Why such an expensive internal heatsink?

[treez]

Why has this flashing LED beacon got such an expensively made aluminium heatsink?
-You can see that the heatsink has a special shape with fins all over it.
This must have been expensive to manufacture.
However, this heatsink does not emerge outside of the plastic enslosure, and so has nowhere to convect hot air currents away to.

So why bother to spend so much money making a heatsink which obviously cannot work well?

**broken link removed**

 

[tpetar]

Do you have better photo, I mean higher resolution and format?

I dodnt see nothing special in this.

Probably they use power leds which needs to cooldown over heatsink, and heatsink is designed to be functional for cooling and maybe as reflector for led lights. But from this small photo, and with device turned off I cant make clear conclusion.

Usually this products are used in city services, police cars, ambulance cars, road maintenance, ... and are not for ordinary citizen. Because of that price is special as usually. :smile:

 

[treez]

sorry i dont have a better photo, but you can clearly see the elaborate ribbed shaping of the aluminium heatsink, which must have been expensive to manufacture.

As you know, a convection heatsink trapped in a plastic enclosure with no ventilation holes is surely not of great quality...why not just put in a cheap, basic slab of aluminium?

 

[tpetar]

Yes I see ribs on top of heatsink, I supose its heatsink, but without clear close clear look there is no clear answer, also can be reflector, and ribs are just consmetic. We dont know that its aluminium material, maybe its plastic.

Various aluminium heatsink shapes are usually maded with aluminium extruder, and process is not expensive, and its simple, but require special equipment and aluminium prepared rod as material. While some other shapes for heatsinks are maded completely diferently.

 

[ZekeR]

So why bother to spend so much money making a heatsink which obviously cannot work well?

My guess is that the engineers suggested metal heatsinking outside the enclosure for proper operation, but marketing demanded that it look like a "normal" beacon—a design that mimics incandescents—and ridiculed the idea of being able to sell weird-looking beacons. Sourcing chimed in saying it'd be difficult to get a customized plastic enclosure with a hole in it, not to mention, for watertightness they'd need new fittings, and so management, with two voices arguing against one, decided to stick with the standard enclosure and "compromise" by placing a very large heatsink inside. Faced with the cost of a new enclosure, I bet management figured a large heatsink would be cheaper.

Just wait until they get field failures though, then the cost equation changes dramatically =)

 

[tpetar]

Also there is some regulations and certification rules for this types of signalizations.

In other hand, in device case you have air which have thermal capacity and capability to transfer heat to outside space.

 

[treez]

in device case you have air which have thermal capacity and capability to transfer heat to outside space

....there is very limited ability to transfer heat to outside space, as there are no ventilation holes, and the entire heatsink is surrounded in non thermally conductive plastic.

 

[tpetar]

One example, laptop psu have high working temp, inside all parts are compactly placed with heatsinks, case is hermeticaly closed. When you touch laptop adapter from outside you notice that is warm, that means heat pass through plastic case. Also heat can pass through walls, metals,.....

Specially take in consideration allowed working temp of parts, maybe its on some higher temperature.

Do not underestimate heat transfer, even today people struggle to keep heat on one place without losses, and guess who wins for now, and now is 2013. year we have PCs on desks and we looking to find Bozon and Tesla Neutrino? I want to say, even though we have world most top modern technology, we dont know how to keep and save heat on one place, heat always find way to go. :smile:

Additionally each material besides coefficient of heat transfer have and heat capacity. To saturate some volumen of material in this case air and surrounding mass of various materials such as plastics, metals and other parts materials you need adequate amount of power expressed in heat shape.
Take example of house heating in winter, what amount of energy you must give to heat house rooms, or to increase for some celsius degree, if house is big or small, and what if oven is with small capacity. In this example we can say house is heatsink for oven.



This products should be tested on longer running time at direct sun light (UV), on very low-high temperature environment, vibrations, water, high humidity, ... I dont think that they forget to do that. :wink:

 

[ArNvC]

Well it looks like more of a Reflector than a Heatsink. May be it works bothways:wink:
"The latest LED and reflector technology produces this Reg65 ECE LED Beacon. The powerfulLEDs are arranged to produce a brilliant 360 degree flash pattern."-this is what it says.

 

[FvM]

It looks like the heatsink is designed for optimal convection cooling, involving large surface area and axial symmetry for an uniform convection stream along the beacon cover. Some details may be intentional stylish.

 

[treez]

convection stream along the beacon cover

....is this worth doing?..i mean , the beacon cover is perspex....very poor in thermal conduction

[

 

[FvM]

....is this worth doing?..i mean , the beacon cover is perspex....very poor in thermal conduction

Right point, wrong conclusion.

If you analyze the thermal problem quantitatively, you'll find out that thermal resistance of the beacon cover, integrated over the complete surface is comparatively low, < 1K/W. The major contribution to overall thermal resistance is created by the air to cover interface, both in- and outside. It depends on the surface area and convective air speed, not the cover material.