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Tuning the dynamic thermal parameters of nanocarbon ionanofluids : a photopyroelectric study
Mohanachandran Nair Sindhu Swapna, Carmen Tripon, Alexandra Farcas, Dorin Dadarlat, Dorota Korte, Sankaranarayana Iyer Sankararaman, 2024, original scientific article

Abstract: The present work delineates the tailoring of the thermal effusivity and diffusivity of the novel class of heat transfer fluids—ionanofluids—by the incorporation of nanocarbons like diesel soot (DS), camphor soot (CS), carbon nanotubes (CN), and graphene (GR). When the thermal diffusivity delivers information on the thermal energy propagation, the thermal effusivity concerns the energy exchange at the interface, enabling energy-efficient thermal system design. The nanocarbons are subjected to morphological characterisation by field emission scanning electron microscopy. Fourier-transform infrared and Raman spectroscopic analyses confirm functional groups and vibrational bands. The microcrystalline size and graphiticity are also understood from the Raman spectrum. Ionanofluids prepared by dispersing nanocarbons into an ionic liquid base 1-Butyl-3-methylimidazolium methyl sulfate (BMMS) are analysed by nondestructive photopyroelectric calorimetry (PPE). The PPE analysis of ionanofluids demonstrates that nanocarbons influence thermal parameters in the base fluid, with soot ionanofluids exhibiting increased thermal effusivity and diffusivity due to their various carbon allotropic composition. This study underscores the importance of selecting the appropriate carbon allotrope for tailoring ionanofluids’ thermal properties, providing insights into manipulating these properties for enhanced performance across various industrial applications.
Keywords: photopyroelectric, ionanofluid, soot, graphene, thermal diffusivity
Published in RUNG: 06.05.2024; Views: 221; Downloads: 3
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Photopyroelectric spectroscopy and calorimetry
D Dadarlat, C Tripon, Iain R. White, Dorota Korte, 2022, review article

Abstract: In this tutorial, we present an overview of the development of the photopyroelectric (PPE) technique, from its beginnings in 1984, through to the present day. The tutorial is organized in five sections, exploring both theoretical and experimental aspects of PPE detection, as well as some important spectroscopic and calorimetric applications. In the “Introduction” section we present the fundamental basics of photothermal phenomena and the state-of-the-art of the photopyroelectric technique. In the “Theoretical aspects” section we describe some specific cases of experimental interest, with examples in both back and front detection configurations. Several mathematical expressions for the PPE signal in specific detection modes (combined back-front configurations and PPE-IRT methods) are also deduced. The “Instrumentation and experiment” section contains two sub-sections. The first describes several examples of set-ups used for both room temperature and temperature-controlled experiments. The second sub-section is dedicated to the configuration of detection cells and to the various sensor/sample assemblies that are currently used in spectroscopic and calorimetric experiments for both liquid and solid samples. The “Applications” section is in fact a collection of experimental results dedicated to the thermal characterization of a wide range of solid and liquid samples. At the end of this section we present some examples that have been selected to convey that the PPE technique is not only useful in the investigation of optical and thermal properties of a variety of condensed matter samples, but also to study physical and chemical processes such as molecular associations, food adulteration or phase transitions. In “Concluding remarks” we summarize the advantages of this technique in spectroscopic and calorimetric applications.
Keywords: photopyroelectric spectroscopy, photopyroelectric calorimetry, phase transitions, condensed matter samples, thermal parameters
Published in RUNG: 16.11.2022; Views: 1265; Downloads: 22
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Thermal Effusivity Investigations of Solid Thermoelectrics Using the Front Photopyroelectric Detection
Carmen Tripon, Dorin Dadarlat, Katalin Kovacs, Victor Petru Tosa, Mladen Franko, 2020, original scientific article

Abstract: The front photopyroelectric configuration (FPPE), making use of air as a coupling fluid between the sample and sensor, was applied to measure the thermal effusivity of some solid thermoelectric materials. The investigated samples were ZnO, CuCrO2, Cu4Sn7S16, TiS3 and two samples of high manganese silicide (HMS) thermoelectric materials. Most of these materials are porous and consequently, the classical PPE method, making use of standard coupling fluids between sensor and sample, cannot be used due to the fact that the coupling fluid penetrates inside the sample and leads to incorrect results. With this work we extend (to thermoelectric solids) the area of application of a method, recently proposed by Salazar et al. (Measurement 121: 96, 2018). Experimentally, the thermal effusivity is obtained from a multi-parametric fit of the phase of the FPPE signal as a function of the modulation frequency (with sample’s thermal effusivity, thickness of the sensor-sample air gap and heat losses by convection and radiation, as fitting parameters). It was demonstrated that, in some particular cases, the three parameters are independent and consequently, the solution of the fit is unique. Where possible, the obtained results have been compared with data from the literature and good agreement was found.
Keywords: Front photopyroelectric configuration (FPPE), Solid thermoelectrics, Thermal effusivity
Published in RUNG: 02.05.2020; Views: 2811; Downloads: 0
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