Voltage optimisation?

[ban-all-sheds]

Go for it - see how popular it is.

 

[winston1]

To the OP. Your equipment is probably designed for 240/415 volts so your voltage is already optimised.
The main company selling this "snake oil" equipment, V-Phase went out of business a few years ago, this should tell you something.

Since harmonisation many EU countries have increased their voltage fron 220 v to 230 v. Would they have done this if it increased their usage and global warming?

The US uses voltage at half UK levels yet they use more power per person than we do.

 

[deadshort]

Yes, and there wiring is used in Barbie houses, your point is ?

DS

 

[ericmark]

I would say two things, the switch mode power supply, and micro generation removed any benefit in using the device.

Be it the electronic HF ballast for fluorescent lamps, or just a simple power supply for TV today voltage variations are auto corrected without the need for the auto transformer.

And with micro generation 230 volt now means 230 volt, the old idea of keeping the tapping as high as one can so volt drop is within limits has gone, as if volts are too high then the micro generation closes down.

At the time it first came out, there was some saving, but not any longer.

 

[ban-all-sheds]

I would say two things, the switch mode power supply, and micro generation removed any benefit in using the device.

And for anything involving heating - kettles, cookers, immersions, washing machines, dishwashers, tumble driers, space heating appliances... there never was any in the first place.

At the time it first came out, there was some saving

Where and how?

 

[ericmark]

In the old days the power supply turned AC to DC charged a capacitor then varied the resistance of a transistor to correct the voltage. If incoming voltage was too high the transistor got very hot as there was a larger volt drop across it, and if too low then it could not maintain voltage in the troughs so you got mains hum, with magnetic fluorescent ballasts again just 10 volts up and the current could jump by 30% and 10 volts down and it could fail to strike.

As to large current using appliances like kettles, cookers, immersions, washing machines, dishwashers, tumble driers, space heating the device normally went into bypass anyway as it could not handle that current. Although it would not save power with a heating device in most cases, it could save power to motors, the tumble drier it would save more than just the reduction in motor consumption. By using less heat and running the dryer for longer to total power used is reduced, many have a switch to select high or low heat. OK I will admit it would likely have never paid for itself, but it could save power in the days when first marketed.

But it's like buying LED lamps at 3 for £10 which deliver 70 lumen per watt, or lamps at £10 each which deliver 100 lumen per watt, the latter save energy, but unlikely to save money.

 

[ban-all-sheds]

By using less heat and running the dryer for longer to total power used is reduced

Power yes, but not energy, which is what you pay for.

Ye cannae change the laws of physics - if you need to evaporate a given amount of water then you need to put in a given amount of energy.

 

[ericmark]

Power yes, but not energy, which is what you pay for.

Ye cannae change the laws of physics - if you need to evaporate a given amount of water then you need to put in a given amount of energy.

Yes latent heat of evaporation is the energy required to remove the water, however unless the dryer is in an environment where the humidity is 100%, then even pumping unheated air will in the end dry the cloths, and also unless the air leaving the dryer is at 100% humidity then there must be some wasted energy. So in real terms if you run a drier with 500W being used to heat the air it will dry cloths quicker than 4 x times the time taken with 2000W being used to heat the air.

White Knight did make a dryer designed to run over night something like a 7 hour drying cycle, however so many tumble driers have gone on fire, people were unwilling to dry cloths over night, the idea was two fold, one use cheap off peak electric, two use an extended dry cycle as no one is waiting for cloths when set to run over night.

There is however a problem measuring energy used with a vented type tumble drier, it takes air from the house heated by the central heating and pumps it outside, so one should factor in the energy used to heat the replacement air by the central heating, also one needs to allow for the fact air in the house likely has more moisture already in the air. We need to look at the dew point of the air, rather than the relative humidity as the latter is effected by temperature.

This is the problem in measuring how much energy an appliance uses, one also needs to work up how much the air is being heated outside of the appliance. In real terms we need air changes, so it may well be using air from the house is a plus point as it forces an air change. However if the house is fitted with a heat recovery unit then you don't need the forced air change. Also of course if there are any open flues in the house, then CO2 or worse can be drawn into the house when air is blown out of the house with either a tumble drier or bathroom extractor.

However I can confirm my tumble drier when switched to half heat takes less than twice the time to dry cloths, in fact more like 1.5 times the time, so although the motor is clearly running longer the net result is less paid for energy is used to dry the cloths. In theory if the replacement are drawn from outside is 100% humidity then yes your laws of physics statement is true, but most of the time replacement air is not at 100% humidity, so your laws of physics statement is flawed. Less paid for Joules are required to dry cloths if the time is increased because we are using more free Joules.

