No abstract

This paper aims to obtain a better heat transfer performance by using vortex generators with different structures in the square channel. To compare the flow pattern of three different vortex generators, the stream‐wise velocity profile, the visualized Q‐criterion, and the stream‐wise vorticity flux distribution were used to obtain the flow structures in detail. The heat transfer performance was quantified by the Nusselt number (Nu) and compared for the different vortex generators. It was found that the concave structure vortex generator has a better heat transfer performance with an increase of about 11.07% for average Nu. This is because the concave vortex generator induces a more complex hydraulic dynamic flow structure due to its two counter rotating vortex pairs in the square channel. Furthermore, the distance from the lower counter rotating vortex pairs to the wall is significantly decreased by the restraint from the upper counter rotating vortex pairs. This can help disturb the thermal boundary layer and improve the heat transfer performance.

A continuous-flow PCR system is presented, which based on the microfluidic platform briefly consists of a PMMA chip with a PCR liquid channel, three heating units. Each of them contained a heat conducting block on a commercially available thin PI substrate. In order to ensure temperature uniformity across the PCR temperature zones and minimal cross-talk between the zones, the design of chip and heating units was assisted by COMSOL. The simulation results presented the most suitable thickness for the chip and heat conducting block as well as the height limit for the liquid channel. Within the optimized parameters, our system not only has the advantages of fast amplification rates, but also has the benefits of small thermal mass and low power consumption.

No abstract

No abstract