Abstract
Carbon dioxide (CO2) has potential usage for cooling applications due to its exceptional thermophysical properties near the pseudocritical condition. However, literature pertinent to these conditions is scarce, and as a result, predicting the fluid flow in equipment and flow restriction elements near the critical condition is challenging. In this study, the depressurization effect on the mass flow rate through channels with multiple micro constriction elements is investigated with silicon-based microfluidic devices consisting of arrays of microchannels (micro-orifices). A close-loop experimental setup was built to provide control and measurement of pressure and temperature at the inlet and outlet. Inlet pressure was set to 5.8 and 6.6 MPa (corresponding to liquid and gas states respectively), and outlet pressure ranged from 1.2 to 6.4 MPa. Mass flow rate and density are controlled and measured by a Coriolis flow controller at the inlet. The mass flow rate vs. pressure drops plot exhibits initial increase followed by a smooth convergence as the outlet pressure decreased. The choking phenomenon was observed for both gas and liquid inlet conditions that led to significant temperature drop along the channel with multi parallel micro-orifices.
