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This paper aims to investigate the thermal performance of equivalent square and circular thermal systems and compare the heat transport and irreversibility of magnetohydrodynamic (MHD) nanofluid flow within these systems.

The research uses a constraint-based approach to analyze the impact of geometric shapes on heat transfer and irreversibility. Two equivalent systems, a square cavity and a circular cavity, are examined, considering identical heating/cooling lengths and fluid flow volume. The analysis includes parameters such as magnetic field strength, nanoparticle concentration and accompanying irreversibility.

This study reveals that circular geometry outperforms square geometry in terms of heat flow, fluid flow and heat transfer. The equivalent circular thermal system is more efficient, with heat transfer enhancements of approximately 17.7%. The corresponding irreversibility production rate is also higher, which is up to 17.6%. The total irreversibility production increases with Ra and decreases with a rise in Ha. However, the effect of magnetic field orientation (γ) on total EG is minor.

Further research can explore additional geometric shapes, orientations and boundary conditions to expand the understanding of thermal performance in different configurations. Experimental validation can also complement the numerical analysis presented in this study.

This research introduces a constraint-based approach for evaluating heat transport and irreversibility in MHD nanofluid flow within square and circular thermal systems. The comparison of equivalent geometries and the consideration of constraint-based analysis contribute to the originality and value of this work. The findings provide insights for designing optimal thermal systems and advancing MHD nanofluid flow control mechanisms, offering potential for improved efficiency in various applications.

The purpose of this study is to investigate the influence of enclosure shape on magnetohydrodynamic (MHD) nanofluidic flow, heat transfer and irreversibility in square, trapezoidal and triangular thermal systems under fluid volume constraints, with the aim of optimizing thermal behavior in diverse applications.

The study uses numerical simulations based on a finite element-based technique to analyze the effects of the Rayleigh number (Ra), Hartmann number (Ha), magnetic field orientation (γ) and nanoparticle concentration (ζ) on heat transfer characteristics and thermodynamic entropy production.

The key findings reveal that the geometrical design significantly influences fluid velocity, heat transfer and irreversibility. Trapezoidal thermal systems outperform square systems, while triangular systems achieve optimal enhancement. Nanoparticle concentration enhances heat transfer and flow strength at higher Rayleigh numbers. The magnetic field intensity has a significant impact on fluid flow and heat transport in natural convection, with higher Hartmann numbers resulting in reduced flow strength and heat transfer. The study also highlights the influence of various parameters on thermodynamic entropy production.

Further research can explore additional geometries, parameters and boundary conditions to expand the understanding of enclosure shape effects on MHD nanofluidic flow and heat transfer. Experimental validation can complement the numerical simulations presented in this study.

This study provides valuable insights into the impact of enclosure shape on heat transfer performance in MHD nanofluid flow systems. The findings contribute to the optimization of thermal behavior in applications such as electronics cooling and energy systems. The comparison of different enclosure shapes and the analysis of thermodynamic entropy production add novelty to the study.

The numerical simulation of practical thermal processes is generally complicated because of multiple transport mechanisms and complex phenomena that commonly arise. In addition, the materials encountered are often not easily characterized and typically involve large property changes over the ranges of interest. The boundary conditions may not be properly defined and or may be unknown. However, it is important to obtain accurate and dependable numerical results from the simulation in order to study, design, and optimize most practical thermal processes of current and future interest. The purpose of this paper is to focus on the main challenges that are encountered in obtaining accurate numerical simulation results on practical thermal processes and systems.

A wide range of thermal systems is considered and the challenges faced in the numerical simulation are outlined. The methods that may be used to meet these challenges are presented in terms of grid, solution strategies, multiscale modeling and combined mechanisms. The models employed must be validated and the accuracy of the simulation results established if the simulation is to form the basis for improving existing systems and developing new ones.

Of particular interest are concerns like verification and validation, imposition of appropriate boundary conditions, and modelling of complex, multimode transport phenomena in multiple scales. Additional effects such as viscous dissipation, surface tension, buoyancy and rarefaction that could arise and complicate the modelling are discussed. Uncertainties that arise in material properties and in boundary conditions are also important in design and optimization. Large variations in the geometry and coupled multiple regions are also discussed.

The paper is largely focused on numerical modeling and simulation. Experimental data are considered mainly for validation and for physical insight.

