Analysis of Conduction Heat Loss From a Parabolic Trough Solar Receiver with Active Vacuum by Direct Simulation Monte Carlo

Abstract

Results are reported of a numerical analysis of conduction heat loss from a parabolic trough solar receiver with controlled pressure within the annular gap between the tubular absorber and the glass vacuum jacket. A direct simulation Monte Carlo (DSMC)model of rarefied gas within the annular gap is coupled to radiation heat transfer for directional- and spectral-dependent concentrated incident solar radiation. This modeling approach is valid for high Knudsen numbers, and consistently predicts slightly higher heat loss than a continuum model using slip boundary conditions in the range of pressures of interest around 1 Pa. 3-D simulations of axial flow through the annular gap predict higher gas conductance by the DSMC method than by slip flow models, with values converging as pressure increases.

Acknowledgments

This study has been conducted in the framework of the EU-Project HITECO (new solar collector concept for high temperature operation in CSP applications), funded by the EU 7th Framework Program (FP7/2007-2013) under grant agreement number 256830.