Coupled Impression of Radiative Thermal Flux and Lorentz Force on the Water Carrying Composite Nanoliquid Streaming Past an Elastic Sheet

Significance of the study: Hybrid nanofluids attract the attention of many current researchers due to the enhanced heat transport rate in many engineering and industrial applications. The influence of an inclined magnetic field over an exponentially stretched sheet in the presence of thermal radiation cannot be ignored and the literature available in this domain is scanty. The novelty of this communication is to explore the impact of inclined magnetic field and thermal radiative heat on the hybrid nanofluid consisting of and nanoparticles in the base fluid, water. Aim of the study: A mathematical model for hybrid nanofluid is proposed to study the influence of oblique magnetic field and thermal radiation on an exponentially elongated sheet. A comparision of the thermal characteristics of the hybrid nanofluid and the mono nanofluids is made. Research methodology: The governing flow equations are transformed into a system of ODEs with the assistance of similarity variables and are then computationally addressed using bvp4c.The graphs are displayed for velocity, heat measure and reduced frictional coefficients for selected flow parameters. Results: Hybrid nanofluid has 1-4 % growth in the rate of heat transfer when compared to mono nanofluid while it is 1-4.5% in comparison to viscous fluid for increasing radiation parameter. Conclusion: The outcomes of this work revealed that the heat transfer as a consequence of the dispersion of dual nanomaterials is more promising than the mono nanofluid. To accomplish very effective cooling/ heating in industrial and engineering applications, hybrid nanofluids can substitute mono nanofluids.

Environment-Monitoring IoT Devices Powered by a TEG Which Converts Thermal Flux between Air and Near-Surface Soil into Electrical Energy

Energy harvesting has an essential role in the development of reliable devices for environmental wireless sensor networks (EWSN) in the Internet of Things (IoT), without considering the need to replace discharged batteries. Thermoelectric energy is a renewable energy source that can be exploited in order to efficiently charge a battery. The paper presents a simulation of an environment monitoring device powered by a thermoelectric generator (TEG) that harvests energy from the temperature difference between air and soil. The simulation represents a mathematical description of an EWSN, which consists of a sensor model powered by a DC/DC boost converter via a TEG and a load, which simulates data transmission, a control algorithm and data collection. The results section provides a detailed description of the harvested energy parameters and properties and their possibilities for use. The harvested energy allows supplying the load with an average power of 129.04 μW and maximum power of 752.27 μW. The first part of the results section examines the process of temperature differences and the daily amount of harvested energy. The second part of the results section provides a comprehensive analysis of various settings for the EWSN device’s operational period and sleep consumption. The study investigates the device’s number of operational cycles, quantity of energy used, discharge time, failures and overheads.

Whistler-regulated Magnetohydrodynamics: Transport Equations for Electron Thermal Conduction in the High-β Intracluster Medium of Galaxy Clusters

Transport equations for electron thermal energy in the high-β e intracluster medium (ICM) are developed that include scattering from both classical collisions and self-generated whistler waves. The calculation employs an expansion of the kinetic electron equation along the ambient magnetic field in the limit of strong scattering and assumes whistler waves with low phase speeds V w ∼ v te /β e ≪ v te dominate the turbulent spectrum, with v te the electron thermal speed and β e ≫ 1 the ratio of electron thermal to magnetic pressure. We find: (1) temperature-gradient-driven whistlers dominate classical scattering when L c > L/β e , with L c the classical electron mean free path and L the electron temperature scale length, and (2) in the whistler-dominated regime the electron thermal flux is controlled by both advection at V w and a comparable diffusive term. The findings suggest whistlers limit electron heat flux over large regions of the ICM, including locations unstable to isobaric condensation. Consequences include: (1) the Field length decreases, extending the domain of thermal instability to smaller length scales, (2) the heat flux temperature dependence changes from T e 7 / 2 / L to V w nT e ∼ T e 1 / 2 , (3) the magneto-thermal- and heat-flux-driven buoyancy instabilities are impaired or completely inhibited, and (4) sound waves in the ICM propagate greater distances, as inferred from observations. This description of thermal transport can be used in macroscale ICM models.

Numerical Analysis of the Convective Heat Transfer Coefficient Enhancement of a Pyro-Breaker Utilized in Superconducting Fusion Facilities

The conductive components of the pyro-breaker in the quench protection system (QPS) have high current density, a large number of electrical contacts and high thermal flux. The water system needs to meet the requirements of cooling and arc extinguishing at the same time. In a previous study, the bottleneck of the steady-state capacity appeared in the barrel conductor of the commutation section, which has a cylindrical cavity. The thermal stability of the commutation section at 100 kA level was simulated in ANSYS/Workbench. The results indicate a certain level of enhancement of the convective heat transfer coefficient of the cavity is required to reach the current capacity. However, the fluid flow inside the cavity is very complex, and the convective heat transfer coefficient is difficult to calculate. In this paper, Computational fluid dynamics (CFD) is applied to the optimization of the cooling water system of the pyro-breaker. By studying the enhancement method of convective heat transfer, optimization of the structure and processing method of the water channel are proposed. The convective heat transfer coefficients of the cylindrical cavity in these optimizations were calculated in CFX. A set of optimizations of the cavity, which can meet the requirements of China Fusion Engineering Test Reactor (CFETR), were obtained and verified by experiments.

