Two-phase flow, pressure drop, and Joule-Thomson effect in a micro-orifice with trans critical carbon dioxide flow

Abstract

Two-phase flow, pressure drop, and Joule-Thomson coefficient (JTh) of sub- and super- critical carbon dioxide expanding through a 81 µm orifice embedded inside a 300 µm microchannel was experimentally studied. It was demonstrated and validated that a flow of CO2 in a micro-orifice can support the thermodynamic conditions that are ripe for the JTh effect to be significant. The inlet pressure, temperature, and mass flux were independently varied between 5.6 MPa and 10.2 MPa, 293 K and 314 K, and 47,277 kg/m2s and 162,101 kg/m2s, respectively. The measured pressure drop and Joule-Thomson coefficient ranged from 0.1 MPa to 5 MPa and from 0 K/MPa to 10 K/MPa, respectively. Pressure drop results were compared with the homogenous two-phase flow model, the separated two-phase flow model, the capillary tube model, and an empirical fit equation that resulted in mean average errors of 0.84 MPa, 1.4 MPa, 0.7 MPa, and 0.75 MPa, respectively.