Question

# this is a heat transfer course. please DO NOT copy others' answers since all answers wrong....

this is a heat transfer course.

need some steps explanations so I can learn, please.

A cylinder, 6 mm in diameter, has a length of 24 mm. One end of the cylinder is open while all other surfaces have external insulation. The inside of the cylinder is diffuse and gray having an emissivity of 0.8 and a uniform temperature of 1000 K.

(a) Draw a sketch and state your assumptions

(b) Determine the radiant power leaving the open end of the cylinder.

(c) Calculate the effective emissivity of the cylinder (NOTE: The effective emissivity of any cavity is defined as the ratio of the radiant power leaving the cavity to that from a blackbody having the area of the opening and a temperature of the inner surfaces of the cavity.).

(d) The length of the cylinder is decreased to 6mm, what is the effective emissivity of the cylinder?

(e) If the length of the cylinder is decreased further, do you expect an increase or decrease in the effective emissivity?