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Table B.2
Latin symbols.
| Parameter | Unity | Description |
|
|
||
| A b | Bolometric Bond albedo of the nucleus surface | |
| A s | m-1 | Reaction surface area per unit of volume of solid reactant |
| a ∗ | m | Critical radius that gives the largest dust grain that can be ejected from the comet |
| a | m | Radius of dust grains in the comet |
| c l | J kg-1 K-1 | Specific heat of the solid component l (l = d for dust, cl for clathrate or i for pure ices of elements x) |
| or of the gas component (l = g of gas) | ||
|
J kg-1 K-1 | Specific heat capacity of amorphous ice |
| C s | J m-2s-1 | Solar constant |
| d | m | Mean diameter of gas molecules |
| d x | m | Diameter of the molecule x |
| f l | Volume ratio in the solid matrix of water ice (l = i when formation of clathrate occurs) | |
| or of clathrate (l = cl when dissociation of clathrate occurs) | ||
| G c | m3 kg-1 s-2 | Gravitational constant |
| G x | mol m-1 Pa-1 s-1 | Diffusion coefficient of gas x in the porous network |
|
mol m-1 Pa-1 s-1 | Knudsen gas coefficient diffusion (Kn > 1) |
|
mol m-1 Pa-1 s-1 | Viscous gas coefficient diffusion (Kn < 10-2) |
| H cl | J mol-1 | Enthalpy of formation/dissociation of clathrate per mole of gas trapped/released |
| H cr | J mol-1 | Latent heat of crystallization per mole of water |
|
J mol-1 | Enthalpy of sublimation of ice x |
| h | Hertz factor | |
| I | J K-1 m-2
 |
Thermal inertia |
|
Initial x/H2O mole fraction of the gas x trapped in amorphous ice | |
|
Mole fraction x/H2O of the gas x trapped in amorphous ice | |
| K m | J s-1 m-1 K-1 | Heat conduction coefficient of the porous matrix |
| K n | Knudsen number | |
| k l | J s-1 m-1 K-1 | Heat conductivity of the solid l (l = i for the solid phase of the icy components x, |
| d for the dust grains and cl for the clathrate) | ||
| K s | J -1 m-1 K-1 | Conductivity of the solid phase of the components (dust and ices) |
| K p | J -1 m-1 K-1 | Radiative conductivity across the pores |
| (m,n) | (0,  )
for the predictor and (,
1) for the corrector |
|
| M n | kg | Comet nucleus mass |
| M H2O | kg mol-1 | Molar mass of water |
|
kg mol-1 | Molar mass of the species x trapped in the clathrate |
| M x | kg mol-1 | Molar mass of the species x |
| n hyd | Hydrate number of clathrate | |
|
mol m-3 | Number of moles of amorphous water ice per unit volume |
| N p | m-2 | Number of cylindrical pores per unit of surface |
| P r | s | Nucleus rotation period of the comet |
| P t | Pa | Total gas pressure |
| P x | Pa | Partial pressure of gas x |
|
Pa | Equilibrium pressure of the corresponding single guest clathrate |
|
Pa | Sublimation vapor pressure of the species x |
|
Pa | Equilibrium pressure of the MG clathrate |
|
mol m-3 s-1 | Rate of trapping/release of volatile molecules x per unit of nucleus volume |
| during the formation/dissociation of clathrate | ||
|
mol m-3 s-1 | Number of moles of gas trapped (k = f for formation of clathrate) |
| or released (k = d for dissociation of clathrate) by the clathrate | ||
|
mol m-3 s-1 | Rate of trapping/release of gas x in/by clathrate per unit of nucleus volume |
|
mol m-3 s-1 | Rate of release of gas x by amorphous water ice per unit of nucleus volume |
|
mol m-3 s-1 | Rate of sublimation/condensation volatile molecule x per unit of nucleus volume |
| R | J mol-1 K-1 | The perfect gas constant |
| R h | UA | Heliocentric distance |
| R n | m | Radius of the nucleus |
| r i | m | Distance of the layer i from the center of the nucleus |
rp,
 |
m | Radius and initial radius of the pores |
| T | K | Temperature |
| t | s | Time |
| V i | m3 | Spherical volume of the layer |
| v t | m s-1 | Thermal velocity of molecules |
| Y cl | J s-1 m-3 | Power per unit volume released/taken during the formation/dissociation of clathrates |
| Y cr | J s-1 m-3 | Power per unit volume released during the crystallization process of amorphous water ice |
| Y chs | J s-1 m-3 | Power per unit volume exchanged between the gas phase of molecule x and the solid matrix |
|
Molar fraction of the volatile x in the gas phase | |
|
Molar fraction of the volatile x trapped in the clathrate structure | |
|
mol m-2 s-1 | Total molar flux of gas x |
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