Applied physics 101

[jpatchett]

Richard,

An exhaust rusts out from the inside due to moisture, but is not from the engine. After the engine is shut off the exhaust begins to cool and the atmosphere inside begins to contact. This draws relatively most/cool air up the tail pipe and this moisture eventually condenses on the inside of the exhaust. This is why there is some much vapor coming out the exhaust after start up in the morning.

Calories do convert to Joules, but NOT to watts or HP, there is a relationship, but they are not the same.

A Calorie or Joule is a unit of energy , and are NOT units to express any work being done.

A Watt is a 1 joule (of energy) being used over a period of 1 second (there is the function of time, again). When energy is used over a period time, it becomes work.

Jim

 

[jpatchett]

Matt,

Correct, but is there that much water vapor being created from the Hydrocarbons and O2 that stays in the exhaust?

I not a chemist, but I would think air coming up the tail pipe is a greater source of moisture.

Jim

 

[mgonitzke]

Jim-

I hated Chem...Stoichiometery was not my thing

...I don't think it's a MAJOR product of the reaction; Gasoline mostly turns into Nitrogen Oxide, Nitrogen Dioxide, Carbon Monoxide, and Carbon Dioxide. If the atmosphere was 100% Oxygen, a lot more water would be produced instead of all the Nitrogen compounds. I guess what I'm saying is, it's not the fact that there is little hydrogen in the atmosphere, it's the fact that there isn't anywhere near as much Oxygen (~21% in the atmosphere) to combine with hydrogen as there is Nitrogen (~78% in the atmosphere).

You are correct about air being drawn into the muffler as it cools.

 

[kide]

Matt and Jim - not challenging, but what drools out of the exhaust pipe of a just started engine ?(especially late model ones).. I was under the impression that was water vapor condensing on the inside of the pipe from the exhaust, prior to the pipe warming enough to prevent condensation....(more mumbling to himself)....

Oh BTW - great discussion - this'll show those guys over at the WFM we know sumthin'...

 

[mgonitzke]

Kendell-

That's probably correct. When I was little, my dad would pull his '67 Camaro out of the barn and run it to charge the battery up in the spring before driving it, and water would drip constantly out of the exhaust pipes for quite awhile after starting it.

It has to be water; I'm not sure what else it would be...

 

[thoffman]

OK, Don't know what everyone else thinks but this pissing match is getting old, I'd burn old horse turds if I thought it made my tractor run better! All this <u><font size="+1">SHOUTING</font></u> , BTU's, rpm's, cid's, ='s, +'s, X's vs Y's, bla, bla, bla........ don't mean

when you out in the back 40 stuck up to you ass in mud. BTDT. Remember what we're talking about here, it's not the space shuttle. Whatever it taked to get it done works for me.

Off the soapbox......NEXT

 

[lbuttke]

If there is movement, there is energy. Correct?
if -472 calvin is considdeder absolute zero does that mean all molectular movement stops?
If so, how do you measure -472 calvin?

movement = engery, energy = heat ?

 

[rpalmer]

Jim Patchett,
I don't know why you keep pointing out a time thing. Everything requires time. I think you can take your weight; the force of gravity the height of a step and the amount of time you spend going up steps and determine how many calories you burned. And that converts to how much HP you used.

Tom Hoffman,
I'm with you.

Lonny Buttke,
Maybe that's why some Cub quit running.

And gentlemen water is a by product of our engines. This is not considering condensation.

I almost burned my sweet potato casserole last night doing this.

Like I said, it has been a long time since I've even thought about this stuff and I'm here without a net. I have miss spoke and spelled wrong. But to say that hp can not be measured with heat is I believe wrong. And to think that higher octane gas does not have more energy is wrong. And IIRC that's what got this started.

 

[kmcconaughey]

 

[mgonitzke]

<blockquote><hr size=0><!-quote-!><font size=1>quote:</font>

But to say that hp can not be measured with heat is I believe wrong.<!-/quote-!><hr size=0></blockquote>

In a perfect, ideal, physics-textbook world, this would be possible...In my Thermodynamics class last semester, we did what is called an "air-standard" analysis of Otto-cycle (4-cycle) engines, in which the work done by the cycle is the net heat added. However, this analysis is only used to perform a simple analysis, as it assumes that the process carried out is reversible (meaning that you can restore the system to its initial state and conditions, which is not possible in real life...you can't turn combustion products back into gasoline and air) and that there are no losses from friction. Since we live in a real world with friction and irreversibility, you cannot directly measure power from heat, or equate the two, for that matter.

 

[rpalmer]

Matt Gonitzke,

I find that I can not enjoy my coffee this morning because I did not address this.

When I was in school there were two types of energy. Potential and kinetic. My understanding this that a third type has been "found" but it is applied to theoretical physics as is the string theory.

What you are referring to are forces. Which is basically how one type or another of energy is applied.

I also can't enjoy my coffee because I said that I spelled wrong. That would mean that I spelled wrong correctly. I should have said that I spelled some words incorrectly. Or that I miss spelled some words.

Now I'm going to try to enjoy this coffee.

 

[mgonitzke]

I'm going to say it again...in addition to potential and kinetic energy, there is thermal, electromagnetic, sound, and light to name a few. This has all been pretty well-known since the late 1800's or before that, for the most part. Energy is the amount of work that can be performed by a force. I'm not sure how you're thinking I'm referring to forces...

