Minimum Pressure Drop Research Articles

A closed-loop sustainable method for the fabrication of electrospun nanofiber using food waste for filtration of particulate matters (PMs) and volatile organic matter (VOCs) from air

Indoor air pollution significantly impacts human health and the environment. Humans suffer the greatest health burden due to inefficient combustion technologies and polluted fuels. Therefore, air filtration is essential for a healthy and prosperous household. This study aims to develop a sustainable approach for the fabrication of biodegradable electrospun nanofibers (ENs) as air filters from food waste materials and offer a closed-loop circular solution and potential replacement for non-biodegradable HEPA air filters. We have tested banana peel extract (BPE), eggshell membrane, chitosan, and starch blended with polyvinyl alcohol (PVA) for fabricating ENs. Among the nanofibers investigated for air filtration application, BPE/PVA nanofiber shows the best performance in terms of maximum particulate matter (PM) removal efficiency and minimum pressure drop while incorporating > 50 % of the food waste into the electrospinning solution. Adding BPE into a 10 % PVA solution leads to a reduction in the hydrophilic behavior of the BPE/PVA nanofiber as compared to neat 10 % PVA ENs. The BPE/PVA nanofiber shows minimum pressure drop (156–160 Pa) and highest quality factor (Qf) in comparison with other waste-derived nanofibers with > 98 % filtration efficiency of PM2.5. Further, BPE/PVA nanofiber shows the highest adsorption of xylene vapor among other food waste derived nanofibers studied. Based on the above results, it can be concluded that BPE based nanofiber shows the best performance as air filter media among all other food waste-based ENs. The study demonstrates a successful regeneration and reuse of the BPE/PVA filter up to 3 cycles. The leftover material from banana peels after BPE extraction was utilized as a soil ameliorant. It showed 55 % soil water retention (SWR) capacity, making it possible to apply in arid regions or crops with high water requirements.

PET nano-woven luminescent fibers for efficient air filtration and fluorescence indication of particulate matter

Inhalable particulate matter poses significant health risks, and current air filtration materials often struggle with efficiently capturing particles smaller than 300 nm and providing real-time feedback on filtration performance. We present the synthesis and characterization of polyethylene terephthalate (PET) nano-woven luminescent fibers (PNWLFs), created through a positive and negative dual high-voltage electrospinning method. The PNWLFs feature a unique nano-woven structure composed of backbone fibers (200–1000 nm) and nanofibers (20–160 nm), which endow them with remarkable mechanical strength, maintaining a breaking force of 117.5 cN and structural integrity under a 138 mm water column. The fibers exhibit excellent breathability and waterproof performance, with a water vapor transmission rate of 4.69 kg/m2/day. More importantly, the PNWLFs demonstrate exceptional air filtration capabilities, achieving filtration efficiencies of 99.77 % for PM5.0, 99.76 % for PM2.5, 99.72 % for PM1.0, 99.53 % for PM0.5, and 99.40 % for PM0.3, with minimal pressure drop of 106 Pa. Additionally, these fibers possess a unique fluorescence-indicating function: the fluorescence intensity decreases in response to increasing particulate matter concentration and the number of filtration cycles, allowing for intuitive visual monitoring of filter performance and particulate levels. These attributes underscore the significant potential of PNWLFs synthesized by this work for advanced air filtration applications and effective air quality monitoring.

Fabrication of microchannel heat sink using additive manufacturing technology: A review

Additive manufacturing is a cutting-edge process that enables the creation and development of complex shapes, opening new avenues for advanced heat sink designs that maximize heat transfer while minimizing pressure drop. This review provides an overview of recent results and insights from global researchers on the additive manufacturing of microchannel heat sinks. It discusses various novel microchannel heat sink types fabricated using additive manufacturing and the complexities involved in their fabrication. Additionally, the review explores geometric configurations, the application of computational optimization methods, and the impact of surface roughness on heat transfer and pressure drop. The primary focus is on the fundamental advantages of additive manufacturing in addressing complex heat transfer designs. However, the review also highlights limitations restricting its benefits in specific applications, such as material handling and availability. This review identifies future challenges for creating novel heat sinks with complex geometries and opportunities for advancements in heat transfer technology.

