Plate Module Research Articles

Prandtl number effect on heat transfer and flow structures in Rayleigh–Bénard convection modulated by an oscillatory bottom plate

In this paper, we study the Prandtl number effect on Rayleigh–Bénard convection systems modulated by an oscillatory bottom plate. Direct numerical simulations are carried out in a Prandtl number range of 0.2≤Pr≤4.6 and a fixed Rayleigh number of Ra=108. The initial drop and subsequent rise evolutionary behaviour of the heat transfer efficiency, characterised by the Nusselt number at the bottom plate Nub, with respect to the characteristic oscillatory velocity Vosc is observed in the whole parameter space under consideration. If the oscillatory bottom plate does not induce boundary layer instabilities but thickens the boundary layer only, then one observes a heat transfer reduction, corresponding to a high Pr and a low Vosc. If periodic boundary layer instabilities are triggered, then both heat transfer reduction and enhancement are possible. The reduction is generally seen when Pr≤1.0. Under such circumstance, the velocity boundary layer is embedded in the thermal boundary layer, if the instability induced by a certain Vosc is not strong enough to compensate the heat resistance of the thermal boundary layer, one still observes a reduction in spite of the boundary layer instabilities. The enhancement is generally seen for a low Pr and/or a high Vosc, in which case violent boundary layer instabilities will be triggered, leading to a sufficient emission of hot plumes. Furthermore, the critical velocity V̄c, characterising the boundary layer instability, is found to be increasing with Pr as Vc̄∼Pr0.5; and the Reynolds number at the equilibrium state evolves in a similar way as Nub. In the end, modal analyses are performed based on standard and extended proper orthogonal decompositions. Energetic contribution of the modes and modal distributions confirm well the modulation of the oscillatory bottom plate and the induced boundary layer instabilities on the heat transfer and flow structures of the convection system.

Cpvlib: A comprehensive open-source tool for modeling CPV systems

The design and simulation of concentrator photovoltaic (CPV) systems necessitate precise modeling tools, for which some commercial and open-source options exist. However, when new technologies or applications need to be modeled, they can present some limitations: lack of documentation transparency and inability to extend existing models, or little flexibility to do it. For instance, the novel hybrid CPV/flat-plate module, conceived by Insolight and developed within the HIPERION project, required the ability to model integrated tracking and dual use of incident irradiance, which was not possible with existing tools. Addressing these issues, cpvlib is introduced as a comprehensive, open-source tool offering modular and adaptable functionalities for CPV-based systems, built as an extension of the popular pvlib python library.cpvlib's design enables the simulation of various CPV-based configurations, incorporating advanced architectures such as integrated tracking and hybrid CPV-flat plate modules. The library uses PVSyst's utilization factors to model deviations from the single-diode model, accounting for spectral and thermal effects. Its class structure leverages object-oriented programming principles, ensuring ease of use and extension.The validation of cpvlib is carried out through the modeling and long-term monitoring of Insolight's hybrid Si/III-V translucent planar micro-tracking modules, achieving a root mean square error of 3.5 % in case of Si cells and 2.7 % for III-V CPV cells. The tool accounts for complex behaviors like air mass impact on CPV performance, angle of incidence limits, and light spillage. The annual energy yield for a hybrid module is computed using typical meteorological year data, showcasing cpvlib's practical application.

Optimization of novel plate acoustic metamaterials and modulation of the low-frequency bandgap

Based on the local resonance mechanism, five new acoustic metamaterial plate structures with low-frequency bandgaps are proposed in this paper. The two new structures obtained by heuristic structural design are capable of suppressing vibrations over a large frequency range in the low-frequency range of 0-400 Hz, which is promising for practical applications. The mechanism of bandgap generation is found to be a shift in the form of local resonance. Among the three original models, model C has the smallest transmission coefficient T min of −154.6. Analysis of the group and phase velocity diagrams reveals that the change in frequency has a great influence on the energy transfer, speed and direction of the wave in the structure. The heuristic structural design allows the mass block of model B1 to undergo angular state changes, which ultimately realizes the regulation of the bandgap position and the total bandgap width within a certain range. It is also found that the variation of the bandgap properties has a certain regularity with the change of the structural parameters.

