not-yet-known not-yet-known not-yet-known unknown In a space station, to ensure the thermal comfort of users, to get rid of infectious contaminants, and to find a solution to the dissipation of body heat, it is necessary to maintain a homogeneous distribution of the air flow under microgravity conditions in a closed environment. In this work, computational fluid dynamic (CFD) methods were applied to study the distribution of airflow and thermal comfort inside an empty room in a space station under microgravity condition. Numerical simulation is performed using a commercial computational fluid dynamic (CFD) package ANSYS CFX software to understand the effect of inlet flow angle change and, air velocity on the performance of the space station thermal comfort. The comfort level was evaluated using the effective draft temperature (EDT) according to ASHRAE (55-210). the scaled down model, are 0.4 × 0.4 × 1.44 m 3. The scale model featured supply inlet and exhaust outlet dimensions of 100 mm × 18 mm and 168 mm × 18 mm, respectively.The simulation results and the relevant data from the literature were in good agreement. The results showed that (i) Comfort zones are defined by speed ranges from 0.036 m/s to less than 0.076 m/s. When the air supply angle was set at 45°, the cabin space exhibited the highest percentage of speeds falling within the comfort range. (ii) The 35 ° air supply angle exhibited the most optimal performance. (iii) The air supply angle was set at 45 °, which gives the best effective draft temperature (EDT) that satisfies the ASHRAE 55-210 criteria: -1.7 EDT 1.1 and 0.076m / s V 0.0203m / s.

This study aims to enhance the insulation property of polypropylene (PP) by developing it into a multi-hollow structured board using 3D printing technology. A previous experimental study determined the effective thermal conductivity of the porous PP board was experimentally determined using a hot box test, yielding a value of 0.0033 W/mK, which represents a significant improvement over conventional building insulator. To validate the experimental results, a numerical simulation using COMSOL Multiphysics software was conducted to model the heat transfer process within the porous PP board. The simulation employed an appropriate methodology, including parameter definition, geometry creation, material definition, steady-state porous heat transfer module, initial and boundary conditions, meshing, and study. The numerical analysis focused on determining the indoor surface temperature, evaluating the total heat flux, and calculating the effective thermal conductivity of the porous PP board. The simulation results revealed an effective thermal conductivity of 0.0036 W/mK, which closely matches the experimentally obtained value from the hot box test. The agreement between the experimental and numerical results validates the effectiveness of the multi-hollow structured PP board as a superior insulating material. This study demonstrates the potential of combining 3D printing technology with materials like polypropylene to develop highly efficient insulation solutions for building applications.

The paper focuses on the simulation and testing of a hybrid solid desiccant vapor compression air conditioning system under different hot-humid climates. The simulation is carried out by a BLUEJ programming framework. Air at the lowest achievable air temperatures from a solid desiccant cooling system is supplied to a standard vapor compression air conditioning system. The cooling capacities of the hybrid system under three modes indicating different supply air conditions to the cabin, are reported in the paper. From the performance study, it is inferred that the hybrid system provides significant energy savings compared to a standard air conditioner, especially in hot-humid ambient conditions. The solid desiccant cooling system thus establishes itself as an effective pre-cooler unit to a standard vapor compression air conditioning system.

Multi-effect distillation shines as a thermal desalination technique due to its economic viability and broad range of application. It effectively tackles desalination for seawater and brackish water, regardless of capacity, using a low-temperature (below 70°C) evaporation and distillation process. This study employs exergy analysis to identify the components within a six-effect Multiple Effect Distillation (MED) system where exergy destruction occurs, followed by an exergy-economic analysis to evaluate the system’s overall performance. Exergy, representing the maximum obtainable work from a substance, is examined for both feed water and distillate in the context of their chemical potential differences. The calculated exergy values for different system states are presented, revealing the exergy destruction attributed to irreversibility such as friction and heat transfer. The system’s overall exergy efficiency is determined to be 74.47%, indicating that only this portion of feed water exergy is converted into useful distillate exergy. The remaining exergy is lost due to irreversibility. An exergy balance for the 6-effect MED system is provided, showing that 25.53% of the energy input is lost as exergy destruction. Three different economic model are used to estimate the distillate cost for different feedwater temperature and distillate cost found to be 3.63, 1.9, 2.45 $/m 3 respectively.

