The article deals with the model equations for describing of convection fluid dynamics in microtubes. The convection is initiated with temperature gradient and described by the Boussinesq buoyancy approximation. The model is supplemented with arbitrary series of chemical reactions described on the basis of Arrhenius chemical kinetics. It is shown that the change of convection flows makes strong impact on the reaction rates. The model demonstrates a possible approach to a numerical simulation of polymerase chain reaction
