Channel Layout Research Articles

The Thermal Effect of Variate Cross-Sectional Profile on Conformal Cooling Channels in Plastic Injection Moulding

Cooling system is an important role in designing a productive plastic injection moulding (PIM). The selection of geometry and layout for plastic injection moulding cooling channels strongly influences the cooling performance such as cooling time and thermal distribution that leads to shrinkage and warpage. This paper presents the study to determine the best cooling channel layout and cross-sectional profile which include circular straight drilled cooling channels, circular conformal cooling channels, square shape conformal cooling channels, elliptical conformal cooling channels and diamond conformal cooling channels. The cooling time and thermal distribution were simulated by Moldflow Insight (MFI) software. Results are presented based on ejection time and temperature variation by using transient analysis in MFI. The results found the best cross-sectional of cooling channels indicated by square shape conformal cooling channels, compare to others due to the shortest cooling time that recorded from simulation. The conformal cooling channel layout also resulted greater thermal distribution compared to straight drilled cooling channel design.

Regulation of the temperature in the ampoule channel with natural circulation of coolant

It has been shown by calculations that it is possible to extend considerably the capabilities for control of temperature conditions in an ampoule channel with natural coolant circulation, using the proposed hydraulic circuit layout, on samples during irradiation in the SM-3 reactor reflector cell by changing the circulation circuit geometry through the arrangement of a bypass heat removal line formed in the upper part above the flow limiter as compared to control only by changing the thermal conductivity of the gas gap in the channel body (through changing the gas pressure or composition). The ampoule channel test conditions, layout and simulation model for thermal-hydraulic analysis using the RELAP5/MOD3.2 code are presented. An investigation was conducted to study the effects of the bypass cooling circuit on the temperature conditions during irradiation of samples in an ampoule channel. The bypass flow rate change is achieved by varying the passage area of the flow limiter orifice. Options have been considered for filling the channel body gas gap with helium and a helium mixture. The calculation showed that the heat removed by the bypass line could reach 40% of the total heat released in the channel. With helium used in the channel body gap, the temperature conditions during irradiation are adjusted in a broader range (200–330 °С) than with a gas mixture of a lower thermal conductivity (279–330 °С), the major temperature variation taking place with the flow limiter orifice area being less than 0.2–0.3 cm2. Any further increase in the flow limiter orifice area does not lead to a major temperature change in the coolant flowing about the samples.

One-Step Approach to Fabricating Polydimethylsiloxane Microfluidic Channels of Different Geometric Sections by Sequential Wet Etching Processes.

Polydimethylsiloxane (PDMS) materials are substantially exploited to fabricate microfluidic devices by using soft lithography replica molding techniques. Customized channel layout designs are necessary for specific functions and integrated performance of microfluidic devices in numerous biomedical and chemical applications (e.g., cell culture, biosensing, chemical synthesis, and liquid handling). Owing to the nature of molding approaches using silicon wafers with photoresist layers patterned by photolithography as master molds, the microfluidic channels commonly have regular cross sections of rectangular shapes with identical heights. Typically, channels with multiple heights or different geometric sections are designed to possess particular functions and to perform in various microfluidic applications (e.g., hydrophoresis is used for sorting particles and in continuous flows for separating blood cells6 , 7 , 8 , 9). Therefore, a great deal of effort has been made in constructing channels with various sections through multiple-step approaches like photolithography using several photoresist layers and assembly of different PDMS thin sheets. Nevertheless, such multiple-step approaches usually involve tedious procedures and extensive instrumentation. Furthermore, the fabricated devices may not perform consistently and the resulted experimental data may be unpredictable. Here, a one-step approach is developed for the straightforward fabrication of microfluidic channels with different geometric cross sections through PDMS sequential wet etching processes, that introduces etchant into channels of planned single-layer layouts embedded in PDMS materials. Compared to the existing methods for manufacturing PDMS microfluidic channels with different geometries, the developed one-step approach can significantly simplify the process to fabricate channels with non-rectangular sections or various heights. Consequently, the technique is a way of constructing complex microfluidic channels, which provides a fabrication solution for the advancement of innovative microfluidic systems.

