Thermal and thermo-mechanical analysis of a novel pass-through all-glass evacuated collector tube by combining experiment with numerical simulation

The collector tube could be a significant component of a solar water heater (SWH), that directly determines its performance and application eventualities. Here, a completely unique pass-through all-glass evacuated collector tube (ETC) is projected, which includes an easy structure composed inner and outer layers with each ends amalgamate along and no free ends. In addition, the flow pattern of the working medium in the tube also changes from laminar to turbulent flow, and natural convection changes to forced convection, greatly improving the convective heat transfer efficiency. Such a solar collector tube reaches 50% thermal efficiency at 54 °C in operation temperature and DNI = 1000W/m², and might reach about 82 °C stagnation temperature at identical condition. Compared to standard Dewar tube, the pass-through ECT includes a higher thermal efficiency thanks to a lower inner layer temperature and better exit temperature. Completely different thermal expansions cause thermal stress within the glass structure, however the utmost stress between the inner and outer tubes was unbroken at intervals 40–120 MPa guaranteeing safe and stable operation at intervals the attainable temperature regime.