bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Experimental Investigation of Flow Boiling Characteristics in Interconnected Microchannels With Different Slot Arrangement
Authors: Li Yun , Wu Huiying 
Published: September 2022

Abstract
Flow boiling in microchannels is a promising approach to solve the heat dissipation problems of the electronic components. In this work, two types of interconnected slot microchannels (SM) with the staggered (SSM) and in-line (ISM) arrangement of the slots (W = 300μm, H = 600μm) are fabricated. Flow boiling experiments are conducted in the SMs (W = 300μm, H = 600μm, L = 35mm) at mass fluxes of 118–370 kg/m2·s, with the deionized water being used as the working fluid. It is found that compared with plain-wall microchannels (PM), the critical heat fluxes (CHF) in ISM are increased by 24.3%∼50.0%, and 30.8∼53.1% for SSM within the test range. The comparative study with PM reveals that SMs can significantly promote the bubbly flow. Equally important, IMs increase the effective heat transfer area while facilitating the redevelopment of the liquid film. Therefore, the heat transfer coefficient (HTC) in ISM and SSM are significantly enhanced by 44.8% ∼ 60.9% and 43.7% ∼ 68.3%, respectively. Furthermore, the connection of the microchannels promotes the mixing of the fluid and enables a more uniform flow distribution in microchannels. The interconnected slots provide the lateral expansion space for bubbles, thus suppressing the reversal flow of the bubbles. Compared with ISM, SSM could break out the long slug bubbles more effectively and prevent gigantic bubbles from forming. The two-phase pressure drop in SSM could be reduced by 23% on average compared with ISM. This work is trying to provide an improved design for microchannels to enhance the flow boiling process.
A New Battery Thermal Management System With Integrated Phase Change Materials and Cold Plate: A Numerical Study
Authors: Xiang Xinrui , Yang Ruibo , Nagarajan Ramaswamy , Sun Hongwei 
Published: September 2022

Abstract
Lithium-ion battery (LIB), as a renewable energy storage device has received considerable attention in recent years for its zero-emission, long life, and high energy density. However, the performance, lifespan, and safety of the LIB systems are greatly affected by their operation and storage temperatures. To ensure the batteries to work in the optimum temperature range, various battery thermal management systems (TMS) have been investigated. This research focuses on the numerical study of the thermal performance of a hybrid battery cooling system which consists of an integrated forced cooling (e.g., liquid flow in a cold plate) and phase change materials (PCM) composite — a graphite foam impregnated by paraffin wax. In the numerical model, the non-equilibrium thermodynamics model and Darcy’s law are utilized to simulate the thermal and momentum transports in the PCM composite. The heat generation rates of the battery cells are mainly determined by the depth-of-discharge (DOD) dependent internal resistance. In addition, the numerical model takes into consideration the anisotropic axial and radius thermal conductivities of the LIB battery. The results show that PCM composite plays a critical role in achieving the temperature control and maintaining the temperature difference of the LIB battery module. The melting rate of paraffin wax in the graphite foam is directly related to the coolant flowrate, coolant inlet temperature, porosity of the graphite foam, and the internal resistance of the LIB battery.
Numerical Study on the Dominant Condensation Mechanism in the Cross-Flow Transport Membrane Condenser
Authors: Al-rifai Saja , Lin Cheng-Xian 
Published: September 2022

Abstract
Interest in the use of transport membrane condenser (TMC) technology for heat and mass recovery from the flue gas of the power plant has been in an increase in recent years. TMC is based on using nanoporous ceramic membrane as a tube wall of the heat exchanger. The heat and mass transfer from the TMC tube bundle have been studied experimentally and numerically, and several models have been proposed to calculate the condensation rate. Researchers have reported that the transport of the flue gas through the membrane condenser involves two mechanisms: the wall condensation and the capillary condensation. However, the dominant condensation mechanism is still under debate and needs more investigation. In this study, a single-phase multi-species model coupled with mixed condensation model was used to investigate the dominant condensation mechanism at different membrane porosity and water vapor mass fraction. The Numerical simulation was executed using ANSYS/FLUENT 2021 R1 software. The mixed condensation model, which is based on the wall condensation and capillary condensation, was written in the user-defined functions (UDF). The flue gas turbulent was modeled using the shear stress transport SST k-ω turbulence model. The results showed that, at the same membrane porosity and water vapor mass fraction, the wall condensation mechanism is the dominant condensation mechanism. As the porosity increases from 0.15 to 0.50, the percentage of the capillary condensation increases from 17% to 50%, which impact in a decrease in the wall condensation percentage from 83% to 50%. Furthermore, about 69% to 87% of the total condensation rate was obtained from the wall condensation mechanism, as a result of an increase in the water vapor mass fraction from 8% to 21%. Consequently, the wall condensation was able to recover more latent heat than the capillary condensation mechanism. The convection Nusselt number decreases as the porosity increases, because of the significant reduction in the effective thermal conductivity of the nanoporous ceramic tubes.
Measuring Thermal Energy From Cross Correlated Modulation in Single Walled Carbon Nanotubes
Authors: Koh Heeyuen , Maruyama Shigeo 
Published: September 2022

