Experimental investigation of water-nitrogen flow in microchannel with high aspect ratio (with the 20 µm gap)

This study is devoted to the experimental investigation of two-phase water-nitrogen flow in the slit microchannel with a gap of 20 µm and a width of 10 mm. The technology of microchannel fabrication has been developed and described in detail. Experiments were conducted in adiabatic conditions. Using a modified schlieren system, four flow patterns have been observed and described: jet, bubble, churn, and annular. Flow pattern map was plotted according to obtained patterns. Moreover, a two-phase pressure drop was measured. Dependencies between two-phase pressure drop and superficial liquid and gas velocities have been investigated.

A review of single-phase pressure drop characteristics microchannels with bends

Microfluidic use in various innovative research, many fields aimed at developing an application device related to handling fluid flows in miniature scale systems. On the other hand, on the use of micro-devices for fluid flow the existence of bends cannot be avoided. This research aims to make a comprehensive study of fluid flow characteristics through a microchannel with several possible bends. This study was conducted by comparing Reynolds number versus pressure drop in a serpentine microchannel to gain bends loss coefficient. The result showed that the fluid flow with Re 100 did not affect the pressure drop, but on the Reynolds number above that, the pressure drop was increased along with the appears of vortices in the outer and inner walls around the channel bends which causes an increase in an additional pressure drop. The other finding shows that the reduction in diameter bend tube can increase the pressure drop.

Development of Empirical Correlation of Two-Phase Pressure Drop in Moisture Separator Based on Separated Flow Model

Pressure drop across the moisture separator installed in the steam generator of a nuclear power plant affects the power generation efficiency, and so accurate pressure drop prediction is important in generator design. In this study, an empirical correlation is proposed for predicting the two-phase pressure drop through a moisture separator. To ensure the applicability of the correlation, a series of two-phase air-water experiments were performed, and the results of the present test and of the benchmark test of high-pressure steam-water were used in developing the correlation. Based on the experimental results, quality, dimensionless superficial velocity, density ratio of the working fluid, and the geometrical factor were considered to be important parameters. The two-phase pressure drop multiplier was expressed in terms of these parameters. The empirical correlation was found to predict the experimental results within a reasonable range.