Experimental assessment of a novel eutectic binary molten salt-based hexagonal boron nitride nanocomposite as a promising PCM with enhanced specific heat capacity

In this study, novel nanocomposites containing the pre-defined mass ratio of binary molten salt (NaNO3-KNO3: 60-40 wt. %) dispersed with hexagonal boron nitride (hBN) nanoparticles with nominal size of 70 nm, were prepared through one-phase preparation method. Four different types of samples including pure binary molten salt and binary molten salt-based hBN nanocomposites with loading concentrations of 0.5, 1 and 1.5 wt. % were prepared. The proposed amount of sodium nitrate and potassium nitrate was added to certain amount of DI water, comprising with 0.5, 1 and 1.5 wt. % concentration of hBN nanoparticles. Scanning electronic microscopy (SEM) was conducted to evaluate the uniformity of the synthesized binary molten salt-based hBN nanocomposites. The SEM images revealed uniform dispersion of hexagonal boron nitride nanoparticles and fractal-like structures were observed clearly. Specific heat capacity (cp) and melting temperature measurements were performed using a differential scanning calorimetry (DSC). The experimental achieved data for melting temperature proved that hexagonal boron nitride nanoparticles do not affect the melting temperature of the synthesized nanocomposites. The experimentally achieved data for the average cp values of the binary molten salt in solid and liquid phases were 1.14 and 1.13 J/g K, respectively. While, the average cp values for the binary molten salt-based hBN nanocomposite with the highest loading concentration of nanoparticles (1.5 wt. %) in solid and liquid phases were 2 and 3.17 J/g K, respectively. The measured average cp value in the liquid phase for binary molten salt-based hBN nanocomposite with the highest loading concentration (1.5 wt. %) of nanoparticles revealed enhancement of ~180% in comparison with pure binary molten salt. Thermal stability measurements expressed enhancement of thermal stability in binary molten salt induced with hBN nanoparticles. Binary molten salt-based hBN nanocomposite with loading concentration of 1.5 wt. % represented ~16% enhancement in thermal stability over the binary molten salt

Optimization of electrocatalyst performance of platinum–ruthenium induced with MXene by response surface methodology for clean energy application

Fuel cell produces clean sources of energy and yielding can be improved using emerging material (MXene) in electrocatalysis performance in a fuel cell system. However, MXene in electrocatalysis area for fuel cell is not discovered yet. Therefore, the aim of this study is to enhance the direct methanol fuel cell (DMFC) electrocatalyst performance using combination of bimetallic PtRu and MXene. Optimization is carried out using response surface methodology (RSM). Composition of MXene, Nafion content and methanol concentration are used as factors (input) and current density is used as a response (output) for the optimization analysis. A cyclic voltammetry (CV) is used to measure the current density. RSM generates optimum factors with MXene composition 78.90 wt%, Nafion content 19.71 wt% and methanol concentration of 2.82M. The optimum response is predicted to be 186.59mA/mgPtRu. The validation test is carried out and the result shows that the average current density is 187.05mA/mgPtRu. PtRu/MXene electrocatalyst produces 2.34 times higher current density compared to PtRu/C commercial electrocatalyst. This indicates that MXene has high potential as a nanocatalyst for cleaner energy production through the fuel cell

ANN Modeling of Thermal Conductivity and Viscosity of MXene-Based Aqueous IoNanofluid

Research shows that due to enhanced properties IoNanofluids have the potential of being used as heat transfer fluids (HTFs). A significant amount of experimental work has been done to determine the thermophysical and rheological properties of IoNanofluids; however, the number of intelligent models is still limited. In this work, we have experimentally determined the thermal conductivity and viscosity of MXene-doped [MMIM][DMP] ionic liquid. The size of the MXene nanoflakes was determined to be less than 100 nm. The concentration was varied from 0.05 mass% to 0.2 mass%, whereas the temperature varied from 19 °C to 60 °C. The maximum thermal conductivity enhancement of 1.48 was achieved at 0.2 mass% and 30 °C temperature. For viscosity, the maximum relative viscosity of 1.145 was obtained at 0.2 mass% and 23 °C temperature. After the experimental data for thermal conductivity and viscosity were obtained, two multiple linear regression (MLR) models were developed. The MLR models’ performances were found to be poor, which further called for the development of more accurate models. Then two feedforward multilayer perceptron models were developed. The Levenberg–Marquardt algorithm was used to train the models. The optimum models had 4 and 10 neurons for thermal conductivity and viscosity model, respectively. The values of statistical indices showed the models to be well-fit models. Further, relative deviations values were also accessed for training data and testing data, which further showed the models to be well fit

