IIR document

Technical feasibility of a novel oil-free co-rotating scroll expander for a kalina cycle.

Number: pap. n. 6

Author(s) : MENDOZA L., SCHIFMANN J.

Summary

Kalina cycle is of great interest since it uses low temperature energy resources and yields better performance than typical power cycles based on Rankine technology. Moreover, the use of natural working fluids like ammonia and water have no ozone depletion potential (ODP=0) and no greenhouse effect (GWP=0). However, Kalina cycles have not been studied in depth for low power range because of the lack of suitable expansion devices that can work in presence of ammonia and water. The main requirements for the expansion device are material compatibility with ammonia (stainless steel or aluminium) and complete oil-freeness to avoid the occurrence of water-oil emulsions. A novel scroll machinery based on co-rotating technology (currently in a prototyping stage) allows to work without internal lubrication in expansion mode. In order to demonstrate the expander’s working principle and characterize its preliminary performance an experimental investigation has been performed. A simplified semi-empirical reduced order model is proposed to predict its performance. Finally, a technical feasibility study about the novel oil-free co-rotating scroll machine working as expander in a Kalina cycle is carried out. The calculations show that the co-rotating scroll expander working in a Kalina cycle could achieve overall isentropic efficiencies in the range 54% - 60% and that the Kalina cycle could achieve net thermal efficiencies in the range of 6.3% - 8.7% and exergy efficiencies between 23.8% and 33.6% depending on the sink water temperature.

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Pages: 8 p.

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Details

  • Original title: Technical feasibility of a novel oil-free co-rotating scroll expander for a kalina cycle.
  • Record ID : 30014582
  • Languages: English
  • Source: 6th Conference on Ammonia and CO2 Refrigeration Technology. Proceedings: Ohrid, North Macedonia, April 16-18, 2015.
  • Publication date: 2015/04/16

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