Posted on 03/13/2013 5:31:03 AM PDT by thackney
Edited on 03/13/2013 5:36:21 AM PDT by Admin Moderator. [history]
I move in interesting circles. About 2 weeks ago I found myself in the presence of real engine guys that test things. They didn't know me, so naturally when I asked poignant questions they looked @ one another and you could almost see their discomfort. Either I was spot on or way off as their responses denote an industry wary of leaks.
My questions were in the arena of Direct Injection and also DI of Gaseous Fuels. The responses were tepid, but I got the sense with everything going DI that supplanting the Gasoline Injector for a Gaseous one, was not as simple as I thought.
A caveat is the large Diesels going from Diesel to LPG etc in their DI environment, but who knows what technical hurdles they had to vault...
Trucks, forklifts and other equipment have been using PROPANE for years. It should not be hard to convert to compressed natural gas.
There is a significant difference in BTU content between propane and methane (nat gas).
For example:
100,000 BTU/hr furnace will use about 97 cubic feet of natural gas (100,000 ÷ 1,030 = 97.1) in one hour
100,000 BTU/hr furnace will use about 40 cubic feet of propane (100,000 ÷ 2516 = 39.7) in one hour
http://www.propane101.com/propanevsnaturalgas.htm
I should check bullet penetration tests. That would be a pretty good indicator.
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CNG Cylinders 101
http://www.cleanvehicle.org/technology/CNGCylinderDesignandSafety.pdf
From what I saw steel CNG tanks are superior to anything else.
According to spec they can absorb a 7.62.
They are just too big and heavy.
The Type 1, all steel, tanks seem be to the ones with the most failures.
I am very cautious about natural gas vehicles, since I have seen two completely burn down into the pavement. Both drivers told me they felt they barely had time to get out of the vehicle. I hope the safety issues with propane are completely addressed. I know gasoline is also flammable but I haven’t personally seen one burn up from a gasoline fuel leak for many years. Only a handful of people here use natural gas for vehicle fuel and I have already seen two burn up so seems they are more likely to do so for some reason. May be coincidence...
Natural Gas is not propane, it is methane. Propane is heavier than air while methane is lighter than air. Because of this, a propane leak will create a flammable pool of gas at the low point, while methane rises up to the atmosphere without accumulation in one spot, unless you have a gas-tight roof over it.
Gasoline is FAR more likely to "go boom" than natgas, either compressed or liquified. Natgas being lighter than air disperses rapidly once released from it's tank, quickly dropping the concentration in air below the LEL (lower explosive limit). Gasoline, on the other hand, puddles on the ground and slowly evaporates, maintaining an air/fuel ratio within the explosive limits. And since the LNG/CNG tankage is FAR STRONGER than the gasoline tank, they are far less likely to rupture, even in a severe wreck.
"GNC tanks need to be re-certified once in a while. Do you think the average automotive driver is gonna actually do that? They rarely change the oil."
They'll be recertified when they get taken to the dealer for long-term maintenance (like replacing a timing belt after 75000 miles).
CNG for non-commercial vehicles makes little sense until the infrastructure is built up.
My state, Texas, requires annual inspection certification displayed in the window. I suspect in the near future, passing the annual inspection will include up to date CNG inspection.
In PA, I have to take my car in for yearly inspection (brakes, headlight alignment, etc) every year. I would imagine they would inspect the tank at the same time. It would also be easy enough for the manufacturer to have the engine computer flash a yellow light if the vehicle has not been put through inspection on schedule, and refuse to start if the yellow light gets ignored for long enough.
Because we all know gasoline vapors and high voltage batteries are completely safe!
Looks like the railroads are taking a swing at it also.
Makes perfect sense because they can insert a fuel tank car between the engine and freight.
http://www.cnbc.com/id/100530572
Hydrogen and CNG are different. Steel vs. Composite is the issue. Gasoline tanks are a bigger threat.
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