DMAX Fuel Pressure

[dually2002]

How do these engines produce these extreme fuel pressures?

[DmaxMaverick]

Engine driven high pressure fuel pump. Located in the engine valley front, gear driven by the crank.

[dually2002]

I have read that these systems have operating pressures from 17000 to 27000 psi. If this is the case I can't see how you can compress a flamable liquid to these pressures and not ignite from the heat of compression. I have worked around aircraft with 3000-4000 PSI hydraulic systems and that is serious working pressures. I guess the amount of fluid being compressed is small and the plumbing is so small these pressures can be reached. One of my last two remaining active brain cells just went into a comma. Thinkin always did hurt my head.

[DmaxMaverick]

#2 fuel, for all intents and purposes on our perceivable scale, is incompressible. To ignite the fuel, you must have heat, in the presence of O2, and the molecules must be exposed to one another at a rate sufficient to cause the reaction. The combustion chamber compression and the previous combustion/compression events provides it the heat. The air, containing 21% O2, is compressed just before the fuel is injected. The friction of the "compressible" air being compressed generates tremendous relative heat, and contains the O2 molecules required to combust the fuel. In order to get #2 to ignite, the molecules must be dispersed, which is accomplished through vaporization or atomization. The injectors (if working properly) will cause the fuel to atomize (a Diesel/kerosene fired steam cleaner or heat blower uses vaporization, or slight atomization with vaporization). This allows the fuel hydrocarbon molecules to mingle with the O2 molecules at a well distributed rate. The high pressure fuel from the pump to the injectors is just fuel, still in a state of emulsion (not atomized), with perhaps a little air (until the dynamic system purges it at lower pressure, because with air in the system, it won't build high pressure). And, true, the actual volume of the fuel under pressure is not great. Heat is generated, but is dissipated through a high turnover rate (a lot of fuel is returned to the tank), with the help of the fuel cooler and the smaller volume of return fuel mixing with the tank volume, before it is sent back to the pump.

The pressures the system will produce is between 4000 PSI at start, up to 23-27K(depending on engine series and programming) at full power at max governed engine speed.

The bottom line.....
While the pressure in the fuel system is sufficient for ignition, other required conditions and elements are not met. Therefore, no ignition. The process is much more involved, but this is about as simple as I can make it.