Thermal optimization design of high-power charging station charging module

Abstract When facing significant heat generation from a 30 kW high-power charging station, traditional air-cooling forced convection methods are insufficient to meet the cooling requirements. In this study, based on an in-depth analysis of power modules, we designed a key component of the liquid cooling system, the cold plate, through theoretical calculations. Using simulation techniques, we analyzed the temperature distribution within the cold plate and performed design optimization under conditions of a 4C charging rate and a thermal load of 1598 W. Considering the actual operating environment of the charging equipment, we selected a 50% volume fraction of ethylene glycol-water solution as the coolant and simulated its performance under extreme outdoor conditions of 50°C. Simulation results showed that the optimized liquid-cooled cold plate module achieved a junction temperature of 69.73°C, significantly lower compared to the initial temperature of 109.9°C, resulting in an approximately 36% improvement in heat dissipation efficiency. This significant enhancement not only highlights the advantages of the liquid cooling system in managing the thermal load of high-power charging stations but also addresses the issue of excessive heat load faced by traditional cooling methods. The outcomes of this research provide important theoretical and practical foundations for the thermal design of charging equipment, which is expected to play a critical role in improving the performance and reliability of charging stations.

Forming of large scale bipolar plates for high power fuel cell stacks

Developing high-power (e.g. megawatt-scale) single fuel cell stacks is of significance to extending the application of hydrogen fuel cells in high-energy-consumption fields such as aerospace, maritime, and rail transportation. Bipolar plate is one of the core components of hydrogen fuel cell stacks. Currently, the mainstream hydrogen fuel cell stacks achieve a maximum power of about 200 kW with a bipolar plate area of approximately 600 cm2. While the megawatt-scale hydrogen fuel cell stacks requires large scale bipolar plates with an area of e.g. >2000 cm2 and higher geometric complexity of flow channel. However, the structural design and manufacturing process for such large scale bipolar plates remain unexplored. Based on the concept of “partitioned modular manufacturing”, the large scale bipolar plate is divided into multiple smaller scale bipolar plate modules in this work, and then integrated into a single component, which is then formed by applying multi-step stamping process to each module. Therefore, a so-called “partitioned multi-step stamping process” is proposed to form large scale bipolar plates with fine flow channels. Experimental validation was conducted using 0.1 mm thick titanium sheets and austenitic stainless steel sheets, demonstrating a prospective solution to manufacture large scale bipolar plates for high power hydrogen fuel cell stacks.

Experimental Study of Heat Transfer of Different-Thickness Plate Modules of Heat and Mass Transfer Device

Experimental Study of Heat Transfer of Different-Thickness Plate Modules of Heat and Mass Transfer Device

Experimental study of the hydraulic resistance of plate modules of a heat and mass transfer device

Experimental study of the hydraulic resistance of plate modules of a heat and mass transfer device

Experimental Investigation of the Desalination Process for Direct Contact Membrane Distillation Using Plate and Frame Membrane Module

Through experiments, the effect of membrane material selection and operating conditions on permeate fluxes in direct contact membrane distillation (DCMD) desalination was investigated. The experiment used a plate and frame membrane module, and with nine different hydrophobic porous membranes, a comparative analysis of the desalination performance of 3 wt% NaCl solution was performed. The results of this experiment were compared to find out the effect of different materials, pore sizes and membrane thicknesses on the permeate flux under same operating conditions. Further, a three-factor, three-level orthogonal experiment was designed. The effects of hot-side temperature, hot-side inlet flow and cold-side inlet flow on the permeate flux of PTFE membranes with a pore size of 0.22 μm were investigated when the temperature on the cold side was set at 20 °C. The results showed that in the DCMD experiments, both PTFE and PVDF membranes performed well, and that hot-side inlet temperatures and cold-side inlet flow rates had significant effects on the permeate flux.

