Numerical and experimental investigation of the hybrid piston compressor using the novel multi-time-scale OpenFOAM®-based model

Strongly coupled thermodynamic and heat exchange models of the hybrid piston compressor with regenerative heat exchange are developed, calibrated, and experimentally validated. The main challenge is the consideration of gas dynamics and heat transfer processes appearing at time scales different by three orders of magnitude. The Finite Volume Method (FVM) within the OpenFOAM® framework is used to discretize the actual three-dimensional compressor domain for heat exchange computation. On the other hand, the lumped zero-dimension approximation is used for gas dynamics. The present study is the first attempt to suggest a multi-time-scale numerical model of the hybrid piston compressor with no constraints on the domain geometry in the heat exchange part. The compressor's heating during operation was reported to cause a reduction in its energy efficiency. Analysis of the three-dimensional fields of temperature and heat flux demonstrated that the piston and the valve plate are the hottest parts of the domain. Their cooling is not possible with standard approaches to heat exchange enhancement, while regenerative heat exchange within the hybrid compressor helps to circumvent such a constraint. The parametric investigation was carried out by determining the hybrid piston compressor transient processes and its integral characteristics using the proposed numerical model.