Journal of Engineering Thermophysics最新文献

The industrial component that transfers heat from one fluid to another most frequently uses Shell and Tube Heat Exchangers (STHE). Enhancing the heat transfer efficiency of heat exchangers has garnered more attention as a result of scarce energy resources and high energy expenditures. In STHE, the pressure drop is considered an important issue that causes cracks and economic losses. An essential factor in improving the performance of a heat exchanger with low pressure drop was the angle and distance of the baffles. Several methods were developed to reduce pressure drop and speed up heat transfer. But those methods were not provide a satisfactory pressure drop reduction, so the optimal baffle configuration was still a task in the heat exchanger. In the proposed model, Horse-herd Optimization Algorithm (HOA) based baffle design and neural network based thermal performance prediction arrangement was developed to reduce the pressure drop and predict the rate of transferring heat. Shells and tubes were developed at the corresponding material, inside the shell, a baffle was designed to barrier the flow of cold water. The optimal solution of baffle configuration was solved through HOA, which finds the appropriate baffle’s distance and angle by reducing the pressure drop. After the water flow modelling, the seven key parameters values were observed, and create a dataset. Using this data, a thermal performance prediction system was developed to analyze each period input value to predict the net energy, heat transfer rate, and Nussle number. The proposed model provides 52 Pa pressure drop, 0.59 effectiveness, 0.59 NTU, 417 U, and 92% accuracy. The output of the suggested approach is contrasted with that of other current methods for validation. The proposed model offers a high heat transferring capacity and reduces pressure effects risk.

First-principles calculations based on density functional theory were used to examine the thermoelectric characteristics of BeO and MgO monolayers in the current study. The energy gap range of these two monolayers reveals the insulating properties of BeO and the semiconductor properties of MgO which is in agreement with those of the previously reported results. Following the band structure and related structure parameters the BoltzTrap method was used to determine the electronic transport coefficients based on Boltzmann transport theory. Calculations relating to thermoelectric characteristics are found in this perspective, including those relating to the Seebeck coefficient, the electrical conductivity, the electronic thermal conductivity, electron heat capacity, Hall coefficient, magnetic susceptibility, and figure of merit The crystal structure, internal energy, and electronegativity all have an impact on the characteristics of heat transport since there is a possibility of variable atomic diameters and the different in electron localization function. The MgO monolayer has a somewhat higher figure of merit than BeO due to MgO’s higher electron conductivity in comparison to BeO and its lower electron thermal conductivity values. The new findings can provide a fundamental understanding of thermoelectric transport and related applications for both BeO and MgO monolayers.

If speaking of timely detection of deviations in operation of pumping equipment, there is a problem of the current coverage of the oil well stock with telemetry sensors. Some data analytics, for example, analysis of dynamograms, is still performed manually. The present work attempts to create an automation solution for diagnostics of the condition of well pumping equipment. For sucker-rod pumps, a dynamogram classification model based on a convolutional neural network has been developed, which makes it possible to identify working conditions of a pumping unit. For electric centrifugal pumps (ECPs), a virtual sensor model has been developed based on modern machine learning technologies, which enables prediction of temperature and pressure gradients at the pump intake in the absence of submersible sensors. In the work, we tested a set of classical machine learning algorithms based on linear models and ensembles of decision trees, as well as advanced deep learning methods, e.g., transformers. The virtual sensor models developed are embedded directly into the automated process control system (APCS), and thus technologists and operators can be warned timely, almost in real time, of a possible shortening of the planned time between failures of ECP units and their possible mailfunctioning for various reasons.

The results of testing the popular IQR (Interquartile Range) method for filtering experimental data are presented. It is shown that if the distributions of measured values differ greatly from the Gaussian distribution, this method gives a large error in the statistical characteristics, especially the higher moments. The earlier-developed statistical filtering method can take into account substantial skewness of distributions of measured values and can greatly reduce the filtering error.

The three-dimensional convection in the Earth’s mantle is studied with a well-known mathematical model, which includes the Navier–Stokes equations in the Oberbeck–Boussinesq and geodynamic approximations. Two numerical models of convection are considered. The first is based on the implicit finite-difference schemes of splitting over spatial variables with correction of pressure. The second numerical model is based on the spectral difference method. The numerical models constructed were compared on model problems of convection in a rectangular parallelepiped in a liquid with constant viscosity, corresponding to the convection in the entire mantle of the Earth [1]. The calculation results are in good agreement with the test results.

