Solar plant with short diffuser concept: Further improvement of numerical model by included influence of guide vane topology on shape and stability of gravitational vortex

Abstract

An alternative renewable energy concept, i.e. the concept of a solar power plant with short diffuser (SPD), was numerically investigated by more advanced computational fluid dynamics (CFD) model. Developed model is characterized by a more sophisticated and streamlined guide vane topology. The main novelty of this work is conducted optimization of the guide vane topology, for a specific novel application related to the alternative renewable energy concept (SPD). Optimization involved determining the required guide vane topology using minimal number of geometry influencing parameters. The objective was to result in vortex genesis and stabilization with respect to the desired circumferential velocity and to minimize the required pressure potential that is necessary for stable operation of the SDP plant. Provided numerical investigation was necessary, and for sure a step forward towards consideration of the experimental plant (which will assume introduction of the turbines). It needs to be taken into account that we deal with complex flow structure that requires gradual numerical investigation, in order to be able to get detail insight in the various influences and processes that can strongly affect SPD operating parameters. The guide vane topology was altered to develop an SPD capable of establishing and maintaining a stable gravitational vortex in pressure ranges which resemble atmospheric vortex phenomena (feasible for development of a compact system, and with maximal velocities in chimney throat regions ranging below 20 m s−1). The study outlines nine cases, each representing the altered guide vane design, where the best case is determined and compared with the available experimental data from other research groups. The comparison indicates that the numerical model, although quite simple, is accurate and robust in predicting the distribution of local velocity and pressure profiles and fit for implementation on wind turbines in order to determine the influence of the installed turbines on the vortex shape and stability in a future study. An important finding is that the swirl ratio can be manipulated by altering the guide vane shape, and it is independent of the Reynolds number (which will be important during the design phase since it can be used as a control strategy for vortex genesis and as a prevention of unintentional genesis regarding additional multiple vortices). The gained numerical results revealed specific operating conditions that will ensure a safer environment around the SPD and that will enable a carbon free electricity production.