Keel cooling schematics help

Hi there,

This spring I will have to make the 5 year dry dock inspection of one of my tug boats. This tug boat is a steel boat equipped with a Russian engine - 3D6

Specifications

Models 3D6

four-stroke, fluid cooling, with direct fuel injection
6R 150x180
Power kW (HP) 110 (150)
Rotational speed, rpm 1500
Mass, kg 1500

I would like to convert this to keel cooling as for now the cooling is working with 3 heat exchangers. 2 for the engine and 1 for the oil. This engine has "dry" oil bath (or how you call it) meaning it consumes 800g of oil/hour.

Could anyone help me with a schematic of the cooling system that incorporates:

- two thermostats - one for by pass and one for internal circuit. I read there is need for two such thermostats. For the moment the engine has no thermostat and the temperature is controlled manually by adjusting the water flow through the engine.

- a way to cool the oil by using the existing heat exchanger and to keep the oil at 80 celsius .

Also would like to know if in such applications I can also cool the dry stack.

The reason for this conversion is the hard winters we get here and the damage the cold does to non working engines. Last week it took me 3 days to start the engine due to ice in the pump and blown out hoses etc. With so much piping it is almost impossible to drain the whole system.

If any of you has practical application of this it would be great to see some pictures of your solutions.

Thank you,

Daniel

 

Do you mean to say this is an engine with a dry sump, where the crankcase oil is pumped back into a tank?
And why does it have 2 heat exchangers?

Basically the keel cooling just replaces the heat exchanger. A single thermostat keeps the cooling circuit closed until operating temperature is reached; a narrow bypass allows the coolant to circulate through the engine.

 

Yes CDK, this is a dry sump engine and it consumes part of the oil (800g/hour).

This is a russia first WW tank engine. It's a tough beast good for tugs. At 1.5t is a heavy machine. I will eventually need to replace it but at the moment i can't aford that.


It has two coolers because it is used in shallow water with mud so one can be bypassed in case of a problem.

I understand quite well the keel cooling part but not quite get the thermostat positioning and the way pipes need to be connected. I found some info but nothing too explicit.

Also i don't understand if the formula for the keel cooler sizing is taking in consideration the cooling of the dry stack.

Cheers,

Daniel

 

Instead of an external keel cooler there are methods of installing a box inside the hull with channels that cool thry the hull skin.

This would be ideal for a shallow mud area , BUT it takes a good bit of room to get the cooling required.

A Naval Architect would be better at working the numbers , worth paying for an hour of his time.

 

This is what I had in mind Daniel.
The thermostat should be a "leaky" one, otherwise there is no flow at all and the device will never open. Some people place a normally open thermostat in the bypass, but with the proper dimensioning you can do without one.

 

Barnaultransmash

 

@ Fast Fred - Yes the inside the hull solution is also doable but for me the external solution with half steel pipe welded to the hull is the simplest and easiest to achieve. The box coolers are not the best option as they might freeze or get filled with floating debris.

I will have a naval architect to make the calculations and planning but the thermostat solution interests me more as the naval architects are not so good at mechanics...

@CDK - You mean the thermostat should be a bit open at all time and just regulate flow by increasing it when hot? Is that a special thermostat or one with some holes in it would do?

@WestVanHan - Yes you are correct - Barnaultransmash in northern Russia. This engine is in production since 1932 and till today it had few modifications. I suspect at the origin it was an American design. On my tug at optimum speed it will consume 20 liters of diesel plus 800-900g of oil. The new engines are not much better in that respect just environmentally speaking .

 

The most common version ( aka Mercruiser) has a small triangular cutout at the rim to ensure flow. Others use a drilled channel in the thermostat housing.

 

The box coolers are not the best option as they might freeze or get filled with floating debris.

NO!

The cooling box is a flat box , say 2- 4 to 6 inches deep that is welded Inside the hull .

2 ft wide 6 -8 -10 ft long depending on engine HP and the warmest water operation contemplated.

AS they are sized for for operation a thermostat is required to prevent over cooling 99% of the time.

The interior has welded fences that cause the coolant to take a longer path inside the box.

The box is filled with engine coolant .

The hull external surface area is the only part that touches outside water , just as now.

 

Dear Fred,

I think we talk about two different things using similar terms. I understand what you say now but I was referring to box cooling as know in the marine industry -


http://fernstrum.com/wp-content/uploads/2013/10/BoxcoolerCatalog.11.13.pdf

This is skin tank cooling you refer too and they are best used in a vertical position for simplicity.



Some documentation I found about this matter:

http://fernstrum.com/wp-content/uploads/2013/10/PassageMaker-Magazine-1996-Article.pdf

http://www.europeanmarine.co.uk/DURACooler brochure 07-16-2007.pdf

http://fernstrum.com/products/gridcooler-keel-cooler/installation-options/

http://www.betamarine.co.uk/inland/keel_cooling.html

I hope this will help others looking into this matter.

Still the thermostat thing is not so clear to me.

 

By the way - this is the tug and the contrast conditions it has to work in...

 

Here is a picture of a Merc thermostat. The wedge cutout is a bit difficult to see:

http://www.iboats.com/mall/image/vendor/16/bigger/18-3650_big.jpg

 

Thank you CDK,

I can see it in the picture. It is a v shaped cutout on the edge of the thermostats seat. That is much clear now for me. I think I can fabricate that easily.

Thanks,

Daniel

 

Keel cooler on EBAY

Hi there,

Can someone help me with this.

On EBAY I have found the following - http://www.ebay.com/itm/40066300483...em=&sspagename=ADME:X:RTQ:MOTORS:1123&vxp=mtr

The owner states this was bought for a 250 hp engine but was never used. By my calculations this is too small and it looks small. Could you advise please?

Attached are some 3d rendering of the cooler with dimensions for ease of calculation. My calculations say - 0.44 square meters of surface. My engine is 100hp @ 2800 rpm with the exhaust manifold cooled by the internal circuit. The calculation for aluminium cooler from Betamarine says - surface needed = HP/5 - in my case 100/5=20 square feet or 1.85 square meters.

The coper has much better conductivity but a minimum of 1 sq meter would be neded for that. Is there something I miss? The alloy of the cooler is - 90% coper 10% nickel.

Here you can find some info about the coolers - http://fernstrum.com/literature/forms-catalogs/
Cheers,
Daniel

 

This is not a sturdy keel cooler but a toy. With only 3/8 width the material can only be flimsy and easily damaged.
There is not much difference in calculations for aluminum and copper in thin walled objects, this cooler is way too small for you.

But the good new is that the seller ships to the US only, so forget about it.