查看更多>>摘要：The Industrial Internet of Things (IIoT) plays a key role in industrial applications and manufacturing processes. Numerous technologies are implementing IIoT to monitor and control manufacturing processes, maintain reliability, and increase productivity. In this study, IIoT was used to demonstrate the heat transfer performance of a double-pipe heat exchanger at the laboratory scale to provide research guidelines. Two types of inner pipes, smooth and corrugated pipes, were used in the experiment. In the experiment, the hot- and cold-water mass flow rates were 9 and 10 L/m, respectively. The cold- and hot-water temperatures were set at 20℃, 22℃, and 24℃ and 35℃, 40℃, and 45℃, respectively. Equipment operation control and reading and recording of the experimental data were performed using PLC and IIoT platforms. The experimental results showed that heat exchange using corrugated pipes was more efficient than smooth pipes when considering the overall heat transfer coefficient, with an effectiveness of approximately 19%. However, corrugated pipes exhibited a 30% higher pressure difference compared to smooth pipes. This reveals that IIoT has been established and can be effectively applied to laboratory thermal solutions, allowing operators to read real-time data at any time, both inside and outside the work area.
查看更多>>摘要：Cryogenic processes often involve the heat interaction of multiple fluids and are highly sensitive to even minor variations in operating conditions. Hence, flow and temperature nonuniformity adversely impact the performance of thermal systems, and their combined occurrence can be especially detrimental. The transient response and thermal effectivity of a cross-flow three-fluid heat exchanger are investigated while considering the flow and temperature nonuniformity at the inlet section. Four modes of combined flow and temperature nonuniformity are opted, which replicates the pragmatic situation existing in the working of heat exchangers, and the effectivity of the thermal system is evaluated by its alignment with the uniform flow mode. Flow nonuniformity is implicated in both the inlet section and within the core all along with the effect of fluid back mixing. The "Dankwert's" boundary condition is specifically used to account for the effects of axial dispersion within the fluids. The model incorporates longitudinal heat conduction in partition walls, with the "finite difference method" employed to solve the partial differential equations. To the best of our knowledge, the present study is the first attempt to analyze both the transient response and effectivity of three-fluid heat exchangers under combined flow and temperature nonuniformity. It is learned that thermal effectivity is degraded by 31.5% and enhanced by 1% under flow nonuniformity mode QPQ and temperature nonuniformity mode 1 respectively. Under the combined mode of both, the effectivity settles down somewhere amid both and is found to be degraded by 8%. The higher NTU comes up with a sharp peak in temperature distribution, which makes the core more prone to cracks.
查看更多>>摘要：Much recent research has focused on dielectric fluids in engineering applications because of their physical properties. In this study, the use of HFE-7100 as a working fluid in a porous pipe exposed to thermal conditions like solar radiation conditions in Baghdad city was studied. The two-phase mixture model with Local Thermal Non-Equilibrium assumption was applied to analyze the flow boiling of a subcooled HFE-7100 in a vertical pipe filled with high porosity metal foam. The Finite volume h approach with MATLAB code was used to solve the governing equations like continuity, momentum based on Forchheimer-extended Darcy model and energy equations. The results displayed that the heat transfer rises with the rise in pore density, porosity and the heat flux while the liquid saturation reduces with the raise in heat flux and pore density and the decrease in , porosity of the metal foam. PPI effect is more effective at low porosity, as it increases the heat transfer coefficient by 101%, 95%, and 88% at 0.8, 0.9, and 0.95 porosity, respectively. But the effect of porosity is very small compared to PPI effect on the liquid saturation where it decreases by 4% when the porosity decreases from 0.95 to 0.85, while it decreases by 23% when the pore density increases from 10 to 110 PPI.
