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The cycle is closed by the exhaust (4-0 and colored blue) stroke, characterized by isochoric cooling and isobaric compression processes. Temperature-Entropy diagram. An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in ...
The Carnot cycle achieves maximum efficiency because all the heat is added to the working fluid at the maximum temperature , and removed at the minimum temperature . In contrast, in an internal combustion engine, the temperature of the fuel-air mixture in the cylinder is nowhere near its peak temperature as the fuel starts to burn, and only ...
Most petrol (gasoline, Otto cycle) and diesel (Diesel cycle) engines have an expansion ratio equal to the compression ratio. Some engines, which use the Atkinson cycle or the Miller cycle achieve increased efficiency by having an expansion ratio larger than the compression ratio. Diesel engines have a compression/expansion ratio between 14:1 ...
In a naturally aspirated engine, air for combustion (Diesel cycle in a diesel engine or specific types of Otto cycle in petrol engines, namely petrol direct injection) or an air/fuel mixture (traditional Otto cycle petrol engines), is drawn into the engine's cylinders by atmospheric pressure acting against a partial vacuum that occurs as the piston travels downwards toward bottom dead centre ...
The Otto Cycle is an example of a reversible thermodynamic cycle. 1→2: ... is the lowest cycle temperature and the highest. For Carnot power ...
The maximum cycle temperature is limited by the turbine materials and required turbine life. This also limits the pressure ratios that can be used in the cycle. For a fixed-turbine inlet temperature, the net work output per cycle increases with the pressure ratio (thus the thermal efficiency) and the net work output. With less work output per ...
A heat engine is a system that converts heat to usable energy, particularly mechanical energy, which can then be used to do mechanical work. [1] [2] While originally conceived in the context of mechanical energy, the concept of the heat engine has been applied to various other kinds of energy, particularly electrical, since at least the late 19th century.
The thermal efficiency of an ideal Otto Cycle depends on the compression ratio and improves from 47% to 56% when this is raised from 8 to 15. [31] Engines in practical vehicles achieve 50-75% of this, with about 60% is suggested as an unlimited-cost limit. [32]