Getting heat out of a box
in [Design]
|
Prev: *** Project for New American Unix, Physics, Electronics, Metalworking - TUTORIAL VIDEOS ***
Next: power outage
From: markp on 5 Aug 2010 10:56 Hi All, I'm looking for a company that could help solve some thermal management issues. Basically I've got a design that dissipates about 30W and need to encase it in a sealed box (not hermetically, but to all intents and purposes there can be no airflow through the box). Current thoughts are an aluminium extruded box with large heatsinks on the outside, and a method of thermally bonding or piping any higher powered components directly to to the box inside. I also need an AC-DC supply which I think needs to be a baseplate cooled type and bond that directly to the side of the box that has the heatsink. I'm unsure of size of box needed or even whether this is a viable solution. I know it's a bit vague, but anyone know a company who could help (preferably one with a vested interest in solving it, like an aluminium extrusion box manufacturer)? Thanks! Mark.
From: Joerg on 5 Aug 2010 17:10 markp wrote: > Hi All, > > I'm looking for a company that could help solve some thermal management > issues. Basically I've got a design that dissipates about 30W and need to > encase it in a sealed box (not hermetically, but to all intents and purposes > there can be no airflow through the box). > > Current thoughts are an aluminium extruded box with large heatsinks on the > outside, and a method of thermally bonding or piping any higher powered > components directly to to the box inside. I also need an AC-DC supply which > I think needs to be a baseplate cooled type and bond that directly to the > side of the box that has the heatsink. I'm unsure of size of box needed or > even whether this is a viable solution. > Sounds like the only viable approach, short of oil-filling the whole thing. Try to do your best to reduce dissipation in the electronics. I suggest to avoid electrolytic capacitors or similar components where the MTBF significantly drops with rising temperature. The AC-DC power supply presents a challenge here. Not because you can't get enough efficiency but because it requires at least one electrolytic capacitor. Any chances to at least send in DC, at whatever voltage? > I know it's a bit vague, but anyone know a company who could help > (preferably one with a vested interest in solving it, like an aluminium > extrusion box manufacturer)? > I know a company (client of mine) that can probably do the heat transfer simulations but it's not going to be cheap. Would be strictly as an engineering service, they don't make boxes. I don't think a box makers would do that or even have the SW tools and engineering know-how to do that. If interested send me an email. Clicking on the reply-to address works. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: markp on 5 Aug 2010 18:08 "Joerg" <invalid(a)invalid.invalid> wrote in message news:8c0nn5Fmt7U1(a)mid.individual.net... > markp wrote: >> Hi All, >> >> I'm looking for a company that could help solve some thermal management >> issues. Basically I've got a design that dissipates about 30W and need to >> encase it in a sealed box (not hermetically, but to all intents and >> purposes >> there can be no airflow through the box). >> >> Current thoughts are an aluminium extruded box with large heatsinks on >> the >> outside, and a method of thermally bonding or piping any higher powered >> components directly to to the box inside. I also need an AC-DC supply >> which >> I think needs to be a baseplate cooled type and bond that directly to the >> side of the box that has the heatsink. I'm unsure of size of box needed >> or >> even whether this is a viable solution. >> > > Sounds like the only viable approach, short of oil-filling the whole > thing. Try to do your best to reduce dissipation in the electronics. I > suggest to avoid electrolytic capacitors or similar components where the > MTBF significantly drops with rising temperature. > > The AC-DC power supply presents a challenge here. Not because you can't > get enough efficiency but because it requires at least one electrolytic > capacitor. Any chances to at least send in DC, at whatever voltage? > > >> I know it's a bit vague, but anyone know a company who could help >> (preferably one with a vested interest in solving it, like an aluminium >> extrusion box manufacturer)? >> > > I know a company (client of mine) that can probably do the heat transfer > simulations but it's not going to be cheap. Would be strictly as an > engineering service, they don't make boxes. I don't think a box makers > would do that or even have the SW tools and engineering know-how to do > that. > > If interested send me an email. Clicking on the reply-to address works. > > -- > Regards, Joerg > > http://www.analogconsultants.com/ Thanks Joerg. I'm going to do a bit of hunting first, if I can get into the right ballpark with an aluminium extrusion manufacturer and get some sample boxes I may even protoype something using dummy resistors and do some temperature profiling myself. This might not catch hotspots in the real thing of course, but it'll give me a good idea of how far off a solution it might be overall. Thanks for the offer, I may take you up on it later :) Mark.
From: Joerg on 5 Aug 2010 18:21 markp wrote: > "Joerg" <invalid(a)invalid.invalid> wrote in message > news:8c0nn5Fmt7U1(a)mid.individual.net... >> markp wrote: >>> Hi All, >>> >>> I'm looking for a company that could help solve some thermal management >>> issues. Basically I've got a design that dissipates about 30W and need to >>> encase it in a sealed box (not hermetically, but to all intents and >>> purposes >>> there can be no airflow through the box). >>> >>> Current thoughts are an aluminium extruded box with large heatsinks on >>> the >>> outside, and a method of thermally bonding or piping any higher powered >>> components directly to to the box inside. I also need an AC-DC supply >>> which >>> I think needs to be a baseplate cooled type and bond that directly to the >>> side of the box that has the heatsink. I'm unsure of size of box needed >>> or >>> even whether this is a viable solution. >>> >> Sounds like the only viable approach, short of oil-filling the whole >> thing. Try to do your best to reduce dissipation in the electronics. I >> suggest to avoid electrolytic capacitors or similar components where the >> MTBF significantly drops with rising temperature. >> >> The AC-DC power supply presents a challenge here. Not because you can't >> get enough efficiency but because it requires at least one electrolytic >> capacitor. Any chances to at least send in DC, at whatever voltage? >> >> >>> I know it's a bit vague, but anyone know a company who could help >>> (preferably one with a vested interest in solving it, like an aluminium >>> extrusion box manufacturer)? >>> >> I know a company (client of mine) that can probably do the heat transfer >> simulations but it's not going to be cheap. Would be strictly as an >> engineering service, they don't make boxes. I don't think a box makers >> would do that or even have the SW tools and engineering know-how to do >> that. >> >> If interested send me an email. Clicking on the reply-to address works. >> >> -- >> Regards, Joerg >> >> http://www.analogconsultants.com/ > > Thanks Joerg. I'm going to do a bit of hunting first, if I can get into the > right ballpark with an aluminium extrusion manufacturer and get some sample > boxes I may even protoype something using dummy resistors and do some > temperature profiling myself. This might not catch hotspots in the real > thing of course, but it'll give me a good idea of how far off a solution it > might be overall. Thanks for the offer, I may take you up on it later :) > I use the Dale RH-50 series for that a lot. You can even get resistors in TO-220, should nicely mimic power transistors and large Schottkys: www.irctt.com/file.aspx?product_id=259&file_type=datasheet Another method that easily lets you "dial in" the dissipation without needing a large variety of power resistors is to take a bunch of LM317 and then use them as constant current sources into ground. It takes only one (smaller) resistor to set the desired current and thus dissipation. The LM317 comes in TO-220 and all sorts of other packages, including some that can sink heat into a chunk of copperclad so you can mimic a circuit board that heats up. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: whit3rd on 5 Aug 2010 18:54
On Aug 5, 7:56 am, "markp" <map.nos...(a)f2s.com> wrote: > ... I've got a design that dissipates about 30W and need to > encase it in a sealed box (not hermetically, but to all intents and purposes > there can be no airflow through the box). > > Current thoughts are an aluminium extruded box with large heatsinks If the box has >30 square inches of external free-air surface, a circulating fan inside the box would do it. Or, does it have to be small? |