Primary nozzle is one of the most important factors which has a large influence on the performance of thermo-compressors. Most of studies carried out until now, have been performed on Single-nozzle thermo-compressors. In this paper, an actual industrial thermo-compressor is considered and the purpose is to study the effect of increasing primary nozzle number on the performance of this thermo-compressor. For this purpose, a triple-nozzle thermo-compressor is simulated numerically and its performance is compared with Single-nozzle thermo-compressor. Ideal gas thermodynamic properties are considered to simulate the compressible flow within the thermo-compressor and numerical result is validated using the experimental result. In addition, the effects of variation in mixing chamber convergence angle and position of nozzles at the radial direction in triple-nozzle thermo-compressor are investigated. The numerical results show that at the same condition, a triple-nozzle thermo-compressor is able to provide superior critical back pressure and entrainment ratio than Single-nozzle thermo-compressor. The proximity of nozzles (with 34% changes in radial distance) increases the critical back pressure about 8% and decreases the entrainment ratio about 5%. By increasing mixing chamber convergence angle about 66%, the value of critical back pressure decreases about 29% and the value of entrainment ratio decreases about 16% in Single nozzle-thermo-compressor and 10% in triple-nozzle thermo-compressor. Also, by 8% reduction of mixing chamber convergence angle, the critical back pressure decreases 6% but entrainment ratio decreases about 2% in Single-nozzle thermo-compressor and increases about 3% in triple-nozzle thermo-compressor.