Mindblown: a blog about philosophy.
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PERFORMANCE MAPS
For critical analysis, the performance of an IC engine under all conditions of load and speed is shown by a performance map. Figure 11.10 shows the performance map of an automotive SI engine and Fig. 11.11 shows the performance map of a four-stroke pre-chamber CI engine. Figure 11.11 also includes a typical curve of BMEP versus piston speed for level road…
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PERFORMANCE OF CI ENGINES
The performance of a CI engine at constant speed and variable load is shown in Fig. 11.7. As the efficiency of the CI engine is more than the SI engine, the total losses are less. The coolant loss is more at low loads and radiation and other losses are greater at high loads. The BMEP, BP,…
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PERFORMANCE OF SI ENGINES
The performance of an engine is generally given by a heat balance sheet. The main components of a heat balance sheet are (i) heat equivalent to the effective (brake) work of the engine, (ii) heat rejected to the cooling medium, (iii) heat carried away from the engine with the exhaust gases, and (iv) unaccounted losses.…
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MORSE TEST
This is a method to determine the indicated power of a cylinder in a multi-cylinder engine. In this method, the engine is first run at the required speed and the output is measured. One cylinder is then cut out by short circuiting the spark plug or by disconnecting the injector, as the case may be.…
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WILLAN’S LINE METHOD
It is a method to determine the frictional power of an engine. In this method, gross fuel consumption v’s brake power at a constant speed is plotted and the graph is extrapolated back to zero fuel consumption as shown in Fig. 11.1. The point where this graph cuts the BP axis is an indication of the frictional…
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HEAT BALANCE SHEET
A heat balance sheet is an account of heat supplied and heat utilised during engine trial.
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BASIC ENGINE MEASUREMENTS
The basic measurements required to be carried out to evaluate the performance of an engine are as follows:
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PERFORMANCE PARAMETERS
The performance of an engine is an indication of the degree of success with which the conversion of chemical energy contained in the fuel is done into useful mechanical work. The degree of success is compared on the basis of following parameters: However, in the evaluation of engine performance, the following performance parameters are chosen:…
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Choke
During cold starting period, at low cranking speed and before the engine has warmed up, a mixture much richer than usual mixtures (almost five to 10 times more fuel) must be supplied because a large fraction of the fuel will remain liquid even in the cylinder, and only the vapour fraction can provide a combustible…
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Acceleration Pump System
It has already been shown that when it is desired to accelerate the engine rapidly, a simple carburettor will not provide the required rich mixture. Rapid opening of the throttle will be immediately followed by an increased airflow, but the inertia of the liquid fuel will cause at least a momentarily lean mixture just when…
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