Chapter 13, Problem 13.106P

Cylindrical pillars similar to those of Problem 4.22 are positioned between the glass sheets with a pillar-to-pillar spacing of W. The inside surface of one glass sheet is treated with a low-emissivity coating characterized by ${\epsilon }_1=0.05$ . The second inner surface has an emissivity of ${\epsilon }_2=0.95$ . Determine the ratio of conduction to radiation heat transfer through a square unit area of dimension $W\times W$ for $W=10,20$ , and 30 mm. The stainless steel pillar is located at the center of the unit area and has a length of $L=0.4\text{mm}$ and diameter of $D=0.15\text{mm}$ . The contact resistances and glass temperatures are the same as in Problem 4.22.