Abstract: A process for the selective sealing of at least one end of a cellular module, the latter having rows of parallel channels for carrying at least two different fluids. The process consists of depositing a tight material on the end of the module to be sealed. Deposition is preceded by a preblocking operation using a material in the channels to be sealed which does not contribute to the actual sealing, but which serves as a mechanical support during the deposition of the sealing material, whereby only those channels having the preblocking material are sealed.

Abstract: A method for selectively obturating at least one end of a structural module provided with rows of parallel ducts for the passage of at least two different fluids, said method comprising the steps of forming notches in those portions of the module end corresponding to the rows through which flows a first one of said fluids, said notches forming openings through the lateral wall of said module, and depositing an impervious material over the end of said module, so as to obturate the ducts through which the other fluid or fluids flow, while laterally leaving free access, by means of said notches, to the ducts through which flows said first fluid, said impervious material being sprayed in a liquid state, then gradually cooled, the angle at which it is sprayed being between 18.degree. and 30.degree. with respect to the direction of the ducts.

Abstract: Process for the production of alveolar modules comprising rows of parallel channels, certain of which issue onto the sidewalls of the module, the process consisting of producing the module by extrusion using at least two independent systems each producing rows of identical channels, whereby the formation of one of the systems is interrupted when the row of channels being produced is to issue onto the sidewalls of the module.The apparatus for performing this process comprises a first extrusion system incorporating first extrusion material supply means and a first spinneret complementary to the cross-section of the rows of channels issuing onto the sidewalls of the module and a second extrusion system incorporating second extrusion material supply means and a second spinneret complementary to the cross-section of the other rows of channels, the first and second supply means being controlled independently of one another.