Otto, Diesel, and Rotary Engine Cycles

Arenas Alejandro

Julian Thompson

Daniel Vertucci

Matthew White

Otto Engine

Few things to remember• Invented by Nikolas Augustus Otto in the 1870’s.• Also know as the four-stroke engine because of its four-

stroke cycle.• Internal combustion engine.• Most commonly used for automotive industrial purposes.• Used for cars, truck, generators, planes, and more.• Requires a sparkplug in order to begin combustion

Four-stroke Cycle

•Intake Stroke•Compression Stroke•Power Stroke•Exhaust Stroke

Intake Stroke

Compression Stroke

Power Stroke

Exhaust Stroke

Four-stroke cycle

1. Intake Cycle2. Compression

Cycle3. Power Cycle4. Exhaust Cycle

Otto Cycle Diagram

                                                                                 

                           

There are a few differences between the diesel engine and the gasoline engine.

•A gasoline engine intakes a mixture of gas and air, compresses it and ignites the mixture with a spark. A diesel engine takes in just air, compresses it and then injects fuel into the compressed air. So the diesel engine does not need a spark plug to operate. The heat of the compressed air lights the fuel spontaneously.

•A gasoline engine compresses at a ratio of 8:1 to 12:1, while a diesel engine compresses at a ratio of 14:1 to as high as 25:1. The higher the compression ratio of the diesel engine leads to better efficiency and more power.

•Gasoline engines generally use either carburetion, in which the air and fuel is mixed long before the air enters the cylinder, or port fuel injection, in which the fuel is injected just prior to the intake stroke (outside the cylinder). Diesel engines use direct fuel injection -- the diesel fuel is injected directly into the cylinder.

Diesel fuel is heavier and oilier than regular gasoline and it smells different. Diesel gas evaporates much more slowly than gasoline because it is heavier. Its chemical compound is C14H30 as compared to gasoline which is C9H20. It takes less refining to create diesel fuelwhich is why it is usually cheaper than gasoline. It has a higher energy density than gasoline.One gallon of diesel fuel contains 155 million joules of energy compared to 132 million with gasoline. The fact that diesel fuel has a higher energy density and diesel engines run more efficiently than gasoline engines creates better mileage when traveling.

The main difference between a gasoline engine and a diesel engine is the spark plug.The injector has to be able to withstand the temperature and pressure inside the cylinder and still deliver fuel in a fine mist. The injection process is also different from gasoline engines. In gasoline engines fuel is injected into the cylinder during Intake stroke and then compressed. The fuel and air mixture limits the compression Ratio of the engine. If the air is compressed to much then the fuel spontaneously Ignites and creates knocking. A diesel compresses air only, so the compressionRatio can be much higher. The diesel cycle includes 4 stages which are the intake Of air, compression of air, fuel injection, and then the exhaust stage. The higher the compression ratio the more horsepower from the engine. It is the heat of the compressed air that ignites the fuel.

Rotary Engines

Rotation and Orbit

• Each tip of the rotor follows a trochoidal path around the housing

Note: The shaft rotates three times for eachRotation of the orbit

Four-Stroke Cycle (Revisited)

• Intake Stroke

• Compression Stroke

• Power Stroke

• Exhaust Stroke

• Same as Otto/Diesel Engine

Rotary Cycle

• No cylinders or pistons

• Separate chambers of air

Intake Stroke

Compression Stroke

Power Stroke

Exhaust Stroke

• 3 Cycles occur simultaneously (120 degrees out of phase)

• Drives rotor around shaft

Mazda

• 1967 Cosmo Sport

• 2004 RX-8

Alternative Fuels for Gas and Diesel Engines

Biodiesel

•It can be made from many different types of plant oils

•Soy beans are the most commonly used.

•This makes biodiesel nontoxic and renewable when compared to fossil fuels

Biodiesel vehicles are starting to increase in popularity, especially among large fleets of vehicles

Park rangers in Yellowstone National park use biodiesel to decrease pollution from their pickups

Almost any type of diesel engine can be converted to run on biodiesel, like this hummer

Biodiesel doesn't hurt an engines performance, but increases safety

Biodiesel can help an engine run better because it acts as solvent

Natural Gas Vehicles

Natural gas is a fossil fuel that is usually found above and below oil deposits

The idea of using natural gas was first developed in the 1930s, but until the invention of the leak-proof pipe transporting gas was difficult

1. NGVs burn natural gas that is compressed and stored in cylinders.

2. When the engine is started, natural gas flows into a fuel line.

3. The gas then enters a regulator where its pressure is reduced.

4. The natural gas feeds into the engine through a fuel injection system where it’s combined with air. The fuel/air mixture is adjusted to burn most efficiently and with the least possible emissions.

5. Natural gas burns in the engine just like gasoline.

6. NGVs can be refueled by attaching a hose at the fueling point.

 Number of Natural

Gas VehiclesNumber of Fueling

Stations

Argentina 1,200,000 1,105

Brazil 600,000 600

Pakistan 410,000 423

Italy 400,800 463

India 159,159 166

United States 130,000 1,300

China 69,300 270

Egypt 47,289 78

Venezuela 44,146 147

Ukraine 42,000 130

Source: International Association for Natural Gas Vehicles. Statistics on IANGV website on December 17, 2003.

http://www.biodiesel.org/

http://www.ngvc.org/ngv/ngvc.nsf

http://www.shermanlab.com/science/physics/thermo/engines/OttoG.php

http://www.geocities.com/henry_yu_84/illustratn/006e.jpg

http://www.rotaryengineillustrated.com/re101/mechanics1.php