Mike
I think you will find that only a tiny airflow is needed for humidity
and temperature control, as long as the need for heating or cooling is
minimal. Cooling a showcase when the temperature differential between
gallery and showcase is more than a few degrees needs much more air flow
through the showcase, and there can be a danger to objects, so louver
design and air path must be very carefully designed.
Some years ago, I entertained myself by performing a number of "kitchen
sink" experiments on the effect of very low airflow/volume air flows in
sealed showcases. Where necessary I used air containing smoke particles
so that I could photograph and record air movement, but I also used
sensors to record temperature differentials that resulted from air
movement.
One of this series of experiments used an extremely small blower (about
5mm X 25mm X 25mm, for computer component cooling) that I further choked
down to create an airflow that was only perceptible by pointing the
device at my eyeball and feeling the need to blink. Needless to say, the
flow was quite small, and beyond my ability to quantify.
For the experiment, I used a very small, and very well gasketed cast
metal enclosure, with a large glass window. I placed one thermocouple
free in the air near the top of the chamber, and the other near the
bottom. I then used a small incandescent bulb located outside the window
to create a temperature stratification of 2 deg C between top and bottom
sensors.
This arrangement proved to be quite stable, until the miniature blower
was energised. The temperature differential disappeared within a few
minutes!
I suggest you try a similar test, using a small aquarium pump (similar
to the Mini One humidity control devices) and a few data loggers. Please
let me know how this works out, especially as you vary your air flows
and case sizes. If you would like to discuss cooling optios, please
contact me off-list.
js
We are currently working on a display case design with circulating air
flow to ensure temperature and humidity is consistent around the case.
We are looking for guidance on acceptable airflow rate that should be
used to ensure there is no harm to objects. Does anyone have any
experience or know of any guidelines in this area?
Many thanks
--
Jerry Shiner
Keepsafe Microclimate Systems
www.keepsafe.ca [email protected]
+1 416 703 4696 +1 800 683 4696
skype: jerry.shiner
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