Published in 2024

Feasibility Study of Coffee Husk Char-Derived Carbon Dots to Enhance Solar Photovoltaic-Thermal Applications

Authors: P. Suraj, S. Sreekumar, P. Arun, C. Muraleedharan

Journal: Journal of Analytical and Applied Pyrolysis

Description:

Coffee is one of the most traded commodities in the world. Coffee husk makes up the majority of the solid debris generated during the dry processing of coffee, which is between 30 to 50%. Pyrolysis is a reliable and feasible technology to valorise the coffee husk. The present study proposes and investigates a novel method for producing carbon dots from coffee husk char through pyrolysis. Nanomaterials are becoming more popular to improve the thermal and optical properties of working fluids used in solar photovoltaic and thermal conversion systems. The coffee husk-char derived carbon dot (CHC-CD) nanofluids are prepared with different char concentrations (1%, 2%, 3% and 4%). The chemical and optical properties of the nanofluid produced from coffee husk char (CHC-CD nanofluid) are investigated. The morphology, size and particle size distribution of the CHC-CD particles were studied using field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The particles were found to have an average size of 5.38 nm. The CHC-CD nanofluid had a basic pH and negative zeta potential, which was found to decrease with an increase in the char concentration and pH. The nanofluid prepared with 2% char was found to have a zeta potential of -61.4 mV. It was evident from the UV-vis transmittance spectra that the CHC-CD nanofluid prepared with a char concentration of 2% had very limited transmittance in the UV region and good transmittance above 735 nm. This transmittance range is found to be favourable for the smooth and efficient operation of silicon-based solar PV cells. The CHC-CD nanofluid also showed a maximum intensity emission wavelength of 522 nm at an excitation wavelength of 450 nm. Characterisation of the carbon phase, surface functional groups, and surface defects was also done using XRD, FTIR, and Raman spectroscopy, respectively. The optical and chemical properties indicate that the developed CHC-CD nanofluid can find application not only in solar photovoltaic and thermal systems but also in applications in biomedical and chemical sensor applications.

Published in 2024

Corrosion analysis and performance investigation of hybrid MXene/C-dot Nanofluid-Based direct absorption solar collector

Authors: -

Journal: Solar Energy

Description:

Nanofluids having exceptional thermo-optical characteristics can enhance the performance of direct absorption solar collectors (DASC). Conventional nanofluids have either high optical properties or thermal properties. In this study, carbon quantum dot (C-dot) nanomaterial with high stability and optical absorption along the UV range, and MXene nanoparticles with high thermal conductivity and absorption along visible and near-infrared (NIR) spectral range was selected for synthesizing a hybrid nanomaterial with synergistic thermo-optical properties. Hybrid MXene/C-dot nanofluid exhibits higher stability, thermal conductivity, and complementary absorption properties of individual nanomaterials. A two-step method was used for the synthesis of nanofluids using water as the base fluid. Thermal conductivity, UV–Vis-NIR spectroscopy, and stability analysis were conducted on nanofluids, and the concentration was optimized for corrosion study and application in direct absorption parabolic trough collector (DAPTC). Optimised concentrations of C-dot, MXene, and hybrid nanofluids were 0.15 wt%, 0.1 wt% and 0.15 wt%, respectively. The corrosion study states that copper electrodes dipped in the hybrid nanofluid exhibited the least corrosion rate of 0.6 mm/year with an anticorrosion efficiency of 64.5 % over DI water. Thermal efficiency and entropy generation in the system with different HTFs were measured and compared with that of the base fluid. The study shows that C-dot and MXene/C-dot nanofluids were producing the highest efficiencies of 50.5 % and 47.5 % at a flow rate of 1.2 lpm. This study shows that hybrid MXene/C-dot nanofluid exhibited exceptional thermal stability, reduced corrosion effects, and considerable enhancement in photothermal conversion efficiency of the DASC.

Published in 2023

Thermo-optical characterization of novel MXene/Carbon-dot hybrid nanofluid for heat transfer applications

Authors: Sreehari Sreekumar, Abhijit Ganguly, Sameh Khalil, Supriya Chakrabarti, Jayanta Deb Mondol, Nikhilkumar Shah

Journal: Journal of Cleaner Production

Description:

Nanofluid has emerged as a promising heat transfer fluid (HTF) due to their significant thermophysical, and optical characteristics enhancement over base fluids. Hybrid nanofluids with multiple nanomaterials have the advantage of synergistic properties in comparison to monocomponent nanofluids. The present study proposes an energy-efficient and cleaner synthesis method for developing carbon quantum dot (C-dot), MXene, and a hybrid MXene/C-dot hybrid nanofluids, for heat transfer application. In-situ microwave pyrolysis technique and two-step method were adopted for nanomaterial and nanofluid synthesis. The morphological, phase structural, chemical, and elemental compositional analysis of the nanomaterials was performed. The material characterization confirms the hybridization of C-dot on MXene nanosheets. The thermal conductivity and volumetric heat capacity of the nanofluids were measured using the transient plane source (TPS) method. Thermal conductivity was observed to increase with nanofluid concentration and temperature. Results indicate that MXene has the highest thermal conductivity enhancement (50 %) over water, followed by hybrid (42.2 %) and C-dot nanofluid (33.2 %). The volumetric heat capacity of nanofluids decreased with concentration and temperature. A semi-empirical correlation, as a function of nanofluid concentration and temperature, was coined for predicting thermal conductivity and volumetric heat capacity. Optical property characterization study shows that C-dot nanofluid exhibited considerable absorption along the UV range, while MXene nanofluid showed absorption in the visible and near-infrared (NIR) region. Hybrid nanofluids demonstrated complementary absorption properties of C-dot and MXene nanofluids.

Published in 2022

Numerical investigation and feasibility study on MXene/water nanofluid based photovoltaic/thermal system

Authors: -

Journal: Cleaner Energy Systems

Published in 2022

Broadband absorbing mono, blended and hybrid nanofluids for direct absorption solar collector: a comprehensive review

Authors: Sreehari Sreekumar, Nihilkumar Shah, Jayanta Deb Mondol, Neil Hewitt, Supriya Chakrabarti

Journal: Nano Futures

Published in 2020

Energy and exergy analysis of SiO2/Ag-CuO plasmonic nanofluid on direct absorption parabolic solar collector

Authors: Albin Joseph, Sreehari Sreekumar, Shijo Thomas

Journal: Renewable Energy

Published in 2020

Development of a low cost nanofluid based direct absorption solar collector

Authors: -

Journal: Materials Today: Proceedings

Published in 2019

Investigation on influence of antimony tin oxide/silver nanofluid on direct absorption parabolic solar collector

Authors: Sreehari Sreekumar, Albin Joseph, C.S. Sujith Kumar, Shijo Thomas

Journal: Journal of Cleaner Production

Published in 2019

Optimisation of thermo-optical properties of SiO2/Ag–CuO nanofluid for direct absorption solar collectors

Authors: Albin Joseph, Sreehari Sreekumar, C.S. Sujith Kumar, Shijo Thomas

Journal: Journal of Molecular Liquids