Questions from Thermal Fluid Science

Q: Consider an insulated pipe exposed to the atmosphere. Will the critical

Consider an insulated pipe exposed to the atmosphere. Will the critical radius of insulation be greater on calm days or on windy days? Why?

Q: A long 35-cm-diameter cylindrical shaft made of stainless

A long 35-cm-diameter cylindrical shaft made of stainless steel 304 (k = 14.9 W/m⋅K, ρ = 7900 kg/m3, cp = 477 J/kg⋅K, and α = 3.95 × 10−6 m2/s) comes out of an oven at a uniform temperature of 500°C...

Q: A pipe is insulated to reduce the heat loss from it.

A pipe is insulated to reduce the heat loss from it. However, measurements indicate that the rate of heat loss has increased instead of decreasing. Can the measurements be right?

Q: A wind turbine is rotating at 15 rpm under steady winds flowing

A wind turbine is rotating at 15 rpm under steady winds flowing through the turbine at a rate of 42,000 kg/s. The tip velocity of the turbine blade is measured to be 250 km/h. If 180 kW of power is pr...

Q: Reconsider Prob. 18–51. Using appropriate software, investigate

Reconsider Prob. 18–51. Using appropriate software, investigate the effect of the cooling time on the final center temperature of the shaft and the amount of heat transfer. Let the time vary from 5 mi...

Q: Consider a pipe at a constant temperature whose radius is greater than

Consider a pipe at a constant temperature whose radius is greater than the critical radius of insulation. Someone claims that the rate of heat loss from the pipe has increased when some insulation is...

Q: Steel rods, 2 m in length and 60 mm in diameter

Steel rods, 2 m in length and 60 mm in diameter, are being drawn through an oven that maintains a temperature of 800°C and convection heat transfer coefficient of 128 W/m2⋅K. The steel rods (ρ = 7832...

Q: Someone comments that a microwave oven can be viewed as a conventional

Someone comments that a microwave oven can be viewed as a conventional oven with zero convection resistance at the surface of the food. Is this an accurate statement?

Q: For heat transfer purposes, an egg can be considered to be

For heat transfer purposes, an egg can be considered to be a 5.5-cm-diameter sphere having the properties of water. An egg that is initially at 4.3°C is dropped into boiling water at 100°C. The heat t...

Q: A pipe is insulated such that the outer radius of the insulation

A pipe is insulated such that the outer radius of the insulation is less than the critical radius. Now the insulation is taken off. Will the rate of heat transfer from the pipe increase or decrease fo...