A spherical vessel 1 m in diameter stores liquid nitrogen at –200°C. Calculate the amount of nitrogen vaporized per day if the container is provided with a 5 cm thick layer of superinsulation having k...

A spherical vessel 1 m in diameter stores liquid nitrogen at –200°C. Calculate the amount of nitrogen vaporized per day if the container is provided with a 5 cm thick layer of superinsulation having k = 0.00017 W/mK. The outside temperature is 30°C, the convective heat transfer coefficient at the outer surface is 15 W/m²K and 200 kJ of energy is required to vaporize 1 kg of nitrogen at that temperature. Find also the temperature at the outside surface of the superinsulation.

The equivalent electrical circuit is shown above.

Total resistance,

Mass of nitrogen vaporized per day

Temperature of the outer surface of superinsulation