查看更多>>摘要：Objective of the paper is to investigate the motion of an unsteady free convective MHD flow of a micro-polar fluid over semi-infinite vertically moving porous plate in the presence of chemical reaction and thermal radiation. A transverse magnetic field is applied, assuming a low magnetic Reynolds number. We have discussed the effects of heat radiation due to a heat source and first order chemical reaction within the medium. The perturbation method is applied to solve the nonlinear coupled partial differential equations in their dimensionless form, converting them into a system of ordinary differential equations, which are then solved analytically. The effects of magnetic field, medium permeability, buoyancy force, heat source, concentration gradient, Prandtl number, thermal diffusion, heat radiation, and first order chemical reaction on velocity, temperature and concentration are discussed graphically. The graphical representations are generated using MATLAB software. For engineering interest, their effects on skin friction, heat and mass transfer in terms of Nusselt number and Sherwood number are discussed; numerical values are shown in tabular form. The results show that magnetic fields reduce fluid velocity, while thermal radiation decreases temperature, and chemical reactions lower concentration. Radiation increases skin friction and heat transfer, while chemical reactions reduce mass transfer. Findings have relevance in various problems and situations arising with micro-polar fluidic devices, industrial like petroleum and lubrication, mixing etc.
Ahmed Dhafer AbdulsahibDhirgham AlkhafajiIbrahim M. Albayati
2456-2470页
查看更多>>摘要：Heat sinks dissipate heat from electronic components, and the increase in heat generation owing to technological advancements has prompted researchers to improve heat sink efficiency. The present study aims to improve heat sinks by high-emissivity nanocoating where the coating is prepared using nanoparticles CuO and MWCNT at a rate of 6% in half a liter of Acrylic resin and solvents Xylene and Butyl acetate at a rate of 30%. After coating the heat sink, the emissivity was examined and it was (0.963) while it was before coating (0.202). The heat sink is examined inside a cubic cavity with a right surface containing heaters that give temperature at the same value as the thyristors (58.5℃, 90℃, and 112.5℃) and a cold left surface (30℃). The temperatures at the tip of each fin are measured before and after coating when they change with time and at a steady state. The results showed that the nanocoating significantly reduced the temperature compared to the uncoated condition with the improvement percentage at a heater temperature of 58.5℃ ranging from 10% to 15% at 90℃ ranging from 24% to 34% and at 112.5℃ ranging from 23% to 35%. It is concluded that the nanocoating showed great effectiveness in improving the performance of the heat sink at all temperatures, but the maximum effectiveness was at high thermal loads.
查看更多>>摘要：Creating a high heat transfer flux is not a common phenomenon and occurs only when a source of heat production (or consumption) is placed in a small volume; in precision casting systems, heat transfer should be done at a high velocity due to the presence of thin molten branches. Nanofluids present a significant opportunity to improve the thermal efficiency. In this research, a combination of different solutions to enhance heat transfer has been evaluated simultaneously. For this purpose, in the current research, aluminum oxide non-Newtonian nanofluid in volume percentages of 0, 0.5, 1.5, and 2 has been investigated in a torsional heat exchanger with a rotating triangular blade around the tube. The base fluid of this non-Newtonian nanofluid consists of water with 0.1% mass of carboxymethyl cellulose. In this study's results, the heat exchanger's performance has been predicted. Combining neural network optimization code with the numerical simulation of the double-tube spiral geometry and using non-Newtonian nanofluid to increase the heat transfer and improve the performance of the heat exchanger is the innovation of the present research.
查看更多>>摘要：The consistency of cooling greatly influences the quality of L-beams. In this paper, the process of cooling high-temperature L-beams by multi-jet impingement is numerically simulated. The VOF model and Realizable k-ε turbulence model were used, and the reliability of the Realizable k-ε turbulence model was verified using experiments. The jet flow rate is mainly 3-11 L/min. Numerical simulation calculations were used to obtain the distribution law of pressure, streamline, and wall shear of the flow field of the multi-nozzle jet impinging on the surface of the L-beam, as well as the distribution of Nusselt number of the L-beam and the temperature distribution at 1/2 thickness. The results suggest that the cooling uniformity of the L-beam can be enhanced by extending the cooling duration of the short edge or by concurrently increasing the water flow and time of the short edge. Based on the above strategy, a relevant industrial test program was developed. After the jet impingement cooling experiment, the L-beam's surface temperature differential decreased by 43.9℃, and the bending of the L-beam was decreased by 10.4 cm. The maximum value of the magnetic field gradient associated with the stress in the L-beams was reduced by up to 80.2%.
