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Research Papers

# Hydronic Coil Performance Evaluation With Nanofluids and Conventional Heat Transfer Fluids

[+] Author and Article Information
Roy Strandberg

Department of Mechanical Engineering, University of Alaska, Fairbanks, P.O. Box 755905, Fairbanks, AK 99775-5905

Debendra K. Das1

Department of Mechanical Engineering, University of Alaska, Fairbanks, P.O. Box 755905, Fairbanks, AK 99775-5905ffdkd@uaf.edu

1

Corresponding author.

J. Thermal Sci. Eng. Appl 1(1), 011001 (Jul 21, 2009) (8 pages) doi:10.1115/1.3159482 History: Received September 26, 2008; Revised April 24, 2009; Published July 21, 2009

## Abstract

The performance of hydronic heating coils with nanoparticle enhanced heat transfer fluids (nanofluids) is evaluated and compared with their performance with a conventional heat transfer fluid comprised of 60% ethylene glycol (EG) and 40% water, by mass (60% EG). The nanofluids analyzed are comprised of either CuO or $Al2O3$ nanoparticles dispersed in the 60% EG solution. The heating coil has a finned tube configuration commonly used in commercial air handling and ventilating systems. Coil performance is modeled using methods that have been previously developed and validated. The methods are modified by incorporating Nusselt number correlations for nanofluids that have been previously documented in the literature. Similarly, correlations for nanoparticle thermophysical properties that have been documented in the literature are employed. The analyses show that heating coil performance may be enhanced considerably by employing these nanofluid solutions as a heat transfer medium. The model predicts a 16.6% increase in coil heating capacity under certain conditions with the 4% $Al2O3$/60% EG nanofluid, and a 7.4% increase with the 2% CuO/60% EG nanofluid compared with heating capacity with the base fluid. The model predicts that, for a coil with the $Al2O3$/60% EG nanofluid, liquid pumping power at a given heating output is reduced when compared with a coil with the base fluid.

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## Figures

Figure 1

Finned heating coil configuration

Figure 2

Actual capacity versus model predicted capacity for two-row heating coil, with constant air velocity and variable liquid velocity

Figure 3

Actual capacity versus model predicted capacity for two-row heating coil, with constant liquid velocity and variable air velocity

Figure 4

Heating coil capacity with high temperature CuO nanofluid at constant air velocity and variable liquid velocity

Figure 5

Heating coil capacity with the Al2O3 nanofluid at constant air velocity and variable liquid velocity

Figure 6

Heating coil capacity versus liquid friction loss (on a unit length basis) for a coil with nanofluids and 60% EG

Figure 7

Liquid pumping power required for a given heating coil capacity (on a unit length basis) for a coil with nanofluids and 60% EG

Figure 8

Comparison of total heat transfer area required for the heating coil for given heating capacities and different fluids

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