5. Polyurethane fibers (such as the ultra-stretchy Spandex® found in athletic gear) are produced by a condensation reaction before being spun into fibers and used for textiles. The polymerization reactor

room is kept at high temperatures because some of the reactants have high melting points and must be in the liquid phase. Thus, the air temperature in this room is typically 125 °F. At one end of the reactor room is the operator's office, which is kept at 75 °F by the air conditioning system. A stainless steel wall 8.0 feet tall and 14 feet wide separates the rooms. The stainless steel wall is 0.68 inches thick. The air on both sides of the wall has a convective heat transfer coefficient, h = 27.6 Btu/h-ft^2-°F. Properties of this stainless steel: Density = 7900 kg/m³ = 493 lbm/ft³ *Heat Capacity = 477 J/kg-K = 0.114 Btu/lbm-°F *Thermal Conductivity = 14.9 W/m-K = 8.61 Btu/h-ft-°F A. Draw a sketch of the problem, using an arrow to show the direction of heat transfer B. Determine the heat flux, q", in Btu/h-ft^2 C. You wish to save money on air conditioning the office by reducing the heat flux into the office to only 5 % of your answer in part B. You have polystyrene insulation that you can use to cover the entire surface of the wall. How thick should this insulation be to achieve the required reduction in q" (q"new = 0.05 *q"part B)? Thermal conductivity of polystyrene insulation (k) = 0.016 Btu/h-ft-°F. D. Should the insulation be placed on the office-side or reactor room side of the wall? Why?