A system and method for controlling cooling of a thermal load having different cooling requirements in different sections based on direct thermal exchange using a two-phase refrigerant employs the pressure/temperature characteristics of the refrigerant to particular benefit for this multi-level cooling system. The two-phase refrigerant is first adjusted to have temperature/enthalpy characteristics chosen as the starting level for different cooling demands at related temperatures. After appropriate generation of a mixture of two-phase refrigerant initial reference temperature and pressure are established. Thereafter, incremental changes in the comprising hot gas and expanded cooled liquid/vapor, an temperature cooling medium area made by lowering the pressure by predetermined amounts, or alternatively by bypassing the pressure drop and proceeding to the next stage.