A wide variety of practical systems, ranging from materials processing to energy, cooling, and transportation is considered.

Future needs in this interesting and challenging area are also outlined in the paper.

Natural convection heat transfer combined with radiation heat transfer is used in electronic cooling. The purpose of this paper is to investigate the thermal loading characteristics of an enclosure.

The goal is to investigate the effect of thermal radiation on thermal and flow characteristics of the cavity. The enclosure lower wall is at constant temperature and the upper wall is adiabatic while there are several discrete heat sources inside the cavity. In addition the effect of parameters such as heating number (Nr), aspect ratio (A), the number of heaters (N), and thermal radiation on the maximum and mean temperature of system, thermal loading characteristics of the system, Nusselt number, and the maximum stream function rate is performed. To solve the governing nonlinear differential equations (mass, momentum, and energy), a finite‐volume code based on Patankar's SIMPLE method is utilized.

Heat transfer by natural convection solely and it's conjugation with thermal radiation on the thermal and flow characteristics of the system is studied. Also a parametric study illustrating the influence of the heating number, aspect ratio, the number of heaters, and thermal radiation on the maximum and mean temperature of system, thermal loading characteristics of the system, Nusselt number, and the maximum stream function rate is investigated. The results have revealed that the thermal radiation have an important effect on the thermal characteristics of system at low heating numbers.

The relevant governing parameters were: the heating number, Nr from 0.05 to 500, the cavity aspect ratio, A=H/L from 0.1 to 1 and the number of heaters, N, is an odd number ranging from 1 to 19

This work is numerical investigation only but can have engineering application such as electronic cooling, transformers, fusion reactors technology, hot structures, fuel cells, fibrous insulations and solar‐energy drying systems.

The effect of radiation in enclosure with discrete heaters within fluid has not been addressed in the literature.

The purpose of this paper is to simulate the thermal performance of fluidic momentum controller (FMC) actuators in two case, with and without thermal distribution system on a three-axis configuration of FMC actuators to an orbital period of satellite. The results show the effectiveness of using a storage with FMC actuators.

One of the challenges during a satellite’s orbital mission is unpredictable external temperature perturbations. This system used as a collaborative thermal subsystem for microsatellite temperature passive control. The operating principles of the system are that each fluid rings are used in a microsatellite surface with pumps to stabilize the satellite. All fluid rings are connected to the satellite thermal distribution system (storage).

Simulation results show that with using of thermal distribution system, damping of satellite different surfaces temperature is rapidly possible to the event of thermal disturbances.

Numerical simulation is obtained by ANSYS Fluent software and pressure-velocity coupling is SIMPLE method and spatial discretization is second order accurate and first order in time, viscous model is k-e. In this regard, a solver algorithm is also developed.

In space research fields about FMC application as actuators to satellite system design, main goal is to research about role of this system to attitude and determination control system (ADCS) of satellites, and no study is performed on its role to satellite temperature damping. This study is exclusively simulated thermal distribution system (includes a storage and its connections) of a microsatellite equipped with FMC actuators. The idea of using a storage for FMC actuators is the innovative step of this research.

The purpose of this study is to, first, provide an overview of the previously conducted works related to thermal analysis of space equipment, including battery packages, especially lithium (Li)-ion ones. Second, the need for a reduced thermal mathematical model (RTMM) and a procedure devising it is defined. Finally, an experimental steady-state temperature distribution test is conducted to finalize the RTMM study.

This study was carried out as part of a development project for thermal analysis of Li-ion battery packages used in a space equipment. The study presents certain stages of the design of the battery pack in parallel with battery technology development. Following a literature review, a numerical thermal analysis is conducted; then interface thermal conductance values are found out by means of the first law of thermodynamics; and the study is completed with the help of an experimental test.

The study provides key aspects for a successful battery-package thermal design for a space equipment. Additionally, the study summarizes the experimental results used in the RTMM process and the computed thermal conductance values between node couples.

Thermal analysis is important and vital in space equipment considering their harsh working conditions and environments. Hence, the study provides a RTMM for the thermal analysis of Li-ion battery packages, instead of a full finite element model, to save computational time and CPU usage. The findings are supported by experimental results. Hence, presented details can be used as guidelines for enterprises having a goal of battery package technology achievement, including design and manufacturing.

