mean effective pressure


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mean effective pressure

[′mēn i¦fek·tiv ′presh·ər]
(mechanical engineering)
A term commonly used in the evaluation for positive displacement machinery performance which expresses the average net pressure difference in pounds per square inch on the two sides of the piston in engines, pumps, and compressors. Abbreviated mep; mp. Also known as mean pressure.

Mean effective pressure

A term commonly used in the evaluation for positive displacement machinery performance which expresses the average net pressure difference in pounds per square inch (psi) on the two sides of the piston in engines, pumps, and compressors. It is also known as mean pressure and is abbreviated as mep or mp.

In an engine (prime mover) it is the average pressure which urges the piston forward on its stroke. In a pump or compressor it is the average pressure which must be overcome, through the driver, to move the piston against the fluid resistance.

The criterion of mep is a vitally convenient device for the evaluation of a reciprocating engine, pump, or compressor design as judged by initial cost, space occupied, and deadweight. See Compressor, Thermodynamic cycle, Vapor cycle

References in periodicals archive ?
System properties were normalized systematically: engine properties by displacement into mean effective pressures, transmission data by input torque capacity, vehicle road load data to coast down deceleration rates, and drive cycle traction power requirement to P/M or Vehicle Specific Power.
The engine operations at different throttle conditions showed a varied range of rich and lean misfiring limits around a reference equivalence ratio that corresponds to the respective maximum indicated mean effective pressure.
The coefficient of variation of indicated mean effective pressure at the reference equivalence ratio remained within 10 percent.
The variation of brake thermal efficiency with respect to the brake mean effective pressure under various compression ratios is shown in the Fig.
The variation of CO emission on volumetric basis with respect to brake mean effective pressure for the various fuel blends and neat diesel are shown in Fig.
6 shows the variation of hydrocarbon emission with brake mean effective pressure under various compression ratios.
Mean effective pressure (mep) where nR is the number of crank revolutions for each power stroke per cylinder (two for four-stroke, one for two-stroke cycles) as:
In addition, indicated horse power, break mean effective pressure and specific fuel consumption calculated from the experiments.
These smaller engines operate at higher cylinder mean effective pressures across the load range than the engines they supersede.
The integration of the measured cylinder pressure curves throughout a work cycle gives the internal work done, which applied to the piston displacement gives the (IMEP) indicated mean effective pressure [1].
The brake mean effective pressure (BMEP) for a four stroke engine is given according to the following equation:
This simulation requires engine geometry, cylinder wall temperatures, a heat transfer model, estimation of friction mean effective pressure and a proper set of both boundary and initial conditions.