Monday, September 2, 2019
Internal Combustion Engines :: physics internal combustion engine
Most motor vehicles today use an Internal Combustion Engine (ICE) to give them power to drive down the road; ICEs are a form of a heat engine. Gasoline is burned to push a piston, which in return forces the car down the road. As the gas in the cylinder is ignited and expanded it forces the piston down the shaft. The force is carried through piston, which is connected to a crankshaft. The force moves through the transmission, down the driveshaft, and out the tires. The Otto Cycle is used to turn as much heat into the driving force as possible. Ã¢â¬Å"A heat engine is a machine that converts heat into workÃ¢â¬ (Heat Engines). A heat engine absorbs a quantity of energy from a hot reservoir, does work, and then gives up a quantity of energy to the cold reservoir. In the example of an ICE, gasoline is burned, creating heat and expanding the gasses. This expansion pushes the piston down the cylinder and the excess heat is carried out through the coolant system or exhaust. The work done by the engine can be determined using the equation: W=Q(hot) - Q(cold) The efficiency of a heat engine can be determined using the equation: e=W/Q(hot) Gasoline engines have four strokes and six processes in each cycle. During the intake stroke, air and fuel are drawn into the cylinder; the volume and potential energy increase. Next, the compression stroke adiabatically compresses the gases; the volume decreases and the temperature increases. The spark does not occur during a stroke but when the piston is fully raised, this causes the gases to ignite keeping relatively the same volume. In the power stroke, the gas adiabatically expands; the temperature decreases and the volume increases. Finally, the exhaust valve is opened so in the exhaust stroke when the piston moves up the gasses are released causing the volume to decrease. A hemi engine refers to the way the pistons, heads and block are designed. This style of engine claims to provide a better flow of air inside the cylinder by creating more room for larger valves in turn providing more power. The chamber on a hemi is hemispherical instead of being flat like traditional engines. This shape provides more surface area on the block allowing room for the larger valves. When the engine can breath better there is less friction and more clean air / fuel mixture providing more power.