Chapter 3, Problem 3.25P

A low carbon steel pipe with an internal diameter of 52.5 mm and a thickness of 3.8 mm that carries dry saturated steam at 20 bar is insulated with an insulator made of diatomaceous earth with a thickness of 30 mm and whose thermal conductivity is 0.1 W / (m ° C). This in turn is covered with a 65 mm thick layer of asbestos with k = 0.073 W / (m ° C). In one test the ambient temperature was 20 ° C and the asbestos surface temperature was 40 ° C. The heat transfer coefficient in the inner part of the tube was estimated as hi = 55 W / (m2 ° C). Neglect radiation losses.   a) What is the heat loss per meter of pipe, in W / m? 1) 61 2) 84 3) 142 4) 575

Your research lab is testing the thermal conductivity of a new polymer before implementing in manufacture. A 3-inch-thick slab of the new polymer initially at 65 °F is placed inside an incubator oven at 375 °F. The density of the material is 63.7 lbm/ft3 and the thermal conductivity is 0.053 Btu/hr-ft-°F and the specific heat is 0.37 Btu/lbm°F. Determine the temperature at the center of the slab at 30 min, 60 min and 90 min

Two composite bars have the following composition. At an initial temperature of 5 degree C, there is an existing gap of 9mm. Bar 1 and 2 have coefficiens of thermal expansion of a1=140x10^-6/°C and a2=67x10^-6/°C, respectively. Determine the temperature at which thr 9mm gap is closed.