Abstract
Recently, it has shown that the equation of motion (EOM) modified with heat diffusion process can replace the drift-diffusion terms in Langevin equation as conserving the total energy and temperature without extra thermalization process for single-walled carbon nanotubes (SWCNT) in coarse-grained (CG) model.[1] The motion of simple beads model from modified EOM maintains well-synchronized macroscopic behavior as observed in all-atom molecular dynamics simulation (AAMD) over couple of nano seconds. The same definition of heat diffusion which is derived from the cross correlated momentum is applied to suspended SWCNT in non-equilibrium molecular dynamics (NEMD) to visualize the heat energy related to macroscopic motion. The energy proportion involved in modulation by heat diffusion process has well observed by analyzing the data from simplified coordinate of trajectory of NEMD result into simple beads condition by averaging the coordinates from all atomic simulation. Further discussion on second sound and Green-Kubo relation from the trend in dispersion plot and Markovian characteristics of heat diffusion are included alongside the brief introduction of derivation.
Anisotropy of Flow and Heat Transfer of Gaseous MHD Flows in a Circular Tube Under the Control of Transverse Magnetic Field: A Preliminary Study
Authors: Zhao Qijin , Mao Baoquan , Bai Xianghua , Guo Jintao , Chen Chunlin 
Published: September 2022

Abstract
Given the potential application of the magnetic field to control the gaseous magnetohydrodynamic (MHD) flows in the tube, the effect of the transverse magnetic field (TMF) on the gaseous MHD flow and heat transfer characteristics in a circular tube is studied. Taking the conductive circular tube as the research object, the physical model and mathematical model are constructed by considering the influence of the non-uniformity of the TMF. The control equations are discretized and the numerical algorithm is designed under the theoretical framework of the finite volume method. On this basis, the distributions of the velocity and temperature under different magnetic induction intensities are numerically simulated, and the influence of the Hartmann number (Ha) on the flow and heat transfer characteristics is analyzed. The results show that the velocity and temperature of the flow near the Hartmann boundary layer and Robert boundary layer show anisotropy. Affected by the transition gradient of the applied TMF, a high-speed jet region appears near the Robert boundary layer. The convective heat transfer intensity of the magnetized region first decreases and then increases with the increase of the value of Ha.
Water Thermodynamic Behavior Under Influence of Electric Field: A Molecular Dynamics Study
Authors: Porterfield Malcolm , Borca-Tasciuc Diana 
Published: September 2022

Abstract
Water phase-change is one of the most widely used mechanisms to transfer heat, with applications in both cooling and energy conversion. Augmenting phase-change effectiveness by application of an electric field is of interest in many situations and may lead to increased system efficiency with sustainability implications. Thus, it is important to develop a better understanding of the effect of an electric field on the thermodynamic properties of water. In this work, molecular dynamics (MD) was utilized to assess two distinct water models, the TIP4P-Ew and the SWM4-NDP, for predicting the effect of an electric field on the density and the enthalpy of vaporization of water. Both water models possess rigid molecular geometry, but the SWM4-NDP model has a negatively charged Drude particle (the “NDP”) attached to the oxygen site in the water molecule, making the SWM4-NDP model polarizable. It is desired to observe how important this polarizability is to predicting density and enthalpy of vaporization. Applying an electric field in MD simulations with each water model results in increased values for both the density and enthalpy of vaporization. The magnitude of these increases are comparable between water models and increase with increasing field strength.
A Loop Heat Pipe for Vehicle CPU Cooling: Peak Performance and Partial Flooding and Dryout Regimes
Authors: Ferreira Julio , Kaviany Massoud , Dupont Vincent , de Laet Olivier , Nicolle Thomas , Yen Erik 
Published: September 2022

