Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Feedwater, to heat or not to heat?  (Read 200 times)

KNO3

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,178
  • Location: Vienna
Feedwater, to heat or not to heat?
« on: July 10, 2019, 04:45:41 PM »

Hello all,[/size]Being in the middle of a steam plant build, I have come to the point in which I should decide how to best feed the boiler with water from the pump. I thought of drawing upon the forum knowledge, as I am sure others have tried this before. Is it worth the trouble heating the boiler feed water in a model steam plant? I am thinking of perhaps building a coil in the condenser, so the feed water gets heated by the spent steam. An alternative would be to place the coil in the chimney, to heat it with the exhaust gases.What are your recommendations?
Logged

rhavrane

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 415
  • Steam passionate collector
  • Location: Saint-Mandé, Val-de-Marne, France
Re: Feedwater, to heat or not to heat?
« Reply #1 on: July 10, 2019, 08:13:39 PM »

Bonjour Calin,
The hotter the you inject water in your boiler the less you need to heat it to steam. In my little tug Jan de Sterke, the input water pipe turns arourd the boiler: https://www.youtube.com/watch?v=iNSEWFAm9uk   better than nothing but not very efficient.
On my larger tug Jan, https://www.youtube.com/watch?v=utYZJDJPBVg as you can see it, the oil separator (not a condensor as the steam is not reused ok2 ) is huge, it is because it contains about 1 meter of rolled water pipe located between the pump and the boiler. After a few minutes of use, the result is very positive.
I am sure that there are other alternatives, I am interested :-))
Logged
Raphaël
Raphaëlopoulos Steam Lines UnLimited
Membre du Modele Yacht Club de Paris http://mycparis.fr/
Ma chaîne YouTube:  http://www.youtube.com/user/rhavrane
Mes albums : https://picasaweb.google.com/104408627118165995713/

Jerry C

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,075
  • Location: Caernarfon, North Wales.
Re: Feedwater, to heat or not to heat?
« Reply #2 on: July 10, 2019, 08:54:32 PM »

Yes, you need to heat your feed water. Otherwise putting cold water into the boiler will kill your steam pressure. A small coil in the base of the chimney will suffice. See Jerry’s Steam Launch Wear.
Jerry.

KNO3

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,178
  • Location: Vienna
Re: Feedwater, to heat or not to heat?
« Reply #3 on: July 10, 2019, 10:25:14 PM »

Thanks for the answers. I am thinking of building a heating coil into the condenser tank., as my boat's chimney is rather narrow and soldered to the boiler.
Logged

KBIO

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 92
  • Location: Dinan (France)
Re: Feedwater, to heat or not to heat?
« Reply #4 on: July 15, 2019, 05:07:23 PM »

 
Hello!
It all depends on the H20 volume injected compared to the engine consumption and the boiler size (heated surface).
Remember that you'll need >+6 time more energy to vaporise one volume of water than to bring it from 20°C to 120°C.
If you go thru the condenser, it does not hurt, but the final gain is peanuts.

If you go thru the chimney, be careful not to stick it down to the bottom, close to the flare , it will vaporize , even partially, and won't be able to open the clack valve.Overheated steam may also destroy the seals and gaskets. O0
You know where to find the proper spreadsheet to have an idea of what you need! ok2
Cheers.

Logged
I do not take it very seriously!

johnv

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 232
  • Model Boat Mayhem is Great!
  • Location: Peterborough
Re: Feedwater, to heat or not to heat?
« Reply #5 on: July 15, 2019, 05:46:11 PM »

Hi just take a flask of hot water with you .so what you don't use in boiler you can make a cup of tea . easy cheers John V
Logged
Pages: [1]   Go Up