Design of a Compressor – Expander Group (CEG) for internal power recovery in cryogenic power plants
The electrical power consumption of refrigeration plants is evaluated to be in the order of 15% of the total electricity consumption worldwide. For this reason, many efforts are spent in the development of energy saving techniques to be applied to refrigeration and air conditioning systems. My PhD activities deal with the development of a device which allows an internal recovery in cryogenic plants, reducing their power consumption. Such a device consists in a Compressor-Expander Group (CEG) developed on the basis of automotive turbocharging technology.
According to the rules of the similarity theory, a preliminary CEG design has been realized modifying commercially available components. In order to address the new requirements, an expander wheel and a compressor wheel derived from the turbocharging technology have been strongly modified. To verify the performance of such machines and suggest improvements, numerical fluid dynamic models have been set up. 3D CFD analysis have been carried out successfully using Ansys commercial code.
Fig.1: Cryogenic cycle with internal power recovery.
Fig. 2 : Compressor wheel geometry and mesh on Ansys; Mach number at compressor mid-span – 30 krpm, pressure ratio 1,41