Abstract
A Loop Heat Pipe (LHP) is assembled and tested for removing up to 400 W from two vehicle CPUs, while keeping their temperature under 95°C and using a 2 m-distanced, 45°C-air cooled condenser, and working fluid R1233zd(E). The capillary evaporator wick uses a liquid artery wick supplying liquid to a sawtooth copper wall evaporator. This novel sawtooth structure extends the evaporation area, spreads the liquid, and allows for the vapor escape space, while minimizing the evaporator resistance. For the application flexibility, it is preferred to place the condenser away from the CPUs. The air-cooled condenser fan-power consumption is also important, influencing the condenser thermal resistance. The loop thermal-hydraulics are analyzed (including the wick effective thermal conductivity, permeability, and maximum capillary pressure) and modeled. These include the role of the liquid accumulation on the evaporator, and the partial, local wick dryout under statistical variation in the microlayer wick thickness. The condenser thermal resistance and pressure drop, the transfer lines pressure drops, and the accumulator volume, which can dominate and limit the overall performance, are addressed in the design selection. The model predictions are compared with the performance of the fabricated LHP under variable thermal load and CPU-condenser separation distance. Good agreements are found, under partial flooding at low thermal load, under partial dryout at high thermal load, as well as under thermal loads with peak evaporator performance. Further improvements realized in the second-generation evaporator wick is expected to raise the peak performance and the maximum thermal load significantly.
Nucleate Pool Boiling of Water on a Heater of the Size of a Capillary Length
Authors: Reed Julia , Dhir Vijay 
Published: September 2022

Abstract
Nucleate pool boiling of saturated water at one atmosphere pressure was investigated on a horizontal circular surface of diameter 2.7 mm. For such a surface aside from the contact angle of the surface itself, the wettability of the surrounding surface is found to have a significant effect on both the dependence of nucleate boiling heat flux on wall superheat as well as the critical heat flux. For heated surface with a contact angle of 90°, with a hydrophobic surface surrounding it, the nucleate boiling heat transfer and critical heat flux are much lower than for the hydrophilic surrounding surface. However, when the heater surface is well wetting, contact angle less than 50°, there was significant improvement that could only be seen with hydrophilic surrounding. Nucleate boiling heat transfer and critical heat flux data are found to correlate with bubble departure volume and frequency of the bubble release.
Numerical Simulation on the Flow and Heat Transfer Characteristics of the Condenser Shell Side in a 3rd Generation Nuclear Power Plant
Authors: Yan Dong , Chen Lin , Xia Yingpei , Sun Yueheng 
Published: September 2022

Abstract
Aiming at the improvement of the band-shaped tube bundle condenser of a 1000MW thermal power unit, this paper uses a porous media model to study the vapor phase flow and heat transfer characteristics of the condenser shell side. The distributions of streamline, velocity, temperature, air mass fraction, and heat transfer coefficient were conducted and analyzed. The back pressure of the condenser with improved band-shaped tube bundle is 5.03 kPa, which is higher than the HEI standard by 0.30 kPa. Analysis shows that the condenser air cooling zone has a better cooling effect, but there are more local vortices at the top and middle of the tube bundle module, which leads to chaos in the flow field and a decrease in heat transfer coefficient. The auxiliary steam inlet channels at the top and middle can be optimized by reducing the flow velocity in the free flow zone, thereby improving the flow field of the condenser and increasing the heat transfer coefficient. The increase of the inlet vapor velocity can enhance the heat transfer of the condenser, but also increase the inhomogeneity of heat transfer coefficient. Therefore, there is still room for optimization of the 1000MW improvement of the peripheral strip tube bundle layout. This study provides a theoretical basis for the optimization design for the condenser.
Optimal Design of Additively Manufactured Metal Lattice Heat Sinks for Electronics Cooling
Authors: Bharadwaj Bharath , Singh Prashant , Mahajan Roop L. 
Published: September 2022

