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The temperature of the battery pack is regulated using a Battery Thermal Management System (BTMS). In this study, a Computational Fluid Dynamics (CFD) method was employed to improve the intake and output channel heights of the traditional Z and U-type BTMS to produce different flow and temperature distributions. Geometry of 6×145×225 mm was used with channel intake and output height, length and width set to 20, 100 and 3 mm, respectively. Channel height varied from 20 to 25 mm. The results show that increasing the intake and output channel heights improves the performance of regular Z-type flow cooling. For this study, the best performance is height with 25 mm intake and 25 mm output channel height. The peak temperature dropped by 11.2 °C while its power consumption and peak difference in temperature reduced by 25% and 5.33 °C, respectively. The cooling effectiveness of a standard U-type flow BTMS is enhanced by increasing the intake and output channel heights to 25 mm. Accordingly, the peak temperature decreased by 8.92 °C, the peak temperature differential diminished by 2.94 °C, and the power usage decreased by 16%. Generally, the outcomes show that intake and output channel height are crucial for BTMS optimization. [ABSTRACT FROM AUTHOR]

Simulations are performed to study the effect of performance parameters on the pressure drop of a vanadium redox flow battery. The effect of flow rate, viscosity, porosity, electrode thickness, effect of channel height, effect of channel width and effect of number of channels on the pressure drop in a vanadium redox flow battery are studied. The channel height, channel width and number of channels are found to have a substantial effect on the pressure drop across the battery. The effect of flow rate, viscosity, porosity, electrode thickness, channel height and channel width are found to be much more pronounced in Serpentine configuration than the Interdigitated configuration. Model results are compared with experimental data and found to compare well.

Simulations are performed to study the effect of performance parameters on the velocity profiles in a vanadium redox flow battery. The effect of flow rate, viscosity, porosity, electrode thickness, and effect of channel height on the velocity profile in a vanadium redox flow battery are studied. Quantitative analysis of velocity profiles at the mid height of channel, at the channel-electrode interface and mid height of electrode thickness is done. The channel height, thickness and porosity are found to have a substantial effect on the velocity profiles across the battery. It was found that the velocity in the electrode-channel interface is about 3 orders of magnitude lower than velocity in the channels.

To enhance the combustion stability and thermal performance of micro-thermophotovoltaic system, a combustor inserted porous media and varying channel heights for premixed H 2 /CH 4 /Air burning is proposed. The experimental and numerical methods are conducted to investigate the effects of CH 4 addition, equivalence ratio, porous media, and chamber setting on combustion characteristics, heat transfer, and flame stability. The results indicate that a small fraction of CH 4 addition and porous media insertion both enhance heat release and transfer of H 2 -fueled combustion, and the optimal CH 4 blending ratio is influenced by chemical energy input. Appropriately increasing the equivalence ratio under high flow rates contributes to stabilize the flame and improve the combustor thermal performance. Furthermore, porous media effectively promotes flame stability and heat transfer efficiency, with longer porous media enhancing heat conduction and convection processes, thereby increasing the radiation temperature. Besides, increasing the channel height of the porous media combustor appropriately enhances the electrical power output of the power system. Besides, the maximum electrical output of 9.7 W is obtained in the porous media combustor with a channel height of 11 mm at m c = 20 %, Ф = 1.0 and m f = 9.448 × 10−5 kg/s, which is 7.2 W higher than the free flame combustor with h = 7 mm. [Display omitted] [ABSTRACT FROM AUTHOR]

The combination of better transport properties of III-V group semiconductors along with excellent electrostatic control of surrounding gate is a promising option for the future low power electronics. Accordingly in this brief, the major figures of merit (FOM) including output current, output conductance (gd), transconductance generation factor (TGF), intrinsic gain (dB), and dynamic power dissipation are computed for surrounding-gate field effect transistors (SG-FETs) considering III-V group semiconductors and Si channel material respectively with respect to different device parameters. It is noticed that the center potential is higher in AlGaN/GaN SG-FET than Si for different values of channel length (CL), channel height (H), oxide thickness (tox), and doping concentration (Nd). The AlGaN/GaN SG-FET provides lower gd than Si for different values of CL, H, tox, and Nd as required for MOS analog circuits to achieve higher gain. The peak value of TGF and intrinsic gain is higher in AlGaN/GaN than Si SG-FET for different values of CL, H, tox, and Nd. In this work, we have analyzed the MOSFET structure for normally off operation of AlGaN/GaN high electron mobility transistors (HEMTs) to reduce dynamic power dissipation (PD). The magnitude of PD is calculated to be lower in normally off AlGaN/GaN SG-FET than Si for different values of CL, H, and tox. [ABSTRACT FROM AUTHOR]

When conducting a photooxidation reaction, the key question is what is the best amount of photocatalyst to be used in the reaction? This work demonstrates a fast and simple method to calculate a reliable concentration of the photocatalyst that will ensure an efficient reaction. The determination is based on shifting the calculation away from the concentration of the compound to be oxidized to utilizing the limitations on the total light dose that can be delivered to the catalyst. These limitations are defined by the photoflow setup, specifically the channel height and the emission peak of the light source. This method was tested and shown to work well for three catalysts with different absorption properties through using LEDs with emission maxima close to the absorption maximum of each catalyst.

