Methane gas is 304 C with 4.5 tons of mass flow per hour to an uninsulated horizontal pipe with a diameter of 25 cm. It enters at a temperature and exits at 284 C. The pipe is smooth and its length is 10 m. temperature is 25 ° C. Since the smear coefficient of the pipe surface is given as 0.8; a-) Indoor and outdoor convection coefficients (W / m2K), b-) Heat loss from the pipe to the environment (W), c-) The surface temperature of the pipe (C), d-) Calculate the required fan control (W) and interpret the results.

a)

b)

c)

d)

Explanation:

Non horizontal pipe diameter, d = 25 cm = 0.25 m

Radius, r = 0.25/2 = 0.125 m

Entry temperature, T₁ = 304 + 273 = 577 K

Exit temperature, T₂ = 284 + 273 = 557 K

Ambient temperature,

Pipe length, L = 10 m

Area, A = 2πrL

A = 2π * 0.125 * 10

A = 7.855 m²

Mass flow rate,

Rate of heat transfer,

a) To calculate the convection coefficient relationship for heat transfer by convection:

Note that we cannot calculate the heat loss by the pipe to the environment without first calculating the surface temperature of the pipe.

c) The surface temperature of the pipe:

Smear coefficient of the pipe,

b) Heat loss from the pipe to the environment:

d) The required fan control power is 25.125 W as calculated earlier above

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