variavel0=Carlos Alberto Melo - carlosam@mecanica.ufu.br Universidade Federal de Uberlândia Abstract. In this work is considered the coupling of the characteristic curves of turbines and compressors to obtain an air refrigeration cycle. Is taking account the dissipation in the external components of air cycle, as pipes, valves, coolers, meters and fittings. A governing nonlinear algebraic equations system, due the conservation laws, is obtained. Specials subroutines are developed to calculate the thermodynamic properties of the working fluids, to interpolate the points of the characteristic curves of turbines and compressors and to the solution technique used in this work. Several operation conditions are tested in this computational algorithmic, to the machines(turbines and compressors),as to external components and the respective influences in air cycle. The optimization of the variables of the cycle, as mass flow rate of the gas and of the air, efficiency of the machines, compression and expansion rate, dissipation in the coolers, air inlet temperature in the compressors, outlet temperatures in the coolers and the performance coefficient, is very important to specification, design and operation of air cycle. Keywords. Energy cogeneration, refrigeration, turbo-compressors, simulation and design.