On the basis of the thermal balance in the heating wall and coking chamber, a general mathematical model is obtained for the temperature distribution at the walls of the heating channels. The model indicates that heat liberation due to combustion of the heating gas predominates over ~37% of the heating-channel height from the hearth (the first interval). In the second (upper) interval, heat transfer of the nonreacting gas–air mixture with the combustion products and the coal charge (through the coke-oven wall) is dominant. The temperature curve described by these equations determines the configuration of the temperature field in the heating channel. To even out this curve by decreasing the maximum temperature in the first interval and increasing the low temperature in the second, inert gas or steam may be supplied to the lower part of the heating channel, but diverted away from the section above 37% of the channel height. In the present work, the expediency of assessing the reproducibility of temperature measurements in the walls of industrial coke ovens by the telemetric method is established. To estimate the influence of the reagent mixing on the combustion rate and hence on the temperature distribution over the height of the heating channel, investigation of the composition of the gas–air mixture at various distances from the hearth is proposed. [ABSTRACT FROM AUTHOR]

It is of great interest to determine the uniformity of heating in coke ovens. Current measurement methods are described. The deficiencies preventing their use for the regulation of coke heating are discussed. A new method is proposed on the basis of telemetric equipment determining the temperature over the height of the heating channels. This method is simple to use: within a single shift, the temperature distribution over the height of all the heating channels in several walls may be assessed. The pace of the measurements is increased because the equipment does not need special cooling before repeated use. In industrial conditions, this method is used to measure the wall temperature of the heating channels in coke ovens. These experimental results are compared with the theoretical equations proposed in the previous part of this research. The results confirm the proposed mechanism of the process, which is fully consistent with the industrial temperature distribution over the height of the heating channel (except for the hearth temperature). In addition, the results emphasize that the general model must take correct account of the composition of the heating medium (a gas–air mixture)—primarily its air excess. [ABSTRACT FROM AUTHOR]

Uniform coke heating within coke ovens is of great importance. The temperature difference along the axis of the coke cake increases with increase in oven length and height and may reach 300°C or more, depending on the coke-battery design and technological factors. The introduction of control devices is a well-established approach to more uniform heating of the coke cake, in combination with methods of temperature calculation at the wall of the heating channel. However, this approach depends on information determined experimentally. That introduces more error in determining the temperature distribution over the channel height. Accordingly, attempts are made in the present work to describe the combustion of the heating gas on the basis of the minimum number of simply and reliably measurable factors. A three-parameter equation is obtained. Its structure is universal in terms of the set of factors. Adopting that equation as a model, the action of various factors on the temperature distribution over the height of the heating channel may be studied. [ABSTRACT FROM AUTHOR]

A mono-block-layer build solid oxide fuel cell model (MOLB type SOFC) is established, which takes into account the contact resistance at the electrode/interconnector interface due to the produce of the oxide scale. The influence of structure parameter on the MOLB type SOFC performance is investigated, which includes that the anode thickness, cathode thickness, the anode/interconnector interface width, the cathode/interconnector interface width, the channel height, anode porosity and cathode porosity. Although most researchers reported that the performance of MOLB type SOFC was superior to that of planar type SOFC, this work revealed that at the condition of the lower cathode thickness (<100 μ m), the MOLB type SOFC performance was worse than that of the planar type SOFC. Moreover, for the MOLB type SOFC, the power density per unit area slightly rises with the increase of channel height, but the power density per unit volume sorely drops with the increase of channel height. Consequently, the structure parameters of the MOLB type SOFC affect the cell performance significantly. • The effect of structure parameters on the MOLB type SOFC performance is examined. • As the thickness of cathode increases, the cell performance sharply rises. • The power density per unit volume sorely drops with the increase of channel height. • The cathode/interconnector interface width exist an optimal value. [ABSTRACT FROM AUTHOR]

