Efficient cooling strategies are very important issues in thermal management of lithium-Ion battery system and these techniques should provide cost effective and energy saving solutions for ...temperature rise of the system during battery operation. A pseudo 2D electrochemical model has been used to investigate the electrochemical and thermal condition of commercial 18650 Lithium-Ion battery. This analysis was compared to previous experimental studies and results showed that the model predicts the temperature rise and thermal power generation very well. Results from the electro-thermal analysis were used to examine a cooling method. In this strategy, the cylindrical Li-ion cell is submersed within a thin cylindrical tank containing water-Al2O3 nanofluid. Air flow is employed to remove the heat from the system during discharge process. After testing this method for a single cell with various sizes of the secondary cylinder, critical and thermally dangerous arrangements of Li-ion cells were analyzed employing the new technique. 3D transient Computational Fluid Dynamics (CFD) simulations were used to see the effect of presence of the secondary cylinder on temperature rise. Results revealed that the new method reduces the maximum temperature of the cells efficiently.
– Forced convection heat transfer in a cavity is of great importance due to its strong relevance to the practical aspects. Most of the studies focus on this topic from a steady perspective. But ...adding a flow modulator enhances a system's thermodynamic performance and makes such a system more realistic and widens the field of application. Such studies are unsteady and often quite expensive. As a result, only a few literatures are available with very idealistic geometric configuration and boundary conditions.
– Two-dimensional unsteady continuity, momentum and energy equations are used for the mathematical modeling of the problem incorporating the Boussinesq approximation. A free triangular discretization scheme is adopted to solve the moving mesh problem by formulating the Arbitrary Lagrangian Euler (ALE) finite element approach.
– Numerical studies are carried out for a fixed Prandtl number (Pr = 0.71) and fixed geometry of the rotating blade while varying the other parameters i.e. Rayleigh number, Reynolds number and Biot number. This dynamic boundary problem encompasses a wide range of parameters i.e. (100 ≤ Re ≤ 103), (103 ≤Bi ≤ 104) and (104 ≤ Ra ≤ 107) to evaluate the thermodynamic behavior of the thermo-fluid system. External flow condition is taken into consideration in terms of Biot number. Effects of these parameters are visualized through streamlines, heatlines, spatially average Nusselt number evaluated on the heated surface and system effectiveness.
– Present computational study focuses on the transient analysis of the conjugate forced convection flow and heat transfer characteristics in a hexagonal, air filled cavity. This cavity is equipped with a floor heater of constant heat flux under the rotational influence of an adiabatic flow modulator. And the blade is placed in the central position of the cavity which is rotating in the clockwise direction. Also, the whole computational domain is composed of four different domains, one convective domain and three solid domains. The solid domains are made of brick and glass as per their practical aspects.
– A Fast Fourier Transform (FFT) analysis is presented to comprehend the thermo-oscillating system response. FFT plots indicate that for all of the cases the fundamental frequency of the system response conforms to the blade frequency. Moreover, present numerical results show that the heat transfer effectiveness has an inverse relationship with the Biot and Rayleigh numbers while improves significantly with the increase of Reynolds number and reaches a critical state for Recr = 650. Higher Reynolds number also attenuates the degree of power spectrum.
– To attain a higher heat transfer effectiveness the thermo – fluid system should be operated at low Rayleigh number with higher Reynolds number.
•Thorough thermal analysis for two modified flat plate heat exchangers (FPHEm1), and (FPHEm2).•Flow distribution inside channels of FPHEm2 is the best.•Thermal stresses in the plates of FPHEm2 are ...the lowest.•Overall thermal performance of FPHEm2 outperforms its counterparts.•Numerical model is verified with experimental studies.
Flat plate heat exchanger (FPHE) can tolerate more mass flow rate, significantly yield lesser pressure drop, and it is easier for manufacturing than the corrugated plate heat exchanger (CPHE). However, the overall thermal performance of FPHE is poor due to its low heat transfer rate. Therefore, the aim of the current study is to improve the thermal performance of the existing conventional FPHE (FPHEC). Thus, two newly developed modified FPHEs are introduced (FPHEm1 and FPHEm2). A computational fluid dynamics (CFD) technique is applied to numerically test the performance of the heat exchangers (HEs). Moreover, experiments are carried out to confirm the validity of the numerical results obtained in this study. The performance of FPHEm2 significantly outperforms that of FPHEC and FPHEm1. Hence, the results of FPHEm2 are compared with those of the conventional corrugated plate heat exchanger (CPHEC). Data of Nusselt number (Nu), fanning friction factor (f), turbulence intensity, JF factor, severity of temperature gradient of the plate (ΔTp), and average temperature through the plate (Tp,avg) are employed to quantify the best performance among all four HEs. The numerical results show that FPHEm2 has the best temperature uniformity and average temperature (the lowest values), and it has the highest Nu, JF, and turbulence intensity among all four HEs. Also, the f data of the FPHEm2 are 18.7% to 33.2% lower than those of the CPHEC. Thus, FPHEm2 could be a probable replacement of its counterparts of both FPHEC and CPHEC. Critical Reynolds numbers (Recr) of FPHEm2, heat transfer correlations and the flow distribution along with other details have been analysed numerically.
