tumble dryer dehumidifiers

On 4 Jul 2004 08:55:30 -0700, snipped-for-privacy@hotmail.com (paulparkie) strung together this:

Throe that useless contraption out of the window and go and buy a proper condenser dryer. If you want it to work that's about your only option.

I've never used one but:

- They seem to come with ice packs that you put in the freezer overnight before use.

- They're not supposed to be much good.

At best - the amount of heat released by water condensing is about twice (per kilo) that of ice melting. So, you'r at best going to need double the amount of water you remove from the clothes. To get a "reasonable" result, say 10C output at 100% RH, you are probably looking at an ice pack that will absorb around 4Kw (heat added by dryer and heat that would be needed to heat the air from 10C-room temp).

Say the dryer runs for 1 hour, 4Kwh is around 15MJ, so will melt around

In fact it's worse than that - at 273K, latent heat of fusion is

Also specific heat capacity of liquid water is 4.2x10^3 J/kg/K, of ice

In more detail, and looking at it slightly differently to you, each kilogramme of water to be condensed and cooled (from say 60 degC) to room temperature (say 20 degC) will release 2.5x10^6 + (4.2x10^3 x 40) =

In other words we would need ~7kg of ice per kilo (~litre) of water soaked into the clothes.

Sounds wrong. Hmm

I think I may have been remembering numbers I was doing for energy absorbtion for a block of ice cooled to around 0K. For this temperature, the number I remembered of around a megajoule/Kg is broadly right. However, few people have a freezer that goes anywhere near 0K.

They don't work. I tried one once and took it back to the shop. The assistant told me that they had almost 100% return rate

Can anybody recommend a good condenser dryer ?

many thanks M

On Mon, 5 Jul 2004 22:05:40 +0100, snipped-for-privacy@clara.co.uk (MLeo) strung together this:

One of the Miele ones, but they're pricey. Bosch are next, then Creda\White Knight. There's some others dotted around in the middle but you should find one of those suitable.

Thanks

Do you have any views on a good washer/dryer ?

Many Thanks M

I hadn't realised there was such a thing. If there really was no way I could squeeze two boxes in, I'd use a clothes line.

Christian.

I've got a Bosch, which is vastly better than any previous one I've used. I prefer it to the Miele too, as the controls are better.

If you can afford it, get a sensor dryer. They are so much less hassle. Just load and press start. They'll probably pay back the extra cost due to reduced energy usage, but I haven't done the sums to be sure.

Christian.