reactor room side or the difficulty of changing the office walls where there

Reactor room side or the difficulty of changing the

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3. Pressurized liquid nitrogen at -80 oC passes through a 20-meter length of stainless steel pipe in an electronics factory at 12 kg/min. The pipe has an inner diameter of 1.0 cm and thickness of 0.20 cm. A layer of insulating urethane foam (2.0 cm thick) coats the outside of the pipe. The surface of the foam is exposed to the room air at 25 oC, which has a convective heat transfer coefficient of 12 W/m2-K. Ignore radiation. Material PropertiesLIQUID NITROGEN STAINLESS STEEL URETHANE FOAM Density, ρ(kg/m3) 1.69 7900 Thermal Conductivity, k (W/m-K) 0.0183 12.6 0.026 Heat Capacity, cp(J/kg-K) 1.043 477 1045 Convective Heat Trans. Coeff., h (W/m2-K) 32.0 --- A. Sketch the problem, labeldimensions and drawan arrow to indicate the direction of heat transfer. B. Draw a thermal resistance diagram indicating all resistances between the bulk temperatures (T) of liquid nitrogen and room air. C. Draw a rough qualitative graph to approximate temperature vs. radius starting from the liquid nitrogen temperature at r = 0 to the air temperature. Mark locations of the steel pipe and foam insulation. D. What is the thermal resistance due to the urethane foam layer (in K/W)? E. If the rate of heat transfer is -84.7 W, what is the surface temperature of the foam exposed to the room air? 70 --- A. B. C. D. E.
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