  Reconstruction of the thermal history of individual meteorites which can be
assigned to the same parent body allows to derive general characteristics of
the parent body, which hold important clues on the planetary formation process.
This requires to construct models for the heating of such bodies by short lived
radioactives, in particular by 26Al, and its cooling by heat conduction, which
then are compared with the cooling histories of the meteorites. The heat
conductivity of the planetesimal material depends critically on the porosity of
the chondritic material and changes by sintering of the material at elevated
temperatures and pressures. Compaction of a granular material is a key process
for the thermal history of the parent bodies of meteorites. The modelling of
the compaction process is improved by applying concepts originally developed
for hot isostatic pressing in metallurgical processes. It is extended to a
binary mixture of matrix and chondrules, as observed in chondrites. By
comparison with published data on sintering experiments it is shown that the
algorithm allows a sufficiently accurate modelling of the compaction of
silicate material. It is shown that the characteristic temperature at which
sintering occurs is different for matrix or chondrule dominated precursor
material. We apply the new method to model the thermal evolution of the parent
body of the H chondrites and determine an improved optimized set of model
parameters for this body.