Enhanced air filtration and ammonia sensing with cellulose nanofibers-based triboelectric nanogenerators under harsh environments

Fire accidents often occur in environments characterized by severe air pollution, toxic gas emissions, and microbial growth, creating significant challenges for developing multifunctional portable healthcare devices. These devices must achieve high filtration efficiency, minimal pressure drop, and the capability to provide early warnings of toxic gas leaks. Triboelectric nanogenerators present a sustainable solution as self-powered energy converters for advanced healthcare applications. In this study, we grafted Ti3C2Tx/MoS2 nanohybrid materials, which form Schottky heterojunctions, onto cellulose diacetate using tetraethyl orthosilicate, followed by electrospinning to produce nanofibrous films. When paired with a negatively charged material, the resulting device achieved an optimal balance with a low-pressure drop (52 Pa) and high filtration efficiency (98.72 % for PM0.3). It also demonstrated exceptional stability under high-temperature and high-humidity conditions. Notably, the device maintained rapid sterilization within 15 min and consistent filtration performance even after multiple washes. Furthermore, the device exhibited precise detection of trace amounts of NH3 (0.1 ppm) and demonstrated a rapid response, achieving an 86 % response rate within 2 s for 100 ppm NH3, providing an early warning 28 s faster than commercial NH₃ monitors. This study introduces a novel approach to the development of multifunctional, self-powered, wearable medical devices that offer high-efficiency air filtration and sterilization, breath monitoring, and rapid toxic gas leakage detection in harsh environments.

Ultra-stable counter flow diverging minichannel heat sink with integrated microstructures for superior cooling performance

Efficient thermal management of miniaturized electronic devices is quite challenging nowadays. It requires dissipation of very high heat flux without considerable elevation of surface temperature. To address this issue, this study proposes the counter flow diverging minichannel heat sink in a compact size of 3 cm2. Additionally, two innovative microstructures have been developed and integrated into the bottom surface of the proposed minichannel heat sink: one with gradient micro pin-fins and another combining gradient microcavities with micro pin-fins. Comprehensive flow boiling experiments are conducted under various operating conditions to identify the best configuration with the most appropriate operating condition to dissipate the highest heat flux with minimal pressure drop and stable two-phase flow patterns. The current study reveals that the synergistic effects of gradient micro pin-fins and optimized gradient microcavities achieve a very high heat flux of 746.14 W/cm2 and a two-phase heat transfer coefficient of 28.18 W/cm2K under the limitation of wall temperature lower than 132 °C. Additionally, it maintains an exceptionally low pressure drop of 2.35 kPa with stable two-phase flow patterns under a mass flux of 600 kg/m2s and a degree of subcooling of 40 °C. Compared to the bare surface, counter flow diverging minichannels with gradient micro pin-fins and optimized gradient microcavities show excellent enhancements of 201.12 % in the effective heat flux and 124 % in the two-phase heat transfer coefficient, suggesting it is the best design in the present study for advanced cooling applications.

Experimental investigation into heat transfer and flow characteristics of magnetic hybrid nanofluid ([formula omitted]/Ti[formula omitted]) in turbulent region