This investigates the fluid flow, as well as the heat and mass transfer phenomena occurring within a vertical channel housing two immiscible fluids. It focuses particularly on slip effects, encompassing no slip, velocity slip, thermal slip, and multiple slips, each being applied with appropriate boundary conditions. The analysis thoroughly examines crucial characteristics such as variations in thermal conductivity and viscosity. By employing a sixth-order Runge-Kutta numerical method implemented via Mathematica, the study achieves precise solutions for complex scenarios. The extensive findings elucidate the intricate interactions among different slip mechanisms and relevant parameters, providing valuable insights for both theoretical comprehension and practical application in engineering contexts. Furthermore, this research offers significant insights into the dynamics of fluid flow, heat, and mass transfer under various slip effects. Noticeable variations in these slip effects are observed and visually represented. Engineering parameters such as Nusselt number, shear stress, and Sherwood number are meticulously calculated and analyzed using bar charts, offering insights into their impact and behavior.

The heat transfer in power-law fluids across three corrugated circular cylinders placed in triangular pitch arrangement is studied computationally in a confined channel. Continuity, momentum and energy balance equations were solved using ANSYS FLUENT (Version 18.0). The flow is assumed to be steady, incompressible, 2D and laminar. A square domain of side 300 Dh is selected after detailed domain study. An optimized grid with 98187 cells is used in the study. The convergence criteria of 10 -7 for the continuity, x-momentum and y-momentum balances and 10 -12 for energy equation were used. Constant density and non-Newtonian power-law viscosity modules were used. Diffusive term is discretized using central difference scheme. Convective terms are discretized using Second Order Upwind (SOU) scheme. Pressure-velocity coupling between continuity and momentum equations was implemented using the SIMPLE (Semi-Implicit Method for Pressure Linked Equation) scheme. Streamlines show wake development behind the cylinders, which is much dominant at large ReN and n. Isotherm contours are cramped at higher values of ReN and PrN, implying higher heat transfer. Global parameters like Cd and Nu are computed for the wide ranges of controlling dimensionless parameters, such as power-law index (0.3 ≤ n ≤ 1.5), Reynolds (0.1 ≤ ReN ≤ 40) and Prandtl numbers (0.72 ≤ PrN ≤ 500). The NuLocal plot attains a pitch near corrugation of surface due to abrupt change in velocity and temperature gradients. Nu increases with ReN and/or PrN and decreases with n under otherwise identical situations. Nu is correlated with pertinent parameters, namely, ReN , PrN and n.

In this research, the radially increasing axisymmetric discharge of an electrically conducting fluid across a surface is accurately evaluated mathematically using the influence of Soret number. The surface is extended at an exponential speed in a radial direction, which causes flow trends. New similarity transformations are discussed in order to transform the governing, transform nonlinear partial differential equations into standard derivatives. The Successive Linearization Method is used to perform mathematical analysis for flow performing. The Chebyshev spectral technique is utilized to resolve the linear system in order to provide accurate solutions that converge effectively to the whole numerical solution. Comparisons with earlier research are conducted to evaluate the validity of the results on the distribution of velocity, temperature and concentration. Verify convergence and accuracy of the solution, the impacts of a few fluid factors are identified and explained.

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We have explored the result of the activation energy, thermal conductivity, and variable viscosity, A vertical wavy surface is passed by heat sources during convective heat transfer. Coupled equations controlling the flow, the nonlinear, mass, and heat transferring an electrically conducting viscous fluid via a vertically wavy surface have been solved with the Runge-Kutta-Shooting approach. ( f′, f ) the velocities, (φ)concentration and (θ)temperature, Sherwood and Nusselt number were discussed for several variations of Ds, Dc, E1, δ, Rd, β, θr, A1, B1, a, ξ. It has been seen that axial velocity increases with rising values of Ds, Dc, E1, Nr and reduces with thermal radiation (Rd), and thermal conductivity (β). Nusselt number (Nu) reduces with temperature dispersion (Ds), variable viscosity(θr), thermal conductivity (β) and enhances with solutal dispersion (Dc), radiation (Rd). Space/temperature dependent heat sources (A1, B1).

