EXPERIMENTAL-STUDY OF THE HEAT AND MASS-TRANSFER IN A HIGH-FREQUENCY THERMAL PLASMA REACTOR

The present study reveals some of the important parameters which contr ol the decomposition of ammonia introduced by radial injection into an induction plasma. Temperature and composition gradients of the plasma stream were evaluated with an enthalpy probe connected to a mass spec trometer. Axial and radial profiles are measured at the exit of the pl asma torch to quantify the important mass and energy transfer mechanis ms occurring at two levels of ammonia flow rate. Other experiments wer e made using the enthalpy probe at a ''fixed point'' along the centerl ine of the reactor, near the exit of the plasma torch. These experimen ts were useful in establishing: 1) the minimum radial flow rate that p ermits the ammonia to completely penetrated the plasma, and 2) to eval uate the maximum load of ammonia that could be decomposed by the plasm a. Finally, the ''fixed point'' configuration is used in combination w ith a 2(3) factorial experiment design to quantitatively determine the important parameters that affected the transport properties of the pl asma during the NH3 radial injection. The controlled experimental para meters employed for the factorial were the flow rate of ammonia, the p late power, the reactor pressure, and the how rate of the central plas ma gas, while the torch exit temperature and the Nz and NH3 concentrat ions formed the studied outputs. The findings of the factorial design showed that the plasma temperature inside the decomposition zone could only be modified by means of plasma plate power and ammonia flow rate changes or adjustments. The diffusion of species during ammonia decom position is strongly affected by the four controlled experimental para meters under study.