Hello, I am trying to achieve a range of temperature (below 0 degC) by heating up liquid nitrogen (77K) with an electric heater (100W) inserted into a copper block. How do I calculate the time taken (t) for the nitrogen vapour to reach temperature T (say 100K). The liquid nitrogen is poured into a 34 litre polystyrene box (420mmx320mmx250mm). Let me know if you have any questions. Thank you in advance.