Transient heat transfer in a rarefied binary gas mixture confined between parallel plates due to a sudden small change of wall temperatures

•The transient heat transfer through a binary gas mixture was considered.•The evolution of macroscopic parameters in time was obtained.•The time needed to reach the steady state conditions was calculated.•The physical analysis of phenomena was made. Transient behavior of the heat transfer through binary gas mixture, confined between two infinite parallel plates, caused by the sudden change of the plates’ temperatures, is studied for two monoatomic gas mixtures: Ne–Ar and He–Ar. The walls’ temperature changes are considered small compared to the equilibrium temperature of the system, so the McCormack kinetic model is used for the numerical simulations. The time evolution of the main macroscopic parameter is investigated for various species concentrations and for different gas rarefactions ranging from near the free molecular to slip flow regime. It is found that the mixture heat flux takes several characteristic times, which is defined by the distance between the plates over the most probable molecular speed, to achieve its new equilibrium state. This time of the steady state flow establishment depends strongly on the gas rarefaction, mixture nature and composition.