Assuming that the process is stationary, the temperature field in the OiABC section in the Descartes coordinate system O1xz with O1 as the initial point is described by the Laplace equation

[4] :

52 71 52 71 (1)

1 1 = 0, дx2 dz2

We will introduce dimensionless variables and parameters [5], the dimensionless temperatures will be described by the formulae:

where

2 is the heat conductivity of the collector plate, W/m-K; q is the density of the solar heat flow, W/m2; h is the plate’s thickness, m.

2b is the distance between the tubes’ axes, m; r0 is the inner radius of a tube, m.

The Laplace equation and boundary conditions in the dimensionless form will be:

The solution to the problems (6)-(10) is

©1 Ы=Q fe2 V)+1-