All-in-one photoelectric logic gates by Dember photodetectors

Photoelectric logic gates (PELGs) are the key component in integrated electronics due to their abilities of signal conversion and logic operations. However, traditional PELGs with fixed architectures can realize only very limited logic functions with relatively low on–off ratios. We present a self-driving polarized photodetector driven by the Dember effect, which yields ambipolar photocurrents through photonic modulation by a nested grating. The ambipolar response is realized by exciting the whispering-gallery mode and localized surface plasmon resonances, which leads to reverse spatial carrier generation and therefore the contrary photocurrent assisted by the Dember effect. We further design a full-functional PELG, which enables all five basic logic functions (“AND”, “OR”, “NOT”, “NAND”, and “NOR”) simultaneously in a single device by using one source and one photodetector only. Such an all-in-one PELG exhibits a strong robustness against structure size, incident wavelength, light power, and half-wave plate modulation, paving a way to the realization of ultracompact high-performance PELGs.

Impact of Integration of FO Membranes into a Granular Biomass AnMBR for Water Reuse

The granular sludge based anaerobic membrane bioreactor (G-AnMBR) has gained emphasis in the last decade by combining AnMBR advantages (high quality permeate and biogas production towards energy positive treatment) and benefits of granular biomass (boosted biological activity and reduced membrane fouling). With the aim to further reduce energy costs, produce higher quality effluent for water reuse applications and improve system efficiency, a forward osmosis (FO) system was integrated into a 17 L G-AnMBR pilot. Plate and frame microfiltration modules were step by step replaced by submerged FO ones, synthetic wastewater was used as feed (chemical oxygen demand (COD) content 500 mg/L), with hydraulic retention time of 10 h and operated at 25 °C. The system was fed with granular biomass and after the acclimation period, operated neither with gas sparging nor relaxation at around 5 L.m-2.h-1 permeation flux during at least 10 days for each tested configuration. Process stability, impact of salinity on biomass, the produced water quality and organic matter removal efficiency were assessed and compared for the system working with 100% microfiltration (MF), 70% MF/30% FO, 50% MF/50% FO and 10% MF/90% FO, respectively. Increasing the FO share in the reactor led to salinity increase and to enhanced fouling propensity probably due to salinity shock on the active biomass, releasing extracellular polymeric substances (EPS) in the mixed liquor. However, above 90% COD degradation was observed for all configurations with a remaining COD content below 50 mg/L and below the detection limit for MF and FO permeates, respectively. FO membranes also proved to be less prone to fouling in comparison with MF ones. Complete salt mass balance demonstrated that major salinity increase in the reactor was due to reverse salt passage from the draw solution but also that salts from the feed solution could migrate to the draw solution. While FO membranes allow for full rejection and very high permeate purity, operation of G-AnMBR with FO membranes only is not recommended since MF presence acts as a purge and allows for reactor salinity stabilization.

Effect of openings on lateral behaviors of corrugated plate module walls and high-rise modular buildings

In modular buildings with container-like modules, the corrugated plates and the opening conditions were proven to have significant influence on the module rigidity. But the effect of openings on failure modes of modules and lateral sway performance of modular buildings were rarely considered. In this paper, shear performance of long modules with different kinds of openings and different beam sections were investigated. A simplified analytical model of perforated module sidewalls was proposed and was applied to the seismic structural analyses of high-rise modular frames. Results indicated that the opening subdivided the corrugated plate sidewalls, which mechanism led to the postponement of plate buckling and the increased elastic shear strengths comparing to intact walls. High stress concentrations and regional plate buckling firstly occurred around the opening, and then the buckled regions expanded toward two side columns as the increase of shear drifts. The frame beams and regional corrugated plates above or below the opening behaved like a kind of coupling beams that channeled short corrugated sidewalls at two sides of the opening. The bending rigidity of the coupling beam system determined the composition effect of short corrugated plates at two sides of the opening, and then directly influenced the drift performance of individual modules and the whole modular buildings.