Control of femtosecond laser generated microfluidic channels inside poly(methyl methacrylate)

In this study, the authors report on femtosecond laser direct generation of microchannels inside poly(methyl methacrylate) with variable dimensions ranging from a channel height of 20 to 350 μm and an aspect ratio down to 1.2. Focused ultrashort laser pulses are used to trigger a material modification in the focal area which can be selectively opened by a subsequent annealing process. A 3D microchannel architecture can easily be realized by moving the specimen using motorized stages, allowing freely chosen complex shaped channel layouts. While the laser wavelength is identified as one of the main parameters determining process effectiveness, another core of this study is the variation of channel dimensions by the numerical aperture of the applied objective to focus the laser. The authors find that both size and shape of the modified region and the resulting microchannel can be controlled by altering the numerical aperture.

Strategy for multiscale numbering-up of microstructured catalytic reactors: A numerical study based on the resistance network model

Abstract This paper presents a numerical framework providing design candidates for optimal multiscale numbering-up of microstructured catalytic reactors. The framework allows to consider flow uniformity, pressure drop and compactness of the reactor system comprising over 104 catalytic reaction channels. Preliminary analysis indicates that an optimal multiscale numbering-up scheme requires a comprehensive evaluation of an entire multiscale flow network. To this end, we adopt a hierarchical resistance network model to complete, enumerated lists of multiscale channel layouts. This enables to choose the best layout taking account of multiple design elements. Our results with regard to up to 104 channels highlight the necessity and value of a suitable strategy that together optimizes the topology and geometry of the multiscale flow network. Appropriate enlargement of the hydraulic diameter of the catalytic reaction channels is suggested on one end, with demonstrated benefits in both flow uniformity and volume usage under the constraints of heterogeneous catalysis for a given production scale. On the other end, new criteria proposed make it possible to optimize the geometries of the multiscale distributors most effectively.

F88. Standardized naming convention for high density EEG

High density EEG (hdEEG) systems and Electrical Source Imaging (ESI) techniques have revolutionized our ability to assess the potential sources of epileptiform activity and other EEG features. HdEEG interpretation is limited by lack of standardized electrode position nomenclature and montages. Inefficient visual review of hdEEG remains a major barrier to incorporating these techniques into clinical care. The aim of this project is to propose an electrode map and nomenclature with digitized electrode locations for easy integration with neuroimaging studies and ESI. The 256 channel EEG net (Geodesic Sensor Net, Electrical Geodesics, Inc.) includes electrode locations approximating the International 10–20 and 10–10 systems, but intervening electrodes do not have a standardized location, and many electrodes over the cheeks and face do not have positions defined by the 10–10 or 10–5 systems. We co-registered average 256 channel EEG net electrode positions to the 10–10 positions based on the Montreal Neurologic Institute using Curry 7.0 software. then clustered the 256 electrode locations to their closest 10–10 electrodes tested several channel layouts (montages) allowing rapid transition from global views (all head regions) to focal views (subregions corresponding to 10–10 electrode coordinates). 256 electrode locations were successfully clustered around their closest 10–10 electrode, deemed its cardinal point. All 256 electrodes within a cluster received the same initial letters according to the 10–10 electrode at its center. Within a cluster, the first subscript identified its position either anterior (a) or posterior (p) to the cardinal 10–10 electrode. The second subscript identified its position either superior (s) or inferior (i) to the cardinal 10–10 electrode. The last subscript, numerical, identified the proximity of the nonstandard electrode relative to the cardinal 10–10 electrode, compared to the other nonstandard electrodes in that cluster. Therefore, the closest nonstandard electrode would have the subscript as 1, and each subscript would increase in numeric value as distance from the cardinal 10–10 electrode increases. Electrode position nomenclature which builds upon the international standard 10–10 system allows electroencephalographers to identify spatial areas of interest in hdEEG relative to positions in routine use. A standard viewing montage for hdEEG and its application with ESI both boosts efficiency when reviewing data, and also improves accuracy in recognizing epileptiform discharges. Furthermore, combining the montage with electrode geopositions will provide greater continuity and ease of use across analysis techniques that would potentially increase adoption of source analysis in clinical care. Our proposed system could also be expanded to higher numbers of electrodes or additional positions on the face or head and is not limited to a specific hdEEG system or electrode count.

