Heatsinks

[lucca brassi]

Roko .... just don't write something you don't understand at all .... get some math and calculate heat transfer ( oil is heat insulator not conductor ) and in transformers is used just and only because of high voltage resistance .

 

[Roko]

Lucca, I suggest you reread my post. I believe I did mention that mineral oil is not that much better than air in terms of thermal conductance, and may be insufficient as a cooling medium for LEDs.

There's no magic line between thermal conductors and insulators, as they perform a reciprocal function.

I will admit I'm not a power engineer, so perhaps I was wrong in my mention of transformers, but even if the primary purpose in transformers is electrical insulation, it's not hard to find many references that do mention cooling as one of the ancillary functions of the oil.

Granted, its a fluid so there's more at play than pure thermal conductivity, but that's getting way beyond the scope of cooling a dive light

Sent from my Zeagle N2ition

 

[BRT]

If oil is a heat insulator how does the heat get out of the oil filled transformer? And why do the big ones have radiators out the back that the oil circulates through. Not to mention the oil cooler on a whale tail Porche.

 

[lucca brassi]

If oil is a heat insulator how does the heat get out of the oil filled transformer? And why do the big ones have radiators out the back that the oil circulates through. Not to mention the oil cooler on a whale tail Porche.

Part of my company work also with big power transformers (400.000 V)( in V because this is transmission line ) mostly produced for north countries which work with wind generators so I have possibility to visit some tests (lightning strike test ) and see building one.

If oil is a heat insulator how does the heat get out of the oil filled transformer?

with big cooling system and pumps (0:55s) Power Transformer Drying (Siemens) - YouTube

 

[Roko]

Here's a good read on transformer cooling:

http://electrical-engineering-portal.com/transformer-cooling-classes

The comparison I drew in my earlier post wasn't the best because I was only considering conductive heat transfer, not the convection process that occurs in naturally cooled transformers that use oil as the cooling medium.

Anyways, that article is an interesting read for those interested.

Sent from my Zeagle N2ition

 

[lucca brassi]

Total OOT , but ok just to clear some uncertainties .

there are in general four things to think about ( all 4 should be considered )

- electric conductivity of liquids (should be very low )

- boiling point (should be high )

- dielectric number (should be low key -Dielectric Breakdown Voltage Testing of Insulating Liquids ) followup to first point

- thermal conductivity (should be high ) Thermal Conductivity Common Liquids

if you cross all these requirements , than come out that transformer oil . It has to be very clean , abolutly without air bubles ( vacuum venting 2-3 months ) and is assemblied in room which is very clear and with moisture low as it possible . Mentioned 400.000V transformer contains 70 m3 of oil . Just opening it if go some wrong costs
more than 1milion €

---------- Post added December 9th, 2013 at 02:42 AM ----------

some good heatsinks for led

adjustable for led in maglite ( depends from used optics ) sink640.jpg Photo by udownload | Photobucket

adjustable for single led ( for aspheric lens ) made from Cu ( heavy , but single led have also 37W out ) http://www.scubaboard.com/gallery/data/5565/adjustable_Cu_Heatsink-LED_holder.PNG

 

[ScubaToneDog]

Food grade mineral oil is also used in the motor units in surface aerators (those pretty fountains you see in ponds). The electric motors (Im talking 1/2hp 120v all the way up to to the 25Hp 3 Phase 480V 60Hz models) are housed in a stainless steel can, sealed and filled with Mineral oil. The oil acts as a coolant and helps keep the seals for the shaft lubricated to keep water out. An air gap is left in the can to accommodate expansion from heat. And boy do they get hot.

Way overkill for your light, but if anyone reading this attempts to use oil, leave an air gap. Pressure will build and you will wind up with oil leaking everywhere.

An alternative is to go to a craft store and pick up some 26 gauge aluminum jewelry wire. Make a wrap around your module big enough to slide in the head. Or get the 8 gauge, hammer a section of it flat and use it as heat sink shims after you place the module in. Quick and easy.