Performance analysis of a hydraulic air compressor

The combined exploitation of different kinds of primary energy source in innovative power plants is a promising way to enhance the energy conversion efficiency. In recent years, a possible utilization of the hydraulic resource for power generation in non-conventional plants has been proposed. The basic concept is to couple a conventional gas turbine combustion chamber and expander with a hydraulic air compressor, a device whose main characteristic is the capability to compress air isothermally using a hydraulic energy source. A hydraulic air compressor-gas turbine power plant, with an extended regeneration at the turbine exhaust, can be characterized by an attractive overall efficiency. The performance of a hydraulic air compressor-gas turbine power plant is strongly influenced by the characteristics of the hydraulic compressor itself. In the present paper, an improved (with respect to the previous literature) model of the hydraulic air compressor and an original loss analysis model are presented. The results of a performance and loss parametric analysis are presented and discussed; maps which relate to the natural site characteristics, the obtainable performance and main plant design parameters are also reported and discussed.