الفهرس 
Chapter One : introductionOnly 14 pages are availabe for public view
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Abstract
Natural gas plays an important role as an alternative fuel for the gasoline and diesel engines. It has a promising future especially with the world crisis in fuel and the lower prices of natural gas compared to the prices of gasoline and diesel. It can be used as a sole fuel in the spark ignition engines because it has similar properties like the gasoline, but in diesel engines it is used as a main fuel while the pilot fuel is injected to the combustion chamber to be an ignition source. This thesis investigates the performance of the dual fuel engine where a diesel engine was modified to work as a dual fuel engine. The air manifold was modified to have air/gas mixer, the cylinder head was machined to have a place for a pressure sensor that can measure the pressure during the cycle, and an EGR system was introduced to the engine so the performance of the engine with the operation of the EGR can be measured. During the engine operation the emissions were measured for comparing the results of diesel, dual fuel and the EGR with dual fuel operation.The variable percentages of fuel supply (Natural gas/Diesel) and the different values of EGR played a role in the results of the experiments to reach the optimum conditions that the engine can be run on it. Based on the obtained experimental results, it can be concluded that the total reduction in engine thermal efficiency increases as the ratio of the used natural gas increases. A maximum reduction of about 5% in engine efficiency is recorded when 80% of diesel fuel is replaced by natural gas to deliver the same engine power. Also, NOx emissions are decreased while CO is increased with utilization of EGR. This thesis consists of five chapters as followings: Chapter 1: An introduction chapter gives an overview of diesel fuel and Natural gas. It illustrates the uses of each fuel , advantages and disadvantages. It also gives a quick review on the fuel crisis in Egypt. Chapter 2: This chapter is concerned with the previous work in the dual fuel operation with different aspects, Engine performance, EGR, Controlled injection, throttling and emission analysis.Chapter 3: Description of the test rig and its preparation. It also includes an error analysis for the measurements.Chapter 4: Outlines in this chapter are the experimental results and discussion. The engine is tested and the performance was analyzed through two stages; firstly as a dual fuel engine without EGR and secondly as a dual fuel engine with different EGR ratios.Chapter 5: This chapter gives conclusions of thesis based on the experimental results and discussion. References Appendices : A. Specifications of the experimental devices that used in the experiments.B. Experimental results of measuring the performance of diesel engine with different values of natural gas and EGR also emissions records.