Heat sink design for LED lighting fixtures

A case on LpR was designed to design a heat sink for LED lights. The author puts his own unique insights into heat sink design from the perspective of bionics.

The current LED lighting gives people the feeling that they are linked with new technologies, high technology, environmental protection and high-end. Most of the designs on the market are based on practical considerations, with no sense of beauty and coordination. Like this:

It looks simple and rude, and the local flavor comes to the fore, like the work of the designer who has just returned from the university of urban and rural areas.
Not to mention this, it seems to be a serious physical discomfort.

Of course, some people realized this, so some LED lights in order to take into account the shape, do not let the heat sink directly exposed to the audience's eyelids, designed the outer cover, inside is the heat sink, both. But to be honest, the heat dissipation of this design is greatly reduced.

So the question becomes: How to design a beautiful, high-performance heat sink with LED lights that coexist harmoniously with the surrounding environment?

Someone tried it.

There is no love for no reason in the world, no hate for no reason, no design for no reason, especially for foreigners, assuming that this heat sink is designed by me, what do foreigners ask me to do? I replied: I dreamed last night. I think this foreigner will jump off the building soon.

Less nonsense, this heat sink is designed according to the principle of natural bionics. In the original text, the author mentioned this fact: nature is a magical designer, after a long evolution of millions of years, human blood vessels, leaves The veins and roots are similar in shape, and they have a common purpose. In order to transmit the largest resources (nutrition) with the least amount of material, the surface area of blood vessels and roots has been screened by nature. It can transmit the largest resources with the least amount of materials.

Speaking of this, it is estimated that you are smart and you understand what is going on. Yes, that's what you think! The bionic object of this heat sink is the shape of the branches of the roots and blood vessels.

In order to compare based on the same standard, the author designed a restriction:

• The LED generates 7W of heat.
• Heat sink size limit: 50mm diameter and 50mm height.
• The core of the heat sink core has a diameter of 5x5mm.

The results of the CFD calculation are as follows:

The No. 3 design has the lowest thermal resistance, that is, the 7-piece heat sink works best. The worst 5th design is 12% worse than the 3rd.
Why is there such a difference?
The answer is that because of the natural convection cooling of the LED luminaire, the heat transfer efficiency of radiation and convection needs to be balanced. If the area is emphasized separately, the result is that the fin spacing is designed to be small, resulting in poor convection effect. Conversely, the fin spacing is too large, resulting in a reduction in the total area, and does not achieve the best results, so the function of CFD is here, we can use it to select the optimal solution.
Here you can refer to this blog to explore the relationship between radiation and convection.
Take the No. 3 design and design a heat sink without a fork, and the cross-sectional area is almost the same as the No. 3 design (error <1%). Compare the effects of both of them:

From the figure, the custom between the teeth on the right is more uniform, and the thermal resistance is about 8.3% lower than the left.
Finally, the author designed such a concept product to achieve a balance between performance and appearance.

I hope that the future LED lighting design will become more and more user-friendly, like the Apple mobile phone, hiding the performance behind the design. I urge everyone to use LED lamps, and hope that this industry will usher in spring as soon as possible.