How to / DIY > Engines

Closed Loop Cooling (With Plate Exchanger)

(1/2) > >>

Hi All,

I have a question...

My 2 cylinder Kubota generator project is almost complete.
I am now working on the cooling system.
My preference is to use a 30 plate heat exchanger that I have kicking around and run a loop from the engine to the plate-exchanger and back.
Then connect whatever I want to the other side of the exchanger to cool the engine water ( Fan/Radiator, floor loop, wall radiator, etc..)
Is it best to have an open (to atmosphere) system on the engine loop? or is it ok to run a closed sealed loop on the engine side?
I prefer to have it sealed so that  I don't need a reservoir/buffer tank, and I assume some type of expansion tank would be required like those used in hydronic heating systems.
Any thoughts, ideas, suggestions on this ?

The engine has it's own water pump and thermostat just like a car engine.


My Blackstone model MP  engine was originally sold as a set with a very large prime power generator. Its duties were to provide air for starting the big engine and to provide emergency power when the large engine was not operating. It was originally set up by Mirrless  Blackstone in a somewhat similar manner as you suggest. The engine water jacket was connected to a 80 gallon tank via thermosyphon and above that tank was a radiator connected via thermosyphon and equipped with a thermostat. The system was pressurized via 4lb cap on the radiator.  In operation that tank cooled the engine and when the tank got to a given  temperature the loop to the radiator opened up to cool the tank water. Odd was the fact that the radiator fan ran all the time being driven via belt from the crankshaft thus consuming power 100% of the time,needed or not.  I understand the added complication IF there was seperation of the fluids  and if heat was being used for some additional purpose. But since it used common fluid and the heat was simply being wasted the entire setup made no sense to me.

 In you case with planned use for the heat it makes sense. Yes you will need an expansion tank on the engine side of the system and I would run that side non pressurized.

I thought engines ran better when above 212 degrees.

Hi Veggie, I think that what you have shown in your diagram will work fine. The thermostat and internal water pump should circulate coolant well enough and allow the engine to run at a suitable temperature for efficiency, correct oil temperature and longevity.

There are a couple of weak points in the system:
Thermostat failure will cause the engine to overheat. I have had plenty of motor vehicles and have only ever had to change one thermostat!

Mechanical failure of the Kubota water pump or belt driving it will cause overheating. Again I have only had to replace a couple of water pumps in 40 years of driving, belts get changed during regular servicing.

Secondary water circulation pump to under floor heating etc. When I lived in the UK we had gas/oil fired central heating with Grundfos circulation pumps These are very simple electric pumps and I never had a problem.

Open or sealed system? I prefer a sealed system because you can run anti-freeze in it, depending on where you live. A pressurized cap will blow off steam in the event of a failure. The alternative might be an open expansion tank with a ball float valve, connected to your water supply, to ensure the header tank is always full.



Thanks guys,

ajaff1, your points about overheating are valid. I will be sure to add a high temp shutdown on the engine.
The engine has a fuel rack solenoid to allow shutdown from various sensors (Eg: Hi temp & low oil pressure)



[0] Message Index

[#] Next page

Go to full version