The study aims to quantify the effect of Dufour number, on flow patterns and heat transfer rates in the exponentially accelerated vertical plate with MHD flow and chemical reaction. The unsteadiness of the flow suggests that time-dependent changes in velocity, temperature, and other relevant parameters are considered. MHD further complicates analysis with the electromagnetic interactions between the fluid and the field. The fluid, be characterized as a gray, absorbing/emitting radiation medium, indicating that it absorbs and emits thermal radiation but does not exhibit scattering behavior. Set of partial differential equations are then resolve using FEM. Graphical results are then discussed. Profiles vary with different, Dufour number, radiation, or temperature-dependent heat source/sink parameter. By varying the values of these governing parameters, on the skin-friction coefficient, Nusselt number, and Sherwood number are also analyzed.

This study examines turbulent convective heat transfer performance (CHTP) and entropy production rate (EPR) of distilled water flowing in outwardly corrugated converging pipes (CCPs) of various diameter ratios (DR). The SST k - ω turbulence models were used to simulate the flow of H 2O inside the pipe. The effects of Reynolds number ( 5 . 0 × 10 3 ≤ Re  ≤ 5 . 0 × 10 4 ), and DR ( 1 ≤ DR  ≤ 2 ) on average Nusselt number ( Nu ), Poiseuille number (fRe) thermal performance evaluation criterion (PEC), EPR, and thermal effectiveness number ( I ) Nu were investigated parametrically. The findings revealed a significant improvement in Nu in the modified pipe compared with the straight pipe. This improvement is attributed to flow acceleration and increases in the mixing rate of hot fluid near the wall with cold fluid at the core fluid zone. Also, Nu , fRe , and EPR increase with increasing Re and DR. However, the opposite is the case for PEC and   I . Finally, the values of PEC, and I revealed that the modified pipe is advantageous compared with a straight pipe at ( 5 × 10 3 ≤ Re ≤ 1 . 0 × 10 4 ) .

The study aims to find the optimal fin length distribution for improved heat transfer during melting and solidification in a tubular PCM heat exchanger designed for heat storage. Three types of horizontal PCM tabular heat exchangers, all with five longitudinal fins, were studied numerically. While maintaining a constant heat transfer area, each model depicts a unique fin length distribution design. The first model, which serves as the reference design, has a homogeneous fin length distribution and each fin is 30 mm long. The second model has shorter upper and side fins and longer lower fins (20 mm for the upper fin, 25 mm for the side fins, and 40 mm for the lower fins). The third model has long lower fins but shorter than that of second model, short side fins and no change in upper fin length with reference design (30 mm for upper fin, 25 mm for side fins and 35 mm for lower fins). The findings indicate that the second model exhibits the best heat transfer performance for the melting process, while the first model is most effective for solidification. Interestingly, the third design emerges as the optimum choice for both melting and solidification processes.

While a variety of solar concentrators have been studied for decades, the study of the spherical glass concentrator has never been reported, to the best of our knowledge. For that, this paper examines the optical characteristics of the novel solar spherical glass concentrator and identifies its performance and features. In addition, the thermal and exergetic performance of the concentrator are studied with three cavity receiver designs under various operating temperatures and different mass flow rates. More specifically, the examined receiver shapes: spiral, conical, and cylindrical. All the cavities are analyzed in order to determine the best design which maximizes the thermal efficiency of the solar collector. According to the results, the spherical collector can concentrate the heat flux up to 25 times the incident flux value. Also, the study is defined the best receiver dimensions that achieve optimum optical performance. Then, the optical analysis is conducted with an optical simulation in COMSOL Ray Optics to validate this work’s findings. Moreover, the best design is found to be the one with a spiral shape, while the conical is the next choice. The cylindrical is the third design in the performance sequence.