Extensive research and empirical evidence demonstrate the superior thermal performance of nanofluids compared to DIW. Magnetic hybrid nanofluids, such as Fe3O4/TiO2, are currently being explored for their enhanced thermal properties. This study evaluates Fe3O4/TiO2 nanofluids for heat transfer and hydraulic resistance across Reynolds numbers from 3200 to 5300 and volume fractions from 0.00625 % to 0.3 % vol. UV–Vis spectroscopy shows that lower volumetric fractions correlate with decreased sedimentation. Over 30 days, nanofluids with 0.3 % vol, 0.2 % vol, and 0.1 % vol exhibited high sedimentation factors (SF) of 31.79 %, 11.88 %, and 11.44 %, respectively, while 0.00625 % vol, 0.0125 % vol, and 0.025 % vol demonstrated better stability with SFs of 8.89 %, 9.82 %, and 10.24 % respectively. Volume fractions significantly impact heat transfer, with CHT coefficients increasing by 11.42 % at 0.3 % vol, 14.03 % at 0.2 % vol, 18.04 % at 0.1 % vol, and 19.98 % at 0.05 % vol. The greatest enhancements are at lower concentrations: 22.91 % at 0.025 % vol, a peak of 26.33 % at 0.0125 % vol, and 24.30 % at 0.00625 % vol. Pressure drops are highest at 21 % for 0.3 % vol at Re 5018, decreasing with lower concentrations: 13.10 % at Re 5144.4 (0.2 % vol), 11.94 % at Re 5041.6 (0.1 % vol), 9.82 % at Re 5112.2 (0.05 % vol), 7.67 % at Re 5258.7 (0.0125 % vol), and 10.29 % at Re 5094.0 (0.00625 % vol). These results highlight that higher nanoparticle concentrations increase pressure drop, impacting energy efficiency. Lower concentrations (0.0125 % Vol and 0.00625 % Vol) provided better heat transfer with lower pressure losses. Total Efficiency Index (TEI), The optimal nanoparticle concentration for maximum thermal efficiency was approximately 0.0125 % Vol. TEI values were highest at this concentration, indicating enhanced heat transfer with minimal thermal resistance and pressure drop. Higher concentrations (0.2 % Vol and 0.3 % Vol) showed lower TEI values, suggesting reduced thermal efficiency due to increased flow resistance. These findings highlight the importance of selecting an appropriate nanoparticle concentration to optimize thermal performance in heat transfer systems, balancing the benefits of enhanced heat transfer with the drawbacks of higher-pressure losses.

Polymer‐Sorbent Direct Air Capture Contactors with Complex Geometries 3D‐Printed via Templated Phase Inversion

AbstractLow‐cost direct air capture (DAC) systems require efficient gas–solid contactors. These contactors provide rapid rates of heat and mass transport with minimal pressure drops. Triply periodic minimal surfaces (TPMS) are a class of geometries that are shown to have heat transfer properties that exceed those of other geometries, and these benefits are expected to manifest in mass transfer as well due to the analogies between heat and mass transfer. However, creating TPMS contactors is difficult using conventional manufacturing techniques such as injection molding. Non‐solvent‐induced phase separation (NIPS) of a polymeric ink containing the adsorbent is one way to construct adsorption contactors with excellent mass transport rates, but contactors have to date only been fabricated in simple geometries (e.g., films, fibers). This study demonstrates that NIPS of polymeric inks occurs within a simultaneously‐dissolving, water‐soluble, 3D‐printed template. This templated phase inversion (TPI) technique can create seemingly unlimited macroscopic architectures, including TPMS contactors, using a variety of potential DAC adsorbents, including zeolite, silica, activated carbon, and metal–organic frameworks. SEM, micro‐computed tomography, and nitrogen adsorption experiments reveal the microscopic pore structures and macroscopic geometries of the resulting sorbent contactors. TPMS DAC contactors with poly(ethyleneimine)/silica adsorbents are shown to have CO2 capture performances that rival or exceed other contactor geometries.

Aerodynamic Size-Dependent Collection and Inactivation of Virus-Laden Aerosol Particles in an Electrostatic Precipitator.

Electrostatic precipitators (ESPs) may enable high particle collection efficiency with minimal pressure drop in HVAC systems. However, studies of pathogen collection and inactivation in ESPs at medium to higher flow rates are limited. Here, a single-stage, wire-plate ESP operated at flow rates of 51 and 85 m3 h-1 was used to study the removal of virus-laden aerosol particles for three different airborne viruses: (1) bovine coronavirus (BCoV), (2) influenza A virus (IAV), and (3) porcine reproductive and respiratory virus (PRRSV). Size-resolved measurements of collection efficiency were obtained using Andersen cascade impactors (ACI) sampling upstream and downstream of the ESP. All measurements were analyzed based on three distinctive but complementary methods: (1) fluorimetry to assess physical collection, (2) RT-qPCR to assess viral RNA concentrations and (3) virus titration to assess virus viability. In general, log reductions by virus titration were highest followed by those from RT-qPCR, and last fluorimetry, suggesting that a portion of virus may be potentially inactivated in flight in the ESP. An effective migration (deposition) velocity ranging from 3.10 to 10.05 cm s-1 was also determined using the spatially resolved measurements of virus collection on the ESP plates.