Air preheating potential with high Opaque Ventilated Façade under natural and forced convection

Opaque ventilated façades (OVF) are increasingly used in building envelope because of their positive impact on building energy efficiency. Usually, air flow is driven by natural ventilation. Recently, there were some attempts to drive air flow mechanically to preheat or precool air in combination with HVAC, Heat pump or Latent Heat Thermal Energy Storage (LHTES) systems. In this framework, an experimental real-scale module of an OVF was built (1.9 m width and 3.5 m height). In this study, OVF is tested during autumn under natural and under forced convection by means of ventilator placed at cavity outlet. Inlet air flowrate are changed from day to day or during the day. For each test, temperature, air velocity, air flow rate and thermal flux are monitored at different locations of OVF. Their analysis shows that collector efficiency and amount of collected energy depend mainly on cavity air flow rate. The measurements are compared to simulation results obtained from two thermal models describing OVF: Trnsys Type 1230 and home-developed pseudo 2D. A good agreement is found for air temperature at cavity outlet while differences are observed in opaque layers due to modelling assumptions. Last, sensitivity analysis on two design parameters is carried out.

STUDY OF THE INFLUENCE OF THE DIAMETER OF MODIFIED TOOLS WITH INTERNAL COOLING CHANNELS UNDER DIFFERENT THERMAL FLOWS

In this work, the effect on heat generation at the chip-machine tool interface was studied by varying the diameter of internal grooves of a tool for the turning process. This tool is modified with internal channels that circulate water as a coolant through a closed system. As an output parameter, the maximum cutting temperature at the chip-tool interface was studied. The input parameters were the thermal flux present at the chip-tool interface and the diameter of the internal channels present in the cutting tool. All the analysis of variation of the internal channels of the tools and also of the thermal flow exerted on the chip-tool interface were carried out using the finite element method by the Ansys® Workbench 19.2 software. The main one was that the variation in the diameter of the tool's internal grooves does not expressly impact the machining specifications.

Analysis about enhancement in thermal characteristics of viscous fluid flow with induction of ferrite particles by using Cattaneo Christov theory

The elevated convective heat transfer process plays vital role in performance of electronic and engineering equipment’s. Over the years various attempts have been executed in this regards, including the insertion of nano elements in poorly conducting liquids. Initially, improvement in thermophysical characteristics of ordinary fluids was observed but with advancement in nanoparticles structuring new classifications in nano elements are found. Among these discoveries experimentations have explored highly fascinating and intrinsically featured class of nanomaterials renowned as ferromagnetic nano constituents. So, the motivation regarding this investigation is execution about change in thermal features of base liquid with insertion of different ferrite particles. Here, water is considered as based liquid and Nickel Zinc Ferrite (NiZnFe2O4) and magnetite ferrite (Fe2O4) as solid particles are inserted. Impact of magnetic dipole is also envisioned to produce optimized effectiveness of ferrite particles. Energy transmission in flow domain is depicted by incorporation of Cattaneo-Christov heat flux model. Mathematical formulation containing thermo mechanical features of ferrite particles are attained in complexly structured partial differential system and afterwards similarity transformations are implemented for transmutation into ODES. Constructed problem is simulated by implementing numerical approaches. Influence of involved variables on associated distributions are displayed through graphs and tables. It is demonstrated that momentum as well as heat transfer of base fluid augments with inclusion of Nickel Zinc ferrite as compared magnetite ferrite. It is inferred that velocity shows declining behavior against Curie temperature whereas reverse behavior is seen for temperature profile. It is divulged that viscous dissipation imparts diminishing impact on momentum whereas contrary behavior is depicted in case of temperature profile. In addition, increment in wall drag magnitude and thermal flux is manipulated by incorporation of (NiZnFe2O4) rather than (Fe2O4).

Generalized Thermal Flux Flow for Jeffrey Fluid with Fourier Law over an Infinite Plate

The unsteady flow of Jeffrey fluid along with a vertical plate is studied in this paper. The equations of momentum, energy, and generalized Fourier’s law of thermal flux are transformed to non-dimensional form for the proper dimensionless parameters. The Prabhakar fractional operator is applied to acquire the fractional model using the constitutive equations. To obtain the generalized results for velocity and temperature distribution, Laplace transform is performed. The influences of fractional parameters α , β , γ , thermal Grashof number Gr , and non-dimensional Prandtl number Pr upon velocity and temperature distribution are presented graphically. The results are improved in the form of decay of energy and momentum equations, respectively. The new fractional parameter contains the Mittag-Leffler kernel with three fractional parameters which are responsible for better memory of the fluid properties rather than the exponential kernel appearing in the Caputo–Fabrizio fractional operator. The Prabhakar fractional operator has advantage over Caputo–Fabrizio in the real data fitting where needed.