3D-printed swirler for enhanced heat transfer in evacuated tube solar collectors

Solar thermal energy is a promising sustainable resource for decarbonizing the energy sector. The optimization of existing solar systems can be a valuable and sustainable approach to promoting a transition to sustainable energy and as well as reducing the land occupation of solar plants. For that reason, in this work, we studied and realized a “swirl generator” device that controls the turbulence of water in the pipe of a solar collector to improve heat transfer. The swirler device is a small insert (2.5 cm in length) with 3 winglets with a helicoidal shape; the customized devices by 3D printing has been used for the retrofitting existing collectors. The swirler has been realized using 3D printing using PA polymer and mounted on the inlet of the evacuated tube collector. We support our experimental work with a numerical thermos fluid-dynamics model based on the Finite Element Method (FEM). The numerical simulations have been effectively performed using the Comsol Multiphysics® software to study in a predictive manner the effect of the swirling device on the fluid dynamics of the collector pipe. The swirler has been tested on a solar collector based on an evacuated tube collector. The experimental results are in good agreement with simulation results, moreover, an improvement in the heat transfer of 25 % and an increase in the homogeneity of the temperature has been observed using the swirler device.