A metamaterial plate with magnetorheological elastomers and gradient resonators for tuneable, low-frequency and broadband flexural wave manipulation

Incorporating magnetorheological elastomers and multiple gradient resonators (MRE–MGRs), a novel metamaterial plate is proposed, which entails low-frequency, broadband and tuneable bandgap features. The proposed MRE-MGR design embeds an adaptive magnetic field adjustment mechanism to alter the elastic modulus of the MRE to modulate the local resonance bandgap frequency and bandwidth. A bandgap prediction model of the metamaterial plate is developed using the plane wave expansion (PWE) method. Integrated into the model through equivalent stiffness terms, the magneto-controlled modulus of the MRE can be estimated using the energy method and magnetic dipole theory. The established model allows for revealing the dispersion relation of the proposed metamaterial plate under various magnetic fields. The predicted tuneable bandgaps, vibration transmission loss and flexural wave modulation of the metamaterial plate are validated through comparisons with finite element simulations. Numerical analyses show the benefit of the gradient resonator design, which alongside the effective MRE tuning, entails broadening low frequency bandgaps at 92 Hz (relative band of 79.3% for the exponential gradient) and 72.7 Hz (relative band of 65.9% for the linear gradient). The mechanisms underpinning the observed bandgap widening phenomenon are analysed and attributed to the combined effects arising from the gradient design of the distributed resonators and the effective tuning of the MRE elastic modulus under magnetic field modulation. The proposed metamaterial plate functionally achieves simultaneous magnetron adjustment of the bandgap frequency and its width, thus holding great promise for applications such as flexural wave guiding as well as vibration and sound radiation control in planar structures.

전산유체해석을 활용한 일체형 침전부상조 미세기포수 및 최종처리수 유공관의 설계인자 검증 연구

In this research, the feasibility of the design parameters for microbubble distribution and perforated drainpipes in the integrated sedimentation and dissolved air flotation (SeDAF) process for an advanced wastewater treatment plant was verified using computational fluid dynamics (CFD) analysis. The flow rates for the raw water and the microbubble distribution stage were 100 and 15㎥/d respectively. In the simulation, the raw water was first introduced into the mixing tank and then passed on to the coagulation, sedimentation, and flotation stages in sequence. The flow velocity for each stage increased at the narrowed cross-sectional points. It was observed that some of the coagulated water flowing into the inclined plate module in the sedimentation stage spilled out. As a result of the CFD analysis, the average flow rate for the four perforated distribution pipes was 0.014 kg/s. The standard deviation (SD) for the simulations of original and alternative model was 0.00050 and 0.00062, respectively, which indicated that the simulations were successful and reliable. The SD for the average flow rate for the four perforated pipes was 0.00706, 0.00779, 0.00833, and 0.00938, respectively. The aver age flow rates for each pipe were decreased by 0.0003, 0.0000, 0.0002, and 0.0002 kg/s, respectively compared to the original model. This simulation of characterization of microbubble distribution and perforated drainpipe demonstrated that the design parameters for the distribution pipes were set so that the microbubbles were distributed evenly and that the perforated drainpipes successfully withdrew the treated water within the integrated SeDAF process.

Performance evaluation of deep eutectic solvent as a draw solute and vertical up-flow forward osmosis module for desalination of seawater.

