A recent attempt to circumnavigate the world in a balloon used a helium filled balloon whose volume was 7240 m3 and surface area was 1800 m2. The skin of this balloon is 2 mm thick and is made of a material whose helium diffusion coefficient is 1?10-9 m2/s. The molar concentration of the helium at the inner surface of the balloon skin is 0.2 kmol/m3 and the molar concentration at the outer surface is extremely small. The rate at which helium is lost from this balloon is
(a) 0.26 kg/h
(b) 1.5 kg/h
(c) 2.6 kg/h
(d) 3.8 kg/h
(e) 5.2 kg/h
(c) 2.6 kg/h
Ci=0.2 [kmol/m^3]
Co=0 [kmol/m^3]
D=1E-9 [m^2/s]
L=0.002 [m]
M=4 [kg/kmol]
A=1800 [m^2]
Ndot=D*A*(Ci-Co)/L
Mdot=Ndot*M*3600
You might also like to view...
When a water regulating valve is used to control the head pressure of a water-cooled system, the valve's spring is acting against which pressure to modulate the water flow?
A. Head pressure of the system. B. Water pressure. C. Suction pressure. D. Atmospheric pressure.
When C-channel stock is used for a frame reinforcement, which of the following must be true?
A. It should welded directly to the frame rail B. It must be of the same dimensions as the original frame rail C. It must have the same yield strength as the original frame rail D. It should be installed on only the outside of the frame rail
A device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc is detected is called a(n) ________________________________________.
Fill in the blank(s) with the appropriate word(s).
As a mixture travels through an evaporator, the liquid percentage:
A) Stays the same. B) Increases slightly. C) Decreases. D) Increases greatly.