 

[bernardgreen]

Could it be more efficient to use energy to create a vacuum to dry the clothes ?.

Boiling Temperature of water under a vacuum of of 29.9 inch Mercury is 1°F ( i.e. boiling normal freezing point ) hence virtually no heating required to dry the clothes.

The down side is a reliable and efficient vacuum generator tht powerful might be a very expensive and noisy item.

 

[ban-all-sheds]

Ha. After I posted, I was pondering it, and I thought "I reckon Eric could be right. You could blow ambient air through the dryer, and the clothes would dry. It would take longer, but the only energy used would be by the motors."

Should have posted it then.

 

[JohnW2]

Could it be more efficient to use energy to create a vacuum to dry the clothes ?. ... Boiling Temperature of water under a vacuum of of 29.9 inch Mercury is 1°F ( i.e. boiling normal freezing point ) hence virtually no heating required to dry the clothes.

Interesting suggestion.

However, unless some heat was fed into the system (hence energy from some source) would not the latent heat of evaporation mean that the clothes would get very cold - so when one took them out of the dryer, heat/energy (from somewhere) would have to be expended in order to get them back to ambient temperature?

Kind Regards, John

 

[ban-all-sheds]

Mmmm - freeze dried underpants.

 

[ericmark]

I remember working on a tunnel boring machine where our overalls, and that is all we wore, were soaking wet at the end of each shift, in Hong Kong so humidity 100% we washed ourselves down in the overalls then needed them to dry for next shift, 40 foot container with 9 kW heater was not good enough, so I put a curtain down the centre of the container, with the heater blowing air around in a circle, and just before air reached the heater I fitted an air conditioning unit. The water simply ran out of the AC, and this is the point.

Air must first be cooled to remove moisture from the air, then heated so it can absorb moisture from the cloths, this means what we want is to start with cold air so it has as low moisture content as it can, in the main that means air from outside, having the vented tumble drier in the garage assuming it's not sharing it with a wet car, is the best location, as it's getting air as dry as it can.

So we want to be measuring moisture in the incoming air, and out going air, and adjusting temperature and air flow so as much energy as possible is taken for the ambient air. There must be an opium speed and heat to dry cloths, if it takes too long and is too cool then energy wasted tumbling the cloths, but too short and too hot, damage to cloths and waste of energy. However the speed and heat would depend on the humidity and temperature of incoming air.

Also unless the drier auto turns off once cloths are dry, then all the gain is lost.

The whole idea of the environment affecting the efficiency of a device is what makes many of the claims as to efficiency invalid.

An example today outside temperature -2°C at night even lower, so use a tungsten lamp bulb and heat is not wasted, in fact since much of the heat is radiated heat, it means air temperature can be lower and still be comfortable in the room, curtains need to be closed to stop heat going out the window, but lights are used at night anyway. So at this time of year the tungsten bulb in a heated area is an energy saving device. But same bulb in the summer wastes energy, also outside it wastes energy. So one would need to measure the energy used by two houses for a year, one with LED lighting and one with tungsten to work out on average which uses the least amount of energy.

I asked the energy saving trust if there were any figures on this, but they pointed out design of house, and if in Lands-end or John O'Groats would also effect the results. So the experiment has never been done, so as to which saves the most energy LED of Tungsten is pure guess work.

However for the voltage correction auto transformer they actually did set up the experiment, and two similar housing estates were selected one with the device and one without, and the two estates were monitored first before the devices were fitted so any adjustment could be made for slightly different life style. The results did show energy was saved, however this was a long time ago, when switch mode power supplies were not the norm as they are today, so I am sure if repeated today it would be very different, but to be fair when originally marketed they did work, and they gathered more evidence to prove their point than the manufactures of LED bulbs have done.

I am sure there was back in history a point where using lime to get a bright white light on the stage of a theatre made very good sense, however that's not the case today, the units are no longer made, so to be fair we must look at if they worked when first marketed not if they would work today.

 

[ban-all-sheds]

There must be an opium speed

In your dreams

So the experiment has never been done, so as to which saves the most energy LED of Tungsten is pure guess work.

You could try an experiment.

You could try heating your house just with light bulbs, and see how you get on.

 

[bernardgreen]

You could try heating your house just with light bulbs, and see how you get on

vitreous silica glass tube heaters are not much different to incandescent lamp bulbs.