Technical and economic evaluation of triglyceride gasoline blends as an alternative fuel for diesel engines
Date
2018
Authors
Lakshminarayanan, Arunachalam, author
Olsen, Daniel, advisor
Marchese, Anthony, committee member
Sampath, Walajabad, committee member
Cabot, Perry, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Developing viable and sustainable alternative fuels is critical in addressing future energy needs. Existing fossil fuels, being limited in nature, are depleting, contribute to climate change, health effects and their markets are volatile resulting in price fluctuations. Liquid fuels comprise a significant portion (about 40%) of a nation's total energy demand and production. Transportation sector being a key contributor national growth and security consumes almost 24% of the liquid fuel, while farming consumes about 15% to 17% of the liquid fuels. Bio diesel and bio ethanol are the two most widely used alternative, renewable fuels available. This work presents the technical and economics of using Triglyceride gasoline blends (TGBs) in a diesel engine. Canola straight vegetable oil (SVO) is highly viscous and has poor flow ability in cold weather. Consequently, it cannot be used in diesel engines without modification to the fuel system. Blending regular unleaded gasoline (10% by volume) to unrefined canola oil results in the specific gravity of the blend being similar to that of diesel. This enables it to be used in off road diesel engines in cold weather without modifications to the fuel system. A series of studies were performed to examine the viability of using TGBs to fuel diesel engines. Engine experiments were conducted on a 4.5L, turbocharged, intercooled Tier-III diesel engine. Lower heating value, higher mass based fuel consumption and slightly higher thermal efficiencies were recorded using TGB10 compared to diesel. The cylinder pressure traces and location of 50% mass fraction burnt for TGB10 and diesel were similar in most load points of the ISO 8178 8-mode test cycle. The average peak pressure of TGB10 was within ±4.5% to that of diesel. The combustion duration of TGB10 was about 12% to 15% shorter than diesel. Increased weighted NOX emissions (+9.8%), slightly lower weighted PM emissions (-5.5%), significantly lower weighted CO emission (-51.7%) and higher metal content (various orders of magnitude) were observed when using TGB10 as fuel in comparison to diesel. Additional engine experiments included varying the gasoline percentage in the TGB, evaluating combustion statistics, engine ECU parameters like start of injection, turbocharger speed and emissions analysis. Overall for blends containing up to 25% gasoline, most of the combustion parameters were identical to 100% triglyceride. As the gasoline content increased up to 55%, the combustion parameters were similar to diesel. For blends containing gasoline greater than 60% the combustion parameters were significantly different than diesel. A durability study (250 hours) on three fuels – (i) off road diesel, (ii) canola based bio diesel, and (iii) canola based TGB10 was conducted on a single-cylinder, naturally aspirated Yanmar diesel engine operating at constant load. Oil samples, injector spray patterns and carbon buildup from the injector and cylinder surfaces for the three fuels were analyzed and compared. Biodiesel had a cleansing effect on the injector tip. TGB10 left behind thick sludge on piston crown while diesel fuel had the least impact on lubricating oil quality. Finally, an economic business case model was analyzed for a complete lifecycle for TGB10. The model includes growing the canola crop, setting up a crushing facility to extract unrefined canola oil to converting it to TGB10 and the cost of ownership for a farm tractor over four different lifespans. The results show that though the cost of producing TGB10 can be lower than diesel, the cost of ownership can significantly vary on the lifespan of engine and its components. Expensive diesel prices and higher engine lifespans are the key to making TGB10 economically viable.
Description
Rights Access
Subject
cost of ownership economic modeling
engine durability
triglyceride gasoline blends
diesel engine
alternative fuel
engine exhaust emission