Abstract
With increasing thermal footprint in electronic packages, metal lattices offer avenues for better thermal management in passively cooled heat sinks. Combined with the advances in metal additive manufacturing, these can be leveraged to realize complex designs that offer superior heat transfer characteristics with smaller and lighter components. In this work, design, analysis, and optimization of metal lattice-based heat sinks for passive cooling by buoyancy-driven convection is presented. Heat sinks based on three types of lattice structures — Simple Cubic, Voronoi and Octet — have been studied by varying lattice parameters such as thickness and height to obtain the optimal design. Numerical computations using the ANSYS® commercial package have been carried out and the steady state junction temperature at the base of the heat sink monitored. The Voronoi lattice structure provides the best enhancement in heat transfer with ∼18% reduction in junction-to-ambient temperature difference as compared to a standard baseline longitudinal heat sink (LHS), while simultaneously reducing the mass of the heat sink by ∼2.1 times. This behavior is attributed to the enhanced surface area, open-celled lattice structure with lower flow resistance and enhanced thermal dissipation due to local flow disturbances. Based on the junction-to-ambient temperature difference and mass of each heat sink, a Figure of Merit (FOM) is defined to quantify the relative performance of all the designs. The Voronoi lattice at 0.8 mm thickness and 25.4 mm height was found to be the optimal design. It provides the best improvement of ∼3 times compared to the baseline LHS. Also, a Design for Additive Manufacturing (DFAM) approach has been implemented. Virtual build-up simulation indicated suitability of the design for fabrication. The predicted deviation after printing was within the commercially acceptable tolerance limits for use in applications. The workflow presented here from design to analysis, optimization and preparation for fabrication is useful for rapid development of customized passive cooling solutions and determination of optimal designs. We believe that the analysis and methodology presented in this paper would be helpful in the development of better thermal management devices aided by additive manufacturing in future.
Analysis of Corner Radius on the Free Oscillating Cylinder With Heat Transfer and Flow Pattern at Low Reynolds Number
Authors: Sarout Yuvraj , Islam Md Didarul , Fatt Yap Yit , Janajreh Isam 
Published: September 2022

Abstract
Flow-induced vibration (FIV) of the modified single-cylinder with a change in corner radius has been investigated in a laminar flow regime with Re = 100 and Pr = 0.7. The corner radius (r: corner radius, :R cylinder characteristic length) is changed from 1 to 0 and two angles α; 0° and 45° are used. The Cylinder is elastically supported with heating at a constant temperature at the boundaries. Vibrations are restricted to the transverse direction. Computation is carried out with a fixed mass ratio m* = 10 and varying reduced velocity Ur = 2 ∼ 8. The two-dimensional incompressible Navier-Stokes equations and energy equations are coupled together. Navier stokes equation used with FIV equation of elastically supported cylinder to have flow solutions. Lock-in synchronization can be observed at Ur = 5 and Re = 100 at r* = 1 which leads to severe vibration and maximum vibrational amplitude A/D while amplitude modulation has been observed at Ur = 5 for the square cylinder. Based on the mode of vibration whole study has been divided into 4 ranges of vibration. Mode-I, where the amplitude is very low; Mode-II, fluctuating amplitude known as hysteresis (Beating); Mode-III; amplitude is at the maximum because of lock-in synchronization; Mode-IV, normal vibrational amplitude. Different modes are compared with the change in Ur, r* and α. The effect of Ur is visible on the Nusselt number as more vibration leads to a high value of averaged Nusselt number NuAvg. Vortex shedding is changed from C(2S) to 2S as the corner radius is modified. Results give a deep insight into heat transfer getting changed by changing three different parameters and will make a base for future study of tube bundles in heat exchangers with FIV.
Improved Femtosecond 3D Light Field Lithography With a Phase-Controlled Spatial Light Modulator
Authors: Jakkinapalli Aravind , Wen Sy-Bor 
Published: September 2022

