Heat Transfer Enhancement using Iron Oxide Nanoparticles

• Main Author: Stuart, Dale
• Format: Others
• Published: VCU Scholars Compass 2012
• Subjects: Iron Oxide Nanoparticles; Heat Transfer; Square Wave Analysis; Thermal Conductivity Enhancement; Heat Capacity; Chemistry; Physical Sciences and Mathematics
• Online Access: http://scholarscompass.vcu.edu/etd/425; http://scholarscompass.vcu.edu/cgi/viewcontent.cgi?article=1424&context=etd

Two different iron oxide nanofluids were tested for heat transfer properties in industrial cooling systems. The nanofluids either had 30 nm particles with a wide size distribution to include particles greater than 1 micrometer or 15 nm particles with greater than 95% of the particles less than 33 nm. Calorimetry and thermal circuit modeling indicate that the 15 nm particle ferrofluid enhanced heat capacity. The smaller particle ferrofluid also demonstrated up to a 39% improvement in heat transfer, while the larger particle ferrofluid degraded the heat transfer performance. Particles from the larger particle ferrofluid were noted as settling out of a circulating system and therefore not participating in the bulk fluid properties. Application of 0.32% 15nm particles in an open cooling system improved cooling tower efficiency by 7.7% at a flow rate of 11.4 liter per minute and improved cooling tower efficiency by 3.3% at a flow rate of 22.7 liter per minute, while applying 0.53% 15 nm particles also improved cooling tower efficiency but was less effective than the lower concentration.