Study on thermal management of rectangular Li-ion battery with serpentine-channel cold plate

In order to investigate a simple and efficient liquid cooling method for the rectangular Li-ion power batteries used in electric vehicles, the cold plate with serpentine-channel configuration shaped like U-tube is established. Subsequently, the effect of cooling channel number, the layout of channels and inlet temperature of coolant on cooling performance of battery thermal management system are analyzed. The numerical simulation results demonstrate that the layout of channels in length flowing-direction with 5-channels has the most efficient cooling performance. This design can reduce the maximum temperature by 26 °C compared with the 2-channels along width flowing direction. And the maximum temperature of cooling system rises with the increase of inlet temperature of the coolant. However, there exists an upper limit on the number of channels and the inlet temperature with the consideration of efficiency and safety of cooling system. The above results will be helpful to design cold plate for thermal management system of Li-ion power batteries.

Minimization of Warpage for Injection Molded Parts by Inverse Thermal Mold Design

Abstract For injection molding, a controlled heat removal is important to produce dimensional accurate parts efficiently. The following article introduces a new concept called inverse thermal mold design. Using this method, a proper cooling channel system for the injection mold can be produced to achieve minimal part warpage. Based on the postulate of a homogeneous material density distribution within the plastic part to achieve homogenous shrinkage, the method calculates the local cooling demand of the part to derive the cooling channel layout of the mold.

DIRECT METAL LASER SINTERING, USING CONFORMAL COOLING, FOR HIGH VOLUME PRODUCTION TOOLING

Existing techniques to manufacture conventional tool steel inserts for the plastic injection moulding process are expensive and time-consuming. Complex mould inserts, difficult to manufacture with conventional processes, can be produced using Direct Metal Laser Sintering (DMLS) with Maraging tool steel (MS1). MS1 is an additive manufacturing (AM) material made available by Electro Optical Systems (EOS) GmbH. Contrary to material removal processes, DMLS can produce MS1 tool steel inserts directly from Computer-Aided Design (CAD) files suitable for high volume plastic injection moulding. Through DMLS it is possible to create conformal cooling channels inside the MS1 inserts that have advantages in reducing heat rapidly and evenly. This can result in a reduction of cycle times, cost per product as well as improving part quality by eliminating defects such as warpage and heat sinks. This paper will present a comparison between Finite Element Analysis (FEA) simulations of the injection mould inserts with actual mould trails of AM and conventional manufactured inserts. It also includes the design and manufacturing of conventional and DMLS inserts and compares the manufacturing costs and lead times. Using FEA simulations, the design of conformal cooling channels is optimised by comparing the mould temperature of different cooling channel layouts.

Dynamic preservation of Texel Inlet, the Netherlands: understanding the interaction of an ebb-tidal delta with its adjacent coast

