Group LED buy

[Neopimp]

how does paint increase thermal dissipation?

If I was to take a stab at it with no research .. I woudl think that the paint woudl be more of an insulator than anything.


You can think of a heatsink as a container for heat. This container has a hole in the bottom and a tap dumping into it.

The physical volume is like the mass of the heatsink you are using,  So the more your heatsink weighs the more heat it will be able to absorb.  The drain hole is comparable to the surface area of you material.  Thats what the fins on the heatsinks are for... more surface area in direct contact with air to conduct more heat away since .  So insufficient hole means that the container will fill, heat, up until it overflows or gets too hot.  Tap is obviously the amount of heat being generated by the leds.

Fans keep the temperature differential highest between the heatsink and the air nbext to it.  The larger the temp differenctial the more heat is transferred per cm^2.

I woudl definitely be interested in the temperature of the leds as well

My fixture feels warm with no fans running and cool with just one fan running.

 

[phatpaco]

Blob, Do you think they might give a discount even though we haven't hit the magic numbers....but are getting X amount of kits in total??? If not than I may order now....I am going out of my head waiting after hearing KK and others comments on these bad boys!!!! I spoke to some people I work with that are electronic's professionals and not electronically challenged like me and they suggested using heatsinks for keeping the LED's alive for the long term of your unit....Fans as well as the heat that come off em is..ehhh...hot!!!! They also mentioned something about a cement or paste or paint that also helps the heat transfer to the heat sink or something like that....They lost me after hello...Can't wait phatpaco death by LED's DIY!!!! LOL

 

[phi delt reefer]

long story short Neo - it does...it just does.


Blob and I didnt believe it when Darryl told us so we literary spent hours on night looking into it and darryl was right. (Dont tell him I said that

its a trick some race guys use on engine blocks - powder coating them black. Even after i read the scientific explaination i still didnt understand it fully - it has something to do with some wierd thermal laws on the molecular level.

 

[Neopimp]

thats powder coating... differenent than run of the mill spray paint... unless the paint is based on a material with a high heat tranfer coefficient then I am still gogin to say that it will hinder

But you have piqued my attention and I am gogin to read up on it

 

[Krazykarl]

what if i drilled a 1/4' hole in between each LED allowing air to pass by the aluminum in between perhaps cooling them a bit more?

 

[pulpfiction1]

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

 

[Blob-79]

We are at the point of getting the group buy discount. The discount will be greater if we get them all shipped to the same place. Even greater yet if this deal with the dosers happens. (we may include some dosers on the group order)

I hear you neo with the paint thing. I dont totally agree with the idea a painted surface can disipate heat. If I remember correctly most citatations were refurring to powdercoat and anodizing. I agree that black enhances heat transfer. just not so sure a regular coat of paint does the same. I know what i read, and it did seem to support the theory..i just have a hard time wrapping my head around it. I think of it the same way as you neo...a coat of paint should really insulate rather then increase heat transfer....who knows lol...all i know is im not going to research it anymore lol...if anything I will probally anodize my sinks

 

[Blob-79]

ok so i lied lol

heres a paragraph from that wilkapedia article

The heat transfer from the heatsink is mediated by two effects: convection via the coolant, and thermal radiation.

Heat transfer by radiation is a function of both the heat sink temperature, and the temperature of the surroundings that the heat sink is optically coupled with. When both of these temperatures are on the order of 0 °C to 100 °C, the contribution of radiation compared to convection is generally small, and this factor is often neglected. In this case, finned heat sinks operating in either natural-convection or forced-flow will not be effected significantly by surface emissivity.

In situations where convection is low, such as a flat non-finned panel with low airflow, radiative cooling can be a significant factor. Here the surface properties may be an important design factor. Matte-black surfaces will radiate much more efficiently than shiny bare metal.[11] A shiny metal surface has low emissivity, so it absorbs and radiates only a small amount of radiant heat, while matte-black has high emissivity so it absorbs and radiates radiant heat highly. The emissivity in the visible spectrum is closely related to color. For most materials, the emissivity in the visible spectrum is similar to the emissivity in the infrared spectrum; however there are exceptions, notably certain metal oxides that are used as \"selective surfaces\".

In a vacuum or in outer space, there is no convective heat transfer, thus in these environments, radiation is the only factor governing heat flow between the heat sink and the environment. For a satellite in space, a 100 °C (473 Kelvin) surface facing the sun will absorb a lot of radiant heat, since the sun's surface temperature is nearly 6000 Kelvin, whereas the same surface facing deep-space will radiate a lot of heat, since deep-space has an effective temperature of only a few Kelvin.

 

[biggy_boie]

A friend of mine tipped me off on your site and this order and now in interested. I thinking of the 72 kit on my 65. What kind of shipping am i looking at if i join you in this. Im north of Barrie, where will they be shipped to.

 

[Darryl_V]

Blob and I didnt believe it when Darryl told us so we literary spent hours on night looking into it and darryl was right. (Dont tell him I said that

My ears are buzzing.   

Just think of those shinny emergency blankets that are like tin foil......they keep the heat in.

No fans here with my cheap U-Channel.....hits about 110degrees.  Not cool but I can easily hold it and no problem for the LEDs.

 

[Krazykarl]

Any thoughts on adding a couple fans at one end of my canopy to blow cool air across the halides and as Darryl pointed out, galvanized steel lol....

 

[BigAl]

If this is still going to happen I would be interested in a 36 kit and maybe a 14 kit.  If its ok I could post the info in my local clubs forum maybe get a couple more takers.

lmk

 

[TORX]

Still going on. Due date is November 13th I think.

 

[Blob-79]

yup its still on. If you want to post the info on another forum feel free.

 

[phatpaco]

Come on already 13th!!!!!!!! This is killing me!!!!

 

[TORX]

I am stoked to phatpaco, it is coming close though.

 

[phatpaco]

Eight days......

 

[TORX]

I heard that these drivers can run a little on the warm side, so I picked up some stuff from the IT guy at work. 6CPU coolers, 5 small cooling fins, 1 medium cooling fin, 1 large coolig and a handful of fans. Think I will use 1 CPU cooler per driver.

 

[phatpaco]

One week!

 

[TORX]

Blob, can you update my order to a 72 LEDs DIY Dimmable Kit, LEDs Color Option: 36 white 32 blue 2 red 2 UV. Shipping is only approx 35$ so I might just get it straight to my place, unless you can work out something better of coarse. 


I would hop into chat, but I am at work right now. Might be on later.