Department of Physics, Faculty of Science and Agriculture, University of Fort Hare, P. Bag X1314, Alice, 5700, South Africa

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Abstract: Energy from wind is envisaged as one of the second largest inexhaustible and clean green energy resource around the world. It has the potential of replacing fossil fuel based energy, which has high carbon dioxide emissions contributing to global warming. In addition, wind energy can provide power in remote areas which are not connected to the national electricity grids. In wind energy technology, wind turbines convert wind energy to electricity. However, most commercially available wind turbines are made for wind speeds greater than 5m/s, therefore fail to operate in areas with low wind speeds. Innovative ways of improving the wind power output include the use of concentrators and diffusers. Although there are notable experimental and computational fluid dynamics researches on concentrator – diffuser augmented wind turbines (CDAWTs), attempts to develop analytical to semi-empirical models are extremely scarce. Only analytical models for diffuser augmented wind turbines (DAWTs) dominate in literature. In this work, a comprehensive review of previously developed analytical models is presented. The information will assist researchers to comprehend current research efforts and to discover the knowledge gaps so as to develop accurate analytical models that incorporate CDAWTs structure. In this review, existing analytical models fail the validity tests due to their underlying assumptions which give incomplete explanations of the major flow phenomena. Once all these issues are considered, an analytical model that predicts accurately the power output of CDAWTs can be developed. This will be a step in the right direction in designing and constructng the CDAWTs for commercialization.

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