Cavitation models with thermodynamic effect for organic fluid cavitating flows in organic Rankine cycle systems: A review

Highlights

• A systematic review of cavitation models with thermodynamic effect is made.

• A method for classification of cavitation models was proposed.

• Methods for implementing thermodynamic effect in cavitation models are summarised.

• Cavitation regimes are not distinguished and applied properly in modelling.

• Nucleation cavitation models for organic fluids in ORC systems are desirable.

Abstract

Organic Rankine cycle (ORC) power plants are considered as one of the most promising technologies to generate power from low temperature heat sources such as biomass combustion, industrial waste heat, geothermal heat, and solar thermal energy. A feed pump is a key component of an ORC power plant to circulate the working fluid within the system. Owing to the low boiling temperature of most organic fluids, the feed pumps of ORC power plants are more vulnerable to suffer from cavitation. Cavitation of the organic fluid in the feed pump in an ORC system can degrade the evaporator performance and cause instabilities in the system operation. Properly determining the required net positive suction head or subcooling for the pump is critical for the ORC system design and operation. Thus, this paper presents a systematic review of cavitation models with thermodynamic effect in simulations of cavitating flows. Methods for implementing thermodynamic effect were summarised. The features of the cavitation models were characterised and criticized, and their drawbacks were identified. A number of newly established cavitation models were explained and discussed in detail. Homogeneous mixture cavitation models have advantages such as less computational effort and easier implementation of thermodynamic effect in comparison with fully coupled multiscale models. However, when the thermodynamic effect is considered in the existing cavitation models, the cavitation regimes are not distinguished and applied properly. Nucleation cavitation models for organic fluids in ORC systems should be developed in terms of experimental nuclei profile and non-condensable gas concentration in future.