Questions from Thermal Fluid Science

Q: Consider two surfaces pressed against each other. Now the air at

Consider two surfaces pressed against each other. Now the air at the interface is evacuated. Will the thermal contact resistance at the interface increase or decrease as a result?

Q: Water mains must be placed at sufficient depth below the earth’s surface

Water mains must be placed at sufficient depth below the earth’s surface to avoid freezing during extended periods of subfreezing temperatures. Determine the minimum depth at which the water main must...

Q: Portable electric heaters are commonly used to heat small rooms. Explain

Portable electric heaters are commonly used to heat small rooms. Explain the energy transformation involved during this heating process.

Q: The thermal contact conductance at the interface of two 1-cm

The thermal contact conductance at the interface of two 1-cm-thick aluminum plates is measured to be 11,000 W/m2â‹…K. Determine the thickness of the aluminum plate whose thermal resist...

Q: A 40-cm-thick brick wall (k = 0

A 40-cm-thick brick wall (k = 0.72 W/m⋅K, and α = 1.6 × 10−6 m2/s) is heated to an average temperature of 18°C by the heating system and the solar radiation incident on it during the day. During the n...

Q: Two 5-cm-diameter, 15-cm-long

Two 5-cm-diameter, 15-cm-long aluminum bars (k = 176 W/m⋅K) with ground surfaces are pressed against each other with a pressure of 20 atm. The bars are enclosed in an insulation sleeve and, thus, heat...

Q: In a volcano eruption, lava at 1200°C is found

In a volcano eruption, lava at 1200°C is found flowing on the ground. The ground was initially at 15°C, and the lava flow has a convection heat transfer coefficient of 3500 W/m2⋅K. Determine the groun...

Q: A 1-mm-thick copper plate (k = 401

A 1-mm-thick copper plate (k = 401 W/m⋅K) is sandwiched between two 7-mm-thick epoxy boards (k = 0.26 W/m⋅K) that are 15 cm × 20 cm in size. If the the...

Q: A large iron slab (ρ = 7870 kg/m3,

A large iron slab (ρ = 7870 kg/m3, cp = 447 J/kg⋅K, and k = 80.2 W/m⋅K) was initially heated to a uniform temperature of 150°C and then plac...

Q: Two identical aluminum plates with thickness of 30 cm are pressed against

Two identical aluminum plates with thickness of 30 cm are pressed against each other at an average pressure of 1 atm. The interface, sandwiched between the two plates, is filled with glycerin. On the...