MATHEMATICAL MODELING OF THE PHASE TRANSITION PROCESSES WITH METASTABILITY EFFECTS FOR TRANSCRITICAL R744 CONVERGING-DIVERGING NOZZLES

摘要

The effects of metastability in the phase transition processes for the transcritical R744 converging-divergingrnnozzles were investigated in this study. The research comprised both numerical simulations and experimentalrnmeasurements, performed for the operating conditions typical for a R744 heat pump. The computationalrnapproach utilized the Delayed Equilibrium Model based on superposition of the homogeneous andrnheterogeneous nucleation. The research was performed at the test facility specially designed for experimentalrninvestigation of the small-scale, ejector-equipped heat pumps. Based on the results for a sample conicalrngeometry, the authors developed and validated a correlation equation for the nucleation work reductionrnfactor. Once validated, the model proved to yield acceptably low discrepancies between the simulation andrnthe experimental results, also for other nozzle geometries.