AbstractTidal inlets and the associated ebb-tidal deltas can significantly impact the coastal sediment budget due to their ability to store or release large quantities of sand. Nearly 300 million m3(mcm) of sediments were eroded from Texel Inlet's ebb-tidal delta and the adjacent coasts following the closure of the Zuiderzee in 1932. This erosion continues even today as a net loss of 77 mcm was observed between 1986 and 2015. To compensate, over 30 mcm of sand has been placed on the adjacent coastlines since 1990, making maintenance of these beaches the most intensive of the entire Dutch coastal system.Highly frequent and detailed observations of both the hydrodynamics and morphodynamics of Texel Inlet have resulted in a unique dataset of this largest inlet of the Wadden Sea, providing an opportunity to investigate inlet sediment dynamics under the influence of anthropogenic pressure. By linking detailed measurements of bathymetric change to direct observations of processes we were able to unravel the various components that have contributed to the supply of sediment to the basin, and develop a four-stage conceptual model describing the multi-decadal adaptation of the ebb-tidal delta.Prior to closure of the Zuiderzee a dynamic equilibrium state (stage 1) existed with a stable ebb-tidal delta. The largest morphological changes occurred in roughly the first 40 years since the closure, and were dominated by the rotation and scouring of large tidal channels and landward retreat of the Noorderhaaks ebb shoal (stage 2; adaptation). Between 1975 and 2001 the general layout of main channels and shoals was stable, but large sediment losses continued to occur (stage 3; equilibrium erosional state). Since 2001, the erosion rates have significantly reduced to 2 mcm a−1(stage 4; stabilisation).Twenty-five years of data on ‘Dynamic Preservation’ prove that sand nourishments are well capable of keeping the coastlines adjacent to the Texel Inlet in place. Moreover, the abundant supply of sediment may also have compensated for the sediment losses on the larger scale of the southern part of the ebb-tidal delta, resulting in a recent stabilisation of its volume. This response illustrates the potential benefits of Dynamic Preservation not only for coastline resilience but also on the larger scale of the inlet system. Such knowledge is essential for future preservation, management and maintenance of inlet systems in the scope of climate change and accelerated sea-level rise.

Investigation on the transferability of algorithms for the numerical optimization of cooling channel design in injection molding on metal gravity die casting

AbstractThe thermal mold design and the identification of a proper cooling channel design are primordial steps in the development of complex molds for injection molding. In order to find a suitable cooling channel system, a lot of effort is needed to avoid part warpage after solidification. In current research, a simulative procedure to optimize the cooling channel layout iteratively is being developed at the Institute of Plastics Processing. These algorithms are transferred to the metal gravity die casting process, which has several similar requirements to the mold. Effectively, the simulation is simplified to a heat conduction problem. Instead of water, high temperature resistant oil is deployed and the casted material is a A356 aluminum alloy instead of semi‐crystalline plastics. The algorithm is adapted to these changed boundary conditions and the calculation of the optimized heat distribution is performed. Aim of this procedure is the construction of a mold producing parts with less warpage than a conventional mold.

Femtosecond laser direct generation of 3D-microfluidic channels inside bulk PMMA.

We report on laser direct generation of 3D-microchannels for microfluidic applications inside PMMA bulk material by focused femtosecond pulses. Inner lying channels with cross sectional areas from 100 µm2 to 4400 µm2 are directly created in the volume of a PMMA substrate. Using the presented process, the channel length is fundamentally unlimited. Here we demonstrate a channel length of 6 meters inside a substrate with dimensions of 20 × 20 × 1.1 mm. The formation of the micro channels is based on nonlinear absorption around the focal volume that triggers a material modification. The modified volume can be selectively opened to form the channel by a subsequent annealing process. The cross section of the channel is strongly influenced by the energy distribution and illumination around the focal volume determined by the optical setup and process design. The 3D channel layout can easily be realized by moving the specimen using 3D motorized stage, allowing freely chosen complex shaped channel architectures. Within a comprehensive parameter study, varying laser power, number of multi-passes, writing speed and writing depths, we identify an optimized process in terms of attainable channel height, width and aspect ratio, as well as process stability and reproducibility. The proof of concept for an application in three dimensional microfluidic systems is provided by florescence microscopy using a dye rhodamine B solution in isopropanol.

Structural optimization of lithium-ion battery pack with forced air cooling system

The forced air cooling system is of great significance in the battery thermal management system because of its simple structure and low cost. The influences of three factors (the air-inlet angle, the air-outlet angle and the width of the air flow channel between battery cells) on the heat dissipation of a Lithium-ion battery pack are researched by experiments and computational fluid dynamics (CFD) simulations. Then the three structure parameters are optimized by using single factor analysis and orthogonal test method. It is shown that the layout of the air flow channels has great impacts on the maximum temperature and the temperature difference. The best cooling performance is obtained under the condition of 2.5° air-inlet angle, 2.5° air-outlet angle and equal channels width. With the optimization method, the maximum temperature and the temperature difference are decreased by 12.82% and 29.72% respectively. Therefore, the presented approach in this paper is able to optimize the battery thermal management system for electric vehicles.

