Hi,
Very interesting stuff on recovering dryer heat -- pumping all that heat outdoors just seems like such a waste.
I just added a set of DIY plans for an HRV made from Coroplast. Maybe there is a way to adapt this for use as a heat exchanger for dryer heat recovery?
DIY Heat Recovery Ventilator (HRV) Plans
I think the Coroplast should hold up to the moisture -- not sure if the dryer exhaust temp is too high, but probably OK. A good lint filter would be needed upstream of the HX.
Another thought would be to supply the dryer air from a free warm source. I've been working on a sort of sunspace the last few days, and the inside air temperature gets as high as 120F when the sunspace is not ventilated -- an attic might be another source in some climates.
For those who have not seen it already, Randy did this for his dryer.
Converting a Clothes Dryer to Use Solar Heated Attic Air For Drying
Gary