AC>It would be quite a problem in MOST applications to usefully  utilise that 
2/3
AC>waste heat. Put the engine in the basement of a very large occupied 
building
AC>in a freezing climate and yes, most of that 2/3 will be useful.
 
AC>Transfer to application into a temperate or tropic climate [lotsa people
AC>there!] and how on earth, would a major recovery succeed?
 
 JM> As a co-gen system, with the engine mounted in the space to be heated,
 JM> all the cooling system heat is recovered and a substantial portion of 
he
 JM> exhaust heat as well.  This gives efficiency as a co-gen system, as:
 JM> 33% (mechanical energy) + 33% (heat recovered from engine cooling) +
 JM> say, a 78% recovery of the heat in the exhaust - .78(.33) or 26%.
 JM> SO.. as a co-gen efficiency is .33 +.33 +.26 = 93%.
 
AC>Logically I think you are describing an oil heated building with engine 
drive
AC>power acquired as an auxiliary. With co-gen capability during a small part 
of
AC>the year in a small part of the world!   Cheers......ALEC
 
Alex,
 
Yes, that's exactly what was being described in the discussion.  I jumped in 
to
clarify the high efficiency claim that was being challenged and to explain 
ow
the manufacturer of these co-gen units could fairly make that claim for the
system.
 
Hereabouts, and probably most places in 40 deg. latitude or more, we have a 5 
or
6 month heating season and the potential to save about US$ 1,000-2,000 per 
year,
per household, with such a system.  There are a lot of us up here too! ..with 
oil
furnaces running right now! (..And that small part of the year would seem 
ery
long indeed to us without them!)
JMcA
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