Subject: Advanced IC engine project. Partners needed.

From: [email-masked] (Gary Swindell)
Date: 3 Nov 1995 21:54:47 GMT

We are actively working on an internal combustion engine design that offers 
the following benefits:

- HP/weight ratios of up to 5:1 (at ideal fuel/air ratio)
- ability to run at very lean mixtures (1:100 fuel/air ratio) 
- normal HP/weight ratios at very lean mixtures, reducing emissions by 98%
- very high real world thermal efficiency

Applications that are being considered include generators, small power 
equipment etc…

We are looking for partners in this process as we are in need of better 
machining capacity and capital.  
If you have any interest in a project like this please respond via e-mail.

---

From: [email-masked] (Chris Pollard)
Date: 5 Nov 1995 01:41:09 GMT

: - ability to run at very lean mixtures (1:100 fuel/air ratio) 
Doesn't this cause most engines to generate nitrogen oxides?
: - normal HP/weight ratios at very lean mixtures, reducing emissions by 98%
: - very high real world thermal efficiency
What do you mean?  Most engines are quite good at turning energy into heat
- it is quite easy to get 100% - surely you mean mechanical efficiency.
What sort of numbers are you anticipating?

---

From: [email-masked] (Paul Probus)
Date: 6 Nov 1995 02:06:41 GMT

In article <[email-masked]>, [email-masked] says...
>What sort of numbers are you anticipating?

I'm afraid you're quite mistaken.  For thermal efficiency, the Carnot cycle is 
the ideal efficiency.  The _only_ way to get 100% thermal efficiency is if the 
exhaust gas coming out of an engine is at a temperature of absolute zero, 
although you can approach 100% efficiency if you can raise the burning 
temperature to near infinity.  If I remember my thermodynamics correctly, the 
_best_ (ie. Carnot) thermal efficiency of a gasoline engine is about 60%.  I 
believe, if I remember correctly, that the average gasoline automotive engine 
is less than 20% efficient, but, remember, I going from memory :).

Here's the thermal efficiency for a Carnot engine:

             T
              L
N   =  1 - ------
 th          T
              H

Where 

N  = Thermal efficiency
 th

T  = Lower temperature reservoir (or exhaust temperature in an IC)
 L

T  = Higher temperature reservoir (or the temperature of the gasoline burning)
 H

Hope that clears things up a little.

Paul Probus
[email-masked]

---

From: [email-masked] (Paul Probus)
Date: 6 Nov 1995 02:31:29 GMT

In article <[email-masked]>, [email-masked] says...
>is less than 20% efficient, but, remember, I going from memory :).
(Carnot Efficiency equation erased)

I may have been misleading in my posting.  The Carnot cycle is the best that 
*any* thermal engine (internal or external combustion) can approach.  The Otto 
cycle has it's own efficiency equation (it's a bit more complicated, but it's 
in any Thermodynamics textbook), and I believe that the Otto cycle efficiency 
for a gasoline engine is about 30% (again, going by memory).  That's the best 
efficency that a gasoline engine running on the Otto cycle can hope to achieve, 
however, a gasoline engine running on the Carnot cycle (no such engine esists, 
BTW) can hope to achieve 60% efficiency.  

Now, I hope that clears things up a little.

Paul Probus
[email-masked]

---

From: [email-masked] (Chris Pollard)
Date: 6 Nov 1995 22:26:39 GMT

I don't believe the ratio of mechanical output to heat input is called
thermal efficiency - it is called efficiency or in your case Carnot cycle
efficiency.  A good example of a 100% thermal efficiency is a stalled
electric motor - 100% of the energy going in is converted into (thermal )
heat energy.

So- definitions aside what do you claim for work output for thermal enrgy
input?

---

From: [email-masked] (darylb)
Date: Mon, 06 Nov 1995 16:42:03 +0000

In article <[email-masked]>, [email-masked] (Paul Probus)

> BTW) can hope to achieve 60% efficiency.  

I thought it was more like a little over 40% for the Carnot cycle and that
was being approached by the likes of stationary power sources since they
could pretty well bolt on any cost effective ascessory to get a few extra
percent efficiency.
God I hated that thermo stuff, dry as toast (maybe it was just the prof -
Eugene Plett - Mr Monotone) and wierd too, like the otto cycle reaches peak
efficiency at 17 or 18:1 compression ratio but no fuel allows that.

---

From: [email-masked] (Paul Probus)
Date: 7 Nov 1995 03:45:31 GMT

In article <[email-masked]>, [email-masked] says...
>So- definitions aside what do you claim for work output for thermal enrgy

The ratio of mechanical output to heat input *is* called thermal efficiency.  
It is possible to get very close to 100% thermal efficiency using electricity 
and a resistor, however, getting 100% thermal efficiency from burning a fuel 
is nearly impossible.  Like I said in my original post, the exhaust would have 
to be at absolute zero temperature, which means that you have extracted every 
bit of energy that can be had from the fuel that you're burning.

I'm not quite sure about your question, but the *maximum* work output 
possible for a given heat input is the difference between the heat input and 
the heat output.

In equation form it looks like this:

W   = Q  - Q
 max   in   out

The Carnot efficiency would be:

     W
      max
N  = ---- 
 th  Q
      in

Which would reduce to:

         Q
          out
N  = 1 - ----
 th      Q
          in

The actual thermo efficiency would be:

         W
          act
N      = ------
 th,act  Q
          in

Where W   is the actual work out as measured from the crankshaft.
       act

I don't know if I can convince you that the ratio of work output to heat input 
is the thermal efficiency, but if you want to, you can look what I'm saying, 
up in a Thermodynamics textbook.  If you can find one written by Kenneth Wark 
Jr. I think he's written his textbook so that it's easy to understand, of 
course I had no choice but to understand it to pass :) and I had the advantage 
of having to read many chapters of thermo. stuff before I got to the thermal 
engine cycles, so take my book recommendation with that in mind.

Paul Probus
[email-masked]

---

From: [email-masked] (Paul Probus)
Date: 7 Nov 1995 03:18:14 GMT

In article <[email-masked]>, [email-masked] says...

>efficiency at 17 or 18:1 compression ratio but no fuel allows that.

You may be correct.  I'm trying to go from memory, but it's been a while.

Paul Probus
[email-masked]

---

From: [email-masked] (Jim Harvey)
Date: Tue, 07 Nov 1995 06:13:20 GMT

[email-masked] (darylb) wrote:

[snip]
>efficiency at 17 or 18:1 compression ratio but no fuel allows that.

Well, not to give away any trade secrets, but we run 18:1 motors
regularly. fuel is Alcohol & Nitromethane. VE is way way over 100%. I
would'nt call them streetable though :^)

Jim Harvey
[email-masked]
[email-masked]
http://www.wp.com/HarveyRacing