Soot effected sample entropy minimization in nanofluid for thermal system design
ǂa ǂthermal lens study
Abstract
The present work suggests a method of improving the thermal system efficiency, through entropy minimisation,
and unveils the mechanism involved by analysing the molecular/particle dynamics in soot nanofluids (SNFs)
using the time series, power spectrum, and wavelet analyses of the thermal lens signal (TLS). The photothermal
energy deposition in the SNF lowers the refractive index due to the temperature rise. It triggers the particle dynamics that are investigated by segmenting the TLS and analysing the refractive index, phase portrait, fractal dimension (D), Hurst exponent (H), and sample entropy (SampEn). The wavelet analysis gives information about
the relation between the entropy and the frequency components. When the phase portrait analysis reflects the
complex dynamics from region 1 to 2 for all the samples, the SampEn analysis supports it. The decreasing
value of D (from 1.59 of the base fluid to 1.55 and 1.52) and the SampEn (from 1.11 of the base fluid to 0.385
and 0.699) with the incorporation of diesel and camphor soot, indicate its ability to lower the complexity, randomness, and entropy. The increase of SampEn with photothermal energy deposition suggests its relation to
the thermodynamic entropy (S). The lowering of thermal diffusivity value of the base fluid from
1.4 × 10−7 m2/s to 1.1 × 10−7 and 0.5 × 10−7 m2
/s upon diesel and camphor soot incorporation suggests the
heat-trapping and reduced molecular dynamics in heat dissipation.
Keywords
soot;entropy;thermal system;photothermal;time series;nanofluid;fractal;
Data
| Language: | English |
|---|---|
| Year of publishing: | 2020 |
| Typology: | 1.01 - Original Scientific Article |
| Organization: | UNG - University of Nova Gorica |
| UDC: | 53 |
| COBISS: |
113289219
|
| ISSN: | 0167-7322 |
| Views: | 516 |
| Downloads: | 0 |
| Average score: | 0 (0 votes) |
| Metadata: |
|
Other data
| URN: | URN:SI:UNG |
|---|---|
| Pages: | str. 1-8 |
| Issue: | ǂVol. ǂ318 |
| Chronology: | 2020 |
| DOI: | 10.1016/j.molliq.2020.114038 |
| ID: | 15786683 |
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