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RE: Compression

To: "'Ronak, TP \(Timothy\)'" <Timothy.Ronak@crna.akzonobel.com>,
Subject: RE: Compression
From: "Bob Palmer" <rpalmer@ucsd.edu>
Date: Mon, 23 Jan 2006 08:35:04 -0800
Tim,

"... there is only so much energy density in the fuel and as I understand
all that is needed to fully burn this is enough compression, a decent spark
and good flame travel and it will completely burn everything that got into
the chamber." 

This statement is fundamentally flawed. When considered abstractly as an
Otto cycle heat engine, the only thing that determines efficiency and HP
output is the peak combustion temperature - the higher the better. Burning
all of the fuel is just one component of achieving the highest practical
temperature, as is raising the compression ratio. This is the basis for
diesel engines and the new ceramic diesels under development are aimed at
increasing the combustion temperature even higher; i.e., achieving the
highest possible combustion temperature, which fundamentally determines the
efficiency of an engine. And, along that vein, a diesel with ceramic heads
might be just the ticket to an SUV that gets 40 mpg. BTW, diesels are a lot
more popular in Europe than hybrids, where they've been fighting high fuel
costs for a lot longer than we have.

Bob




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