The effects of cross-links, introduced in the channel core of an array of parallel scaled microchannels, were investigated by comparison of the flow distribution in six different multichannel configurations. A standard straight channel test section and five other test sections, which incorporated cross-links were used. One case includes two cross-links located at 1/3 and 2/3’s of the channel length, with their width varied by one, two, and three times the channel width. Whereas, four and six cross-links were used for the other case. All test sections had 45 parallel rectangular channels, with a hydraulic diameter of 1.59 mm, and were fabricated from clear acrylic to enhance flow visualization. The flow distribution was monitored at four select channels. The working mixture was air and water with superficial velocities ranging from 0.03 to 9.93 m/s, and 0.04 to 0.83 m/s, respectively. This corresponds to an observed range of flow quality between 0 and 0.25, whereby the mass flux range is from 42 kg/m2s to 834 kg/m2s. The cross-linked designs permit fluid communication between channels, and the results showed that there is a significant impact on flow distribution when compared to the straight channel design. This is due to flow sharing between neighboring channels. Flow patterns were presented in terms of fractional time function, and provided further insight to flow characteristics. Comparing with a single channel flow regime map, the expected intermittent flow regime was observed 84% to 90% of the time for the cross-linked designs, whereas 65% to 80% of that for the straight channel design.
Mass flow rate of liquid, kg/s j Superficial gas velocity, m/s Thermal management for high performance of miniaturized electronic devices using microchannel heat sinks has recently become of interest to researchers and industry. Obtaining heat sink designs with uniform flow distribution is strongly desired. A number of experimental studies have been conducted to seek appropriate designs for microchannel heat sinks. However, pursuing this goal experimentally can be an expensive endeavor. The present work investigates the effect of cross-links on adiabatic two-phase flow in an array of parallel channels. It is carried out using the three-dimensional mixture model from the computational fluid dynamics (CFD) software, Fluent 6.3. A straight channel and two cross-linked channel models were simulated. The cross-links were located at 1/3 and 2/3's of the channel length, their width varied by one and two times the channel width. All test models had 45 parallel rectangular channels, with a hydraulic diameter of 1.59 mm. The results showed that the trend of flow distribution agrees with experimental results. A new design, with cross-links incorporated, was proposed and the results showed a significant improvement, up to 55%, on flow distribution, compared to the standard straight channel configuration without a penalty in the pressure drop. The effect of cross-links on flow distribution, flow structure, and pressure drop was also documented.
Thermal management as a method of heightening performance in miniaturized electronic devices using microchannel heat sinks has recently become of interest to researchers and the industry. One of the current challenges is to design heat sinks with uniform flow distribution. A number of experimental studies have been conducted to seek appropriate designs for microchannel heat sinks. However, pursuing this goal experimentally can be an expensive endeavor. The present work investigates the effect of cross-links on adiabatic two-phase flow in an array of parallel channels. It is carried out using the three-dimensional mixture model from the computational fluid dynamics software, FLUENT 6.3. A straight channel and two cross-linked channel models were simulated. The cross-links were located at 1/3 and 2/3 of the channel length, and their widths were one and two times larger than the channel width. All test models had 45 parallel rectangular channels, with a hydraulic diameter of 1.59 mm. The results showed that the trend of flow distribution agrees with experimental results. A new design, with cross-links incorporated, was proposed and the results showed a significant improvement of up to 55% on flow distribution compared with the standard straight channel configuration without a penalty in the pressure drop. Further discussion about the effect of cross-links on flow distribution, flow structure, and pressure drop was also documented.
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