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Consider the first triangular diagram below, which shows all possible mixtures of methane, oxygen and nitrogen. Air is a mixture of about 21 volume percent oxygen, and 79 volume percent inerts (nitrogen). Any mixture of methane and air will therefore lie on the straight line between pure methane and pure air – this is shown as the blue air-line.
The fuel turbopump is driven by the fuel-rich preburner, and the oxidizer turbopump is driven by the oxidizer-rich preburner. [ 5 ] [ 4 ] Benefits of the full-flow staged combustion cycle include turbines that run cooler and at lower pressure, due to increased mass flow, leading to a longer engine life and higher reliability.
Amable Liñán introduced a modified mixture fraction in 1991 [6] [7] that is appropriate for systems where the fuel and oxidizer have different Lewis numbers. If L e F {\displaystyle Le_{F}} and L e O 2 {\displaystyle Le_{O_{2}}} are the Lewis number of the fuel and oxidizer, respectively, then Liñán's mixture fraction is defined as
The heart of the Mitsubishi's MVV system is the linear air–fuel ratio exhaust gas oxygen sensor. Compared with standard oxygen sensors, which essentially are on-off switches set to a single air/fuel ratio, the lean oxygen sensor is more of a measurement device covering the air/fuel ratio range from about 15:1 to 26:1. [19]
Raptor's full-flow staged combustion cycle will pass 100 percent of the oxidizer (with a low-fuel ratio) to power the oxygen turbine pump, and 100 percent of the fuel (with a low-oxygen ratio) to power the methane turbine pump. Both streams—oxidizer and fuel—will be completely in the gas phase before they enter the combustion chamber.
The limiting oxygen concentration is shown in the lower right of the diagram. The limiting oxygen concentration (LOC), [1] also known as the minimum oxygen concentration (MOC), [2] is defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. It is expressed in units of ...
The reasons that the fuel pump is typically located in the fuel tank are: By submerging the pump in fuel at the bottom of the tank, the pump is cooled by the surrounding fuel; Liquid fuel by itself (i.e. without oxygen present) isn't flammable, therefore surrounding the fuel pump by fuel reduces the risk of fire
VSA typically draws the gas through the separation process with a vacuum. For oxygen and nitrogen VSA systems, the vacuum is typically generated by a blower. Hybrid vacuum pressure swing adsorption (VPSA) systems also exist. VPSA systems apply pressurized gas to the separation process and also apply a vacuum to the purge gas.