cooling radiator air supply

Discussion in 'Boat Design' started by rick gray, Nov 6, 2016.

  1. rick gray
    Joined: Dec 2012
    Posts: 87
    Likes: 4, Points: 8, Legacy Rep: 30
    Location: port coquitlam B.C.

    rick gray Junior Member

    Hello: I am trying to design air supply to radiation my Amphibious Vehicle project. have some design details . since the engine and radiator are inside hull under a hooded compartment( with sealed doors and hood for access) the radiator is about 15"X27" in area. i am designing rear air exit vents at transom. i am adding air scoops at front windshield in deck also at side of deckhouse at deck. the air ducting will deliver air to under floor plates to get to shrouded radiator.(with elect fans) the air has to pass by and under engine to get to a secondary (primary radiator, i may restock front radiator water to avoid to much heat in cabin area upfront. air will go through rear radiator( has fans on rear side to pull air and push air out transom vents. will try to post photos, some on my site if you search amphibians?
     

    Attached Files:

  2. messabout
    Joined: Jan 2006
    Posts: 3,168
    Likes: 333, Points: 83, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    You have the engine in a sealed compartment with no ventilation? Is this a gas engine? If it is a gas engine, there is more than a radiator to deal with.
     
  3. rick gray
    Joined: Dec 2012
    Posts: 87
    Likes: 4, Points: 8, Legacy Rep: 30
    Location: port coquitlam B.C.

    rick gray Junior Member

    WHAT?? i explained it isn a engine cover in hull. i am adding vent ducts and fans. see photos in my site on the search Rick Gray or search amphibian
     
  4. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    I love radiators in a boat fresh water fluid cooling and you can add a internal or external keel cooling style addition if you need to.http://www.boatdesign.net/forums/at...ing-engine-compartment-nissan-remote-fuel.jpg

    But I also had my safe remote fuel system to make sure no gas fumes could build up inside my hull so things could be built different from conventional boats.

    It was a pleasure to feel safe and a nice warm boat for camping.
     
  5. gonzo
    Joined: Aug 2002
    Posts: 15,498
    Likes: 1,039, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    If the vent area and ducts are larger than the radiator, it will be fine. However, that assumes there are no sharp turns that will reduce flow.
     
  6. Barry
    Joined: Mar 2002
    Posts: 1,491
    Likes: 280, Points: 83, Legacy Rep: 158

    Barry Senior Member

    so what are you trying to get help with. I don't see a question
     
  7. CatrigCat
    Joined: Jul 2016
    Posts: 35
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Greece

    CatrigCat Junior Member

    The electric fan in picture will *recirculate* plenty of air through the radiator but will flow little air to the duct.
    It will soon overheat.
     
  8. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    Images show a boat with radiator fitted in front of the inboard motor outside of the cabin in the engine cover.
    Air is taken from inside the hull through the engine box by the original radiator and fan past the motor and under a cover and up into the air in front of the
    cover containing the remote fuel system at the rear.
    A fan was tried at the exit but not really needed.
    A nice easy to maintain very smooth fully soft rubber mounted and retractable shaft drive and very quiet motor for camping and living aboard.
     

    Attached Files:

  9. rick gray
    Joined: Dec 2012
    Posts: 87
    Likes: 4, Points: 8, Legacy Rep: 30
    Location: port coquitlam B.C.

    rick gray Junior Member

    air

    thanks Tom! I wish mine was the same? KEEP IT SIMPLE STUPID TO LATE FOR ME? cooling system will be overfitted air ,fans water cooling,muffler in sea bay cofferdam exhaust pipe air and water cooled, since will be out of water at most times no heatexchanger planned as yet Rick
     
  10. rick gray
    Joined: Dec 2012
    Posts: 87
    Likes: 4, Points: 8, Legacy Rep: 30
    Location: port coquitlam B.C.

    rick gray Junior Member

    air flow

    GONZO: I think I am on the right track ? i am installing air scoops to ducts that i am running down from front windshield and dash. area P&S should be AS YOU SAY same area as Rad!! with little or no obstructions, also escape duct at rear the same area about 300 sg inches.? some say elect fans do better pulling air through rad with air from driving going in front face of rad. so rad at rear will have fans on aft side to pull air (from ducts at side shell) through to rad,but also push air rearward and out transom vents. thinking about adding separate duct to deliver air from deckhouse top ,to top of carb to help pull air into shrouded engine compartment area( since an engine is actually an air pump) . i hope to cool engine water primarily in rear rad( under floor near jet drive) and pipe it forward to second rad at front of engine ,to reduce heat at engine compartment (on which I will be sitting at helm. may need air conditioning and cabin air vents to make it livable?
     
  11. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    I have seen radiators fitted at an angle on cabin tops on some early inboards it`s not as silly as it may sound.
    I was going to try that myself, and would probably do so if I built another boat.
     
  12. gonzo
    Joined: Aug 2002
    Posts: 15,498
    Likes: 1,039, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Air circulates because of a pressure difference. The design and type of fan may make it more efficient at pushing or pulling air. Whether it is electrically driven of belt driven makes no difference.
     
  13. rick gray
    Joined: Dec 2012
    Posts: 87
    Likes: 4, Points: 8, Legacy Rep: 30
    Location: port coquitlam B.C.

    rick gray Junior Member

    radiator fan

    GONZO I just got a fairly new Dodge truck rad with twin fans that would pull air back toward engine( fan is mounted on rear side of rad) and also rely on driving forward air pushing air to rear ,it has a transcooler and ac heat exchanger(condenser?) was thinking of using ac (condenser) unit for water? to help cool my exhaust manifolds and double walled water cooled exhaust pipes and connect it to my rad system which will fresh water cool everything or i may have to break it into two separate systems?. i will have to experiment with temperature readings? and add on or simplify system at sea trial.
     
  14. EXTENDBC
    Joined: Nov 2016
    Posts: 2
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Australia

    EXTENDBC New Member

    A solution might be adding a ventilation fan, came across www.jecmarine.com who supply dc brushless marine engine room ventilation fans
     

  15. Barry
    Joined: Mar 2002
    Posts: 1,491
    Likes: 280, Points: 83, Legacy Rep: 158

    Barry Senior Member

    A couple of things come to mind and may or may not be relevant
    If the engine is a gas carbed engine, all of the electrical, starter, alternator, distributor must be flame arrested so you do not blow up the amphib if the carb should flood and a non arrested spark fires the fuel off
    You are talking about, possibly, installing fans which might not meet this criteria.

    As you are installing a jet pump that probably will require a lot of horsepower the radiator system should be much larger than would be on a vehicle for a few reasons
    1) your engine will be enclosed and not have any air (except that provided by your fans) cooling the engine surfaces
    2) You will probably be running the engine at higher sustained loads so the engine will have to dissipate much more heat than a vehicle. ie more heat transfer required at 250 hp than 50 hp running down the highway
    3) The inlet velocity will be lower than say 80 kph and fan assist

    A rad 15 by 27 does not seem to me to be able to handle the high heat transfer that you will ultimately need. ( but we have not been given the hp rating) The number of layers of cooling tubes will be something to look at as rads can have from one and many above 4. If you only have one or two, it is unlikely that you will be able to take enough heat out of the water. You could also gang them together for better heat transfer

    As your construction pictures show a robust vehicle, ie a lot of weight with all the systems, you will have to ensure that the cut of your impeller is designed to deliver higher thrust at lower speeds.

    Anyway, just some random thoughts
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.