11. |
12. |
13. |
14. Thermal diffusivity downscaling of molybdenum oxide thin film through annealing temperature-induced nano-lamelle formation: a photothermal beam deflection studyS. Soumya, Vimal Raj, Mohanachandran Nair Sindhu Swapna, Sankaranarayana Iyer Sankararaman, 2021, original scientific article Abstract: The present work proposes a method of downscaling the thermal diffusivity (α)
of MoO3 thin films through annealing temperature-induced nano-lamelle formation. The
thermal diffusivity modification of the MoO3 films, prepared by the doctor blade method,
is investigated by the sensitive transverse photothermal beam deflection technique. The X-ray diffraction analysis confirms the structural phase transformation from monoclinic to
orthorhombic in the films annealed from 300 to 450 °C. The thermal induced anisotropy of
the film is evident from the variation of the morphology index and texture coefficient. The
field emission scanning electron microscopic analysis unveils the morphology modifications
from blocks to the nano-lamelle structure with layers of average thickness ~ 77 nm. The
thermal diffusivity measurement reveals a 53% reduction upon annealing the film to 450 °C.
The drastic reduction is achieved through the annealing temperature-induced nano-lamelle
formation and the phase transformation from monoclinic to orthorhombic in the MoO3 films. Keywords: thermal diffusivity, molybdenum oxide, thin film, nano-lamelle, photothermal beam deflection Published in RUNG: 04.07.2022; Views: 2165; Downloads: 27
Link to full text This document has many files! More... |
15. Thermal diffusivity of molybdenum oxide nanowire film: a photothermal beam deflection studyMohanachandran Nair Sindhu Swapna, 2021, original scientific article Abstract: The paper reports the preparation of thin film with MoO3 nanowires (NWs) by the doctor blade method and the
study of its thermal diffusivity (α) by the sensitive photothermal beam deflection (PTD) method. When the Field
Emission Scanning Electron Microscopic and Atomic Force Microscopic analysis unveil its morphology as NW
bundles, the X-ray diffraction analysis reveals the structure to be orthorhombic. The NWs formed are of diameter
~ 20 nm and length up to 5 μm. The standardization of the transverse PTD setup is done by determining the
value of α of iron, which agrees well with literature reports. The thermal diffusivity of MoO3 NW film is obtained
as 0.0036 cm2
/s, which is 9.48% of its bulk counterpart. The reduction in the thermal diffusivity of NW makes it
a suitable candidate for thermoelectric applications. Keywords: Nanowires
Molybdenum oxide
Photothermal beam deflection
Thermal diffusivity Published in RUNG: 04.07.2022; Views: 2192; Downloads: 0 This document has many files! More... |
16. Laser-induced thermal lens study of the role of morphology and hydroxyl group in the evolution of thermal diffusivity of copper oxideRiya Sebastian, Mohanachandran Nair Sindhu Swapna, Vimal Raj, Sankaranarayana Iyer Sankararaman, 2022, original scientific article Abstract: The paper explores the evolution of thermal behavior of the material by studying the variations in thermal diffusivity
using the single beam thermal lens (TL) technique. For this purpose, the decomposition of Cu(OH)2 into CuO is studied in a
time range up to 120 h, by subjecting the sample to morphological, structural, and spectroscopic characterizations. The time
evolution of thermal diffusivity can be divided into three regions for demonstrating the dynamics of the reaction. When the
reaction is complete, the thermal diffusivity is also found to be saturated. In addition to the morphological modifications,
from rods to flakes, the variations in the amount of hydroxyl group are attributed to be responsible for the enhancement
of base fluid’s thermal diffusivity by 165%. Thus the study unveils the role of hydroxyl groups in the thermal behavior of
CuO. Keywords: thermal diffusivity, CuO, thermal lens, morphology, hydroxyl group Published in RUNG: 04.07.2022; Views: 1975; Downloads: 0 This document has many files! More... |
17. Acclimatisation through thermal diffusivity tuning of coconut oil – A mode mismatched dual-beam thermal lens studyMohanachandran Nair Sindhu Swapna, 2022, original scientific article Abstract: Background: Ayurvedic medicinal oils traditionally prepared by blending herbal extracts in different
compositions are commonly used for treatment and improving health. The estimation of the thermal
properties of medicinal oils is essential for practical applications.
Objective: The present work aims to expound the ability of medicinal oils for the acclimatization of body
temperature by determining its thermal diffusivity and thereby providing a validation to the traditional
knowledge.
Materials and methods: The medicinal oils are prepared by incorporating black pepper (Piper nigrum),
aloe vera (Aloe barbadensis), hibiscus bud (Hibiscus rosa-sinensis) and Ocimum sanctum in coconut oil
base. The samples are subjected to thermal diffusivity study using the mode-mismatched dual-beam
thermal lens technique.
