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Determination of aerosol deliquescence and crystallization relative humidity for energy saving in free-cooled data centers
Ferrero, L.; D’Angelo, L.; Rovelli, G.; Sangiorgi, G.; Perrone, M. G.; Moscatelli, M.; Casati, M.; Rozzoni, V. & Bolzacchini, E.
Abstract
This study examines an innovative application
of the aerosol deliquescence and crystallization determination,
for corrosion prevention and energy-saving strategies
in free-cooled data centers. Aerosol deliquescence and
crystallization were investigated by combining standardized
aerosol sampling techniques (i.e. EN-14907) with the
assessment of the electrical effects of aerosol, while
varying relative humidity within a specially designed aerosol
exposure chamber. Aerosol samples collected in the
Po Valley (Northern Italy) were analysed; a clearly defined
hysteresis cycle (deliquescence and crystallization at
60.5 ± 0.8 and 47.9 ± 0.7 % of RH, respectively) was
found. Results were applied to a data center designed for
the Italian National Oil and Gas Company, making it
possible to identify a critical area for direct free cooling at
this data center. As a result, aerosol hydration was avoided
(thus preventing aerosol from damaging electrical components)
and a large amount of energy saved (using free
cooling instead of air-conditioning); the potential energy
saving achieved in this way was 79 % (compared to the
energy consumption of a traditional air-conditioning system):
215 GWh of energy was saved, and 78 fewer kt of
equivalent CO2 was emitted per year. Moreover, in order to
evaluate whether a real-time estimation of the aerosol
hydration state within a data center could be performed,
measured deliquescence and crystallization were compared
through simulations performed using three different models:
two thermodynamic models for deliquescence and a
parametric model for crystallization. The results obtained
tend to converge in terms of deliquescence, whereas in the
case of crystallization, they failed to effectively simulate
experimental aerosol behaviour.
Keywords
Conductivity; Aerosol chamber; Hygroscopicity; Models; Energy; Carbon footprint
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