So I am a college student writing a paper on tug boat propulsion…only problem is I study business so I only have a basic understanding of what is at work here. I am trying to make a case for hybrid/diesel-electric propulsion over traditional diesel-mechanical. I’ve found that the vast majority of the lifespan of a tug’s engines are spent at under 30% load. Next, I came to the conclusion that these engines (2,000-3,000 horsepower two stroke turbocharged diesel engines) run at their most inefficient point under low load situations. I have three sources supporting this. Using my non-engineering background I have determined the following: Diesel-mechanical engines are inherently inefficient because they have the dimensions and capabilities to produce large amounts of horsepower, however most of the time these large engines are being used to transport the boat which does not require large amounts of horsepower. Secondly, a turbocharger at low loads is not as effective as at high loads because the exhaust gas spinning the compressor is cool and at a lower volume. As the load on the engine increases, the turbocharger is introduced to more hot air and spins faster creating a more efficient burn. Thus the gallons used per unit of power created is greater under low load conditions.
Is this a sound explanation? If not can someone point me in the right direction? I am trying to prove why electric power is a viable option to increase efficiency and reduce emissions.
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