Attainment of maximum levels of natural convective heat transfer across major cavities using as a coolant a mixture of two pure gases instead of air

The enhancement of heat: transfer in natural convection cavities is a very difficult task because of the intervening low fluid velocities. It is of fu ndamental and practical interest to explore alternative instruments that ar e power-independent and exclude surface modifications for the augmentation of heat transfer in these cavities. One feasible way for enhancing heat tra nsfer rates passively in cavities filled with a gas is to stimulate the mec hanism by natural convection of heat. The central objective of this paper i s to employ a mixture of two pure gases that yields levels of heat transfer increments that are unattainable by each pure gas acting along (or even by air). In general, dimensional analysis insinuates that four transport prop erties affect natural convection flows: density, isobaric specific heat cap acity, dynamic viscosity and thermal conductivity. Simple correlation equat ions of power form are useful to engineers for a quick estimate of the magn itudes of the space-mean heat transfer coefficient. Detailed computations w ere made for four different gases: air, pure helium, pure argon, and a mixt ure of pure helium and pure argon and the relative merits of each of them h ave been discussed. Five major cavities of relevance in applications of the rmal engineering have been analyzed in this work.