Thermal and optical properties of paraffin-filled CNTs for solar thermal applications

T.J. Choi, S.P. Jang
Korea Aerospace University,
Korea

Keywords: CNTs, paraffin wax, specific heat

Summary:

In this paper, we experimentally observe the heat capacity of paraffin-filled CNTs and also measure the extinction coefficient of water-based CNT filled with paraffin for developing the novel working fluids which can dramatically absorb and store the solar thermal energy. For this purpose, the four cases of paraffin-filled CNTs are prepared. With the four cases of paraffin-filled CNTs, we measure the heat capacity using differential scanning calorimetry (DSC). To identify the absorption characteristics of the nanofluids with paraffin-filled CNTs, the extinction coefficients of nanofluids are measured by the in-house developed laser transmission system at a fixed wavelength of 632.8nm. The results of specific heat on paraffin-filled CNTs, it is increased by 31.5% as compared to the DI-water in the temperature range from 53℃ to 60℃. Also, extinction coefficients of water-based paraffin-filled CNT nanofluids are linearly increased according to the CNT with paraffin volume fractions. Base on the results, it shows dual functionality of the paraffin-filled CNT nanofluids as desired for solar thermal energy.