The Steamboating Forum

Howdy all,

I have been in the keys for a few days so have not been watching the conversation. I am set up similar to Mike with no vacuum pump. Here is the heat exchanger I was going to run my main exhaust thru, it is rated at 450 PSI so I figured if I do a good enough job in connecting it to the feed water loop it will survive my hydro test.

Will I be OK running my feed through this ?

jon

http://www.ebay.com/itm/150947335446?ss ... 1439.l2649

P.S. - I went for a ride on the african queen, had a chance to talk to the captain, took some pics. I will try to post stuff later, it was very cool !!!

Bought it today. Went out to Packless' website and checked out the dimensions. Will be more than adequate. Thanks John

What does that heat exchanger look like on the inside? Is the smaller tube just running down inside the length of the larger tube, or is it coiled inside the larger tube? A picture or sketch would be good to show the inside configuration.

Fred,
My oil cooler/heat exchanger has a set of .200 I.D. tubes just like a small fire tube boiler. 43 of them. Very well designed.
Mike

The Mercruiser Heat Exchanger that I posted a pic of is now here. Looking inside, it appears to be two flat plates sandwiched together and then rolled up. This is connected to the two 3/8" tubes on the side, that is where I will bring the feedwater through. I'm a little suspect on just how much heat transferring is going to be happening. I'm sure these things have transfer coefficient rating, flow rates etc. Of course Ebay sellers aren't going to know all of that, it's just a gamble.

-Ron

Hey Ron,

I was running that exact cooler this fall and the water was definitely heating up. Of course I was reciriculating the hotwell so I am sure that was part of it.

jon

DetroiTug wrote:The Mercruiser Heat Exchanger that I posted a pic of is now here. Looking inside, it appears to be two flat plates sandwiched together and then rolled up. This is connected to the two 3/8" tubes on the side, that is where I will bring the feedwater through. I'm a little suspect on just how much heat transferring is going to be happening. I'm sure these things have transfer coefficient rating, flow rates etc. Of course Ebay sellers aren't going to know all of that, it's just a gamble.

-Ron

Suggest you invite Rainer to comment. He (and many in Europe/UK) use flat plate heat exchangers for condensers and feedwater heaters. Compact and efficient. Great for our little boats.

Ron wrote an article detailing some of his techniques in building the pump. It's in the Jan/Feb 2013 Steamboating Magazine, http://www.steamboating.org, (to be in the mail this weekend).

On the 22 Feb 2013 post from Jon on this thread, the HXR-100 heat exchanger. I also bough one on e-bay, for $20 it looks like a good buy.

It is all copper, welded construction, and consists of a 1-1/4 inch pipe (just right for the sidewheeler's steam exhaust pipe), with 1/2 inch OD water connections, the same size as my feedwater pump discharge tubing. A corrigated inner tube runs for about 12 inches inside a 1-3/8 outer shell tube, so the inside steam path looks like internal screw threads. The water runs between this corrigated tube and the outer shell, which is 1-3/8 OD copper.

A quick calculation shows that, with atmospheric steam exhaust thru the exchanger, and 100 PPH of 70F feedwater entering the tubing connections, about 140F - 150F outlet temperature will result, not bad. The Margaret S. uses only about 60 PPH feed flow, so I will get somewhat higher outlet temperature, maybe 160 - 170F. That will give very roughly about 7%-10% reduction in fire needed to generate steam, or about 7% - 10% extra steaming capacity with the same original fire.

The pump is finally in and all piped up and ready to run.

I remounted it on rubber because the shuttle valve noise transferred to the steel hull sounded like someone rapping the hull with a hammer. Unpleasant.

On the heat exchanger I wound up cutting all the tubes down and then machining 1/4" NPT fittings to slide on and soldering them to get rid of the hoses.

So, the first decent day will prove if this is going to work like I'm hoping.

Also, not by design, but a happy accident, the heat exchanger sets lower than the exhaust, which means hot water should get "trapped" there and do a much better job for the heat transfer to the feed water.



-Ron