State-of-the-art heat transfer fluids for parabolic trough collector

Solar thermal energy conversion is gaining more attention among researchers due to the recent development in nanofluids and molten salt technology. Among various solar collectors, parabolic trough collector has received significant attention from researchers due to their operating temperature range (150-800 °C) feasible for power generation. Parabolic trough collector is currently having a higher number of installations compared to other concentrated solar power technology around the globe. Most of the conventional heat transfer fluid used in PTC have poor heat transfer and light to heat conversion properties. Therefore, it is advantageous to enhance the thermophysical properties of heat transfer fluid to improve the overall efficiency of the system. Well-engineered nano-enhanced heat transfer fluid is advantageous because a very low mass fraction of nanoparticles brings considerable enhancement in thermophysical properties. This paper focuses on the most recent advancement in heat transfer fluids, their preparation and stability issues when doped with nanoparticles. Various heat transfer fluids currently used in parabolic trough collectors and the nano-enhanced heat transfer fluids having the properties better than conventional heat transfer fluids are compared and their preparation methods and properties are discussed. Enhancement of thermophysical properties of molten salts by doping nanoparticles and their enhancement in thermal stability at high temperature, the possibility of using mono and hybrid nanofluid, ionic liquids, gaseous heat transfer fluid and vegetable oil as the heat transfer fluid in parabolic trough collectors are the key highlights of this review

Optical, stability and energy performance of water-based MXene nanofluids in hybrid PV/thermal solar systems

Solar thermal collectors have been recognized as promising devices for solar energy harvesting. The absorbing properties of the working fluid are crucial because they can significantly influence the efficiency of the solar thermal collectors. The performance of photovoltaic-thermal (PV/T) systems can be optimized by applying nanofluids as working fluids. MXene is a newly developed 2-D nanomaterial that has proven excellent potential in electrical applications with a lack of research in the thermal and optical applications. The present work extensively studied the optical potential of the water/MXene nanofluids with respect to the variation of MXene concentrations (0.0005–0.05 wt%) and types of surfactant (CTAB or SDBS) used in a hybrid PV/T system. The relationship between the investigated parameters was evaluated through an experimental correlation. The evaluation of the nanofluids in term of the transmittance was conducted through the Rayleigh method. The MXene concentrations and the types of the surfactant play predominant role in the transmittance, absorbance and dispersion stability of the water/MXene nanofluids. The corresponding effects due to these factors become the most noticeable in the wavelengths of 300–1350 nm. Low concentration of the MXene and shorter path lengths lead to higher transmittance. The application of the low concentration of water/MXene nanofluids as the optical filtration in a hybrid PV/T system yields a higher performance compared to a conventional PV/T system. Therefore, this research work provides novelty value in understanding the impacts of using water/MXene nanofluid in the hybrid PV/T solar collectors to harness additional energy

Improved thermo-physical properties and energy efficiency of hybrid PCM/graphene-silver nanocomposite in a hybrid CPV/thermal solar system

In this research work, novel hybrid graphene-silver (Gr-Ag) nanomaterial has been used for first time with paraffin wax as a phase change material (PCM) to improve its thermo-physical properties. Thermal and electrical energy efficiencies of the novel synthesized nanocomposite (PCM/graphene-silver) has been investigated in solar thermal collector systems (CPV/T). This paper focuses on preparation, characterization, thermo-physical properties and energy efficiency in concentrated photovoltaic/thermal (CPV/T) system of new class of nanocomposites induced with hybrid Gr-Ag nanomaterial in three different concentrations. The specific heat capacity (cp) of hybrid PCM/graphene-silver nanocomposite increased by introducing hybrid Gr-Ag nanomaterial. Electrical and thermal energy performance of the hybrid PCM/graphene-silver is investigated in a CPV/T system using MATLAB 2017b program. The improvement of cp is found to be ~ 40% with 0.3 mass% of hybrid Gr-Ag nanomaterial loaded in PCM. The highest thermal conductivity increment is found to be ~ 11% at 0.3 mass% concentration of hybrid Gr-Ag nanomaterial in PCM. The endothermic enthalpy value of the hybrid PCM/graphene-silver nanocomposite is found to be ~ 75.6 J g−1 at 0.1 mass% loading concentration of hybrid Gr-Ag nanomaterial. Melting point of hybrid PCM/graphene-silver nanocomposite with loading concentration of 0.3 mass% is measured to be 73.2 °C. The highest thermal efficiency using the hybrid graphene-silver nanoparticles reached the value of 39.62% which represents 4.16% increment in comparison with the pure PCM. The equivalent electrical efficiency is improved by 2.8% at the loading concentration of 0.3 mass% of the hybrid Gr-Ag nanomaterial. These new class of nanocomposites represented the capability of enhancement in the performance of the CPV/T system consisting of lower PV temperatures, higher temperature gains across the cooling fluid and higher electrical and thermal efficiencies

