Exhaust Temperature

[JonRiley56]

All,

How hot will the exhaust be coming off my engine ? I am trying to figure out the best way to route it to the transom to enter my condensing loop. Given the architecture of the boat, using a floexible marine rated hose would be convenient, but I need to make sure it is hardy enough.

jon

[gondolier88]

Well, you take the mean pressure of the steam expanding in the cylinder, correlate that on the steam table to it's corresponding temperature. Then you make losses through condensation flashing up in compression and entry- around 10% say.

When you have a guestimate add a factor of safety in of 80%- so a temperature of steam of 100deg. would use a hose rated to 180deg. for example.

That said- if your 'architecture' requires flexible hosing, have you thought about running it outside the hull- inside the hull, with frames, bearers and who knows what else in the way your asking for trouble with air locking.

Greg

[Lopez Mike]

I use a 3/4" automotive heater hose. So far, so good.

[fredrosse]

Automotive heater hose will work well here. Condensing at atmospheric pressure will have exhaust temperature at 212F (100C). Running with vacuum exhaust will provide lower exhaust temperature, but the piping should at least be suitable for atmospheric exhaust pressure, which will always produce 212F (100C) temperature. This will often occur even with a vacuum exhaust condensing system.

If there is significant vacuum in the exhaust (good for better steam cycle efficiency), then an ordinary automotive hose may collapse with the vacuum. This can be solved by fitting a coil spring inside the hose. I would use metal exhaust piping (ordinary thin wall galvanized electrical conduit is good, or copper tubing, or steel pipe, etc.), with short pieces of automotive hose and metal hose clamps to assemble the system. This allows for expansion without loading the engine connection or the hull connection.

[artemis]

... I would use metal exhaust piping (ordinary thin wall galvanized electrical conduit is good, or copper tubing, or steel pipe, etc.), with short pieces of automotive hose and metal hose clamps to assemble the system. This allows for expansion without loading the engine connection or the hull connection.

I take it you're not running a vacuum as the system you've described will leak like a garden aereator hose.

[fredrosse]

Ron, perhaps I did not describe these connections well. The attached photo shows the use of automotive hose and stainless steel worm drive hose clamps for steam exhaust piping. I have these type connections at several locations throughout the exhaust system, and they are very reliable and leakproof for moderate pressure and for full vacuum. The exhaust piping here is 1 inch Type L Copper, all joints Sil-Brazed, except where I may want to take down a joint.

I hook up a refrigeration type vacuum pump to the engine exhaust piping to turn over and dry out the engine before layup. A sniffer tells me the only places where there are vacuum leaks is thru the valve stem packings.

[artemis]

Figured you didn't mean to have a gazillion short pieces of hose and hose clamps, but wanted to make sure that others also used a minimum of connections and fittings. As much as I could I used plumbing "sweep el" fittings to give the greatest radius on bends in order to reduce friction. For those not in the know, directional changes in piping can "steal" a lot of "work" due to resistance to fluid/gas flow and using sweep el fittings can reduce this.