查看更多>>摘要：The effect of suction/injection on magnetohydrodynamic (MHD) slip flow across a shrinking sheet in a porous medium is examined in this work, taking chemical reactions and thermal radiation into account. Understanding the effects of these variables on heat and mass transport, material characteristics in magnetic fields, and boundary conditions in a variety of technical and industrial processes including metallurgy, polymer processing, energy systems, and medicinal treatments is the major goal. The study investigates the combined effects of radiation, chemical processes, magnetic fields, and suction/injection on flow properties and boundary layer behavior using the Keller Box Method. To simplify the analysis, the controlling partial differential equations are transformed into nonlinear ordinary differential equations using similarity transformations. The results are intended to maximize system efficiency and performance in these various applications. Flow patterns and heat transfer rates are significantly impacted by slip flow, which happens when the fluid velocity at the boundary is greater than zero.
查看更多>>摘要：This study investigates the thermal behavior of a thick elliptical plate subjected to a moving laser heat-source using a novel application of the time-fractional heat conduction equation with the Caputo-fractional derivative. By incorporating a long-tail power kernel to account for the memory-dependent heat flow, this approach provides a more accurate representation of heat transfer dynamics in functionally graded materials (FGMs) under transient conditions. The material properties of the elliptical annulus plate, including thermal conductivity, heat capacities, and Poisson's ratio, are axially graded to model ceramic-metal-based FGMs, specifically titanium carbide and nickel. Analytical solutions for the displacement and temperature distributions are derived using the extended Mathieu function, Laplace transform, and perturbation methods, while numerical methods are employed for stress computation. The study introduces a comprehensive framework to evaluate the influence of time-fractional parameters on thermal, deformation, and stress profiles, offering enhanced predictive capabilities for high-temperature applications in advanced material design. The novelty lies in the integration of fractional-order modeling and a moving laser source, which provides deeper insights into the thermal-mechanical responses of FGMs, paving the way for optimized designs in thermal industries. The merit of this study lies in its innovative modeling approach, novel application to FGMs with elliptical geometry, and relevance to high-temperature industrial applications. The integration of fractional calculus and moving heat sources represents a significant advancement in understanding and optimizing thermal behavior in advanced materials.
查看更多>>摘要：Regarding the various issues and incidents pertaining to Rayleigh-Benard convective system in industrial and technical domains, a great deal of important information and research has emerged. However, there are still certain physical phenomena that are not explored but have a significant impact on the Rayleigh-Benard convective system. One example of such a phenomenon is the simultaneous action of two concentrated solutes mixed with Newtonian fluid from opposite ends, with an external time-modulated magnetic field influenced by the internal heat source. The mathematical representation of the considered problem is based on the fundamental laws of fluid dynamics. This article attempts to shed some light on the impact of the internal Rayleigh number and the Chandrasekhar number on the convective system. To understand the impact of two concentrations with internal heat source and magnetic field modulation on the transport process, a weakly nonlinear theory and Fredholm's solvability condition are applied. A nonautonomous differential equation, known as the Ginzburg-Landau (GL) equation, is derived in terms of the amplitude of convection. An in-built function of the software MATHEMATICA is used to determine the solution of GL equation and to plot the graphs of dimensionless parameters vs transport phenomena. The Chandrasekhar number (Q), Le_1, Le_2 delayed the transport process while Ri and Pm contribute to increase the heat and mass transport.
NETL
NSTL
Wiley