Investigating the combined effect of square microgrooves and CNT coating on condensation heat transfer

The combined effect of square grooves fabricated using picosecond laser treatment and CNT coating deposited using dip coating technique on the condensation surface was studied. Apart from being a highly time efficient process, the utilisation of laser texturing technique allows for precise control of the groove dimensions. The fabricated surface was characterized for its surface morphologies and wettability characteristics and the results are placed appropriately. A condensation experimental setup was designed and fabricated, in which the experiments were carried out to analyse the performance of modified copper surfaces. The values obtained from the plain copper surface served as a reference to compare the performance of various modified surfaces. The combined effect of square grooves and the CNT coating were evaluated and compared with its counterparts. Wettability of the modified surfaces was measured using contact angle meter which is very crucial for condensation heat transfer. Results corresponding to the modified surfaces were found to have improved performance as compared to the plain copper surface. In case of modified surfaces, the sample with the combination of square grooves and CNT coating was found to excel in heat transfer performance when compared to its counterparts. An enhancement of approximately 63%, 29% and 96% were obtained for grooved, CNT coated surface and grooved CNT coated surface respectively in the heat flux values, when compared against bare copper surface. Similarly, heat transfer coefficient values registered an improvement of 29%, 31% and 58% respectively for grooved, CNT coated surface and grooved CNT coated surface. The CNT coated surface was hydrophobic in nature, while the micron scale grooves reduced the departure diameter and increased the sweeping cycle rate, which has a positive effect on the heat transfer rate. Droplet departure diameter reduced by nearly half and departure frequency increased by nearly 3 times for grooved CNT coated surface, against the bare copper surface.