The present numerical work investigates by means of Constructal Design the influence of the geometry of an inclined passive wall solar chimney on the ventilation performance of an attached room. The main purpose is to maximize the mass flow rate of air in the chimney/attached room. The problem is subjected to two constraints: the chimney and room areas. Three degrees of freedom are investigated: the ratio between the exit and inferior bases widths of the chimney ((W_{e}/W_{g})), the ratio between the width of the chimney inferior basis and the absorber wall height ((W_{g}/H_{a})), and the ratio between the opening that connects chimney and room and the absorber wall height ((H_{i}/H_{a})). It is considered unsteady, incompressible, free convective, turbulent flows in a two-dimensional domain. The finite volume method is used to solve the time-averaged equations of continuity, momentum and conservation of energy. For closure of turbulence, it is employed the (k)-(varepsilon) model. Results showed that the best geometric configuration led to a mass flow rate 5.7 times superior than the worst configuration, showing the importance of solar chimney desing in this problem. Moreover, a strong sensibility of the investigated ratios on the mass flow rate was noticed.

Magnetohydrodynamic boundary layer flow and heat transmission processes with a hybrid nanofluid film over a steady stretched sheet are taken into consideration. The impressions of an angled magnetic field, tangent hyperbolic flow, and viscous dissipation upon the momentum and thermal boundary layer are investigated. The leading equations are PDEs transfigured into nonlinear, ordinary ones that apply a non-dimensional transformation. Spectral relaxation methods are exploited for numerical solutions to non-dimensional governing equations with no-slip boundary conditions. This simulation was constructed with the cooperation of the application MATLAB. Present outcomes are matched with literature in the limiting cases and are an excellent agreement. To analyze the flow behavior, thermal physical characteristics, and the nature of the hybrid nanofluid particles’ transport properties, we look at various kinds of hybrid nanofluid particles with the base fluid ethylene-glycol ((EG)), which are Ferro–Copper, ((Fe_{3}O_{4})–Cu) and Single walled carbon nanotubes–Copper Oxide, (SWCNT{-}CuO). The consequences of emerging parameters such as Magnetic parameter, Prandtl number, Brinkman number, Power law index, Weissenberg number, and Angle of inclination are explored through graphs The local skin friction and Nusselt number are also graphically displayed with respect to the above parameters.

Condensers represent an indispensable part of equipment of any power, chemical-technological, cryogenic, refrigeration and other installations used in industry. Reducing the weight, dimensions and cost of devices is always an urgent task. The process of condensation in real devices is a very complex phenomenon. The intensity of energy transfer from vapor to a solid cooled wall is determined, other things being equal, by three interrelated factors: (i) variable irrigation density and change in film flow hydrodynamics as the irrigation density changes, (ii) variable vapor velocity affecting a condensate film in the varying film and vapor flow regimes, and (iii) effect of the diffusion process on heat transfer during condensation of vapor with non-condensable impurities. The authors consider that they have to describe the issues that are poorly covered in the literature, although these issues are of fundamental importance for understanding the process under study. In this paper, the main factors that determine heat transfer during stationary vapor condensation on horizontal tube bundles are considered. An algorithm for calculating a condenser at film condensation of stationary vapor without non-condensable impurities is proposed. A critical analysis of modern experimental studies on heat transfer during condensation has been carried out.

The impinging jet technique is a high-performance cooling technology for microchips which are basic elements of electronic systems and having high heat generation rates in small volumes. In this study, the improvement of heat transfer of the microchips used in all technological products today by air impinging jet has been examined. For this purpose, numerical research has been carried out on the cooling of copper plate surfaces with two different patterns, reverse triangle and reverse semi-circle shaped having 1000 W/m² constant heat flux in rectangular cross-section ducts with adiabatic surfaces, by one and double air jets with distances of D(_{h}) and 2D(_{h}) between them. Numerical computation has been performed for energy and Navier–Stokes equations as steady and three-dimensional by employing the Ansys-Fluent computer program with the k-(varepsilon) turbulence model. The obtained results have been compared with the numerical and experimental results of the study in the literature and it has been seen that they are compatible with each other. The results have been presented as the mean Nu number and the variation of surface temperature for each of both patterned surfaces in single and double jet channels with different distances. Streamline and temperature contour distributions of the jet flow along the channel for different H/D(_{h}) ratios and jet numbers have been evaluated for both patterned surfaces. In double-jet and 2D(_{h}) distance channels compared to D(_{h}), at H/D(_{h}) = 12 and Re = 11,000, the Nu number increases of 67% and 65.9% have been observed on the first-row reverse triangle and semi-circular patterned surfaces, respectively.