## Very low pressure and Temperature to high P, high T (constant volume, constant heat)

Hi all,

There is a block of ice (say 20 cm^3) sitting inside a box (50cm^3, constant volume) at very low P and low T (say P = 10^(-8) kPa and T = 100 K .... roughly ambient moon P and T).

There is a constant heat flux incident on the box. I want a 'path-way' (explicit phase transition regimes etc) that will take this ice block to high T (~ 500 K) and high P (~ 18 MPa), and quantify energy requirement in each step. The heat source is infinite. Please make any other assumption that may prove helpful.

My approach:

The given P and T is well below the triple point. If I heat the ice, it will increase its T under the same initial P. Once it hits the sublimation line, the energy input will convert it directly to vapor (under constant P, is this assumption valid?) .

Now, after everything is vapor, if I continue heating, I am not sure how to quantify the path-way in the P-T diagram. (Assuming ideal gas under constant V.... P has linear relationship with T but I can't tell anything about the slope). How does the P and T change now (after sublimation) under constant volume and constant heat source?