الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Thermal throttling combined the advantages of both diesel engines and SI engines because it provides higher part-load thermal efficiency over mechanical throttled engines due to lean operation without a pressure-reducing throttle, high power to weight ratio. The system of thermal throttling replaces the mechanical throttle valve with a heat exchanger to heat the intake air by the exhaust gases. This method will decrease the density of intake air and its mass flow rate as well. An auxiliary throttle valve is used to cope with the low load especially at idling and engine cold start. A Simulink Matlab model with an analytical zero degrees solution applied on Mercedes Benz 250se does the comparison between the thermal and mechanical throttling engine. Improvements were done on this model to take load controlling by throttle valve angle into consideration. The natural gas was used as fuel because it has high octane number and high lean misfire limit. The selected heat exchanger was plate type heat exchanger due to its compactness. A completed design and performance analysis was done for this heat exchanger type. Two schemes of operation for the heat exchanger were analyzed to choose the best approach. The final results show an improvement in engine performance especially fuel consumption which decreased by 90 gm. /kWh. Also the thermal efficiency and the volumetric efficiency increased by 12% and 40% in order.