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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.
To calculate the actual efficiency of an engine requires the energy density of the fuel being used. Different fuels have different energy densities defined by the fuel's heating value. The lower heating value (LHV) is used for internal-combustion-engine-efficiency calculations because the heat at temperatures below 150 °C (300 °F) cannot be ...
Afterburner-equipped engines may also open the nozzle for starting and at idle. The idle thrust is reduced which lowers taxi speeds and brake wear. This feature on the J75 engine in the F-106 was called 'Idle Thrust Control' and reduced idle thrust by 40%. [28] On aircraft carriers, lower idle thrust reduces the hazards from jet blast.
Reciprocating engines at idle have low thermal efficiency because the only usable work being drawn off the engine is from the generator. At low speeds, gasoline engines suffer efficiency losses at small throttle openings from the high turbulence and frictional (head) loss when the incoming air must fight its way around the nearly closed ...
Exhaust brakes are simpler in operation than an engine brake.Essentially, the exhaust pipe of the vehicle is restricted by a valve.This raises the pressure in the exhaust system, forcing the engine to work harder on the exhaust stroke of its cylinders, so again the engine is acting as an air compressor, with the power required to compress the air being withheld from the exhaust pipe, retarding ...
A compression release brake (also known as a Jacobs brake or "jake brake"), is the type of brake most commonly confused with real engine braking; it is used mainly in large diesel trucks and works by opening the exhaust valves at the top of the compression stroke, so the large amount of energy stored in that compressed air is not returned to ...
This is a reduction in the effective exhaust velocity, versus the actual exhaust velocity achieved in vacuum conditions. In the case of gas-generator cycle rocket engines, more than one exhaust gas stream is present as turbopump exhaust gas exits through a separate nozzle. Calculating the effective exhaust velocity requires averaging the two ...
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, [1] or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack, or propelling nozzle.