Hydrodynamic behaviors of adiabatic and diabatic two-phase flow within various particle beds

초록

In this paper, we comprehensively evaluate the hydrodynamic behaviors of fluid flow through porous particle beds using various types of experimental and numerical results including single-phase flows of both gas and liquid, and two-phase flows under both adiabatic and diabatic conditions. Moreover, the examined porous beds were constructed with both uniform and non-uniform sized particles (range of particle diameters: 0.5–10 mm). The experimental data clearly showed the featured trends of the two-phase pressure loss depending on relative intensity of the individual forces, such as gravitational, gas drag, liquid drag, and interfacial drag forces. Particularly, the numerical prediction results to the pressure loss indicate the importance of a proper model for the interfacial drag force considering the flow regime transition within the particle beds. From the two-phase experiments, the counter-current flooding limit (CCFL) and dryout heat flux (DHF) phenomena were observed for adiabatic and diabatic (boiling) cases, respectively. The existing models greatly overestimated the superficial gas velocity at which the CCFL occurs in the adiabatic experiments, and we modified the assumption of zero liquid flow into the gravitational liquid flow resisted by the viscous force. The modifications can properly predict the two-phase pressure loss and CCFL in the adiabatic experiments. The results of two-phase pressure loss and DHF in the boiling experiments indicates a relatively strong effect of the interfacial drag force due to the phase-change. We examined and analyzed quantitatively the physical relevance of existing models to simulate the hydrodynamics governing boiling phenomenon in porous beds. Additionally, the phenomenological descriptions associated with the numerical results on the local thermal and hydraulic behaviors can contribute to give a physical insight into the complicated two-phase flow phenomena involving the phase-change in porous particle beds. © 2022 Elsevier Ltd

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