After providing a literature review of studies conducted on satellite subsystems including Li-ion batteries, this study presents a clear, complete and verified process of a RTMM for a Li-ion battery package in aero/space structures design. It presents details of building up a model and calculation methodology through an iterative procedure in which an optimization algorithm known as particle swarm optimization (PSO) was benefitted. In the RTMM, additionally, experimental temperature distributions obtained through thermal vacuum test were presented. It has been shown that the model can be used reliably in designing space equipments.

A shape design sensitivity analysis (SDSA) of two‐dimensional transient heat diffusion problems is proposed based on the BIE formulation. The adjoint variable method is used by using the Ionescu—Cazimir integral identity. The procedure is checked against the analytical solution in the case of a rod example, and by numerical comparisons with the finite differencing for a rectangular block under thermal shock and a plunger model. An optimal design problem is then formulated for the plunger and solved to obtain a realistic shape.

SYNOPSIS DURING the last ten years or more an outwardly unnoticeable change has been taking place on board a variety of ships, in that the traditional method of heating cargo, engine room services and accommodation by steam, has been replaced by a thermal fluid which remains in the liquid phase throughout the entire heating system.

This study aims to numerically scrutinize the entropy generation minimization and mixed convective heat transfer of multi-walled carbon nanotubes–Fe₃O₄/water hybrid nanofluid flow in a lid-driven square enclosure with heat generation in the presence of a porous layer on inner surfaces, considering local thermal non-equilibrium (LTNE) approach and the non-Darcy flow model.

The dimensionless governing equations for hybrid nanofluid and solid phases are solved by applying the finite volume method and semi-implicit method for pressure-linked equations algorithm.

The roles of the internal heat generation in the porous layer, LTNE model and nanoparticles volume fraction on mixed convection phenomenon and entropy generation are introduced for lid-driven cavity hybrid nanofluid flow. Based on the investigation of entropy generation and heat transfer, the minimum total entropy generation and average Nusselt numbers are found at 1 ≤ Ri ≤ 10 where the effect of the forced and free convection flow directions being opposite each other is very significant. When considering various nanoparticle volume fractions, it becomes evident that the minimum entropy generation occurs in the case of φ = 0.1%. The outcomes of LTNE number reveal the operating parameters in which thermal equilibrium occurs between hybrid nanofluid and solid phases.

The analysis of entropy generation under various shear and buoyancy forces plays a significant role in the suitable thermal design and optimization of mixed convective heat transfer applications. This research significantly contributes to the optimization of design and the advancement of innovative solutions across diverse engineering disciplines, such as packed-bed thermal energy storage and thermal insulation.

This study aims to examine the effects of cross-flow and multiple jet impingement on conductive panel cooling performance when subjected to uniform magnetic field effects. The cooling system has double rotating cylinders.

Cross-flow ratios (CFR) ranging from 0.1 to 1, magnetic field strength (Ha) ranging from 0 to 50 and cylinder rotation speed (Rew) ranging from −5,000 to 5,000 are the relevant parameters that are included in the numerical analysis. Finite element method is used as solution technique. Radial basis networks are used for the prediction of average Nusselt number (Nu), average surface temperature of the panel and temperature uniformity effects when varying the impacts of cross-flow, magnetic field and rotations of the double cylinder in the cooling channel.

The effect of CFR on cooling efficiency and temperature uniformity is favorable. By raising the CFR to the highest value under the magnetic field, the average Nu can rise by up to 18.6%, while the temperature drop and temperature difference are obtained as 1.87°C and 3.72°C. Without cylinders, magnetic field improves the cooling performance, while average Nu increases to 4.5% and 8.8% at CR = 0.1 and CR = 1, respectively. When the magnetic field is the strongest with cylinders in channel at CFR = 1, temperature difference (ΔT) is obtained as 2.5 °C. The rotational impacts on thermal performance are more significant when the cross-flow effects are weak (CFR = 0.1) compared to when they are substantial (CFR = 1). Cases without a cylinder have the worst performance for both weak and severe cross-flow effects, whereas using two rotating cylinders increases cooling performance and temperature uniformity for the conductive panel. The average surface temperature lowers by 1.2°C at CFR = 0.1 and 0.5°C at CFR = 1 when the worst and best situations are compared.

The outcomes are relevant in the design and optimization-based studies for electric cooling, photo-voltaic cooling and battery thermal management.