Optimization Path of the Freight Channel of Heilongjiang Province to Russia

Heilongjiang Province becomes the most important province for China's import and export trade to Russia due to its unique geographical advantages and strong complementary between industry and product structure. However, the existing problems in the trade freight channel layout and traffic capacity restrict the bilateral trade scale expansion and trade efficiency improvement. Therefore, the government should engage in rational distribution of cross-border trade channel, strengthen infrastructure construction in the border port cities and node cities, and improve the software support and the quality of service on the basis of full communication and coordination with the relevant Russian government, which may contribute to upgrade bilateral economic and trade cooperation.

Generating optimal heat conduction paths based on bionic growth simulation

This paper proposes a novel topology optimization method for designing the best-possible heat conduction paths. The design idea is originated from the natural observation that plant roots or leaf veins care by self-adaptive growth to minimize the flow resistance through the whole networks. Based on the analogy between fluid flow and heat flow problems, the natural growth rule is systematically transformed into a mathematical model and written as an algorithm, where the high conductivity material is treated as being alive and the topology optimization process is viewed as plant morphogenesis process. Specifically, a new treatment called ‘conductivity spreading approach (CSA)’ is proposed to transform nodal temperatures of cooling channels into those of the background mesh, by which cooling channels can be separated from the underlying grid so that they can branch and extend freely along any direction. The growth method is used to construct the heat conduction paths for a fundamental ‘volume-to-point’ problem. Unlike other methods, layout solution produced by the suggested method is favorable to practical problems because it provides clear information about the location, orientation and dimensions of each cooling channel. In addition, the growth method requires little of human involvement and is easily delegated to computers, offering great advantage of automated design for large-scale cooling channel layouts in heat conduction systems.

Topological Network Analysis of Electroencephalographic Power Maps.

Meditation practice as a non-pharmacological intervention to provide health related benefits has generated much neuroscientific interest in its effects on brain activity. Electroencephalogram (EEG), an imaging modality known for its inexpensive procedure and excellent temporal resolution, is often utilized to investigate the neuroplastic effects of meditation under various experimental conditions. In these studies, EEG signals are routinely mapped on a topographic layout of channels to visualize variations in spectral powers within certain frequency ranges. Topological data analysis (TDA) of the topographic power maps modeled as graphs can provide different insight to EEG signals than standard statistical methods. A highly effective TDA technique is persistent homology, which reveals topological characteristics of a power map by tracking feature changes throughout a filtration process on the graph structure of the map. In this paper, we propose a novel inference procedure based on filtrations induced by sublevel sets of the power maps of high-density EEG signals. We apply the pipeline to simulated and real data, where we compare the persistent homological features of topographic maps of spectral powers in high-frequency bands of EEG signals recorded on long-term meditators and meditation-naive practitioners.

The effect of dilution on the dispersion with respect to microfluidic channel geometries

In most microfluidic devices, single or multiple dilutions of reagents are required to perform reactions or measurements over a range of concentrations using a set of sample solutions to fill the inlets. In this paper, we discuss the results of a study to understand the effects of different dilution schemes on the Taylor dispersion of sample plugs in microchannels. Taylor dispersion arises due to axial spreading of the solute plug due to variations of fluid velocity in the transverse direction. Dilution ratios (DR), channel dimensions, and channel layouts are varied. The results show that the one-sided dilution scheme provides a wider plug of 1.9%, 1.2% and 0.7% when DR=0.5, DR=0.25 and DR=0.1, than its two-side dilution counterpart, independent of dilution channel angle and shift. This deviation increases by increasing the Péclet number, where σ1ch2-σ2ch2∼Pe2. Moreover, we discussed the effects of the compression ratio of the plug, the width ratio between plug and dilution channel, the angle of the dilution channel, the staggered dilution channel, and the 3-dimensional case having different width to height ratios. The compression and width ratios change the final length of the plug dramatically, whereas the channel geometry, i.e. channel angle and shift variation do not. For the 3-dimensional extension, the converged Taylor dispersion values increase with decreasing aspect ratios. These physical understandings and findings for fundamental fluid flow are important for the design of microfluidic devices.

