Experimental investigation of the effect of hydrophobic coating on heat transfer and gasketed plate heat exchanger performance

Abstract

In this study, the effect of hydrophobicity on the plate surface on heat transfer, pressure drop, and pump power was investigated without changing the existing designs of gasketed plate heat exchangers (GPHEs). The wet surfaces of the plate were coated with carbon-based polymer solutions with four different hydrophobic groups, that is, FEP, FH3, FH7, and FH10. To increase the hydrophobicity of the FEP material, a new coating solution was synthesized by adding 3, 7, and 10 wt.% h-BN nanoparticles. Heat transfer, pressure loss, and pump power performances of heat exchangers with hydrophobic surface coating were tested at five different Reynolds numbers and compared with the uncoated heat exchanger performance. Also, the efficiency analysis of the GPHE under different hydrophobic conditions was carried out. As a result, the addition of 3 and 7 wt.% h-BN nanoparticles increased the contact angle. However, the addition of 10 wt.% h-BN decreased the contact angle as it increased the rough structure and film thickness on the surface. It was determined that the heat exchanger efficiency increased proportionally with the increase in hydrophobicity. While the highest heat exchanger efficiency value was 0.525 in FH7 coated. However, it was found that there was a 25.6% decrease in heat transfer of FH7 coating compared to uncoated exchanger. The pressure drop of the FH7 surface-coated heat exchanger with the highest hydrophobicity was 207.6% lower than that of uncoated heat exchanger. Energy savings of approximately 41% were achieved in FH7 coated compared to uncoated heat exchangers. It has been emphasized that heat transfer in GPHE systems should be evaluated together with pressure drops and local losses. It was found that the use of hydrophobic surface coating on plates in heat exchangers will contribute to the development of heat exchanger designs, reducing pump costs, and energy consumption.