Optimizing turbine meter performance through geometrical parameter analysis: A simulation-based approach using TOPSIS

The number of blades and their angle in a turbine gas meter directly affect its performance and the amount of lift force, pressure drop and flow rate passing through the blades. In this research, the combination of software simulation and optimization method has been used as an effective research tool to investigate the effect of these geometric parameters on the amount of pressure drop, volume flow rate and lift force. First, the flow in a turbine gas meter is simulated using computational fluid dynamics. The set of governing equations including continuity, linear momentum and angular momentum have been solved by Fluent software. To simulate the turbulent flow, the standard k-ε model is used. In the next step, with the help of TOPSIS model, it has been optimized to check the effect of each of the parameters and determine their optimal values. The results of this research showed that by increasing the number of blades and increasing the blade angle, the lift force increases. Among the two parameters, the number of blades and the angle value, changing the number of blades has a significant effect. Reducing the number of blades and decreasing the blade angle can be effective strategies to minimize pressure drop. Also, the effect of changing the number of blades plays an important role in pressure drop. The pressure drop in the number of 20 blades is the highest and this's due to its large number of blades. In this article, 21 cases have been investigated with the help of TOPSIS and it can be seen that the angle of 30 ° with 12 blades is an optimal model. The ratio of lift force to drag force is observed at an angle of 30°, the number of 20 blades is the highest and its dimensionless value is 78.23. For an angle of 37.5°, the ratio of lift force to drag force for 20 blades has the highest value and its dimensionless value is 915.9. Also, for an angle of 45°, the ratio of lift force to drag force and the number of 20 blades has the highest value, and its dimensionless value is 1190.94.

Role of physical structure on performance index of crossflow microchannel heat exchanger with regression analysis

Microchannel heat exchangers have become the preferred choice in contemporary technologies like electronics, refrigeration, and thermal management systems. Their popularity stems from their compact design and exceptional efficiency, which outperform traditional heat exchangers (HE). Despite ongoing efforts, the optimal microchannels for enhancing heat management, minimizing pressure drop, and boosting overall performance have yet to be identified. This study seeks to deepen our understanding of heat transmission and fluid dynamics within a cross-flow microchannel heat exchanger (CFMCHE). Utilizing numerical modeling, it examines how various physical aspects—such as channel geometry, spacing between channels, the number of channels, and the velocity at the inlet—affect key performance indicators like pressure drop, effectiveness, Nusselt number, and overall efficiency. To enhance the design, we analyze six unique shapes of crossflow microchannel heat exchangers: circular, hexagonal, trapezoidal, square, triangular, and rectangular. We employ the Galerkin-developed weighted residual finite element method to numerically address the governing three-dimensional conjugate partial differential coupled equations. The numerical results for each shape are presented, focusing on the surface temperature, pressure drop, and temperature contours. Additionally, calculations include the efficacy, the heat transfer rate in relation to pumping power, and the overall performance index. The findings reveal that while circular shapes achieve the highest heat transfer rates, they underperform compared to square-shaped CFMCHEs. This underperformance is largely due to the increased pressure drop in circular channels, which also exhibit a 1.03% greater reduction in effectiveness rate than their square-shaped counterparts. Consequently, square-shaped channels, boasting a performance index growth rate of 53.57%, emerge as the most effective design among the six shapes evaluated. Additionally, for the square-shaped CFMCHE, we include residual error plots and present a multiple-variable linear regression equation that boasts a correlation coefficient of 0.8026.

Enhanced Air Filtration Efficiency through Electrospun PVC/PVP/MWCNTs Nanofibers: Design, Optimization, and Performance Evaluation.

This study presents a novel approach for creating an effective air filtration medium using electrospun nanofibers comprised of poly(vinyl chloride) (PVC), poly(vinylpyrrolidone) (PVP), and impregnated with multiwall carbon nanotubes (MWCNTs). The membrane production was optimized using an experimental design methodology, resulting in a hydrophobic membrane that exhibits excellent dispersion of MWCNTs. Scanning electron microscopy images illustrate the nanofibers' morphology, featuring an average diameter of approximately 240 nm, minimal bead formation, and optimal MWCNT dispersion. Air filtration tests conducted with NaCl nanoparticles (7-300 nm) demonstrated superior permeability (10-12 m2) and minimal pressure drop (approximately 780 Pa at a 5 LPM airflow rate) compared to other electrospun materials. Both MWCNT-impregnated samples and individual PVC/PVP nanofibers exhibited filtration efficiencies nearing 96%. These results underscore the potential of this developed material for air filtration, particularly in indoor environments, where MWCNTs effectively adsorb and maintain low levels of gaseous and particulate pollutants. This study emphasizes the design, optimization, and comprehensive performance evaluation of PVC/PVP/MWCNT nanofibers, showcasing significant advancements in filtration efficiency with high flux. The findings suggest promising applications for this composite material in advanced air purification systems.

