Can anyone tell me about Liquid Cooling and its use in Cooling down the Switching MOSFET's.

Is the approach necessary or are there any alternates for the same?

 

Typically a switching MOSFET doesn't dissipate enough power that you would have to resort to water liquid cooling, a small, air-cooled heatsink should be sufficient.
What is the application?

 

Can anyone tell me about Liquid Cooling and its use in Cooling down the Switching MOSFET's.

Is the approach necessary or are there any alternates for the same?

Awhile back I tried liquid cooling using a Peltier junction to cool the water. Just mounting the power transistors to the heat sunk of the Peltier worked better. If the thing you are cooling has an irregular surface liquid cooling might make more sense. The cooling power is limited and it certainly does not save any power. If you have open space CO2 cooling might be better.
I used distilled water. Other liquids might be better. Liquid silicone, antifreeze or an oil, maybe.

 

Can anyone tell me about Liquid Cooling and its use in Cooling down the Switching MOSFET's.

Is the approach necessary or are there any alternates for the same?

Liquid cooling allows the heat to move through a given cross-sectional area faster because it can be physically pumped or otherwise flow (siphon or evaporation/condensation). The heat can be extracted/radiated from the hot liquid many meters away from the heat source.

A standard aluminum heat sink relies only on conduction of heat from a hot spot to the edge of the heat sink (radiator fins). Flow rate of heat is limited to the material, heat sink design and temperature gradient and radiation is typically fairly close to the heat source.

Fans can be used with both types to extract heat from the radiant side of the unit.

 

Air actually doesn't conduct heat very well. That's why air-cooled applications typically require a heat sink; to get more surface area in contact with more air.

Liquids conduct heat much better than air. For the same circuit in air-cooled and liquid-cooled versions, the liquid cooled version would/could be much smaller, possibly without any heat sinks at all. Often the PCB itself is a sufficient heat sink if the PCB is immersed in oil or other nonconductive/noncorrosive coolant. Also with the PCB immersed in coolant, the legs of the transistors are cooled as well, not just the package.

 

Highly refined mineral oil (kerosene/liquid paraffin/jet fuel)
has been successfully used as a heat sink for an overclocked gaming computer system.
Just one example. Google it up to see the story.

 

I would use liquid Sodium.

 

Would that work better than molten sulfur?

 

There are oodles of CPU liquid cooling products for computers off-the-shelf that might be adaptable to your use case. For example:

https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias=aps&field-keywords=CPU+liquid+cooling

They are fully enclosed, ready to go. Both my home and work PC are liquid cooled, and to be honest, air cooled is more reliable. i.e. a big heatsink and fan. On my home PC, the manufacturer used sub-par antifreeze/coolant and it started turning to gel, plugging up the internal cooling fins on the CPU attachment and causing overheating. I had to take the it apart, clean out the goo and refill with better coolant. A messy PITA. With air-cooling only, you just blow off the dust once in a while. So my advice is, use liquid cooling if you need to remove a whole bunch of heat from a small area, but use air cooling if you can get away with it.

 

I would use liquid Sodium

.... which would short out all the components?

 

I would use liquid Sodium.

.... which would short out all the components?

No, it is placed inside an aluminum heat sink and temperature gradient allows it to flow in a loop (heated alkali metal rises to the radiator part, cools, then sinks.

Unfortunatly sodium metal only melts at about 100C so it is impossible to get the siphon working without an external heater.

Fortunately, there is a sodium potassium alloy that melts well below room temp and can be used for this. The other good thing is that the liquid, when sealed in a steel enclosure must be heated to 800-degrees C before reaching 1 atmosphere of pressure.