Question

Air at 1.00 atm is passed through a horizontal 1.5-in. Schedule 40 (steam-jacketed) steel pipe at a velocity of 2.10 ft/s and an inlet and outlet temperature of 25.0 °C and 95.5 °C, respectively. The pipe wall temperature is maintained at 121.1 °C. (HINT: You may neglect the viscosity correction in your calculations.) a) Assuming only heat transfer by forced convection, how long must

Answer 1

missing question; How long must the heated section be

answer : 5.898 meters

Step-by-step explanation:

Given parameters:

Diameter of steel pipe = 1.5 inches = 0.0381 m

velocity of air = 2.10 ft/s = 0.64 m/s

Inlet temperature = 25°C

Outlet temperature = 95.5°C

pipe wall temperature = 121.1°C

Average temperature = ( 25 + 95.5 ) / 2 = 60.25°

determine Reynolds number of air at 60.25°

= VD / v = ( 0.64 * 0.0381 ) / ( 1.83 * 10^-5 )

= 1332.46 this means the flow is laminar

hence mass flow rate ( m ) = eAv = 1.08 * πd^2 * velocity

= 1.08 * 0.0046 * 0.64 = 0.0032 g/s

attached below is the remaining part of the solution