View Single Post
Old 06-14-2009, 11:15 AM   #49 (permalink)
MechEngVT
Mechanical Engineer
 
Join Date: Jun 2008
Location: Richmond, VA
Posts: 190

The Truck - '02 Dodge Ram 1500 SLT Sport
90 day: 13.32 mpg (US)

The Van 2 - '06 Honda Odyssey EX
90 day: 20.56 mpg (US)

GoKart - '14 Hyundai Elantra GT base 6MT
90 day: 30.24 mpg (US)

Godzilla - '21 Ford F350 XL
90 day: 8.69 mpg (US)
Thanks: 0
Thanked 7 Times in 6 Posts
Quote:
Originally Posted by Christ View Post
Yeah, it's about $25... and welding grade O2 isn't pure oxygen, either. I don't remember if they actually add anything to it, but it's not even close (relative to terminology) to medical grade (pure, for all intents and purposes) oxygen supplies, which are stored in plain old aluminum tanks that have been vacuumed and boiled (heated to just over 100*C) prior to filling.

The problem doesn't rest with O2 being reactive to metals as a whole, it comes with O2 reacting pre-combustion with other elements in the combustion chamber, such as nitrogen and what not in the air. Pure oxygen is in fact an oxidizer, but the maintained reason for the nitrous in nitrous oxide is stability of the gas itself.
Elemental oxygen is highly reactive. So much so that at standard temperature and pressure it forms a diatomic bond with itself to form the stable O2. At STP oxidizing by the presence of 20% O2 is a slow process for most materials.

The elevated temperatures will cause the O2 to split into 2x O- which is a highly reactive oxidizing agent. It's been a while so I don't recall how easily O2 separates when compared to N2O.

I've read somewhere that oxygen for industrial purposes (welding, smelting) has more critical purity requirements than medical oxygen. I've also read that there's no difference between industrial/medical oxygen except medical applications include secondary humidification after packaging the O2 from a common source.

I think roflwaffle is right; maintaining an "ideal" piston speed is only relevant if that speed is maintained at a high load. Almost all roadworthy vehicles are a degree overpowered and maintaining that load would result in acceleration, not steady-state operation. Over-gearing to run at a sub-optimal engine speed would be more efficient for throttled engines, not sure how it would impact diesels.
__________________
  Reply With Quote