAL 1212 taught by Professor Ümran during the Spring '10 term at Istanbul Technical University.

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Report - DETERMINATION OF THE PERFORMANCE AND HEAT BALANCE...

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