Re: What is the power/weight ratio of a Stirling engine?


Dan Bloomquist wrote:
dezakin@xxxxxxx wrote:

Generally the best heat reclamation device on the ICE today is a
turbine on the exhaust.

This has nothing to do with 'heat reclamation'. It works because you
increase the 'effective' compression ratio at the intake. Nothing more.

You described why supercharging gets more power, but the 'turbo' part
is essentially a combined cycle heat engine. What powers the
compressor?

Most often this is hooked up to a compressor on
the air input for a turbocharger, but you can just hook it up to an
alternator also.

And it would be most assuredly much less efficient than driving the
alternator from the mechanical end.

It most assuradly isn't. The question is if you get more efficiency
running the compressor or the alternator or some mix of the two.

More esoteric heat reclamation techniques involve thermophotovoltaics
on the catalyctic converter...

thermophotovoltaic!? 300c ain't going to get it.

Cat converters run at 900c...

steam generator on the engine (BMW
turbosteamer)

Why not the diesel cycle and eliminate the low compression loss of gasoline?

Yes yes, use a diesel cycle. No reason not to. Now theres still extra
heat in the exhaust and engine block that can be used, even with
diesels... otherwise you would have to supercharge with a belt driven
compressor rather than a turbocharger, and turbodiesels wouldnt work.

and crower's water injection for a six cycle engine
(speculative on its effectivness).

???

A speculative six cycle engine where after the gas (or diesel) power
stroke vents the exhaust, water is injected and flashed into steam from
the engine heat. If it works, it would be a neat way to get closer
ideal carnot efficiency and save space on the radiator. Bruce Crower
supposedly has a prototype that runs now.

I expect that it wont work for a variety of reasons, especially
incompatible lubrication.

The stirling power to weight ratio might be just fine, but the problem
is that its expensive, hard to seal, and the nature of it requires more
radiator capacity, and that is what will kill the power to weight.

Yet you have room for the bmw turbosteamer?

I dont know. Neither do you. It might be a total waste of time. Steam
does have the advantage that you can just throw it overboard when
you're done with it

The second law is just that.

The second law tells us what ideal limits are, not that stirling
engines power to weight ratio is commercially acceptible.

When you are dealing with an ICE, you just don't have enough delta T to
minimize your machinery. The diesel cycle is the simplest solution. It
has been around for many decades. Nothing new here....

There are still plenty of optimization options avaliable for diesels,
especially for narrow powerband engines.

.

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