•Newly modified corrugated plate heat exchanger (CPHE) is proposed.•Thorough comparison among the modified CPHE and other PHEs is carried out.•The resulted turbulence kinetic energy of the modified ...channel is the highest.•Overall thermal performance of the modified CPHE is the best.•The best performance of the modified CPHE takes place at Re=1600.
Corrugated plate heat exchangers (CPHEs) have been extensively adopted especially for systems that require high thermal efficiencies such as aerospace and gas turbine power plants. According to several factors (i.e. required heat duty), CPHEs can be optimized to meet the application requirements. However, the number of the required thermal plates (Np) could be very large (Np>40) which in turn would cause several disadvantages (i.e. sever flow maldistribution). Therefore, the present study aims to introduce an innovative modification that can boost the thermal performance of the basic CPHE which in turn would reduce the number of required plates for the same heat duty. The thermal performance of the modified CPHE has been numerically investigated by using Computational Fluid dynamics (CFD) software. The numerical data have been validated with experimental measurement from the literature. The impact of the new modification has been studied on Nusselt number (Nu), fanning friction factor (f), Stanton number (St), Turbulence kinetic energy (TKE), flow maldistribution, j factor, and quality index factor (JF). The result has been compared with previously reported data of the basic corrugated and flat PHEs. At the same mass flow rate, Nu, f, and TKE of the modified CPHE are respectively 1.3, 1.7, and 3.5 times greater than those of the basic CPHE. Moreover, JF data of the modified CPHE are 1.4, and 64 times greater than those of the basic corrugated and flat PHEs, respectively. In addition to the superior thermal performance, the present modification offers larger contact area between the plates which could boost the overall mechanical integrity of the heat exchanger. Thus, this modification could pave the way for CPHEs to be incorporated in new applications that require more compact and durable HEs. The heat transfer correlations of the modified CPHE have been developed.
•Solidification of multilayer PCM within a fined triplex capsule is modelled.•A two-dimensional finite volume numerical technique is used for simulations.•Variation of liquid fraction values and PCM ...layers temperatures are reported.
Efficient latent heat storage systems represent an important opportunity to improve the thermal performance and operational capability of industrial systems (e.g. solar thermal). In this paper, numerical study is performed to evaluate the heat transfer and solidification features, phase change period and temperature distribution of double-layer Phase Changing Materials (PCM) in a finned triplex tube. A two-dimensional finite volume numerical technique is used to solve the governing equations considering conduction and convection heat transfer mechanisms at a fixed Rayleigh number of 106. After comparing the results for single and double layer configurations, possible arrangements of two different PCMs are discussed in terms of different thicknesses of each PCM, fin sizes and different heat transfer fluid temperatures. Results are illustrated as the form of temperature, liquid fraction, stream function and velocity magnitude contours and their changes over the freezing time. Variation of liquid fraction values, average and minimum temperatures of layers in a double-layer PCM are reported for better insight into the heat transfer features of the latent heat thermal energy storage system to enable uniform discharging designs and balance the phase changing rate within the whole annulus.
•This study proposes a unique PHE that can boost its thermal performance significantly.•The overall tests have been conducted on two symmetric chevron angles (β) of 30°/30° and 60°/60°.•The ...enhancement for Nu is up to 75% and for ϵ is up to 42%.•Based on the numerical result, a new correlation to predict Nu has been developed.
Compact heat exchangers have become an essential necessity for power production and multi other purposes on a daily basis. The corrugated plate heat exchangers (CPHEs) are well-known for their high thermal performance. This study proposes a unique CPHE with a simple modification that can boost its thermal performance significantly. The overall tests have been conducted on four CPHEs for two symmetric chevron angles (β) of 30°/30° and 60°/60° Two CPHEs belong to the newly CPHEs, and the other two belong to the well-known basic CPHE. Data are obtained for steady-state, single-phase (water-water), counter-current arrangements, and for Reynolds number (Re) ranges from 500 to 2500. Sophisticated mesh techniques have been adopted to develop the mesh for the plates and the fluids between the plates. An appropriate grid refinement test has been carried out for the accuracy of the numerical results. The results have been validated with benchmark experimental and numerical data. A realizable k−ε turbulence model with scalable wall treatment found to provide the most consistent and accurate prediction of the thermal performance of CPHE. The numerical results showed that the Nusselt number (Nu) and the effectiveness (ϵ) of the newly developed CPHEs are much higher than that of the basic one, which can be very useful when a heavy heat duty is required. The enhancement for Nu is up to 75% and for ϵ is up to 42%, and generally both exhibit a direct proportional relationship with Re. Based on the numerical result, a new correlation to predict Nu has been developed.
