An electrical engineer mulls over various things around him...
Saturday, October 25, 2008
Ceiling fans can do better
A typical 75 W-input ceiling fan only generates about 15 W of mechanical power, making it only 20% efficient. The balance of 60 W is dissipated as heat. Winner of Farnell’s Live EDGE design contest, John Nobel identified this problem and tried to solve it. He designed a product called MyFan, a ceiling fan that combines an electronically commutated motor and controller, and aerodynamically efficient blade design that reduces fan input power by up to 66 percent of that of a traditional ceiling fan. In other words, the new design is three times as efficient as the conventional design. It boasts auxiliary output channels that drive up to 20 watts of integrated LED lighting with up/down lighting modules. The motor construction is totally enclosed and is available with an IP5x environmental rating. Here's an article that highlights the achievement.
Ceiling fan design promises reduced power consumption
Recently chosen as the grand prize winner of distributor Premier Farnell’s Live EDGE design contest, a ceiling fan dubbed MyFan by designer John Noble combines an electronically commutated motor and controller with an aerodynamically efficient blade design to promise input-power reductions of up to 66% over traditional ceiling fans. Noble, a Malaysia-based design engineer, came up with the idea in early 2007, before he even heard about the contest, which he ultimately found out about the through Farnell’s Web site while placing an order in May 2007.
Premier Farnell CEO Harriet Green presents a $50,000 check to John Noble, winner of Farnell’s Live EDGE design contest.
On hiatus from his job, Noble had been pondering how to move his career toward efforts that were more socially or environmentally focused. The answer, as it turned out, was closer than he knew.
“In our house we have nine ceiling fans, and at any time of the day or night there are at least three of those running,” he said. “Quite literally the first thing see every morning when I wake up is a ceiling fan. One morning I woke up and decided I should have a closer look.”
While ceiling fans have been on the market for over 100 years, their motor design has really changed very little. And current fans are terribly inefficient. According to the award-winning designer, a typical 75-W-input ceiling fan only generates about 15 W of mechanical power, making it only 20% efficient. The balance of 60 W is dissipated as heat.
A fan constructed with modern components—specifically electronically commutated motors—has an efficiency of about 60% reducing input power to about 25 W to offer drastic power-consumption reduction.
Noble’s research shows that in the United States alone, there are about 158 million ceiling fans installed consuming 150 petajoules (PJ) annually. Fans designed with the high-efficiency ac motors can reduce that by about 100 PJ and eliminate 14 million metric tons of CO2 emissions.
While the technology could be applicable for other types of fans, this particular design is focused on the specific characteristics of ceiling fans. “It is a relatively low-absolute-power module that generates quite high torque at low speeds,” Noble said. “Generally, industrial fans tend to operate at higher speeds and draw more power.”
Suprisingly, Noble used Microsoft Excel for the bulk of the design effort. “I do most of my electronic circuit analysis actually using Excel, which now has a wide range of features that allow very good simple numerical analyses to be done,” he said. “I did 3-D and mechanical design using Alibre Design Software, I used a company called Field P for doing magnetic field simulation, and circuit-schematic capture and PCB layouts are done on [Altium’s] Protel.”
Using advanced motor control algorithms such as field-oriented control or vector control could further improve the efficiency, though I'm not sure whether Nobel's design already incorporates such an algorithm. The Indian fan market is estimated at 2.5 million fans per month and it is growing at about 10% per annum . Also, there are currently several millions of fans that have percolated down to the millions of households in India. Incorporating energy efficiency into them could lead to huge savings in power. The Bureau of Energy Efficiency (BEE) in India is to shortly issue a notification suggesting raising of energy efficiency parameters for fans manufactured in the country. The implementation of the new standards would help save between 15 and 20 per cent electricity in new fans while conserving over 30,000 MW of electricity over the next five years in the country. We can do even better if we were to take a cue from Noble's work. Is there an enterprising entrepreneur somewhere who's listening?