Comparative study for electrochemical and Single-Cell performance of a novel MXene-Supported Platinum–Ruthenium catalyst for Direct methanol fuel cell application

Direct methanol fuel cell (DMFC) is one of the reliable sources of energy owing to numerous benefits it offers and its suitability for portable electronic applications. Therefore, this study aims to overcome the main issues confronting anodic electrocatalyst part by introducing the novel formulation of platinum–ruthenium (PtRu) bimetal into the 2D Ti3C2Tx structure to boost the electrocatalytic activity and single-cell performance. A comparative study for electrochemical measurement and DMFC performance is conducted between as-synthesized electrocatalyst PtRu/Ti3C2Tx and two other electrocatalysts, PtRu/C and Pt/C. This comparative study between electrocatalyst revealed that PtRu/Ti3C2Tx exhibits the highest electrochemical surface area (55 m2 g-1), electrocatalytic and intrinsic activity (449 mA mgPtRu−1/ 1.36 mA cmECSA−2), carbon monoxide tolerance (1.56), and smallest charge-transfer resistance (2.66 Ω) compared with other electrocatalysts. Furthermore, the validation by DMFC single-cell test showed that PtRu/Ti3C2Tx electrocatalyst improves the performance almost 70 % compared to the Pt/C electrocatalyst. This excellent electrochemical and single-cell performance of PtRu/Ti3C2Tx electrocatalyst validates its potential to be one of the promising candidates for the anodic electrocatalyst in DMFC application

Experimental investigation of thermal stability and enthalpy of eutectic alkali metal solar salt dispersed with MGO nanoparticles

In this study, nanocomposites containing a pre-defined mass ratio of solar salt (NaNO3-KNO3: 60-40 wt.%) dispersed with magnesium oxide (MgO) nanoparticles with nominal sizes of 100 nm were prepared in solid and liquid states. The proposed amounts of sodium nitrate and potassium nitrate were added to certain amounts of ultrapure deionized (DI) water comprising a 5 wt.% concentration of MgO nanoparticles. Afterward, the prepared mixture was placed in a dry oven to mix in a liquid state to obtain well-dispersed nanocomposites. Scanning electronic microscopy (SEM) was conducted to evaluate the uniformity of synthesized, molten salt–based magnesium oxide–nanoparticles, revealing a uniform dispersion. Enthalpy and melting point measurements were performed using differential scanning calorimetry. The experimental results of solar salt–based MgO indicated decreases in melting point and enthalpy by 7% and 12.4%, respectively. The reduction of enthalpy indicated that, with the addition of magnesium oxide to solar salt, the final nanocomposite tends to have more exothermic reactions and enhanced thermal conductivity performance at the melting point. Lower melting points constitute one of the major concerns regarding molten salt–based nanofluids. MgO nanoparticles with a concentration of 5 wt.% have a melting point decreased by 7%. Mass loss and thermal stability measurements were conducted using thermogravimetric analysis (TGA). The experimentally acquired results revealed an increment of decomposition temperature from 734.29°C to 750.73°C, demonstrating the enhancement of thermal stability at high temperatures

Numerical study on the convective heat transfer performance of a developed MXene IoNanofluid in a horizontal tube by considering temperature-dependent properties

In this study, the heat transfer performance of [MMI][DMP] ionic liquid solution (20 vol% IL + 80 vol% deionized water) in the presence of Mxene nanoparticle is investigated based on computational fluid dynamics numerical method considering temperature-dependent properties. It should be noted that the thermophysical properties of IoNanofluid were experimentally measured in our previous published study. The modeling results are validated with numerical and experimental works, and the validation results indicate good agreement between them. The effect of adding Mxene nanoparticle to the base liquid was carried out in a horizontal tube with 1–50 range of Reynolds number. The results found that the heat transfer coefficient increased by increasing the Reynolds number and also the nanofluids’ concentration. Moreover, it raises by increasing the fluid inlet temperature while the Nu number decreases. This is because the Nusselt number is in a reverse relationship with the heat transfer coefficient. The maximum heat transfer coefficient observed for 0.2 mass% INf at 308 K fluid inlet temperature and Reynolds number of 50 was 2207.83 W m 2 K −1. However, the maximum Nusselt number detected for pure base fluid at 298.15 K fluid inlet temperature and Reynolds number of 50 was 13.22. Furthermore, the maximum heat transfer enhancement was observed for 0.2 mass% INf at Reynolds number of 50 and 308.15 K fluid inlet temperature (43.6%). Finally, a novel correlation is proposed to estimate the Nusselt number of nanofluids with R 2 = 0.992 and AREP = 2.8%