The bottom of a steam-producing still of 200-mm diameter is heated by radiation. The heater, maintained at 1000?C and separated 100 mm from the still, has the same diameter as the still bottom. The still bottom and heater surfaces are black.

(a) By what factor could the vapor production rate be increased if the cylindrical sides (dashed surface) were insulated rather than open to the surroundings maintained at 27?C?

(b) For heater temperatures of 600, 800, and 1000?C, plot the net rate of radiation heat transfer to the still as a function of the separation distance over the range from 25 to 100 mm. Consider the cylindrical sides to be insulated and all other conditions to remain the same.

Transcribed Image Text:

Vapor Water, 100°C D = 200 mm 100 mm Heater, 1000°C