docUsing Straight Vegetable Oil as Fuel in a Combustion Engine or
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Using Straight Vegetable Oil as Fuel in a Combustion Engine or
Biofuels and Big Green Buses Luke Scruby University of Virginia Mechanical Engineering Why?? An Engineering Problem: Possible Solutions • • • • Biodiesel Ethanol Gasification Waste Vegetable Oil Design Constraints • Time • Money • Technical Alternate Transport Mission: Demonstrate the feasibility of vegetable oil as a fuel and spread awareness of alternative automotive fuels. Existing Diesel Technology • Injection pattern defined by Viscosity and Surface Tension • Viscosity 2-5 cSt at 40°C • Injection Pump wear defined by particulate/ water load Hydrocarbon Molecule, C12H26 Diesel Injector Vegetable Oil Vegetable Oil: • Triglyceride • Long history as compression engine fuel • Relatively higher and more temperature dependent viscosity Material Properties of Diesel vs Vegetable Oil Property Diesel Canola Density, kg/L .84 .92 Energy/Volume, MJ/L 38.3 36.9 Viscosity @ 20ºC, c-St 4-5 70 Viscosity @ 40ºC, c-St 4-5 37 Viscosity @ 70ºC, c-St 3-4 10 Cetane number 40-50 45 An Aside: Biodiesel • Methyl or Ethyl Ester • Excellent substitute for diesel • Relatively lower viscosity and less temperature dependent viscosity Vegetable Oil Alcohol Base Transesterification Water Methyl or Ethyl Ester Soap Design Challenges • Viscosity • Bacteria • WASTE Vegetable Oil Fuel Supply in Indirect Injection Diesels Diesel Tank • Lift Pump provides excess fuel to Injection pump • Some fuel returns to tank • Injection pump is Piston/cylinder chained to crank Pre-Filter Lift Pump Fuel Filter Fuel Injector Engine Injection Pump Changes to Fuel Supply Diesel Tank Veggie Tank PreFilter • Viscosity approaches that of diesel with increasing temperature • Close to cold diesel around 150°F Hose in Hose Heat Exchanger PreFilter 6 Port Solenoid Lift Pump Fuel Filter Return From Engine Fuel Injector Engine WASTE Vegetable Oil Processing Waste Vegetable Oil Contaminants: Chicken Nuggets/ Dead Squirrels (3.5”) Water Removal Technique: Suction Strainer Heating and settling, water block filter media Particulate Matter Carbon Black 0.000023” Water washing, filtration On the Road: • • • • • Collect Heat Settle Filter Burn May 2005 January 2005 “Catastrophic Engine Failure” Cause of Death • Engine oil increasing • Injection Pump Failure • Failed cup seal • Bent push rod Iterate (new vehicle) • Pump – Rotary Vane – Impeller • Settling Tank • Storage On the Road Again Problems • • • • Clogged Filters 2 Flat Tires Punctured radiator Shifter linkage Related to Vegetable Oil: NONE Success? Money – nearly every dollar Time – every waking minute Injection Pumps Destroyed - 2 Vehicles Totaled - 1 Crazy Alaskans Met Fish Caught Mountains Climbed Average Mileage per gallon of diesel: 280 “Next” Semester • Find method to monitor injection pump wear • Compare processed vegetable oil quality to diesel fuel standards • Separating wax to change viscosity pour point • Acidity of Waste Oil Questions?