Abstract
Through years of development, we have successfully demonstrated 3D light field lithography with UV continuous light. We recently combined this approach with femtosecond laser sources as two-photon femtosecond 3D light lithography. It is found that consistent results can happen under limited conditions with this direct combination. Our theoretical analysis reported last year shows that the experimental difficulty can be attributed to digital micro-mirror devices (DMD) and microlens arrays (MLA) used in the current 3D light field projection. Though they can control the propagation directions and interact at designed 3D locations, rays from such a system diverge with respect to the propagation distance. As a result, 3D voxel intensity in the 3D projection changes as a function of the separation distance with respect to the MLA in the 3D projection. To solve this problem, we replace the combination of DMD and MLA with a phase-controlled spatial light modulator. With a lab-developed algorithm, a single femtosecond laser pulse can generate up to a million sub-rays through the phase-controlled spatial light modulator. These sub-rays with a precisely controlled propagation direction can intersect at designed 3D locations as voxels for 3D virtual object constructions. Moreover, these sub-rays have minimum divergence angles to ensure that the voxel intensities are maintained consistently at each 3D location. We also demonstrated that versatile 3D patterns could be generated with two-photon femtosecond 3D light field lithography based on this innovative approach.
Buoyancy-Driven Convection in Additively Manufactured Cubic Lattices
Authors: Singh Prashant , Phanikumar Mantha S. , Mahajan Roop L. 
Published: September 2022

Abstract
We present an experimental study on buoyancy-driven convection transport in additively manufactured lattices comprising of cubic unit cells, where we have studied the effect of lattice aspect ratio (width-to-height ratio) and heating orientation with respect to the gravity vector. The lattices were manufactured via Binder jetting process in Stainless Steel 420 (with 40% bronze infiltration). The solid-phase thermal conductivity was measured on a solid sample manufactured through the same technique and was found to be 20.8 W/mK. Each lattice configuration had a porosity of 0.87. These lattices with aspect ratio varying from 0.5 to 2 and three different heating orientations, viz. bottom wall (0°), side wall (90°), and top wall (180°) heating, were tested for Rayleigh numbers ranging from 105 to 4 × 105. We found that the lowest aspect ratio lattice had the highest convective heat transfer coefficient for all three heating orientations. Further, an inter-comparison of the heating orientations at a fixed lattice aspect ratio revealed that the sideways heating orientation (90°) had the highest heat transfer, followed by bottom wall (0°) and top wall heating orientations (180°).
Delayed Functional Independence After Neurothrombectomy (DEFIANT) score: analysis of the Trevo Retriever Registry
Authors: Jadhav Ashutosh P , Desai Shashvat M , Gupta Rishi , Baxter Blaise W , Bartolini Bruno , Krajina Antonin , English Joey D , Nogueira Raul G , Liebeskind David S , Veznedaroglu Erol , Budzik Ronald F 
Published: September 2022

BackgroundChronological heterogeneity in neurological improvement after endovascular thrombectomy (EVT) for large vessel occlusion (LVO) stroke is commonly observed in clinical practice. Understanding the temporal progression of functional independence after EVT, especially delayed functional independence in patients who do not improve early, is essential for prognostication and rehabilitation. We aim to determine the incidence of early functional independence (EFI) and delayed functional independence (DFI), identify associated predictors after EVT, and develop the Delayed Functional Independence After Neurothrombectomy (DEFIANT) score.MethodsDemographic, clinical, radiological, treatment, and procedural information were analyzed from the Trevo Registry (patients undergoing EVT due to anterior LVO using the Trevo stent retriever). Incidence and predictors of EFI (modified Rankin Scale (mRS) score 0–2 at discharge) and DFI (mRS score 0–2 at 90 days in non-EFI patients) were analyzed.ResultsA total of 1623 patients met study criteria. EFI was observed in 45% (730) of patients. Among surviving non-EFI patients (884), DFI was observed in 35% (308). Younger age (p=0.003), lower discharge National Institutes of Health Stroke Scale (NIHSS) score (p<0.0001), and absence of any hemorrhage (p=0.021) were independent predictors of DFI. After age 60, the probability of DFI declines significantly with 5 year age increments (approximately 7% decline for every 5 years; p(DFI)= 1.3559–0.0699, p for slope=0.001). The DEFIANT score is available online (https://bit.ly/3KZRVq5).ConclusionApproximately 45% of patients experience EFI. About one-third of non-early improvers experience DFI. Younger age, lower discharge NIHSS score, and absence of any hemorrhage were independent predictors of DFI among non-early improvers.