Insight into the Investigation of Diamond Nanoparticles Suspended Therminol®55 Nanofluids on Concentrated Photovoltaic/Thermal Solar Collector

At a Glance

Metadata	Details
Publication Date	2022-08-28
Journal	Nanomaterials
Authors	Likhan Das, Fazlay Rubbi, Khairul Habib, Navid Aslfattahi, R. Saidur
Institutions	Sunway University, Czech Technical University in Prague
Citations	6
Analysis	Full AI Review Included

Executive Summary

This research investigates the formulation, characterization, and numerical performance of Therminol®55 (TH-55) oil-based nanofluids (NFs) containing diamond nanoparticles (DP) for use in Concentrated Photovoltaic/Thermal (CPV/T) solar collectors.

Superior Heat Transfer: The addition of diamond nanoparticles significantly enhanced thermal conductivity (TC) by up to 73.39% (at 0.1 wt.% DP and 70 °C) compared to pure TH-55 oil.
Enhanced Optical Absorption: Photo-thermal energy conversion efficiency increased by 120.80% at 0.1 wt.%, confirming the nanofluid’s suitability for direct absorption solar applications.
High Stability and Flow Behavior: The formulated NFs exhibited good suspension stability (Zeta potential > ±30 mV) and maintained dominant Newtonian flow characteristics, with viscosity dropping rapidly at elevated temperatures (20-100 °C).
Improved CPV/T Performance: Numerical simulations demonstrated that the NF-operated CPV/T system achieved an 11% enhancement in thermal efficiency (η_th) and a 1.8% enhancement in electrical efficiency (η_el) at optimal flow conditions (3 LPM, 5000 W/m²).
Effective Cooling: The nanofluid provided a maximum PV cell temperature drop of 21 °C compared to the base fluid, crucial for preventing overheating under high concentrated solar irradiance.

Technical Specifications

Parameter	Value	Unit	Context
Nanoparticle Material	Diamond (Carbon-based)	N/A	Purity 98.3%, Spherical morphology
Nanoparticle Size Range	3-10	nm	Used for NF formulation
Base Fluid	Therminol®55 (TH-55)	N/A	Synthetic oil, Normal boiling point 351 °C
NF Concentration Range	0.001-0.1	wt.%	Concentrations tested
Max Thermal Conductivity Enhancement	73.39	%	TH-55/DP NF at 0.1 wt.%, 70 °C
Max Photo-Thermal Absorbance Increment	120.80	%	TH-55/DP NF at 0.1 wt.%
Dynamic Viscosity (20 °C, 0.1 wt.%)	38.48	mPa·s	Decreases rapidly with temperature
Flow Behavior	Newtonian	N/A	Viscosity constant up to 100 s^-1 shear rate
Min Absolute Zeta Potential (25 °C)	34.81	mV	At 0.1 wt.% (Indicates good stability)
Max Solar Irradiance (G)	5000	W/m²	Numerical simulation condition
Optimal Flow Rate	3	LPM	Used for efficiency calculations
Max Electrical Efficiency (η_el) Enhancement	1.8	%	Relative to base fluid system
Max Thermal Efficiency (η_th) Enhancement	11	%	Relative to base fluid system
Max PV Cell Temperature Drop	21	°C	Achieved using 0.1 wt.% NF
PV Module Power (Nominal)	300	W	Used in CPV/T numerical model

Key Methodologies

Nanofluid Formulation (Two-Step Method): Diamond nanoparticles (DP) were dispersed into Therminol®55 (TH-55) oil at concentrations of 0.001, 0.05, and 0.1 wt.%.
Mechanical Stabilization: Initial mixing involved magnetic stirring for 30 minutes at 700 rpm and 80 °C.
Ultrasonication: Final stabilization was achieved using an ultrasonic homogenizer (1200 W, 20 kHz) for 30 minutes at 80 °C to ensure uniform particle dispersion.
Thermal Conductivity Measurement: TC was measured using the TEMPOS instrument (transient hot wire method) across a temperature range of 30 °C to 70 °C.
Viscosity and Rheology Characterization: Dynamic viscosity was measured using an MCR-92 Rheometer over a temperature range of 20 °C to 100 °C and a shear rate up to 100 s^-1.
Stability Assessment: Suspension stability was determined by measuring the electrophoretic mobility in terms of Zeta potential (ζ) at 25 °C and 80 °C.
Optical Characterization: UV-Vis spectroscopy (Lambda 750) was used to analyze absorbance characteristics (200-800 nm), and FT-IR spectroscopy was used to confirm chemical stability and identify functional groups.
Numerical Simulation: The performance of the NF-operated CPV/T system was modeled using COMSOL Multiphysics® (version 5.6), utilizing CFD and heat transfer modules. Experimentally derived correlations for TC and viscosity were integrated via User-Defined Functions (UDF).

Commercial Applications

Concentrated Solar Power (CSP) and CPV/T Systems: Direct implementation as a high-performance heat transfer fluid (HTF) in concentrated solar collectors (e.g., parabolic trough, solar tower) to maximize both electrical and thermal energy output.
High-Temperature Industrial Cooling: Utilization in industrial processes requiring efficient heat removal at medium-to-high temperatures, replacing conventional synthetic oils like Therminol®55.
Thermal Energy Storage (TES): Application in advanced TES systems where high thermal conductivity and stability at elevated temperatures are critical for efficient charging and discharging cycles.
High-Flux Heat Exchangers: Use in compact, high-performance heat exchangers where the enhanced TC of the nanofluid allows for smaller system footprints and improved heat transfer rates.
Advanced Materials Manufacturing: Validation of diamond nanoparticles as a viable, carbon-based additive for creating stable, high-performance nanofluids in non-aqueous (oil) bases.

View Original Abstract

Nanofluids are identified as advanced working fluids in the solar energy conversion field with superior heat transfer characteristics. This research work introduces carbon-based diamond nanomaterial and Therminol®55 oil-based nanofluids for implementation in a concentrated photovoltaic/thermal (CPV/T) solar collector. This study focuses on the experimental formulation, characterization of properties, and performance evaluation of the nanofluid-based CPV/T system. Thermo-physical (thermal conductivity, viscosity, and rheology), optical (UV-vis and FT-IR), and stability (Zeta potential) properties of the formulated nanofluids are characterized at 0.001-0.1 wt.% concentrations of dispersed particles using experimental assessment. The maximum photo-thermal energy conversion efficiency of the base fluid is improved by 120.80% at 0.1 wt.%. The thermal conductivity of pure oil is increased by adding the nanomaterial. The highest enhancement of 73.39% is observed for the TH-55/DP nanofluid. Furthermore, dynamic viscosity decreased dramatically across the temperature range studied (20-100 °C), and the nanofluid exhibited dominant Newtonian flow behavior, with viscosity remaining nearly constant up to a shear rate of 100 s−1. Numerical simulations of the nanofluid-operated CPV/T collector have disclosed substantial improvements. At a concentrated solar irradiance of 5000 W/m2 and an optimal flow rate of 3 L/min, the highest thermal and electrical energy conversion efficiency enhancements are found to be 11 and 1.8%, respectively.

Tech Support

Original Source

DOI: https://doi.org/10.3390/nano12172975

References

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