Forward osmosis (FO) has gained prominence in recent years particularly in desalination due to its ability to operate at low or no hydraulic pressure, with relatively limited membrane fouling and high-water recovery. However, pre-treatment of seawater is required to reduce membrane fouling caused by the presence of suspended solid particles. Also, a significant area of research in forward osmosis is still finding a suitable draw solute(DS) with the ideal characteristics. In this study, a novel deep eutectic solvent (DES) draw solute was used and able to extract water after the 500% dilution of DS. This signifies it as the potential candidate for the ideal DS. A comparative study of plate and frame and vertical up-flowforward osmosis (VUF) FO modules has been evaluated to eliminate the drawbacks associated with FO in terms of membrane fouling and draw solute. In addition, the performance of a novel DES as reline (choline chloride-urea) has been tested in both the modules. In VUF module, significantly less fouling was observed than in the plate and frame module. The initial water flux in plate and frame module was 2.30 LMH with seawater (without pre-treatment) as feed. However, it dropped to 1 LMH after 26h of run. However, initial water flux in VUF was 1.90 LMH, and it was maintained to 1.50 LMH after 89h of run. Regeneration of draw solute was carried out using a phase separation method and it was observed that phase separation was only observed for 10% dilution of DES.

(Invited) Automated Production of High Performance PEMFC Stacks and Components According to Automotive Requirements

EKPO Fuel Cell GmbH was founded in 2021 by two parent companies, ElringKlinger and Plastic Omnium, whom both are strong and established automotive suppliers with mass manufacturing capabilities and strategic approaches to hydrogen and the fuel cell businesses. The aim of EKPO is the development and production of proton exchange membrane fuel cell stack components and stack modules. Drawing from the experiences of the pilot automated production line since 2016, a fully optimized automated production, with improved production technologies and products, was developed by EKPO in 2021 to achieve an output capability of 10,000 stacks per year. The line was designed with a modular and scalable approach that allows flexibility as well as increased capacity by parallelization. The implementation is successful of producing EKPO’s various stack platforms while maintaining a high level of quality and production standard for the automotive industry.Since EKPO offers a wide range of products, the automated line can cover stack power ranges from 10 kW up to > 200 kW. As a prerequisite for excellent technical performance, in addition to function quality measures were set as key targets from the start of the development. EKPO has thus established consistent and stringent quality process flows and processes for all production steps. These measures include the early involvement of measurability and manufacturability assessment on all process and analysis steps on the different levels (i.e., components and stack). The feedback from each workflow can then continuously improve products, processes, and documentation regarding product specific codes standards and regulations (CSR).The accumulative knowledge from two decades of activity of fuel cell component and stack development enabled EKPO to establish a production range starting from cell and stack components (i.e., bipolar plates, sealings, and plastic end plate modules) to fuel cell stacks and modules produced by fully automated MEA and stack assembly and end-of-line testing. The automated production covers all processes from bipolar plate manufacturing and assembly, CCM and GDL roll good cutting, MEA-assembly, stacking, and the final compression and characterization of the fuel cell stack. The quality matrixes include inspecting performance key figures as well as quality and geometries of the stack and its components. The incoming materials are typically supplied as roll goods, (i.e., GDL, CCM, and metal coil) or as raw material (i.e., plastic granules). As the incoming materials and finished components are very sensitive to environmental conditions and particle contamination, the entire MEA processing and stack assembly process takes place in a cleanroom with controlled climate for maximum process stability and reliability.With a key approach of “design to manufacture” and deep understanding of stack technology and component requirements, EKPO is able to deliver two best in class stacks, namely the NM5 evo and NM12 single and twin platforms.

The Application of Cellulose Acetate Membranes for Separation of Fermentation Broths by the Reverse Osmosis: A Feasibility Study.

