Pumpless Coolant system

**NAP2626** · Jul2-09, 11:47 PM

Hey All,

Is there a cooling system similar to your car's radiator coolant system that does require a fluid pump?

I am looking for a simple system that will behave similar to such a system, but the difference in heat ( or resulting pressure) from hot source to cold area (which would be chilled used a radiator like structure and fan) would drive the fluid flow. The temperature difference we are looking at his about 100C to room temp.

Thanks for any help or advice

**ank_gl** · Jul3-09, 11:13 AM

Originally Posted by NAP2626

Hey All,

Is there a cooling system similar to your car's radiator coolant system that does require a fluid pump?

I am looking for a simple system that will behave similar to such a system, but the difference in heat ( or resulting pressure) from hot source to cold area (which would be chilled used a radiator like structure and fan) would drive the fluid flow. The temperature difference we are looking at his about 100C to room temp.

Thanks for any help or advice

Do you mean

"Is there a cooling system similar to your car's radiator coolant system that DOESN'T require a fluid pump?"

If yes, sure there are. Have you heard of thermo compression?? Try reading something about a vapor absorption cycle.

**chayced** · Jul3-09, 11:46 AM

What you are looking for is natural circulation.
http://en.wikipedia.org/wiki/Natural_circulation
It's caused by temperature differential and is used in nuclear power plants among other things. The key to natural circulation is the heat source is low, the heat sink is high, and the pipes connecting the two are large and smooth with few restrictions.

**Mech_Engineer** · Jul3-09, 11:48 AM

heat pipes are efficient fluid cooling systems that make use of vapor phase change of the coolant rather than a pump. They have gained quite a bit of popularity in the electronics cooling industry.

Originally Posted by Wikipedia Heat Pipe Article

A typical heat pipe consists of a sealed pipe or tube made of a material with high thermal conductivity such as copper or aluminium. ... the pipe is filled with a fraction of a percent by volume of working fluid, (or coolant), chosen to match the operating temperature. ... Due to the partial vacuum that is near or below the vapor pressure of the fluid, some of the fluid will be in the liquid phase and some will be in the gas phase. Having a vacuum eliminates the need for the working gas to diffuse through another gas and so the bulk transfer of the vapour to the cold end of the heat pipe is at the speed of the moving molecules. The only practical limit to the rate of heat transfer is the speed with which the gas can be condensed to a liquid at the cold end.

http://en.wikipedia.org/wiki/Heat_pipe

**Astronuc** · Jul3-09, 12:32 PM

Originally Posted by chayced

What you are looking for is natural circulation.
http://en.wikipedia.org/wiki/Natural_circulation
It's caused by temperature differential and is used in nuclear power plants among other things. The key to natural circulation is the heat source is low, the heat sink is high, and the pipes connecting the two are large and smooth with few restrictions.

Natural circulation works on the difference in density between hot and cold liquids or liquid and vapor, i.e. it requires a difference in head (differential pressure). Natural circulation is proposed in the ESBWR rather than pumps, but the system still uses feedwater pumps.

Heat pipes are another example of pumpless heat transfer via a working fluid.

A lot will depend on the amount of heat and rate of heat transfer, and the size of the system.

Pumps are usually necessary for forced convection.

**NAP2626** · Jul3-09, 02:49 PM

Hey guys thanks!!! this is exactly what I am looking for