Results: The study reveals that the incorporation of black pepper (Piper nigrum), having hot potency
(Ushna veerya), to the base fluid lowers the thermal diffusivity value, suggesting its potential in heat-trapping. The addition of aloe vera (Aloe barbadensis), hibiscus bud (Hibiscus rosa-sinensis), and
O. sanctum dissipates heat energy quickly, thus increases the thermal diffusivity of coconut oil revealing a
cold potency (Sheeta veerya). The study provides a validation for traditional knowledge and delineates
the possiblity of thermal diffusivity tuning of the base fluids.
Conclusion: The thermal diffusivity tuning through incorporation of herbal extracts can effectively be
used to acclimatize the human body temperature with the surroundings. A higher thermal diffusivity
value induces a cooling effect and the lower value causes heating effect. This, opens up the possibility of
using thermally tuned oils depending on climate and geographical location. Keywords: Ayurveda, Acclimatization, Medicinal oils, Thermal lens spectroscopy
Thermal diffusivity Published in RUNG: 04.07.2022; Views: 1928; Downloads: 0 This document has many files! More... |
18. Allotropic transformation instigated thermal diffusivity of soot nanofluid: Thermal lens studyMohanachandran Nair Sindhu Swapna, RAJ VIMAL, Sankararaman S, 2019, original scientific article Abstract: This paper employs the sensitive single-beam thermal lens technique for analyzing the thermal behavior of gasoline soot containing allotropes of carbon by preparing its nanofluid (NF). The soot, annealed at different temperatures up to 400 ○C (the samples), used for preparing the NF, is found to enhance the thermal diffusivity (α) up to 95% without changing the solid volume fraction, suggesting its possible use in
coolants. The thermal induced modifications are understood from the field emission scanning electron microscopic, X-ray diffraction (XRD),thermogravimetric, and Raman spectroscopic analyses. The variation of α of the sample is found to exhibit similar variations observed in XRD and Raman spectroscopic analyses. The study stresses the significance of the optimum temperature (300 ○C) for the soot NF above which morphological and structural modifications may lead to thermal energy trapping rather than dissipation or cooling. Keywords: petrol soot, thermal lens, thermal diffusivity Published in RUNG: 04.07.2022; Views: 2097; Downloads: 0 This document has many files! More... |
19. Tuning the thermal diffusivity of the seed matter for enhanced biosynthesis: A thermal lens studyMohanachandran Nair Sindhu Swapna, Sankararaman S, 2020, original scientific article Abstract: The thermodynamics of the seed matter after imbibition is highly significant as the growth and germination involve complex biochemical exergonic process. The germination of seed and compositional variation of the seed matter has always been a fascinating field of research. The present work unveils the thermodynamics associated with the changing thermal diffusivity of the seed matter through the green technology-based single-beam thermal lens technique. Investigations are carried out in Vigna radiata seeds, germinating in media with and without carbon allotropes, through various spectroscopic techniques. The morphology of the soot and carbon allotropes is understood from the field emission scanning electron microscope images. The thermal lens study throws light into the energy trapping nature of the seed matter of the seed growing in carbon allotropic media which facilitates biosynthesis. The observed increased rate of growth of the seed is substantiated through
the ultraviolet–visible–near-infrared (NIR), Fourier transform infrared, and photoluminescence (PL) spectroscopic analyses. The NIR and PL studies also reveal the formation of chlorophyll molecule during germination. Thus, the study suggests a mechanism for tuning the thermal diffusivity of the seed matter as to trap the biochemical energy to facilitate the further biosynthesis and thereby to enhance the growth rate. Keywords: seed matter, thermal diffusivity, thermal lens, carbon nanoparticle, soot Published in RUNG: 04.07.2022; Views: 2155; Downloads: 0 This document has many files! More... |
20. Absolute Porosity Analysis in Carbon Allotropic Nanofluids: A Sankar–Swapna Model ApproachMohanachandran Nair Sindhu Swapna, SREEJYOTHI S, Sankararaman S, 2020, original scientific article Abstract: Porous materials have gained significant attention in recent years as a class of material exhibiting
interesting chemical and physical properties. The existing methods of porosity analysis have limitations that
prevent absolute porosity measurement. Hence, a technique independent of surface physical properties alone
can give the absolute porosity of the material. The porosity greatly influences the thermal diffusivity of a
material. The manuscript is the first report of employing the Sankar–Swapna model for analyzing the porosity variations in carbon allotropic nanofluids. The model helps not only in getting information about the absolute porosity variations among samples, but also suggests morphological modifications through the thermal diffusivity study using the sensitive single-beam thermal lens technique. The variations in thermal diffusivity and absolute porosity values are also correlated to morphological modifications based on the theoretical model and thereby proposing this as a surrogate method for absolute porosity analysis. Keywords: absolute porosity, Sankar–Swapna model, thermal diffusivity, thermal lens, thermal conductivity Published in RUNG: 04.07.2022; Views: 2378; Downloads: 0 This document has many files! More... |