 

[jpatchett]

Richard,

As you state HP = Heat (not my words)

Now imagine a watermill, the falling water over the water wheel is turning the drive shaft that enters the mill and attaches to a series of gears and cogs. The rotating output shaft could be rated at some HP, ft*lb, etc. The water up stream in potential energy and the falling water on the wheel is kinetic energy. The energy of gravity is used to create HP, but where is the heat if HP=heat is true?

This mechanical energy could be used to create heat through some other mechanical process.

Jim

 

[dfrisk]

WOW, You Guys all discussed a LOT after I went outside to do a little yardwork yesterday.

RICHARD - re: Steam engines. Not to get another discussion going but I believe the efficiency the paper I mentioned about the Honda F-1 engine being the most efficient and a steam engine being most efficient must have some significant qualifiers to them. While a steam engine because of the multiple times it is used to exert force on the pistons in multi-cylinder engines, they can extract almost ALL of the energy from the steam, but the making of the steam is inefficient in most instances. The fact they are External combustion by design is the cause of the loss of efficiency.

I can't remember all the specifics about the Honda engine. But normal measurement of internal combustion engine efficiency is measured in HP Hours per gallon of fuel and brake specific fuel consumption. Several of the books I have are recaps of the Nebraska tractor tests dating WAY back to the 1920's until 1985. In round numbers without being specific a good gasoline engine makes 11 to 12 HP/hours per gallon of gasoline, no mention of what octane it is, it really doesn't matter, but the older engines it could have been as low as 70. LP gas engines make about 8 to 9, And a good turbo-diesel will be in the 12 to 14 range and there are a few that have exceeded 15.

Now You study the test information and the gas & LP engines will be the same except for the carb equipment and either higher compression pistons or cyl. head. The octane of the LP is higher so the tuning can be biased towards the higher octane and the engines may make 1-2% more HP in "SOME" cases, but to get approximately the same HP much more LP is burned because there are fewer BTU's of heat energy in a unit of LP than there is of gasoline.
The diesel engines are normally larger displacement, but they make the same HP as the gas engines while burning LESS fuel. And that's because there is about 25-30% more BTU per unit in diesel fuel than there is in gasolene. And #2 diesel doesn't even HAVE Octane! It does have cetane which in layman's terms is the octane equivalent.
In an acohol fueled engine the octane of the fuel is much higher, but the BTU is much less, but due to the cooling effect of the vaporization of the alcohol the intake charge is much cooler and more dense and more fuel can be burned making more HP than gasoline with the corresponding increase in fuel consumed. That's why gasohol & E85 give comparable HP to straight gasoline with lower MPG's.

I'm not even going to comment on the "Forms of Energy Discussion" other than to say I don't think it's really relevent to an overall discussion of engine fuels and relative efficency and durability different fuels provide.

OH, TOM, I couldn't find an octane or BTU rating for dried horse manure but I'm sure they'd work fine in a "Steam Engine".

 

[proessler]

Dennis F Thanks for that refreshing chat!!! All the previous chat was boring me &

me crazy...

 

[rpalmer]

Jim Patchett,

Relatively speaking, the same place it is in my example of one walking up stairs. Both examples in theory are the same.

Dennis,
So what we have with steam, by way of your example, is a very efficient engine with an inefficient fuel. Sound familiar?

 

[aschumacher]

Just an observation of what Dennis F. mentioned...that diesel fuel has a higher BTU rating...but the cost at the pump is about 15% higher than gas. I suppose the advantage is torque for trucks, otherwise wouldn't more cars have a diesel engine??

 

[kide]

OK, time for homework... read this before more discussion of heat as "HP"....

Oh, BTW - the main forum may not be as "boring" for those not interested (it's just like the telly, kids - you can turn the channel)...

 

[aschumacher]

Mr Ide. RE: reading assignment. I went to the suggested reference and immediately knew I was in troble when the subject line said 'HEAT (disambiguation)'. Anyway further reading reminded me of why/how I failed calculus many years ago. So I'm just gonna

stay in the background and read any new updates of "As The World Therms"

 

[dfrisk]

ALLEN - Calc was almost My undoing in college. As a "Pre Engineering major" I kinda needed it! Therefore I got my degree in GEOGRAPHY and I've given all the engineers I've ever worked with FITS!

Also, diesel has come down in price, about the same here in WI as reg. no-lead. A fill-up of both tanks on my pickup still sets Me back $100 so I don't run both tanks dry anymore.

PAUL - Glad You liked it. Dave Kirk & I discussed engines a couple years ago one trip I made up to FDL, I was mighty impressed because He read all the same articles by Gordon Jennings I think his name was, in Cycle magazine that I read! He had an ability to describe the most technical things in layman's terms. Did You know piston rings revolve around the piston in most engines Once for every 400 revolutions of the crankshaft? Kinda makes lining up ring gaps a waste of time!

RICHARD - Yep, steam engine sounds like a gas engine with a carburator! EFI is much better, but I still prefer a turbo-diesel.

KENDELL - O-K if I turn my home-work in tomorrow? My favorite TV show is on tonight. I got TOTALLY addicted to BONES about 3 months ago. Bad part is there's been some weeks TNT has run 15-20 episodes!