Microplastics have become omnipresent in the environment, including the air we inhale, the water we consume, and the food we eat. Despite limited research, the accumulation of microplastics within ...the human respiratory system has garnered considerable interest because of its potential implications for health. This review offers a comprehensive examination of the impacts stemming from the accumulation of microplastics on human lung airways and explores the computational benefits and challenges associated with studying this phenomenon. The existence of microplastics in the respiratory system can lead to a range of adverse effects. Research has indicated that microplastics can induce inflammation, oxidative stress, and impaired lung function. Furthermore, the small size of microplastics allows them to penetrate deep into the lungs, reaching the alveoli, where gas exchange takes place. This raises concerns about long-term health consequences, such as the development of respiratory diseases and the potential for translocation to other organs. Computational approaches have been instrumental in understanding the impact of microplastic deposition on human lung airways. Computational models and simulations enable the investigation of particle dynamics, deposition patterns, and interaction mechanisms at various levels of complexity. However, studying microplastics in the lung airways using computational methods presents several challenges. The complex anatomy and physiological processes of the respiratory system require accurate representation in computational models. Obtaining relevant data for model validation and parameterization remains a significant hurdle. Additionally, the diverse nature of microplastics, including variations in size, shape, and chemical composition, poses challenges in capturing their full range of behaviours and potential toxicological effects.
•A numerical model deals with heat transfer and air flow in a V-shaped enclosure.•Transition to a chaotic flow is presented in details based on Rayleigh number.•The Lyapunov exponent of periodic and ...chaotic flows have been described.•The power spectral density and the phase space trajectory are also presented.
Natural convection in a V-shaped cavity heated from below and cooled from top is investigated owing to its extensive presence in industrial systems and in nature such as in a valley. Two dimensional numerical simulation is performed for natural convection in the cavity using a Finite Volume Method. A wide range of Rayleigh numbers of Ra = 100 to 108 for the aspect ratio of A = 0.5 and the Prandtl number of Pr = 0.71 is considered. A set of supercritical bifurcations in a transition to a chaotic flow are described, which include a Pitchfork bifurcation from symmetric to asymmetric state and a Hopf bifurcation from steady to unsteady state. It is found that the Pitchfork bifurcation occurs between Ra = 7.5 × 103 and 7.6 × 103 and the Hopf bifurcation occurs between Ra = 1.5 × 107 and 1.6 × 107. Additionally, a further bifurcation from periodic to chaotic state occurs between Ra = 5 × 107 and 6 × 107. The power spectral density, the phase space trajectory and the largest Lyapunov exponent of unsteady flows in the transition to a chaotic state have been described. Further, heat transfer in the cavity is calculated and the corresponding dependence on the Rayleigh number is discussed and quantified.
Obstructive Sleep Apnea Syndrome (OSAS) disrupts millions of lives with its burden of airway obstruction during sleep. Continuous Positive Airway Pressure (CPAP) therapy has been scrutinized for its ...biomechanical impact on the respiratory tract. This study leverages computational fluid dynamics to investigate CPAP's effects at 9 cm H2O (882.6 Pa) on the computed-tomography-based nasal-to-14-generation full respiratory tract model compared to ambient conditions, focusing on static pressure, airflow velocity, and shear stress. Our findings reveal that CPAP significantly increases static pressure, enhancing airway patency without adverse changes in airflow velocity or harmful shear stress on lung tissue, challenging prior concerns about its safety. Notably, the larynx experiences the highest shear stress due to its narrow anatomy, yet CPAP therapy overall supports airway walls against collapse. This investigation highlights CPAP's critical role in OSAS treatment, offering reassurance about its safety and efficacy. By clarifying CPAP therapy's physiological impacts, our study contributes vital insights for optimizing OSAS management strategies, affirming CPAP's benefit in maintaining open airways with minimal tissue strain.
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•First Simulations: CPAP effects on the full human respiratory tract explored.•Easy Breathing: CPAP significantly boosts airway static pressure.•Minimal Impact: CPAP's effect on airflow velocity remains low.•Safe Breathing: CPAP's influence on shear stress levels is minimal.•Wall Support: CPAP provides substantial support to the airway wall.
The fluid flow and heat transfer inside a triangular enclosure due to instantaneous heating on the inclined walls are investigated using an improved scaling analysis and direct numerical simulations. ...The development of the unsteady natural convection boundary layer under the inclined walls may be classified into three distinct stages including a start-up stage, a transitional stage and a steady state stage, which can be clearly identified in the analytical and numerical results. A new triple-layer integral approach of scaling analysis has been considered to obtain major scaling relations of the velocity, thicknesses, Nusselt number and the flow development time of the natural convection boundary layer and verified by direct numerical simulations over a wide range of flow parameters.
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