Diesel engines were patented by rudolf Diesel in 1892, using a different mode of fuel ignition from petrol engines.
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Diesel engines make use of fuel injection and spontaneous ignition due to temperature generated by compression. the pressure is higher than an Otto cycle engine, and offers several advantages: 40% efficiency (compared to 30% in Otto engine), lower speed, more torque. And finally diesel is not very flammable, making it safer for ships and military applications