Particle diffusion with gravitational sedimentation in
displacement and mixing ventilated rooms is investigated
numerically. The drift flux model, which considers the settling
of particles under the effect of gravitational sedimentation, is
adopted to simulate particle diffusion, while the simplified
model for solving the continuous fluid flow is combined.
Since the PM 2.5 and PM 10 particles are mostly
concerned in indoor environment, passive contaminant and
2.5-20 micron particles are investigated in this paper. The
numerical results show that in a mixing ventilated room, the
distribution of nonpassive particles does not differ much from
that of passive contaminant when the particle diameter is less
than 20 microns. Meanwhile, in the displacement ventilated
room, the gravitational settling should be taken into account
when particle diameter is larger than 10 microns.
Comparison also demonstrates that displacement ventilation
will bring particle contaminants generated by mannequins
to the working zone and upper part of the room; in
contrast, mixing ventilation will carry up the pollutant in a
relatively small amount.
Evaporative cooling systems have been criticized for their
water use and acclaimed for their low energy consumption,
to determine the overall effectiveness of cooling systems,
water and energy need to be considered; however, data are
needed to compare the amount of energy used at the site to the
amount of water used at the power plant.
plants and their water consumption was completed to effectively
analyze evaporative cooling systems.In thermoelectric plants,
water is evaporated per kilowatt-hour (kWh) of electricity
consumed at the point of end-use.
an average of 18 gallons (68 L) of fresh water per kWh
used by the consumer.
gallons (7.6 L) of evaporated water per kWh of electricity
consumed at the end-use. From this information, different types
of building cooling systems can be compared for relative water
Revision of the RF-number has been made to give RF2 for
assessing more precisely the combustion hazard in treating
flammable gases and their mixtures.
expectancy of the combustion hazard, which takes into account
the heat of combustion, flammability limits, and burning velocity
in a systematic way.