Recently, there has been a special research focus on the bioconversion of glycerol to 1,3-propanediol (1,3-PD) due to its significance in the chemical industry. However, the treatment and separation of fermentation broths is a great challenge. Currently, the reverse osmosis (RO) process is a reliable state-of-the-art technique for separation of biological solutions. This study (as the first to do so) investigated the feasibility of separation of 1,3-PD broths with the use of cellulose acetate (CA) membrane by the RO process. The experiments were carried out using the installation equipped with the plate module, under the transmembrane pressure (TMP) and temperature of 1 MPa and 298 K, respectively. It was found that the used membrane was suitable for broth separation. Indeed, it was noted that 1,3-PD, as a target product, migrated through the membrane; meanwhile, other broth components were rejected in various degrees. Moreover, it was proven that retention of carboxylic acids tended to increase with increasing molecular weight, according to the following order: succinic acid > lactic acid > acetic acid > formic acid. With regards to ions, retention degree increased with the increase of ionic radius and decrease of diffusion coefficient. Finally, it was demonstrated that the CA membrane is resistant to irreversible fouling, which has a positive effect on the economic viability of the process.

Low-cost, open-source contact angle analyzer using a mobile phone, commercial tripods and 3D printed parts

Measurement of contact angle is important in many areas of science and engineering research. Contact angle analyzers are however not easily accessible due to their expensive cost, which hinders their use in research and also in education. In this study we propose a low-cost contact angle analyzer that can be assembled with 3D printed parts. Mobile phone is used for imaging, and the image is analyzed using an open-source ImageJ plugin. Commercial camera tripods are used as platform that provides movement in many degrees of freedom, which are important in leveling of the substrate and proper imaging of droplets. We utilize the tripods to build imaging modules, sample plate module and volume metering module, each of which perform distinct tasks. Especially, we characterize the usefulness of the volume metering module, which helps users dispense same volume of liquid to reduce human error during measurement. The cost of an analyzer is $255.10, which is an order of magnitude lower compared to commercial products. With the advancement in open source software and upgrades in the hardware modules, we expect that the proposed contact angle analyzer to have a positive impact in resource limited research labs and educational environments.

Numerical Simulation of Heat Transfer in Plate Modules of Heat and Mass Exchange Device

Numerical Simulation of Heat Transfer in Plate Modules of Heat and Mass Exchange Device

Experimental Investigation of Heat Transfer in Plate Modules of a Heat and Mass Transfer Contact Device

Experimental Investigation of Heat Transfer in Plate Modules of a Heat and Mass Transfer Contact Device

Air-to-Air Heat and Moisture Recovery in a Plate-Frame Exchanger Using Composite and Asymmetric Membranes.

The present work studied an air-to-air exchanger comprising a flat plate module with a diagonal channel and a counterflow configuration for the air streams. The objective of this study was to remove moisture and sensible heat from an exhaust air stream by indirect contact with another air stream. The temperature and flow rate of the exhaust air was in the range of 40–80 °C and 1–5 L·min−1, respectively, and the fresh ambient air to exhaust air flow ratio was 1–5. An asymmetric porous membrane (P-MEM), a thin film composite membrane (C-MEM), and a kraft paper were used as the core for the heat exchange module. The most influential parameter was the humid air temperature, with a direct positive effect (50–60%) due to the increase in the kinetic energy of the water molecules. The other effective parameter was the flow rate of the humid gas with a reverse effect on the enthalpy exchanger performance (25–37%). The ratio of “fresh” air to “exhaust” air had the lowest positive effect (8–10%) on the total effectiveness. The sensible effectiveness of different membranes under the studied conditions was relatively the same, showing their similar heat conductivity. However, the kraft paper showed the best performance compared to the synthetic membranes due to having a porous/hydrophile texture. P-MEM with an asymmetric porous texture showed the closest performance to kraft paper. Furthermore, it was found that under limited conditions, such as higher temperatures (70 and 80 °C) and flow rates (5 L·min−1) for the humid air, the performance of P-MEM was a little better than the kraft paper. However, C-MEM with the lowest total effectiveness and overall heat transfer coefficient (150–210 W·m−2·K−1) showed that the hydrophile PEBAX layer could not contribute to moisture recovery due to its high thickness.