Mathematical simulation of heat transfer and chemical reactions in an equilibrium dissociating gas

Results of investigations of the heat exchange in the turbulent fl ow of nitrogen tetroxide in a cylindrical channel are presented. The equilibrium stage of the dissociation reaction N₂O₄ - 2NO₂ was considered. It was established that an increase in the temperature of the wall of the channel leads to an intensifi cation of the chemical reaction proceeding in the N₂O₄ fl ow and causes the absorption of the heat, transferred from the channel wall, in this fl ow to increase, with the result that the temperature of the near-wall layers and the thickness of the thermal boundary layer in the chemically reactive gas fl ow decrease to a level lower than those of a chemically inert heat-transfer agent. It is shown that the use of a dissociating heat-transfer agent in a short channel is advantageous in the case where the rate of its fl ow is small, and, to increase the effi ciency of heat exchange in a high-velocity fl ow of such an agent, it is necessary to increase the length of a heat exchanger. Approximation formulas for determining the criteria of heat exchange in fl ows of chemically inert and reactive gases have been obtained.
Results of investigations of the heat exchange in the turbulent fl ow of nitrogen tetroxide in a cylindrical channel are presented. The equilibrium stage of the dissociation reaction N₂O₄ - 2NO₂ was considered. It was established that an increase in the temperature of the wall of the channel leads to an intensifi cation of the chemical reaction proceeding in the N₂O₄ fl ow and causes the absorption of the heat, transferred from the channel wall, in this fl ow to increase, with the result that the temperature of the near-wall layers and the thickness of the thermal boundary layer in the chemically reactive gas fl ow decrease to a level lower than those of a chemically inert heat-transfer agent. It is shown that the use of a dissociating heat-transfer agent in a short channel is advantageous in the case where the rate of its fl ow is small, and, to increase the effi ciency of heat exchange in a high-velocity fl ow of such an agent, it is necessary to increase the length of a heat exchanger. Approximation formulas for determining the criteria of heat exchange in fl ows of chemically inert and reactive gases have been obtained.
Author:  O. V. Matvienkoa, and P. S. Martynov
Keywords:  heat exchange, chemical reaction, dissociation, boundary layer, computational hydrodynamics
Page:  437-449