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In piston engines, static compression ratio is determined using the cylinder volume when the piston is at the top and bottom of its travel. The compression ratio is the ratio between the maximum and minimum volume during the compression stage of the power cycle in a piston or Wankel engine.
Variable compression ratio (VCR) is a technology to adjust the compression ratio of an internal combustion engine while the engine is in operation. This is done to increase fuel efficiency while under varying loads. Variable compression engines allow the volume above the piston at top dead centre to be changed. Higher loads require lower ratios ...
In aeronautical engineering, overall pressure ratio, or overall compression ratio, is the amount of times the pressure increases due to ram compression and the work done by the compressor stages. The compressor pressure ratio is the ratio of the stagnation pressures at the front and rear of the compressor of a gas turbine .
There are several differences, but the main one in practice is that compression ratio is applied to piston engines, pressure ratio to gas turbines. Compression ratio is the cause of the compression, pressure ratio is the result of this compression and increase in pressure. Compression ratio can be calculated easily from the engine's geometry.
A high compression ratio is used in the auxiliary combustion chamber. A moderate compression ratio is used in the main combustion chamber wherein a homogeneous air-fuel mixture is compressed / heated near, yet below, the auto-ignition threshold.
The Continental O-190 (Company designations C75 and C85) is a series of engines made by Continental Motors beginning in the 1940s. Of flat-four configuration, the engines produced 75 hp (56 kW) or 85 hp (63 kW) respectively. [1] The two variants shared the same bore, stroke and compression ratio.
The fuel efficiency and working principle of a PPC engine resemble those of Diesel engine, but the PPC engine can be run with a variety of fuels. Also, the partially premixed charge burns clean. [6] Challenges with using gasoline in a PPC engine arise due to the low lubricity of gasoline and the low cetane value of gasoline.
This can be achieved by modifying the air-fuel mixture drawn into the engine, modifying the static or dynamic compression ratio of the engine, modifying the fuel used (e.g. higher octane, different fuel types or chemistries), injection of water or methanol, modifying the timing and dwell of ignition events, and compressing the intake air.