re: enviro friendly hand drying
27 jul 2000
andrew heggie quotes me:
>>how about adding a plexiglas box in front of a hot air dryer, with
>>an opening that you put your hands up into, so most of the hot air
>>can be returned to the dryer intake, vs venting it into the room?
>trouble with this is that by then the some of the air you recycle will
>be saturated with water at the return temperature, this will be
>reheated and have a lesser ability to absorb more water from your
>hands than ambient air.
this potential-problem-in-principle may become insignificant with some
real numbers. can the surface of two hands hold a tablespoon of water?
if it evaporates in a minute, how much does that increase the rh of a
200 f (?) 50 cfm (?) airstream with 10% fresh 70 f 50% rh room air?
steve spence writes:
>thermal shutdown due to excessive heat? just a guess.
maybe. especially if a passing busload of people use it continuously
for a few minutes. maybe the heating element needs a thermostat or
some other way to adjust the temperature, eg a semiconductor dimmer.
and does the dryer use the incoming airstream to cool the motor? if
it's rated for 104 f continuous duty (many are), the wire insulation
or bearings may fail prematurely. that could be solved with a higher
temp blower with the motor out of the airstream, like grainger's $75
4c941, which moves up to 136 cfm with 450 f max inlet and 104 f max
ambient motor temp specs.
how would this compare to paper or roll-fed cloth towels, considering
energy, environment and economics? some people say that throwaway paper
plates are more environmental than china, if we include dishwashing...