The crop of orange trees can be destroyed by extended exposure to subfreezing temperatures. When acold front moves in at night, a spherical orange (r = 1,000 kgm-3 ; c = 4,200 Jkg-1 K-1 ; k = 0.60 Wm-1 K-1 )of 10 cm diameter and 15 ̊C initial temperature is suddenly subjected to an ambient temperature of -5.0 ̊Cwith convective heat transfer coefficient of 12 Wm-2K-1 To protect orange trees from cold fronts with subfreezing temperatures, water sprinklers are installedon the trees to spray water on oranges when the temperature dips below a certain level. Use lumpedcapacity analysis to estimate the time it would take for a 2-mm-thick water layer (initially at 15 ̊C)around a 10-cm-diameter orange to freeze upon sudden exposure to the ambient conditions of thecold front. Can you explain the basic mechanism behind the protection measure? The latent heat offusion of water is 334 kJ/kg.
The crop of orange trees can be destroyed by extended exposure to subfreezing temperatures. When a
cold front moves in at night, a spherical orange (
r = 1,000 kgm-3 ; c = 4,200 Jkg-1 K-1 ; k = 0.60 Wm-1 K-1 )
of 10 cm diameter and 15 ̊C initial temperature is suddenly subjected to an ambient temperature of -5.0 ̊C
with convective heat transfer coefficient of 12 Wm-2K-1
To protect orange trees from cold fronts with subfreezing temperatures, water sprinklers are installed
on the trees to spray water on oranges when the temperature dips below a certain level. Use lumped
capacity analysis to estimate the time it would take for a 2-mm-thick water layer (initially at 15 ̊C)
around a 10-cm-diameter orange to freeze upon sudden exposure to the ambient conditions of the
cold front. Can you explain the basic
fusion of water is 334 kJ/kg.
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