(183g) Enhancing Capillary Evaporation for Advanced Heat Transfer Applications with PbTe Nanoparticle Coating Layer

In this study, we explore the use of lead telluride (PbTe) nanoparticles as a coating on copper sheets to enhance capillary evaporation for thermal management. PbTe nanoparticles are known for their excellent thermoelectric properties and potential in waste heat recovery and cooling applications. Capillary evaporation, crucial in heat transfer, depends on the surface properties and structure of the material. By using a dip-coating method, we aim to develop structured surfaces that promote efficient heat transfer through capillary evaporation. The impact of surface treatment with Diethyl zinc (DEZ) and Hydrazine on the evaporation rate and hydrophilicity of various solutions is also investigated to assess the improvement in capillary evaporation.

To analyze evaporation rates, 10 µL of super wetting solutions acetone, ethanol, and n-heptane were dispensed onto various surfaces, including a copper sheet (Copper), a PbTe dip-coated layer on copper (PbTe), a PbTe layer with DEZ treatment (PbTe with DEZ), and a PbTe layer with hydrazine treatment (PbTe with Hydrazine). The average evaporation rates for acetone were 0.273 µL/s on Copper, 0.434 µL/s on PbTe, 0.476 µL/s on PbTe with DEZ, and 0.526 µL/s on PbTe with Hydrazine. For ethanol, the rates were 0.0615 µL/s, 0.148 µL/s, 0.160 µL/s, and 0.190 µL/s, respectively. For n-heptane, they were 0.116 µL/s, 0.128 µL/s, 0.172 µL/s, and 0.217 µL/s, respectively. The evaporation rate of all solutions increased in the order of Copper, PbTe, PbTe with DEZ, and PbTe with Hydrazine. Overall, the evaporation rate compared to Copper increased from 10.3% to 209%.

To investigate the hydrophilicity and hydrophobicity of each Copper, PbTe, PbTe with DEZ, and PbTe with Hydrazine surface, a 0.5 µL droplet of DI water was applied to each surface and the contact angle in the equilibrium state was measured. The contact angle in the equilibrium state was 67° for copper, 95° for PbTe, 91° for PbTe with DEZ, and 70° for PbTe with Hydrazine. Subsequently, the evaporation rate was recorded. For the copper sheet, it declined from an initial rate of 0.707 nL/s to 0.226 nL/s at the conclusion of evaporation, indicating a 68.0% reduction. In contrast, the evaporation rate for PbTe began at 0.658 nL/s and decreased to 0.329 nL/s, resulting in a 46% reduction. For PbTe with DEZ treatment, the rate dropped from 0.609 nL/s to 0.418 nL/s, a 31.4% decrease. The PbTe with Hydrazine surface experienced a decline from 0.773 nL/s to 0.475 nL/s, amounting to a 38.6% reduction. However, due to the higher absolute evaporation rate on this surface, evaporation was completed more swiftly than on the other surfaces.