Naked Science Forum
Non Life Sciences => Technology => Topic started by: neilep on 19/10/2007 14:47:36
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Dearest Lovers Of Sitting-Upon-Washing-Machine-Luff & Joy !
See this washing machine ?
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Nice isn't it ?...notice how still and tranquil it but ready to perform multi-vibtational spinning luff ?
When they spin..they spin very fast and really move about a lot don't they ?
Are they wasting a lot of energy this way ?....If it was possible to make the out case rigid and taught would this help the efficiency of washing machine joy ?
ewe see...I don't know !!...how about ewe ?
whajafink ?
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Making the case rigid would be unlikely to give much benefit, either in vibration reduction or energy saving - since a rigid case would merely transmit the vibration through.
Making the case absorbent to vibration would reduce vibration, but would simply convert it to heat rather than reduce energy usage.
The better way to deal with it is simply to balance things better to reduce the noise at source. Ofcourse, one problem is that to some extent you actually want to shake up the washing a bit to make sure it is thoroughly washed.
I suppose you could always try and mount the washing machines on a suspension unit that included linear alternators as shock absorbers to dissipate the energy of the vibration. I doubt the energy gained this way would be significant in terms of the overall energy used by the machine, but I suspect it may be enough to power a small light bulb.
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Thanks George..very muchly.
I get straight upon my pet hanging washing machine project immediately !! *grins*....your answer is of course appreciated....I suppose I thought that containing the outer cabinet with a rigid lock would help to hone some of the lost energy into a faster more efficient spin.....Perhaps...it's supposed to move and rattle like that.
THANK YOU GEORGE
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The motor is not very powerful - 1kW max and only runs at full speed for a few minutes. No significant energy wasted.
The biggest economy measure has been taken already - low temperature washing with small quantities of water. We now suffer from more parasites than in the past, as a consequence!
btw, I bought a Miele, rather expensive, washing machine recently. It weighs 20stone (the delivery man told me) and it is virtually silent and vibration -free. The programs that machines run these days manage to reduce vibration by re-distributing the wet clothes using appropriate speeds at the run-up to max spin.
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The reason that they let the drum wobble is that if they didn't it would exert huge forces as it rotated and would probably damage the bearings. I think the drum is often suspended on bungee cords to allow it to move a bit and not break things.
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Yes - you have to let the drum / balancing mass system wobble around its combined centre of mass. The bigger the balancing mass, the less the wobble and the less out of balance the clothes are, the best all round. I don't know if the smarter machines actually sense imbalance, slow down and start again when the clothes have re-distributed themselves. I don't think mine does but it is uncannily quiet.
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Couldn't one harness the energy that the spinning drum would make by perhaps storing energy from the drums turning on a cell or battery etc so that in turn could power a different appliance or something. You know how solar panels work could the electricity drying our clothes be kind of harnessed back into a power cell through the action of the turning drum like a bicycle could power a light.. etc, only store it in a battery, I have a bout four days a week at least 8 hours a day when my washing machine is running and the dryer is drying! Seems like we could use all that turning to serve an outside purpose besides drying clothing!
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Sorry that was a tad off topic..!
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When the machine has finished spinning, it will have some kinetic energy - you could use a generator to reclaim most of that, as it is slowing down. There would be little point in using the generator during spinning - you'd just need to supply power from the mains.
As for the energy in the wobbling, the 'mechanical' energy of the wobbling is really not a lot. Most of the motor power (say 700W) is used to get it going. Once it is spinning, the motor power would be a small fraction of that - just enough to overcome friction. The actual energy involved in the wobbling would not be a lot . It seems more because it builds up in the resonance of the vibration.
On the subject of 'effectiveness' of energy; mechanical energy (work) transfers are extremely good value, compared with the equivalent transfers to heat. All that thrashing around with the motor represents only a fraction of the energy used in warming up the water.
Heaters are, typically, up to 3kW, in the home, and run for a long time. Motors, in the home, are seldom more than 700W (peak output) and usually don't run for more than a few minutes. The only motor which consumes serious amounts of energy is the refrigeration unit and that is used to move HEAT about.
Another example: The energy needed to carry an elevator full of people (1000kg load, say) to the top of a 100m high building would be only about 1000kJ. (Ignoring the efficiency factor). Sounds like a serious bit of work to do.
That same amount of energy would only run a 1kW heater for 16minutes. It would just about be enough to warm up the elevator on a cold day!
If you want to get economical, deal with heat waste first. Karen - you'll just have to start hanging your washing outside. Tumble dryers cost you a fortune!