Heat Transfer by Free Convection of Air through open-type-vertical Pipes with Annular Space

Abstract

A general case was treated, in which surface temperature distribution of vertical and concentric pipe-walls with annular space varied axially. In theory, Fourier series, Bessel function and Hankel function with imaginary variable, Laplace transformation and homogeneous integral equation were used and, as a new attempt, method of numerical solution of Volterra's integral equation of the 2nd kind was used. Theory was compared with experiment of air, using the zero-approximation of theoretical solution calculable numerically and simply, partially experimental, and a partially theoretical solution, which showed the experimental results, was conducted. The influences of dimensions of every parts, temperatures and Grashof number, which influenced on heat transfer, were made clear and practical formulas were found.