[Greenbuilding] ENERGY STAR Clothes Dryers Program Launch

John Salmen terrain at shaw.ca
Sun Jul 29 11:08:17 CDT 2012


Varying air flow effects only the rate of evaporation - not the energy. In
using a dryer you can reduce the energy considerably by reducing the amount
of water to be removed and ironically reducing the amount of moisture that
has to be replaced (overdrying). Fabric has a natural water content bound up
in the fabric weave, in the yarn and in the fibres themselves - they also
absorb and release differing amounts. Some fibres hold more water (cotton,
etc.), blends (cotton, polyester) tend to hold more water between the types
of fibre used - and less dense weaves tend to hold more water. 

Surface tension also holds water on the fabric requiring aggressive spin
cycles - i think spinners are useful as a separate item. Rinse additives
like vinegar and alcohol can reduce the surface tension leaving clothes with
less water. It is conceivable to reduce the water load by 1/3 



-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of nick
pine
Sent: July-29-12 4:37 AM
To: greenbuilding at lists.bioenergylists.org
Subject: Re: [Greenbuilding] ENERGY STAR Clothes Dryers Program Launch

Reuben Deumling <9watts at gmail.com> writes:

> The fact is that in the 1930s and 40s many of our (US) household 
> appliances were very efficient: water heaters, refrigerators, kitchen 
> stoves, toilets, etc.

A lot of appliances are more efficient today. I lived with an old sidearm
water heater with NO insulation.

Benjamin Pratt <benjamin.g.pratt at gmail.com> writes:

>The easiest way to make a dryer more efficient would be to increase the 
>amount of air passing through the clothes, and decrease the amount of heat.

But it still takes about 1000 Btu to evaporate each pound of water. We could
capture and store the sensible heat and use it to warm air for the next
dryer cycle, but how can we capture the significant additional latent heat
without a heat pump?

"John Straube" <jfstraube at gmail.com> writes:

> Heat pump condensing clothes driers have ratings of around 250 kWh per 
> year vs 900 for straight electric. These use almost 1/4 as much energy.

Is there a way to make this close to zero?

> I live in a climate that gets below 30F for months. And I have a very 
> energy efficient house with triple glazed fiberglass windows.  Drying 
> clothes on a rack is possible, but results in condensation streaming 
> from the windows.

Slow drying in an insulated airtight closet with a small heat source and a
dehumidistat and a condensing heat exchanger with closet water vapor on one
side and room air on the other would avoid condensation on windows, with
welcome heat of condensation in wintertime, but that still requires 1000 Btu
per pound of water. How can we make that closer to zero? Multiple-effect
dehumidification?

Nick 


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