Exposure to high concentrations of gaseous ammonia can cause lung damage. To prevent gaseous ammonia from leaking out, ammonia is transported in its liquid state page 232 through a pipe ( k = 25 W/m .K, D i =25 cm, D o =4 cm and L= 10 m) . and Since liquid ammonia has a normal boiling point of -33.3°C, the pipe needs to be properly insulated to prevent the surrounding heat from causing the ammonia to boil. The pipe is situated in a laboratory, where the average ambient air temperature is 20°C. The convection heat transfer coefficients of the liquid anunonia and the ambient air are 100 Wm2K and 20 Vin2K. respectively. Determine the insulation thickness for the pipe using a material with k = 0 .75W/m 2 .K, to keep the liquid ammonia flowing at an average temperature of -35°C, while maintaining the insulated pipe outer surface temperature at 10°C.
Exposure to high concentrations of gaseous ammonia can cause lung damage. To prevent gaseous ammonia from leaking out, ammonia is transported in its liquid state page 232 through a pipe ( k = 25 W/m .K, D i =25 cm, D o =4 cm and L= 10 m) . and Since liquid ammonia has a normal boiling point of -33.3°C, the pipe needs to be properly insulated to prevent the surrounding heat from causing the ammonia to boil. The pipe is situated in a laboratory, where the average ambient air temperature is 20°C. The convection heat transfer coefficients of the liquid anunonia and the ambient air are 100 Wm2K and 20 Vin2K. respectively. Determine the insulation thickness for the pipe using a material with k = 0 .75W/m 2 .K, to keep the liquid ammonia flowing at an average temperature of -35°C, while maintaining the insulated pipe outer surface temperature at 10°C.
Solution Summary: The author analyzes the thermal resistances of different layers by solving for the insulation thermal conductivity yields kins = 0.75 W/m-K.
Exposure to high concentrations of gaseous ammonia can cause lung damage. To prevent gaseous ammonia from leaking out, ammonia is transported in its liquid state page 232 through a pipe
(
k
=
25
W/m
.K,
D
i
=25 cm, D
o
=4 cm and L= 10 m)
.
and Since liquid ammonia has a normal boiling point of -33.3°C, the pipe needs to be properly insulated to prevent the surrounding heat from causing the ammonia to boil. The pipe is situated in a laboratory, where the average ambient air temperature is 20°C. The convection heat transfer coefficients of the liquid anunonia and the ambient air are 100 Wm2K and 20 Vin2K. respectively. Determine the insulation thickness for the pipe using a material with
k = 0
.75W/m
2
.K,
to keep the liquid ammonia flowing at an average temperature of -35°C, while maintaining the insulated pipe outer surface temperature at 10°C.
In an aluminum pot, 0.796 kg of water at 100
°C boils away in four minutes. The bottom of
the pot is 1.03 × 10-3 m thick and has a
surface area of 0.0294 m². To prevent the
water from boiling too rapidly, a stainless
steel plate has been placed between the pot
and the heating element. The plate is
2.67 x 10-3 m thick, and its area matches that
of the pot. Assuming that heat is conducted
into the water only through the bottom of
the pot, find the temperature in degrees
Celsius at the steel surface in contact with
the heating element.
Number
i
Units
the latent heat of vaporization is about 2.44 x 10⁶ J/kg and the density (density) of the vapor is 0.598 kg/m³ at 100 °C per km. Determine the rate of change of the boiling point with altitude approaching sea level in °C per km. It is known that the density of air at 0°C and 1 atm is 1.29 kg/m and the density of water is 1000 kg/m³. Assume the air temperature is 300°K. The change in pressure with altitude is given by the relationship P(z) = P(0)exp - (mgz)/(kT)
Example 7
A cooking pan whose inner diameter is 20 cm is filled
with water and covered with a 4-kg lid. If the local atmospheric
pressure is 101 kPa, determine the temperature at which the
water starts boiling when it is heated. Answer: 100.2°C
Patm = 101 kPa
mlid = 4 kg
H,0
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