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This page describes a scheme and some experiments in using
night air to cool thermal mass inside the living space to store "coolth"
for the next day. Fans are used to circulate outside air at
relatively high velocity over over the thermal mass during the evening
hours when the outside air is cool. For the system described here,
the thermal mass comes in the form of barrels filled with water, but
other forms of thermal mass could be used.
The system is VERY simple -- basically a fan on a timer. There
is not much of anything to go wrong or leak or require maintenance.
I have been using this scheme to cool my 25 by 25 ft shop. The
thermal mass consists of 4 water barrels arranged inside a cooling
"tunnel". A fan pulls outside air in through a vent in the
wall, and forces the air down the cooling tunnel to cool the water mass.
The cooling tunnel channels the air to keep the air velocity up near the
barrels, which increases the heat transfer. To retrieve the stored
"coolth", I reposition the fan so that it blows shop air over the cool
barrels and cools the air.
I go over the calculations involved in designing and sizing this
system in some detail because I get feedback that these calculations are
helpful to people who want to design their own systems. If the
calculations are not your cup of tea, just skip over them and go to the
build and performance sections. |
