The boiling temp of nitrogen at 1 atm is -196°C. If the temperature of liquid nitrogen in a tank open to the atmosphere at sea level will remain constant until it is depleted, then any heat transfer to the tank will result in the evaporation of some liquid nitrogen, which has a heat of vaporization of 198 kJ/kg and a density of 810 kg/m3 at 1 atm. Consider a 3.25-m-diameter spherical tank that is initially filled with liquid nitrogen at 1 atm and -196°C. The tank is exposed to N; vapor ambient air at 18°C, with a convection heat transfer coefficient of 35 W/m2- °C. The temperature of the thin-shelled spherical tank is observed to be almost the same as the temperature of the nitrogen inside. Determine the I atm Liquid N3 -196°C rate of evaporation of the liquid nitrogen in the tank (in kg/s) as a result of heat transfer from the ambient air if the tank is (a) not insulated, (b) insulated with 6.5-cm thick fiberglass insulation (k=0.032 W/m-°C) and (c) insulated with 4-cm thick super-insulation which has an effective thermal conductivity Insulation of 0.00004 W/m-°C.

The boiling temp of nitrogen at 1 atm is -196°C. If the temperature of liquid nitrogen in a tank open to the atmosphere at sea level will remain constant until it is depleted, then any heat transfer to the tank will result in the evaporation of some liquid nitrogen, which has a heat of vaporization of 198 kJ/kg and a density of 810 kg/m3 at 1 atm. Consider a 3.25-m-diameter spherical tank that is initially filled with liquid nitrogen at 1 atm and -196°C. The tank is exposed to N; vapor ambient air at 18°C, with a convection heat transfer coefficient of 35 W/m2- °C. The temperature of the thin-shelled spherical tank is observed to be almost the same as the temperature of the nitrogen inside. Determine the I atm Liquid N3 -196°C rate of evaporation of the liquid nitrogen in the tank (in kg/s) as a result of heat transfer from the ambient air if the tank is (a) not insulated, (b) insulated with 6.5-cm thick fiberglass insulation (k=0.032 W/m-°C) and (c) insulated with 4-cm thick super-insulation which has an effective thermal conductivity Insulation of 0.00004 W/m-°C.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter9: Heat Transfer With Phase Change

Section: Chapter Questions

Problem 9.15P

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