The effect of CESL and dummy poly gate for n-type MOSFETs with short Si0.75Ge0.25 channel

In this investigation, the n-channel metal–oxide–semiconductor file–effect transistor (MOSFET) with contact–etch–stop–layer (CESL) stressor, SiGe channel, and dummy poly gate is proposed. The simulated technique is utilized to explore the stress distribution of nMOSFET with the channel region induced by foregoing mechanical. We use ANSYS software, which is based on finite element analysis (FEA), to simulate the stress distribution in the channel region. The simulation results indicated the CESL and SiGe channel significantly affected the stress distribution within the channel region. The sources of loading are 1.1, 2, and 3 GPa tensile CESL (t-CESL) and a SiGe channel structure with 25% germanium (Ge) mole fraction. The effect of dummy poly gate is discussed, including the dummy poly gate number and various pitches of the dummy poly gate. The simulation results indicate that the pitch of the dummy poly gate substantially influences the number of dummy poly gates. The electron mobility enhancement in the inversion layer of n-channel MOSFET was discussed. Electron mobility enhancement was evaluated by piezoresistance coefficients. Hence, the percentages of improvement of electron mobility with different structural conditions were compared. The relationships between stress distribution in the channel and dummy poly gate layout could be understood clearly through systematic analysis.

SLM additive manufacture of H13 tool steel with conformal cooling and structural lattices

Purpose Additive manufacture (AM) such as selective laser melting (SLM) provides significant geometric design freedom in comparison with traditional manufacturing methods. Such freedom enables the construction of injection moulding tools with conformal cooling channels that optimize heat transfer while incorporating efficient internal lattice structures that can ground loads and provide thermal insulation. Despite the opportunities enabled by AM, there remain a number of design and processing uncertainties associated with the application of SLM to injection mould tool manufacture, in particular from H13/DIN 1.2344 steel as commonly used in injection moulds. This paper aims to address several associated uncertainties. Design/methodology/approach A number of physical and numerical experimental studies are conducted to quantify SLM-manufactured H13 material properties, part manufacturability and part characteristics. Findings Findings are presented which quantify the effect of SLM processing parameters on the density of H13 steel components; the manufacturability of standard and self-supporting conformal cooling channels, as well as structural lattices in H13; the surface roughness of SLM-manufactured cooling channels; the effect of cooling channel layout on the associated stress concentration factor and cooling uniformity; and the structural and thermal insulating properties of a number of structural lattices. Originality/value The contributions of this work with regards to SLM manufacture of H13 of injection mould tooling can be applied in the design of conformal cooling channels and lattice structures for increased thermal performance.

Numerical simulation and experimental verification of heating performance of an integrally water-heated tool

Design and manufacturing of composite tooling are crucial in producing cost effective composite components with high quality. Aimed at identifying the optimal design of integrally heated tools in terms of their thermal performance, a number of design variables were investigated numerically in a previous study. Statistical analysis of the simulation results revealed that a parallel layout of heating channels can significantly improve the heating performance, and channel separation should be determined according to the production requirement. In the present work, an integrally water-heated tool is manufactured according to the optimal design after some geometry amendments. Thermal properties of the constituent materials of the produced tool are also measured. A numerical model of the tool geometry is simulated with actual material properties and boundary conditions to calculate the response variables of temperature uniformity and heating rate. The numerical results are verified by experimental testing, using a thermal camera and thermocouples. Good agreement between the simulation and the experimental results confirmed the suitability of numerical simulation in predicting the thermal performance of integrally heated tooling and the validity of the boundary conditions.