Optimizing thermal performance in tube-in-tube heat exchangers with metal foam inserts: experimental and RSM analysis

ABSTRACT This study investigates tube-in-tube heat exchanger performance under steady-state conditions, examining co-current and counter-current flows. It explores various configurations, including metal foam enhancements, to optimize heat transfer efficiency and minimize pressure drop. Driven by the potential of metal foam to enhance heat transfer, the study aims to demonstrate significant improvements in thermal performance compared to conventional designs. Experimental methods involve testing four configurations with Nickel foam (10 PPI, 0.90 porosity) inserts, evaluating temperatures and pressure drops across flow rates of 25 to 50 LPH. Hot water at 65°C flows in the annulus, while normal water at 31°C flows in the outer annulus. Results show metal foam’s substantial enhancement in heat transfer, with counter-current metal foam configurations achieving up to 3.71 times greater efficiency than parallel flow setups. Moreover, comprehensive performance evaluation reveals that the counter-flow heat exchanger with metal foam is 2.03 times more efficient than the conventional co-current flow without metal foam. Conclusions highlight metal foam’s effectiveness in improving heat transfer performance and optimizing thermal systems through systematic parameter optimization using response surface methodology.

Enhancing thermal efficiency in twisted tri-lobe double pipe heat exchangers via integrated CFD and AI approaches

Industrial energy efficiency relies on precise heat exchanger design. Engineers aim to enhance heat transfer while minimizing pressure drop. Twisted tube Double Pipe Heat Exchangers (DPHEs) excel, inducing secondary flows that disrupt boundary layers and enhance fluid mixing. This investigation aims to provide insights into the relationships among specific factors and the thermal performance of a DPHE with twisted tri-lobe tubes, utilizing water as the working fluid. This is accomplished by employing an approach that integrates computational fluid dynamics with an artificial neural network, coupled with a single-objective genetic algorithm. Data inquiry was facilitated using response surface methodology, considering five design variables including the Reynolds numbers of the outer and inner twisted tubes, outer and inner twist ratios, and twisting direction. The simulation employed the turbulent k-ω shear-stress transport model, and the governing equations were solved using the finite volume method. The results underscored the efficacy of the developed multi-approach algorithm in maximizing the Performance Evaluation Criterion (PEC) both within the specified domain (10000 ≤ Re ≤ 20000 & 5≤twist ratio≤20) and beyond the domain (5000 ≤ Re ≤ 50000 & 2.5≤twist ratio≤25) of design variables. In the specified domain, a PEC of 1.16 was achieved, demonstrating the algorithm's effectiveness. Furthermore, the proposed method, extrapolated to the data space, yielded a noteworthy improvement in PEC of 16.35 %. In both domains, the optimized set of design variables for maximizing the PEC comprised a minimum outer Reynolds number, maximum inner Reynolds number, maximum outer twist ratio, and minimum inner twist ratio.

Thermo-hydraulic performance of parallel multi-shell and multi-helical coiled tube heat exchanger CFD model with Taguchi-grey relational analysis