Summary: Metallic bipolar plates (BPPs) are regarded as the most promising substitute of traditional carbon‐based BPPs due to their good mechanical properties, electrical conductivity, high productivity, and low cost in mass production. However, conventional design guidelines on flow channels of carbon‐based BPPs are not perfectly valid to metallic BPPs due to the formability of thin metallic sheets, which are at risk of material rupture especially when flow channels decrease. The objective of this work is to develop a forming limit model to establish the relationship between the channel height and channel geometric dimensions by the micro stamping process, and the maximum channel height can be predicted to guide channel design of metallic BPPs from the formability perspective. Firstly, an instability criterion for micro‐scale forming was proposed to estimate when the rupture occurs during the forming process. Forming height as the function of channel features is established, and the limit of forming depth can be predicted. Series of micro stamping experiments with various dimensions are conducted to validate the accuracy of the model. Influences of main parameters on the channel forming limit and evaluation of channel design are discussed based on the model. The model in this study is an effective supplement to the channel design principle for metallic BPPs. Based on the model, design, fabrication, and testing of metallic BPPs will be done in the following research, Part II: Experiments. [ABSTRACT FROM AUTHOR]

Highlights • Design and fabrication of BPP is further introduced based on our previous study. • Round corner and clearance of moulds play important role in maximum channel height. • Channel dimensions are selected by formability model and reaction efficiency. • Channel height, channel thickness and effect of blank holder are discussed. • Performance of single cell and short stack is tested to evaluate method reliability. Abstract This study offers an efficient design method of flow channels of metallic bipolar plates (BPPs) to improve manufacturing technique of BPPs and maximize power density in proton exchange membrane (PEM) fuel cells. Stamped thin metallic BPPs with anticorrosive and conductive coating are promising candidates for replacing conventional carbon-based BPPs. Nevertheless, unlike carbon-based BPPs, the flow channel design of metallic BPPs should take into account not only the reaction efficiency, but also formability due to the possible rupture of the metallic channel during the micro-forming process. In our previous study, a forming limit model was first proposed to predict the maximum allowable channel height by the forming process. This study is conducted to further propose the method of the design and fabrication of metallic BPPs based on the numerical model. In order to determine channel geometry design from formability perspective, response surface method is utilized to build a formability model. Combining the formability model and reaction efficiency, flow field design for metallic BPPs (channel width of 0.9 mm, rib width of 0.9 mm, channel depth of 0.4 mm and radius of 0.15 mm) is proposed. Experiments on BPP fabrication and assembled 20-cell fuel cell testing are conducted to observe forming quality of micro channel and output performance on the real fuel cell. It is shown that the stamping force grows with increasing channel depth in a nonlinear manner and a blank holder is needed to eliminate the sheet wrinkle in the forming process. The uniformity of the voltage distribution in the 1000 W-class stack further proves the reliability of metallic BPPs designed by our method. The methodology developed is beneficial to the fabrication management of metallic BPPs and effective supplement to the channel design principle for PEM fuel cells. [ABSTRACT FROM AUTHOR]

This study suggests a novel method for determination of the channel height in asymmetrical flow field-flow fractionation (AF4), which can be used for calibration of the channel for hydrodynamic radius determinations. The novel method uses an oil-in-water nanoemulsion together with multi angle light scattering (MALS) and elution theory to determine channel height from an AF4 experiment. The method is validated using two orthogonal methods; first, by using standard particle elution experiments and, secondly, by imaging an assembled and carrier liquid filled channel by x-ray computed tomography (XCT). It is concluded that the channel height can be determined with approximately the same accuracy as with the traditional channel height determination technique. However, the nanoemulsion method can be used under more challenging conditions than standard particles, as the nanoemulsion remains stable in a wider pH range than the previously used standard particles. Moreover, the novel method is also more cost effective. [ABSTRACT FROM AUTHOR]

Highlights: [•] In tangential electrokinetics, flow becomes undeveloped at channel heights>150μm. [•] Streaming-current coefficient is a sub-linear function of channel height. [•] Numerical simulation of undeveloped flows improves interpretation. [•] It is advisable to use channel heights below 100–150μm. [Copyright &y& Elsevier]

The results of studying the average and local heat transfer on the surface of hemispherical protrusions arranged on one side of the flat channel are presented. The experiments were carried out at the turbulent flow regime in varying the density of protrusions arrangement and the channel height. [ABSTRACT FROM AUTHOR]

Abstract: Micro-free flow electrophoresis (μFFE) is a technique that facilitates continuous separation of molecules in a shallow channel with a hydrodynamic flow and an electric field at an angle to the flow. We recently developed a general theory of μFFE that suggested that an electric field non-orthogonal to the flow could improve resolution. Here, we used computer modeling to study resolution as a function of the electric field strength and the angle between the electric field and the hydrodynamic flow. In addition we used our general theory of μFFE to investigate other important influences on resolution, which include the velocity of the hydrodynamic flow, the height of the separation channel, and the magnitude and direction of the electroosmotic flow. Finally, we propose four designs that could be used to generate non-orthogonal electric fields and discuss their relative merits. [Copyright &y& Elsevier]

