22 March 2014

UGetLight’s liquid-cooled LED bulb: Does it stand a chance against Switch?

 Even if you don’t pay much attention to LED lighting. It’s the beautiful, liquid-filled lamp that is unlike any source of light you’ve seen. These lamps are expensive starting at $30 for a 40W-equivalent but they are available today and they work well. Thanks to their unique design the properties required to liquid cool a bulb, and Switch’s patent portfolio, it has seemed unlikely that the company would ever have any competition in the liquid-cooled bulb market. Even so, we’ve learned that another company is trying their hand at such a product and that it will be revealed at the end of this month.

The company in question is called UGetLight, and at the Build+Light 2014 conference in Frankfurt it will unveil 60W-, 75W-, and 100W-equivalent liquid-cooled LED bulbs. UGetLight is based in China, and despite being relatively unknown (at least from the best I can tell) has taken on the difficult task of producing this bulb.

Switch’s use of the LQD liquid cooling system solves problems that are inherent to the design of LED lights. Foremost, the liquid silicone used in the bulb transmits heat quite well. This means that the heat can get away from the LEDs, which have to be properly cooled in order to last as long as they should. Better cooling means more power can be pushed through the LEDs, and that more of them can be used. This is what allows Switch to have not just 40W- and 60w-equivalent bulbs, but to offer a 100W model ahead of a number of other manufacturers.

At Build+Light 2014 UGetLight will introduce two liquid-cooled designs: the S14 Mini series and the A19 Aqua series. The latter is the more interesting of the two as it uses a standard bulb size and shape (known as A19) and will be available in a full range of flavors, from 3000K and 8W all the way up to 6500K and 12W.

S14 bulb

The bulbs in the A19 series are frosted so we can’t tell exactly what’s happening inside, but in some shots there does appear to be an air pocket, a design which is duplicated in the S14 series. This would seriously limit cooling if any of the LEDs were to be exposed to the air inside, but presumably the LEDs are covered regardless of the orientation of the bulb. This could be a low-tech solution to one of the main problems with liquid cooling: expansion. It’s not clear what liquid UGetLight is using for the cooling, but it’s likely that it expands as it warms. If you don’t want the bulb to turn into a bomb, then you’ve got to account for that expansion.

Switch patented a bladder system that compresses to compensate for the expansion of the thermally conductive material (in this case liquid silicone). It’s a clever, reliable fix for the problem, and one for which Switch owns the IP. Interestingly, the patent specifically mentions why leaving a the air bubbles is not a good approach:

However, it is undesirable to have a pocket of air or bubble in the liquid-filled bulb. First, a pocket of air reduces the cooling efficiency of the bulb by creating an air barrier between the liquid and at least a portion of the outer shell housing. Second, the bubble may distort the light created by the LED, resulting in a non-uniform light distribution. The bubble may create a bright reflection or darkened area detracting from the visual appeal of the bulb. Third, an air bubble draws attention to the fact that the bulb is filled with a liquid, which may not be appealing to customers.

Sounds about right. And that’s just one one of many patents that Switch has on its liquid-cooled design. Of course, that doesn’t mean that UGetLight couldn’t engineer its way around some of the issues, but the company clearly hasn’t worked out everything. For example, we can see that the S14 uses a “corn cob” design, with LEDs placed around a vertical cylinder. It’s an old school design that has been largely bypassed at this point, but aside from that it does nothing to control the flow of the liquid inside. If you’re going to use liquid you’ll want to control its movement to ensure the best possible convective cooling in all orientations. Switch uses a system of fins, on which the LEDs are mounted, to do this.

We won’t know how good the UGetLight will be until we test it out, so for now it will remain an interesting concept with some potential problems. Given the pricing of Switch’s bulbs it is possible that someone could undercut them and bring liquid-cooled LED bulbs to the market, but that would be a serious challenge. In the very least we can guess that UGetLight has been able to learn from Switch, as seen in the company’s choice of a polycarbonate shell as opposed to glass, which follows the choice of Switch’s lower cost Infinia.

For now these bulbs look good on paper with a CRI above 80, omnidirectional light, 50,000-hour lifetime, 70-80 lumens-per-watt operation, and a color temperature range from 3000K up to 6500K. The specs reveal other issues the bulb isn’t dimmable and a weight of just 150g compared to the Switch’s 280g which could affect cooling efficiency but we’ll have to wait until the end of the month to learn more.


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