This study utilized four distinct shell and helical tube heat exchanger layouts to numerically evaluate the thermal and hydraulic efficiency of each arrangement. The numerical research was conducted using ANSYS FLUENT 2022R1. Currently, there has been no research conducted on the investigation of multiple helical coiled tubes enclosed by multiple shell heat exchangers. This study aimed to optimize various tasks using the Grey Relational Analysis approach in combination with the Taguchi method to maximize thermal efficiency and minimize pressure drop.A parallel configuration was used to connect two to three concentric helical tubes, with each helical tube being enclosed by a shell to control the flow of fluid. The P–P-2M − 36 design, consisting of two helical tubes, has the highest enhancement ratio of Uo = 26.75 %, when compared to the P–P-3M − 36 configuration. Similarly, the P–P-2M − 42 configuration enhances Uo by 38.42 % in comparison to the P–P-3M − 42 configuration. These findings demonstrate that a configuration consisting of two helical tubes exhibits a higher enhancement ratio of Uo compared to a configuration consisting of three helical tubes. The P–P-3M − 36 design, which consists of three helical tubes, exhibits a minimum pressure drop of 39.19 % compared to the P–P-2M − 36 configuration. Similarly, the P–P-3M − 42 configuration reduces pressure drop by 37.76 % compared to the P–P-2M − 42 configuration. The P–P-3M − 36 configuration is designed to simultaneously reduce pressure drop and boost heat transfer rate. The model achieves the optimal values for heat transfer rate and pressure drop at a Reynolds number of 55,000.

Heat Enhancement in a Short Air Channel with Solid and Permeable Baffles

Heat transfer enhancement to turbulent air flow in a short rectangular constant-wall temperature channel fitted with either solid or permeable baffles were numerically studied based on COMSOL® simulations. The number of used baffles (1 to 7), Reynolds number (10000, 20000, and 30000), and baffle permeability (1 × 10−11 to 1 × 10−6) were investigated. Operations under turbulent flow conditions were considered, which has not been extensively studied. The average temperature of air at the channel exit and the pressure drop along the channel were obtained via simulation for different cases. For solid baffles, the heat transfer enhancement parameter ranged from 0.30 to 0.35 due to the high friction, while for permeable baffles, it ranged from 1 to 35 as the permeability and number of baffles increased. This is due to the heat-transfer-area increase and pressure-drop reduction when the flow passes through the permeable baffles. For permeable baffles, a minimum heat exchanger temperature approach of 10 K was achieved with minimal pressure drop at a permeability of approximately 4 × 10−8 when using 4–6 permeable baffles. Accordingly, the results demonstrated that using four permeable baffles with a permeability of approximately 4 × 10−8 m 2 is optimal from thermal, economical, and mechanical viewpoints.

Experimental comparative analysis of an air-breath direct methanol fuel cell (DMFC) using serpentine and spiral flow fields

In the present study, an experimental comparative analysis of Air Breathe Direct Methanol Fuel Cells (DMFC) was conducted using two different flow field patterns, namely spiral and serpentine. The impact of flow field plates on cell performance, CO2 gas bubble behavior and pressure drop was examined at various mass flow rates and current densities. The experiments were conducted with the same hydraulic diameter and channel length for both flow field patterns, varying mass flow rates from 0.25 to 4 ml/min, and exploring reactant concentrations ranging from 0.25 M to 4 M. From the results it is observed that, for both the flow field patterns, pressure drop increases and CO2 bubble formation decreases with increase in mass flow rate. It is also observed that, under identical operating conditions, the serpentine flow field exhibits higher values for both pressure drop and peak power density compared to the spiral flow configuration. The study reveals that, the serpentine flow appears more efficient in terms of peak power density, while the spiral flow outperforms in terms of minimizing pressure drop under the specified operating condition.

Optimization of Lithium-ion battery thermal performance using dielectric fluid immersion cooling technique

Lithium-ion batteries (LIBs) are crucial for portable electronics, electric vehicles, and renewable energy systems. However, conventional cooling techniques for LIBs struggle to efficiently dissipate heat during rapid charging and discharging, potentially compromising performance and safety. This study explores the immersion cooling technique to optimize the thermal performance of 4S2P LIB module at 3 C discharge rate. The MSMD-NTGK battery model is utilized in numerical simulation to analyze the electrochemical and thermal characteristics of LIBs. Initially, static and forced convection immersion cooling methods are compared using two different cooling media: ester-oil and air. Static convection with ester oil reduces temperature rise by 8.3 % compared to natural air convection, while forced convection with ester oil achieves optimal temperatures (< 5 °C) at a fluid velocity of 0.077 m/s (20 LPM), lower than forced air convection. Furthermore, the study enhances forced convection with ester oil-based immersion cooling for LIB with different inlet and outlet structural designs. Among these, the middle inlet and middle outlet-center (MIMO-C) flow model demonstrates optimal temperature at reduced flow rate of 5 LPM and minimal pressure drop of 230 Pa compared to others. These findings underscore the potential of forced convection-based immersion cooling to improve LIB performance and lifespan.