Heat transfer characteristics of a submerged circular jet impingement with a confined plate was studied numerically. The continuity, momentum and energy equations were solved simultaneously. FIDAP, a finite element code, was used to formulate and solve the matrix equations for fluid elements. The effects of channel height and Reynolds number on the local Nusselt number were considered in the range of H=0.5–1.5 and Re=100–900, respectively. It was found that the channel height influenced strongly on the surface temperature, shear stress and pressure drop. The peak temperature was observed and gradually moved outward to the rim of the heated circular plate with increasing the Reynolds number, which may be related to flow recirculation region in the channel. It is also noted that the pressure drop increased more than the average heat transfer coefficient as the Reynolds number increased. For Pr=7, the Nusselt number was much more dependent on the Reynolds number than the channel height, and the magnitude of the second peak in the Nusselt number distribution increased as the Reynolds number increased. The local Nusselt number calculated based on a mixing-cup temperature was considerably different from that using the inlet nozzle temperature for H=0.5 and Re=100. The present study showed that the local Nusselt number of a confined submerged jet was significantly larger than that of the unconfined free jet which was available in the literature. [ABSTRACT FROM AUTHOR]

• 3D unsteady laminar mixed convection air flow in upward SAH was achieved. • The numerical study was performed for large aspect ratio at low Reynolds numbers. • The obtained results are different from that of forced convection regime. • The effect of channel's height has been performed at the same heat flux but for different Grashof numbers. • The obtained results are interesting and can be useful for engineers in designing and testing solar collectors. A 3D Numerical study of mixed convection air flow in upward solar air heater with large spanwise aspect ratio (A = 10 to 40) was performed using CFD commercial code Fluent 14.5 (ANSYS). The main objective of this study is to investigate the channel height's effect (aspect ratio) on flow pattern and heat transfer in upward solar air heater in the particular case of low Re and high aspect ratio. The bottom plate (absorber) was submitted to Constant Heat Flux (CHF) in the range of 200 to 1000 W/m2 and Reynolds number was varied from 50 to 1000. Our results are in concordance with most of authors conclusions about Poiseuille–Rayleigh–Benard flows. In mixed convection, increasing heat flux enhances heat transfer unlike forced convection flows. Simulation results of flow visualizations and Nusselt number calculations have shown that depending on Ri*, the velocity and temperature distributions in SAH vary greatly with the channel's height. The obtained results were different from previous studies. Indeed, our investigation of channel's height was achieved for the same heat flux but different Grashof numbers. For low channel's heights (high aspect ratio), increasing heat flux has not a significant effect but for higher channel's heights, an augmentation of heat flux enhances buoyancy effects in the flow and causes high turbulence. Also, increasing Reynolds number in low channel's heights (high A), can enhance substantially heat transfer. For higher channel's heights (low A), increasing Reynolds number decreases Ri* and thus buoyancy forces. Heat transfer is reduced and so Nusselt number. The obtained results may be very useful for engineers in designing and testing solar collectors. [ABSTRACT FROM AUTHOR]

• An integrated model of a membrane-based absorptive dehumidification module was developed. • The module performance was evaluated for various channel heights and three flow configurations. • There was a trade-off between the effects of the solution channel height on the sensible and latent effectivenesses. • The maximum total effectiveness was achieved at the smallest channel heights. • The countercurrent flow configuration was observed to be superior to other configurations. This paper presents an integrated theoretical model to evaluate the performance of a flat-sheet membrane-based absorptive dehumidification module with different flow arrangements (i.e., cocurrent, countercurrent, and cross-flow configurations) using an aqueous lithium chloride desiccant. The model results showed good consistency with experimental data, with a maximum relative error of approximately 7%. The performance of the flat-sheet dehumidification module was evaluated for various air and solution channel heights ranging from 1 to 5 mm at a constant Reynolds number in both channels, in terms of sensible, latent, and total effectivenesses. The sensible effectiveness increased with a decrease in the air channel height and an increase in the solution channel height; in particular, the effect of the solution channel height was more pronounced in the cocurrent flow configuration. In addition, the latent effectiveness increased with a decrease in both channel heights. Thus, there was a trade-off between the effects of the solution channel height on the sensible and latent effectivenesses; consequently, the effect of the solution channel height on the total effectiveness was mitigated. The total effectiveness was observed to decrease in the order of countercurrent, cross-, and cocurrent flow configurations; here, its value in the countercurrent flow configuration was approximately 0.788 when both channel heights were 1 mm. [ABSTRACT FROM AUTHOR]