Design calculations of thermohydraulic parameters of the secondary target of the intense neutron source (INS) based on muon-catalyzed fusion (CF) (the CF-INS) are presented for a liquid deuterium-tritium (D-T) mixture. The synthesizer is connected to an external cooler by input and output pipelines. The optimal mixture composition, synthesizer layout, and dimensions are determined. The possibility of creating a D-T mixture flow with a quasi-uniform velocity distribution is demonstrated. Possible vortexes were found to be eliminated by installation of corresponding hydraulic resistance in the shape of a spherical shell segment. At the CF-INS operation with its design parameters [neutron flux as high as 1014 n/(cm2s)], the total heat deposit in the D-T mixture due to fusion and charged-particle ionization losses is estimated at ~117 kW. However, even at such conditions, with the appropriate synthesizer geometry and mass flow rate, the mixture temperature does not exceed the boiling point in any part of the synthesizer.