The testing of an evacuated tubular collector with a heat pipe using the Fourier frequency domain

Abstract

An outdoor method for the testing of an evacuated tubular collector with a heat pipe under a variable insolation has been described. Based on a heat balance of the collector defined in the Fourier frequency domain, a set of equations corresponding to selective values of the Fourier variable can be formulated. The main collector parameters such as the absorptance-transmittance product, the heat loss resistance and the efficiency factor, follow from a least-square approximation. At least two series of experimental measurements with a different fluid inlet temperature are required.