Condensation heat transfer enhancement in a horizontal non-circular microchannel

• A numerical model for film condensation in non-circular microchannel is developed.
• Microchannel shapes and contact angle on condensation heat transfer is investigated.
• Reducing microchannel diameter will reduce film thickness and increase heat transfer.
• Increasing contact angle from 6 to 15 will improve heat transfer up to 100%.
• The lowest average Nusselt numbers are obtained for the square microchannel.

Numerical investigation of steam condensation in a non-circular microchannel is conducted. The conservation equation of mass, momentum and energy have been solved in both phases for various microchannel hydraulic diameters. Different correlations established for condensation flow heat transfer are evaluated. It is found that the correlation of Dobson et al. and Koyama et al. are the closest to the calculated steam condensation average heat transfer. Results are given for different microchannels shapes, aspect ratio, and for various inlet vapor mass fluxes and contact angle. Reducing the microchannel hydraulic diameter from 250 to 80 μm reduces the condensate film thickness and increases the average heat transfer coefficient up to 39% for the same mass flux. The enhancement factor of the heat transfer coefficient reaches 100% by increasing the contact angle from 6 to 15°. The influence of the microchannel shape on the condensation heat transfer is highlighted too. Thus it is seen that the lowest average Nusselt numbers are obtained for the square microchannel.

Effect of microchannel shape and aspect ratio on the condensation heat transfer.Figure optionsDownload as PowerPoint slide