CFD modelling of a novel liquid Nitrogen/Air engine and cryogenic heat exchanger for small scale applications

Liquid nitrogen/air is considered as a promising energy storage vector where a number of mathematical and thermodynamic studies have shown its feasibility to provide cooling and power for both domestic and commercial applications. The current work presents a CFD modeling of storage system that uses liquid Nitrogen/Air generated using surplus electricity at off peak times or renewable energy sources, to provide cooling and power for domestic applications. Ansys Fluent 17.2 software was used in this study to model the main two components of the proposed system (cryogenic heat exchanger which provides cooling effect and expander (cryo-engine) that generates electrical power). The CFD modelling of boiling process of LN2 in the cryogenic heat exchanger was compared with an experimental data that available in the literature and showed a good agreement. Also, the model showed encouraging results where the engine power output reaches 2.2 kW at inlet pressure of 20 bar. Taking to account the generated cooling energy the total energy output reaches 14.6 kW which is enough to run domestic hoses at the peak times.