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We examined the thermo-hydraulic characteristics for conjugate heat flow in the solar power plant having wavy channel with porous blocks (WCPB), while taking the thermal dispersion effect into account. The flow field inside the porous blocks is modelled using the Darcy–Brinkman–Forchheimer equations and the finite element method-based solver to solve the transport variables numerically. The temperature field, conductive heat flux, local Nusselt number, average Nusselt number and performance factor has been examined by changing the thermal dispersion coefficient, Reynolds number and Darcy number. We found that the average temperature decreases and conductive heat flux enhances by thermal dispersion near the bottom wall close to porous blocks. The rate of increase in average Nusselt number and performance factor with increase in dispersion coefficient is seen to be higher at the higher Reynolds number. It's interesting to note that the average Nusselt number underestimated with greater extent at higher dispersion coefficients as a result of ignoring the conjugate heat transfer effect. Moreover, the performance factor with the higher Reynolds number (= 500) is found to be more than unity. Also, when Reynolds number is 500, the performance factor for WCPB becomes larger than the plane channel with pours block at higher dispersion coefficient and Darcy number. The results of this analysis suggest that the proposed system is cost-effective to be used in the solar power plant. [ABSTRACT FROM AUTHOR]

In this study, the stability and viscosity of four different nanoparticles are discussed in conjunction with the physical properties of these nanoparticles. The aim is to provide guidance for nanoparticle selection in future nanofluid applications. Additionally, our goal is to examine hybrid nanofluids in comparison to single nanofluids, exploring their potential benefits and evaluating their industrial applications. A two-stage approach was employed, using ethylene glycol (EG) as a base fluid, to create these nanofluids. Single nanofluids were formed with SiO2, TiO2, MWCNT, and ZnO nanoparticles at 0.1%, 0.5%, and 1% volume concentrations. Additionally, binary (SiO2–TiO2/EG), ternary (SiO2–TiO2–MWCNT/EG), and quaternary (SiO2–TiO2–MWCNT–ZnO/EG) hybrid nanofluids were formed with 0.1% volume concentrations. The dynamic viscosity of all nanofluids was evaluated over the temperature range of 20–50 °C. Analysis of nanofluids was extended by characterization studies using field emission transmission electron microscopy (FE-SEM), field emission scanning electron microscopy (FE-TEM), Zeta potential testing, and visual inspection. SiO2 nanoparticles exhibited the greatest stability, remaining in suspension for more than 28 days without sedimentation, while ZnO nanoparticles were the least stable, collapsing in < 7 days. Compared to ethylene glycol, ZnO/EG had the most increased viscosity (42.79%) at 20 °C and a 1% volume concentration. However, SiO2–TiO2–MWCNT/EG showed the largest decrease in viscosity (9.99%) at 20 °C. Hybrid nanofluids exhibit better viscosity performance compared to their base fluids and single nanofluids, enhancing the thermal efficiency of these heat transfer fluids. Additionally, this study is groundbreaking research as it emphasizes the efficiency of hybrid nanofluids as well as introducing quaternary nanofluids to the literature. [ABSTRACT FROM AUTHOR]

We consider the influence of the ion-partitioning effect, enabled by the permittivity difference at the interface, to investigate the formation of blue energy within the nanochannel having pH-sensitive polyelectrolyte layer (PEL) under a salinity gradient. By altering the pH of right reservoir (pHR) and permittivity ratio of electrolyte solution to PEL, respectively, we investigated the electric-double layer (EDL) potential field, cationic concentration field, transference number, maximum power generation, optimum power production and its density, conductance, and optimum energy conversion efficiency. It turns out that due of the decrease in screening effect caused by the reduction in cationic concentration, the EDL potential is significantly increased by the ion-partitioning effect. We found that PEL permittivity and pHR have a considerable impact on ionic selectivity of nanochannel. For strongly acidic solutions, it implies that power generation decreases at smaller PEL permittivity. Additionally, at both lower and higher pHR values, the maximum energy conversion efficiency decreases as PEL permittivity decreases. Furthermore, the higher power generation density attained at lower pHR—an analysis conducted in this work, supports the novelty of the current energy-generating nanofluidic device when compared to the previously published work. [ABSTRACT FROM AUTHOR]

We examined the energy production assessment for heat flow of non-Newtonian ionic liquids within a wavy microchannel, considering the impact of finite ionic size and electroosmotic actuation induced by the applied electric field. A numerical method based on the finite element approach was utilized to determine the associated flow, electrical-double layer potential, and temperature fields. The current model was validated against existing theoretical results. Entropy production, including viscous, thermal, Joule, and total entropy generation within the wavy microchannel, was explored by varying the Brinkman number, thermal Peclet number, steric factor for finite ionic size, Carreau number, and dimensionless amplitude. Increasing the Carreau number resulted in higher shear-thinning behavior of the liquid, leading to higher total entropy generation. Conversely, an increase in finite ionic size reduced entropy generation. Entropy generation decreased with increasing amplitude of the wavy wall. Notably, compared to the plane channel, wavy microchannels consistently exhibited reduced entropy generation. The insights gained from this study are relevant to the development of efficient heat-exchanging devices for electronic cooling. [ABSTRACT FROM AUTHOR]

According to review of the literature, the influence of nanoparticle diameter with irregular shapes on viscosity requires further research since there is no relation between particle size and nanofluid stability. In this study, SiO2/EG–water-based nanofluid samples were prepared, and their viscosities were experimentally determined. SiO2 nanoparticles had sizes of 7, 15, and 40 nm, and the base fluid was a 50% ethylene glycol and 50% water mixture. Nanofluid samples were prepared using a two-step technique. Viscosity change was measured every 10 °C from 20 to 60 °C. The maximum viscosity values were observed for 7, 15, and 40 nm particles over an entire concentration range. Considering all measurements, the highest viscosity increase was 60.51% for 3% SiO2 (7 nm) at 60 °C, and the lowest viscosity change was 7.72% for 1% SiO2 (40 nm) at 40 °C. The most stable sample of the current study was 1% SiO2 (15 nm), and its Zeta potential was − 35.6 mV. Finally, a new empirical equation that included temperature, particle diameter, and concentration terms is suggested to predict dynamic viscosity, with Radj2 = 0.98. It was also compared with previous correlations. [ABSTRACT FROM AUTHOR]