Find the total conductive thermal resistance of a 2-m long two-layered cylindrical insulation jacket as shown in the figure. The first (inner) layer is made of foam and has a thermal conductivity of 0.12 W/m-°C. The second (outer) layer is made of rubber and has a thermal conductivity of 0.27 W/m.°C. 0.176Ķ W 55 mm 40 mm 50 mm Inner Outer

A dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheathing with a thermal conductivity of ks = 0.1 W/m-K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an L = 25-mm-thick layer of extruded insulation characterized by k; = 0.029 W/mK to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an Lg = 5-mm-thick architectural glass with kg = 1.4 W/m-K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are Too₁ = 22°C and T∞,0 = -20°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5 W/m²-K and h, = 25 W/m²-K, respectively. The heat flux through the original walls is i The heat flux through the retrofitted walls is i W/m². W/m².

Temperature distribution of a wall is given as T(x) = -100x + 50 and the cold surface is exposed to a convection environment at temperature of 20 °C. If the wall thickness is 10 cm and the conductivity is 1 W/mK what is the convection coefficient between the cold surface and the environment?