Well, the concept is unusual, and if it hadn't come from Sir James Dyson himself, I would be more concerned.
But if you have a look at the product home page here, or the related video where Sir James explains the principles here or (my favorite) a wonderful explanation of how it works here you will see a concept that is strange, but obviously effective.
Now I'm not going to expect that the concept will scale to something suitable for frost protection. However, it is a very real and somewhat related example of engineering applying solutions to problems that are out of the square.
This same development needs to continue for frost fans.
In short, the concept of using an inversion layer to provide warmth to a crop is a good one. Frost fans are an effective means of achieving this end. However, they have side effects.
The Defender has taken a step to reduce those side effects by employing a more aerodynamic blade and making it rotate more slowly and then compensating for the reduced flow by making the blade larger with a higher pitch.
The C49 from Frost Boss has taken a step further by using their already quiet 4 bladed technology and implementing an aerodynamic blade in conjunction with cleverly examining the airflow from the perspective of the actual job that the fan is doing (this is a relatively low speed fan compared to aircraft propellers) and designed their blades to suit. This is what puts them one step ahead of the Defender.
The end result for both these manufacturers is quieter fans that do the same (or perhaps better) job than before. This same evolution needs to continue but with an even bolder change in direction to allow for greater reduction in noise. A bladeless Dyson fan will probably not be the answer, but the answer WILL be something different from a conventional fan. Keep your thinking caps on.
3 comments:
Thanks for posting the Dyson item, which has some very slick graphics, I might add. This idea is far from new, and has been used in the food industry for decades. A popular brand of airmover is the Brauer, distributed in NZ by Kerr Cowan. Here's some info on the Brauer for those interested.
http://www.kerrcowan.co.nz/categories/display/33
http://www.brauer.co.uk/php/airmoveroverview.php
These devices are not very energy efficient, in terms of air moved per unit of energy required. They need at least 6 times the energy input to do the same work ... so a 150 hp frost fan would be replaced by a 900 hp airmover. I don't think you would want a valley full of 900 hp donks running all night.
And you may well ask, where does all that extra energy go ? It goes into mixing fast air with slow air, which means turbulence, which means more noise ......
Frost fans will get quieter in the future ... but the real issue is how the District Councils can get the existing, noisy fans quieter ? Serving abatement notices doesn't seem to work, so what next ?
Many thanks for the insightful comment and the links. Very interesting indeed. The information on the relative horsepower of the systems is well made. The technology is unlikely to be practical as a direct replacement for frost fans, but the overall concept that there are clever solutions that can be applied or even new ones to be developed is still valid. I have no doubt that use of an inversion layer for frost protection is viable and at the same time I think it will be able to be done at a fraction of the noise level of current systems. The trick will be the first person to work out how to do it.
I think of the first time I saw reference to a magnetohydrodynamic engine. I was flabbergasted that such a thing was possible (the debate on practicality is obviously still valid there too). One day someone will work is out. The trick will be to make the incentive for development of a quieter system a strong motivator. It seems a pity to be doing it via legal wranglings as is currently happening, with so much enmity on all sides.
Hey, really interesting technology there. As you say, practicality is questionable, but who knows what is around the corner. Which brings me to another thing. Have you seen tonights Marl Express. Very interesting advert for electrical frost protection.
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