A modified Evacuated Solar Tube: heat transfer and fluid dynamic study, modelling and experimental results

This article deals with a first proposal for a development of a new evacuated solar tube to increase the efficiency and the performance of a solar collector partly avoiding heat losses from the solar tube itself, by conduction, convection or radiation. The solution is partly on the materials selection for the manufacturing of a modified evacuated solar tube and partly on the applied fluid dynamic to the solar collector. After the modelling and simulation of several possible configurations using a finite element modelling tool, we are conducting the first experimental steps using a first prototype of a modified solar tube. The work has been focusing in some main aspects: contact resistances between the different layers from the cermet to the vector fluid; materials used for the evacuated tube; conditions for a turbulent flow to increase the convection heat transfer to the fluid.