Performance investigation on a novel single-pass evacuated tube with a symmetrical compound parabolic concentrator

Development of the cost-effective single-pass evacuated tubular collector (SPETC) for the solar processes heat is a particular topic of active research. A novel SPETC with a symmetrical compound parabolic concentrator (CPC) has been introduced, experimentally investigated and theoretically analyzed in this paper. The novel SPETC is mainly composed of a double-glass evacuated tube deposited the selective absorbing coating, as well as six expansion joints. Correspondingly, the symmetrical CPC has been designed and fabricated using the high-reflectivity 3M mirror films pasted over the stainless steel substrate. In addition, detailed numerical models for thermal behaviors of the SPETC with the CPC reflector, based on the three-dimensional CFD method, have been developed and validated with experimental data. The objective of this paper is to report the test results of the novel SPETC with the CPC, evaluate optical and thermal performances including the heat flux distribution on the absorber surface, heat losses, as well as thermal efficiencies, thereby providing useful data for practical solar process heat application. Experimental results indicate that a daily thermal efficiency of 48% can be reached at a difference of 59.6 K between inlet and ambient temperatures under a volume flow rate of 0.0077 m3 s−1. Corresponding numerical prediction shows that the operational volume flow rate between 0.007 and 0.01 m3 s−1 is suggested to the SPETC using the HTF (air) under the geometry and operational conditions in this paper. These results suggested that the novel SPETC is feasible for industrial process heat and solar cooling system combined with the adsorption chiller or the desiccant wheel.