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Date: | Sat, 9 Oct 2021 13:09:43 -0400 |
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My quest is to understand "why & how" things work. I am not a fan of just because or blackbox experiments.
Here is another one from the University of Guelph from about 10 years ago. I have used many of the concepts to build my "mental" hive enclosure ventilation model. https://www.uoguelph.ca/canpolin/Publications/ThompsonCody_MSc2011_edited.pdf
You will find interesting tidbits throughout the document. Just skip over the formulas. He does a good job of describing the processes he is attempting to model.
page 29 - 2.3 Honeybees and Ventilation
Here is an extract from future work I wish they would have conducted.
Conclusions are worth reading from page 92
sample from page 95
"5.3.1 Moisture transport and honey drying
The current investigation neglects the influence of moisture exchange on flow within
the hive. This is a significant simplification since the process of honey ripening in-
volves the evaporation of water from the dilute nectar, which foraging bees collect
and deposit inside empty cells of the honey super. By the time nectar has condensed
into honey, it has given up a large volume of water to the hive environment. Water
content in nectar varies a great deal depending on plant species and geographic loca-
tion. Some plants produce thick nectar (tending towards sap) while others produce
nectar having a water content as high as 80%, which must be reduced to around 20%
to become honey [15]. Honeybees have been shown to express preference for hive
humidty around 75% [8], while the constant flux of moisture from the nectar stores
work to increase hive humidity. Therefore excess moisture from the honey ripening
process must be expelled through passive and/or active ventilation to maintain the
desired set point.
Our first study revealed that air circulation in the hive depends on both heat and
mass transfer processes, and it is reasonable to assume that the inclusion of moisture
transport in the hive model will have a significant impact on both the resultant energy
and mass balance. The position of the honey super above the brood chamber (which
is also found in the natural nest [41]) implies that fresh (relatively dry) air warms
as it must pass through or around the hot brood cluster before reaching the nectar
drying region above. The fresh air mass will then lose energy as it picks up water by
evaporation. The air mass will tend to increase in density by two mechanisms: by
picking up moisture and losing energy. Considering the physics of mass transfer, the
now stale air mass will be driven downward due to an amplified density gradient. By
this logic, the inclusion of moisture transport in the existing model would serve to
strengthen the existing flow pattern.
To simulate the transport of moisture from the comb cells of the honey super, a
mathematical description of the ripening process must be defined. Honeybees fill the
honey super starting at the top row and progressively working downward as the cells
fill. Once a cell of ripened nectar is full, the bees cap the cell with wax and continue
to fill the lower rows of the comb. In commercial beekeeping, empty honey supers
are added below existing supers as they are filled. Therefore, to obtain a reasonable
model of moisture transport from honey ripening, one should consider fully ripened,
capped honey exists at the top of the honey super (n˙ H20 = 0) and fully unripened,
uncapped nectar exists at the bottom of the honey super (n˙ H20 = MAX). In this way
a ripening gradient is defined that dictates moisture source and energy sink terms,
which can be applied as boundary conditions on the comb surfaces of the honey super."
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