Search

A PAT normally has a lower efficiency than a conventional turbine applied at the same site. In the long term, a higher efficiency is important for users in that more energy is produced. A pump’s geometry can be modified to improve its efficiency in turbine mode. Several methods of PAT geometry modification are presented for the improvement of PAT efficiency. Optimization of the internal pump geometry for reverse use is fundamental also for the reduction of the cost of PAT maintenance. Therefore, the industrial aspects of PAT reliability in terms of different design methods, solutions and recommendations are described. Practical technical skills relating to the PAT inlet/outlet parts and impeller geometry modification in order to improve the PAT efficiency are presented. Basic concepts in relation to mechanical reliability are given and the analytical methods to assess the reliability of an industrial PAT are provided.

Users, researchers and engineers require a fundamental knowledge of reverse pump theory. In this chapter first, a complete description of all PAT components is given. Then, the theory of small reverse pumps is described, based on the results of theoretical analyses, experiments and numerical simulations. PAT characteristic and efficiency curves are introduced and, the influence of pump size and rotational speed on such curves is considered. The possibility of using numerical simulations instead of experimental results is discussed. Finally, additional aspects like cavitation and the incidence of pressure surges are presented and different tools, commonly used for PAT sizing and hydropower plant design, are described. The reader will be prepared, by means of the theoretical basis provided, for the comprehension of the hydraulic and mechanical processes connected with a PAT operation.