Fabrication and investigation of superhydrophobic surface by dip coating

The present research work is focused on to fabricate and examine the characteristics of a superhydrophobic surface on copper (Cu) substrates by dip coating method. Three different samples of ‘Cu’ are set with chemical etching, mechanical rubbing and the combination of above two methods. The variations in the exteriorsurface morphologies have been examined by profilometer, scanning electron microscope and energy-dispersive X-ray spectroscopy. The adapted samples are immersed in a solution of silver nitrate follow by immersing in a combination of ethanol and perflurodecyltriethoxysilane for 10 min. The presence of leaf and dendrites assemblies have been observed on the surface, which are useful to trap the air between them and the entrapment allows water to roll off from the surface. The outcomes reveal that the modified substrates have a water contact angle (WCA) of 159° in the case of ‘Cu’ using combination of chemical etching and mechanical rubbing followed by immersion coating. The proposed methodology has the advantage of size compatibility and easy scale up for the development of superhydrophobic surface on copper in a cost and time effective manner

Fanning friction (f) and colburn (j) factors of a louvered fin and flat tube compact heat exchanger

In the present study, the heat transfer and pressure drop characteristics of air over the louvered fins in a compact heat exchanger, used as a radiator in the automobiles have been experimentally investigated. The experiments were conducted at various flow rates of air and the results showed a decrease in goodness factor of 22.7% with respect to increase in Reynolds number from 231 to 495. The experimental results were compared with the CFD results and the ‘f’ and ‘j’ factors from the CFD analysis are in good agreement with the experimental data. Also, the experimental ‘f’ and ‘j’ factors were compared with the predicted values from the available correlations in the literature for the louvered fin and tube compact heat exchangers. The large deviation of the predicted results revealed that the correlations are not reliable for the design of the compact heat exchanger. Hence, the CFD analysis is more advantageous for the optimal design of compact heat exchanger, which also reduces the experimentation time and cost

Melting/solidification characteristics of paraffin based nanocomposite for thermal energy storage applications

The present work aimed to investigate the melting and solidification characteristics of nanoparticle enhanced phase change material (NEPCM). The NEPCM were prepared using paraffin as the phase change material and multiwall carbon nanotube (MWCNT) as the nanomaterial without using any dispersant. Thermal conductivity of the NEPCM was measured with respect to temperature and the measured data showed higher enhancement than the phase change material both in liquid and solid state, due to inherent high conductive and the continuous networking of the MWCNT. A reduction in solidification and melting time of 42% and 29% was achieved in the case of NEPCM with 0.9% and 0.3%, respectively. It is concluded that enhanced heat transfer characteristics of NEPCM is highly beneficial towards design and development of efficient thermal energy storage system for various applications