In the periodic table, symbols for the elements are arranged according to _____
a. size
b. charge
c. mass number
d. atomic number
e. electronegativity gradient
d
You might also like to view...
Water flowing in a long aluminum tube is to be heated by air flowing perpendicular to the exterior of the tube. The ID of the tube is 1.85 cm and its OD is 2.3 cm. The mass flow rate of the water through the tube is 0.65 kg/s and the temperature of the water in the tube averages 30°C. The free stream velocity and ambient temperature of the air are 10 m/s and 120°C, respectively. Estimate the overall heat transfer coefficient for the heat exchanger using appropriate correlations from previous chapters. State all your assumptions.
GIVEN
• Air flowing perpendicular to the exterior of an aluminum tube with water flowing within the tube
• Tube diameters
? Inside (Di) = 1.85 cm = 0.0185 m
? Outside (Do) = 2.3 cm = 0.023 m
• Mass flow rate of water (mw) = 0.65 kg/s
• Average temperature of the water (Tw) = 30°C
• Air free stream velocity (Va) = 10 m/s
• Air temperature (Ta) = 120°C FIND
• The overall heat transfer coefficient (U)
ASSUMPTIONS
• Steady state
• The variation of the Prandtl number of air with temperature is negligible
• The aluminum is pure
SKETCH
PROPERTIES AND CONSTANTS
thermal conductivity of aluminum (kal) = 238 W/(m K) at 75°C
for water at 30°C
Density (?w) = 996 kg/m3 Thermal conductivity (kw) = 0.615 W/(m K)
Absolute viscosity (?w) = 792 × 10–6 (Ns)/m2
Prandtl number (Prw) = 5.4
for dry air at 120°C
Thermal conductivity (ka) = 0.0320 W/(m K)
Kinematic viscosity (?) = 26.0 × 10–6 m2/s
Prandtl number (Pr) = 0.71
During a total solar eclipse, which occurs?
A. the Moon passes just outside the Earth’s umbra B. the Moon’s umbra touches the Earth C. the Moon’s umbra just misses the Earth D. the Moon moves through the Earth’s umbra
The position of a mass that is oscillating on a spring is given by x = (17.4 cm) cos[(5.46 s-1)t]. Write an expression for the velocity of the particle as a function of time
What will be an ideal response?
What happens after the helium flash in the core of a star?
A) The core quickly heats up and expands as helium fusion begins all at once throughout the core. B) The star breaks apart in a violent explosion. C) The core suddenly contracts because the helium disappears after being fused. D) The core stops fusing helium. E) The star starts to fuse helium in a shell outside the core.