Numerical modeling and parametric optimization of a dual media tank thermal energy storage system for enhanced industrial heat processes

ABSTRACT In this study, a 1-D numerical model is developed to investigate the Dual Media Tank (DMT) thermal energy storage (TES) system. A physical model of 29 kWTH DMT is designed to evaluate the effect of parameters such as inlet velocity, pebble diameter and void fraction on discharging efficiency, friction factor and thermocline thickness. In addition, a Response Surface Methodology (RSM) is also used to optimize the design and operating parameters for maximum discharging efficiency and minimum pressure drop. The analysis result indicates a 41% increase in discharging efficiency and a 53% drop in friction factor for Reynolds number ranging from 16–23. However, a sharp increase in thermocline thickness (0.25–0.75 m) is found for Reynolds numbers ranging from 16–18; thereafter, the growth of thermocline thickness is slower. This shows that thermal degradation is higher for low Reynolds numbers. In this analysis, the effect of pebble diameter is also studied, and the result shows a 22% drop in discharging efficiency for pebble diameter varying from 0.03–0.09 m. In addition, the pebble diameter also affects the discharging time, and the result indicates a maximum discharging time of 40 minutes for smaller pebble diameters. Accordingly, parametric optimization has also been done to optimize the mass flow rate and pebbles diameter for maximum efficiency and minimum friction factor. The optimization result shows that a mass flow rate of 0.10 kg/s and pebbles diameter of 0.07 m is the optimum value for both minimal pressure drop and maximum discharging efficiency.

Investigation of novel type of cylindrical lithium-ion battery heat exchangers based on topology optimization

The in-depth research on the heat exchanger for lithium-ion batteries is of significant importance due to its crucial role in ensuring the safe operation of electric vehicle (EV) power systems. To enhance the thermal and flow characteristic of the heat exchangers, the novel heat exchangers for 18650-cylinderical lithium-ion batteries have been proposed by topology optimization with the minimization of pressure drop and the lowest average temperature (∏1) and the minimization of pressure drop and the lowest temperature difference (∏2) as two different optimal goals. The topology optimization based on the variable density method is utilized to get two-dimensional (2D) optimal channels, and then the optimized results are extended to three-dimensional (3D) heat exchangers. The 3D heat exchangers are named TOHE-1 which is gotten by stretching the topology channels with ∏1 as optimal goal and TOHE-2 which is gotten by that with ∏2 as optimal goal. Subsequently, a detailed thermodynamic analysis is performed to assess the effect of the type of heat exchangers, channel heights, weight factor of topology optimization function, mass flow rates and discharge rates on the cooling effect of the batteries. The results show that compared with the traditional channel heat exchangers, the heat transfer coefficient of topological heat exchangers have increased by 49.92%, while reducing pressure drop by 27.81%. Meanwhile, compared to TOHE-1, heat transfer coefficient of TOHE-2 is increased by 9.70%, while pressure drop is saved by 4.70%. Other studies have indicated that for a 4 C discharge of the battery, a topological heat exchanger with a channel height of 1.5 mm, a thermal performance weight factor of 0.1, and a mass flow with 3.3 × 10−3 kg s−1 is the optimum heat dissipation scheme. Finally, the numerical studies are verified by conducting the convective heat transfer experimental tests.

Energy-saving characteristics of pneumatic conveying based on the Dune model of elbow installation with different radius of curvature

Abstract During pneumatic conveying, particles undergo rapid horizontal movement and experience significant wear and collision when changing direction at the elbow pipe due to inertia. Consequently, to minimize energy consumption in transportation, a Dune model has been developed specifically for bends with varying radii of curvature. In this paper, the pressure drops the additional pressure drop coefficient, and the energy loss coefficient of the system are studied. At the minimum pressure drop velocity, PIV is used to capture the particle velocity at different locations in the vertical pipe. The findings reveal that the Dune model installation successfully minimizes the minimum pressure drop velocity, and the maximum pressure drop velocity is reduced by 10.36%. In addition, the energy loss coefficient decreased by 11.56%. Particles in vertical pipes have greater axial velocity than particles in pipes without dunes.