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Back pressure is the term used for the hydraulic pressure required to create a flow through a chromatography column in high-performance liquid chromatography, the term deriving from the fact that it is generated by the resistance of the column, and exerts its influence backwards on the pump that must supply the flow.
Adding exhaust gas therefore reduces pressure and temperature during the isentropic compression in the cylinder, thereby lowering the adiabatic flame temperature. In a typical automotive spark-ignited (SI) engine, 5% to 15% of the exhaust gas is routed back to the intake as EGR. The maximum quantity is limited by the need of the mixture to ...
The Turbo-back (or turbo back) is part of the exhaust system from the outlet of a turbocharger to the final vent to open air. Turbo-back systems are generally produced as aftermarket performance systems for cars with turbochargers. Some turbo-back (and header-back) systems replace stock catalytic converters, while others have less flow restriction.
An exhaust brake is a valve which essentially creates a back-pressure in the exhaust system, which applies enough force onto the engine's pistons to slow the engine. In most cases, an exhaust brake is so effective that it can slow a heavily-loaded vehicle on a downgrade without ever applying the vehicle’s service brakes.
An exhaust brake works by causing a restriction in the exhaust, much like the intake throttle causes in a gasoline engine. In simple terms, it works by increasing the back-pressure of the exhaust. Nearly all of these brakes are butterfly valves similar to a throttle valve, mounted downstream of the turbocharger if there is one.
When the pressure ratio across a convergent nozzle exceeds a critical value, the flow chokes, and thus the pressure of the exhaust exiting the engine exceeds the pressure of the surrounding air and cannot decrease via the conventional Venturi effect. This reduces the thrust producing efficiency of the nozzle by causing much of the expansion to ...
When the descending piston first exposes the exhaust port on the cylinder wall, the exhaust flows out powerfully due to its pressure (without assistance from the expansion chamber) so the diameter/area over the length of the first portion of the pipe is constant or near constant with a divergence of 0 to 2 degrees which preserves wave energy.
The aim of exhaust system development is to obtain maximum smokebox vacuum with minimum back pressure on the pistons. Little development of the basic principles of smokebox design took place until 1908, when the first comprehensive examination of steam-raising performance was carried out by W.F.M. Goss of Purdue University.