| Summary: | Approved for public release; distribution is unlimited === A high pressure and temperature combustion chamber was designed to compare the ignition properties of different fuels, including conventional F76 diesel and hydrotreated renewable diesel (HRD), derived from algae. Conditions were selected to capture the operating conditions within a large number of Navy systems, testing at a range of temperatures from 8001340 F and pressures as high as 20 atm. Three Navy-relevant injectors were procured for the testing as well as a commercial injector made by Sturman Industries. The Sturman diesel injector was characterized up to a fuel tip pressure of 9600 psi and produced Sauter Mean Diameters of approximately 90 microns, generally showing improved atomization for F-76 when compared to HRD at similar conditions. The combustion chamber utilized dynamic air injection with increased turbulence and the ability to alter the amounts of combustion products including CO, CO2 and H2O that typically exist in real engines from the previous combustion event. Qualification testing of the combustion chamber evaluated final pressures of up to 15 atmospheres and temperatures of 472 F, but revealed heat losses during the dynamic air injection events, resulting in temperatures below expected values and auto-ignition conditions for fuels under consideration. A fluidized bed heat exchanger will be implemented to supplement the existing design and reach the desired temperatures.
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