Converting air cooled to water cooled...maybe
 

This has degenerated from a discussion of possibilities into what I
would expect in a board meeting, not in an engineering lab. So I am
bailing out to look elsewhere.

By the way, I didnt reject air cooling, only expressed my concern that
it could cause corosion. BTW, thanks for those comments, they WERE
valuable.

Keith Hughes wrote:
jim.isbell wrote:
Keith Hughes wrote:

Jim,

Sorry, but changing the mode of cooling for an engine without proper
engineering *is* jury rigging.


I didnt say I wanted to do it "without proper engineering."

OK, but 'wrapping copper tubing around the cylinders' doesn't sound like
an approach resulting from much engineering analysis.

That is why I am here, to get information on how to properly engineer
it. I am an engineer so with proper input I think this can be done.

Well then, surely you must know that you first need the designed
combustion chamber temperature range and the thermal conduction profile
for the cylinder sleeve (top to bottom), to properly size the multiple,
vertically segmented, cooling loops you'll require. You could estimate
the vertical temperature cline by analyzing the relative fin surface
areas, air flow rates, and standard thermal conduction value (F sub r, U
sub L as ASHRAE defines it) and the emissivity of the fin material. And
that just gets you the info you need to design the heat exchange
process. You need to go through the same exercise with the copper
tubing with the bonding method, heat transfer characteristics, mass flow
requirements, baffling to ensure turbulent flow, etc., etc. Not a
trivial exercise.


As you say, it may not be economical, but to reject it out of hand is
shortsighted.

As you seem to have rejected, out of hand as you say, the most simple
way of achieving your stated goal? I.e., not air cooling with "salt"
air. Properly trapped (i.e. collection drain) demisters are the
standard method for achieving these results. Used all the time to pull
moisture from ductwork.

I always like to point out to young engineers that if we didnt try what
couldnt be done, nothing would ever be accomplished.

You might also want to point out that trying to create novel designs and
implementations when existing designs *meet all customer requirements*
results in nothing but higher development costs and, typically,
unnecessary process complexity. This, IME, is the biggest failing of
most engineers (excepting R&D of course).

And, I might point out, this thread epitomizes that situation; trying to
redesign the end point of the process (i.e. the engine) instead of
addressing the problem earlier in the process (i.e. the cooling air
supply) where it can be solved easier, cheaper, and with less complexity.

Almost any
engineering project has never been done before or it wouldnt be in the
engineering department, the technicians in the lab would have looked it
up and done it by now.

Well, sorry but that's just ridiculous. Virtually all day to day
engineering projects are varying implementations of basic
systems/processes that are done all the time. The vast majority of
engineers are not involved in R&D work; they're doing practical process
applications using basic engineering principles. I'm not trivializing
the Engineering process. The most difficult engineering exercise, IME,
is taking an existing process or piece of equipment and implementing
that process or equipment into a specific/unique application and
achieving a result that is timely rugged, efficient, cost-effective, and
meets the specific needs of the end user. If you can do all of those
five, you're a damn fine engineer.

Keith Hughes

Converting air cooled to water cooled...maybe
 

On Sat, 29 Jul 2006 09:20:49 -0700, Keith Hughes
wrote:

That is why I am here, to get information on how to properly engineer
it. I am an engineer so with proper input I think this can be done.

Well then, surely you must know that you first need the designed
combustion chamber temperature range and the thermal conduction profile
for the cylinder sleeve (top to bottom), to properly size the multiple,
vertically segmented, cooling loops you'll require. You could estimate
the vertical temperature cline by analyzing the relative fin surface
areas, air flow rates, and standard thermal conduction value (F sub r, U
sub L as ASHRAE defines it) and the emissivity of the fin material. And
that just gets you the info you need to design the heat exchange
process. You need to go through the same exercise with the copper
tubing with the bonding method, heat transfer characteristics, mass flow
requirements, baffling to ensure turbulent flow, etc., etc. Not a
trivial exercise.

You could always just measure the temp of the head and block in
different locations and under different loads. Knowing the difference
in block temp at idle and full load would be very useful.

Using a thermocouple(s) to measure the block temp between the fins
would be a good start. It may be the fins are designed to give a
fairly even temp throughout the block itself.

Some slightly oversized copper tube that's squashed to give an
interference fit between the fins should give good conduction, if not
enough then use more than one layer.

In testing the thermocouple could be used to monitor the block temp
under water cooling, to ensure it's within the same values as for air
cooling.

One issue with copper is that it may fracture through vibration if not
supported properly, so stainless may be better for some parts.

A tank, manifold, thermostat, pressure relief, and raw water heat
exchanger would also be needed. Also a thermal cutout if the cooling
fails. Different temps at top and bottom of block could be accomodated
by different thermostats.

Doing some practice on an old engine might give some useful lessons.

cheers,
Pete.

Converting air cooled to water cooled...maybe
 

"Brian Whatcott" wrote in message
...
You could try this. A fan sucking from a long duct inside the hull.
If the hull is steel or aluminum, it would be quite effectively cooled
air from the sea water. The duct plays over the cylinder then exhaust
manifold.

Brian Whatcott.



I have actually done this with excellent results.

Basically, I contained the diesel generator in a soundproofed box and sucked
air out of the box. The air inlet sucked air that was first passed over a
large area of the steel hull. The incoming air being specifically directed
at the cylinder head area.

As a finishing touch I installed a fire detector and two heat sensors both
of which can independently cut the engine and fuel in the event of the
compartment overheating.

Hope this helps.

Adrian Smith.

Converting air cooled to water cooled...maybe
 

"jim.isbell" wrote in message
oups.com...
This has degenerated from a discussion of possibilities into what I
would expect in a board meeting, not in an engineering lab. So I am
bailing out to look elsewhere.

By the way, I didnt reject air cooling, only expressed my concern that
it could cause corosion. BTW, thanks for those comments, they WERE
valuable.


Don't bail out too soon, there will always be more 'you can't do that' types
than 'that sounds interesting, let's have a think around the problem' types.

Adrian Smith.

Converting air cooled to water cooled...maybe
 

Adrian Smith wrote:

Don't bail out too soon, there will always be more 'you can't do that' types
than 'that sounds interesting, let's have a think around the problem' types.

Adrian Smith.

I will continue to look at the problem, not bailing out yet.

I dont have a metal hull anymore. My current boat is Fiberglass. The
last one was steel but I sold it.

However, my research seems to indicate that I need about 1500 cfm and
that shouldnt be too hard to get.

Converting air cooled to water cooled...maybe
 

"jim.isbell" wrote in message
ups.com...
Adrian Smith wrote:

Don't bail out too soon, there will always be more 'you can't do that'
types
than 'that sounds interesting, let's have a think around the problem'
types.

Adrian Smith.

I will continue to look at the problem, not bailing out yet.

I dont have a metal hull anymore. My current boat is Fiberglass. The
last one was steel but I sold it.

However, my research seems to indicate that I need about 1500 cfm and
that shouldnt be too hard to get.


How did you arrive at 1500cfm? (Asking cause I just guessed.)

I used an oversized fan, linked to a temperature controlled speed
controller, with auto shut down should things get too hot.

Even at full tilt, 3 KW, the cooling fan never reaches anywhere near full
speed.

Adrian Smith