Inlet Hole Research Articles

Experimental, modeling, and numerical simulation of ultrasonic assisted drilling of CFRP/Ti stacks

Carbon fiber reinforced polymer (CFRP) and Ti-6Al-4V alloy (Ti) stacks structures are increasingly utilized in aircraft load-bearing applications, where the quality of hole processing significantly impacts their connection performance. Conventional drilling (CD) methods for CFRP/Ti stacks often encounter challenges such as severe interface damage, high cutting forces, and excessive heat generation. This study investigates the application of ultrasonic-assisted drilling (UAD) on CFRP/Ti stacks by integrating finite element method (FEM) modeling with experimental approaches to analyze the machinability of these materials under different machining methods and parameters. A self-developed high-frequency vibration spindle was employed to process CFRP/Ti stacks using both CD and UAD techniques. The newly developed numerical model effectively elucidates the mechanical and thermal coupling involved in the machining process and the transfer behavior of temperature and stress at the laminate interface. The experimental results of cutting force, hole inlet and outlet surface morphology, inner wall condition, chips, tool wear, etc. under different machining parameters were studied and analyzed. To ensure the reliability of our findings, experimental data were validated against simulation results. The findings reveal that UAD, when optimal separation conditions are achieved, significantly reduces cutting forces and enhances the surface morphology of both the inner and outer hole surfaces. Specifically, UAD lowers cutting forces by 27.2 % and the damage coefficient (Fd) by 15.7 % compared to CD. Furthermore, the high-frequency vibration generated by UAD markedly extends tool life. The specially designed high-frequency vibration spindle successfully meets drilling requirements, thereby significantly improving the machining performance of CFRP/Ti stacks materials, and it provides a certain reference for practical industrial applications.

Investigation on the thermal activation of peroxydisulfate by using the hydrodynamic cavitation: A case study on tetracycline degradation

The synergetic technology of hydrodynamic cavitation (HC) and peroxydisulfate (PDS) has been adopted for the treatment of organic pollutants, while the rationale behind the thermal-activation of PDS in this process remains lacking. This paper presented investigation on the degradation of tetracycline under two types of operating conditions, including “internal reaction conditions” (pH value and TC/PDS molar ratio) and “external physical conditions” (hole shape, solution temperature and inlet pressure). Special emphasis was paid on the analysis of thermal effects through a robust modeling approach. The results showed that a synergy index of 6.26 and a degradation rate of 56.71 % could be obtained by the HC-PDS process, respectively, when the reaction conditions were optimized. Quenching experiment revealed that •OH and •SO4- were the predominant free radicals and their contribution to the degradation was 75.4 % and 24.6 % respectively, since a part of •SO4- was transformed into •OH in the solution. The thermal activation of PDS mainly occurred near the hole where the fitting temperature was around 340 K, while •OH was generated in the bubble collapse region downstream the hole, where the temperature was much higher and favorable for the cleavage of water molecular. The average temperature under different external physical conditions was in good consistence with the degradation rates. This research developed a useful method to effectively evaluate the activation extent of PDS by HC and could provide reliable guidance for further development of cavitational reactors to treat organic pollutants based on this hybrid approach.

Study on lubrication characteristics of multi-layer structure hinge under the influence of clearance dynamic

This paper presents a methodology for investigating the lubrication characteristics of multi-layer structural mechanical hinges based on clearance dynamics. By multi-layer hinged structures, we mean the four mediums: the journal, lubricating oil film, bearing sleeve, and connecting rod. Initially, a dynamic model that incorporates clearance is established using the automatic dynamic analysis of mechanical systems, revealing that the primary contact area is located between 50° and 70°. Subsequently, a lubrication model for the multi-layer structural mechanical hinge is constructed using ANSYS FLUENT software, which demonstrates the effects of critical parameters—such as contact angle, sleeve installation angle, inlet pressure, and shaft neck speed—on lubricant flow, pressure, and void fraction. The findings indicate that the motion offset angle significantly influences the pressure distribution within the oil film area, with high-pressure and low-pressure zones oriented counterclockwise and clockwise, respectively, relative to the offset angle axis. Furthermore, as the distance between the offset angle and the oil inlet increases, the volume fraction of cavitation decreases from 1.77% to 1.16%. When the sleeve installation angle aligns with the motion offset, the volume fraction of cavitation reaches 1.9%. Conversely, when the assembly angle aligns the oil inlet hole with the injection hole, the volume fraction of cavitation is minimized to 0.36%, resulting in an approximate performance improvement of 81.11%. This study provides a theoretical foundation for optimizing the lubrication design of multi-layer structural mechanical hinges and offers substantial guidance for the lubrication of mechanical hinges.

Investigation of the enhanced cavitation model considering turbulence effects of fuel flow in the injector nozzle holes

The cavitation model is essential in simulating cavitation flow characteristics of injector nozzles, with its accuracy directly impacting simulation precision. This paper developed a quantitative relationship between critical cavitation pressure, turbulent kinetic energy, and shear stress, and introduced a modified cavitation model that considers turbulence effects. A simulation study was conducted on the fuel flow characteristics inside the nozzle of a high-pressure common rail diesel injector with seven nozzle holes. The results indicate that compared to the original model, the cavitation development calculated by the modified model is enhanced at different injection pressures. In terms of axial distribution, cavitation inside the nozzle hole increases, but the impact on cavitation of different intensities varies, with the development of moderate to low-intensity cavitation being promoted, while strong cavitation is inhibited. In terms of radial distribution, the intensity of cavitation on the upper wall inside the nozzle hole increases, which is caused by the higher mass transfer rate near the upper wall at the nozzle hole inlet. As the injection pressure increases from 120 to 240 MPa, the change rate of cavitation volume ratio inside the nozzle holes calculated by the original and modified models increases from 5.1% to 9.7%. It is necessary to use the modified model for the calculations of gas/liquid two-phase flow within the nozzle hole, especially at high injection pressure.

Functional failure analysis of the graphite crystallizer used in horizontal continuous casting process of copper tube

The presence of a particular type of white powder has emerged as a significant challenge in the horizontal continuous casting process of copper. This white powder leads to the blockage of the graphite crystallizer, resulting in a functional failure that adversely affects the mold’s lifespan, increases production costs, and reduces overall efficiency. The issue has posed significant challenges for engineers due to its complex and unclear formation mechanism. This investigation employed various experimental characterization methods to analyze the composition, element distribution, phase properties, and other relevant factors of the white powder. Meanwhile, a high-temperature experiment was also designed to examine the potential reactions between copper oxide (Cu2O) and the furnace lining (3Al2O3·2SiO2). It is found that the main component of the white powder blocking the inlet hole of the graphite mold is SiO2, which is traced back to the furnace lining. Under high temperatures, oxygen reacts with liquid copper to form Cu2O. Subsequently, this Cu2O reacts with Al2O3 in the furnace lining to produce CuAlO2. Meanwhile, SiO2 becomes isolated as Al2O3 is deprived. The resultant SiO2 accumulates at the inlet hole of the graphite mold due to rapid cooling. The accumulated SiO2 in the form of white powder blocks the inlet hole of the graphite mold, leading to functional failure of the graphite mold. To address this issue, several improvement measures are proposed including drying the raw and protective material, enhancing the sealing of the furnace, and reducing the holding time.

Growth chamber gas dynamics in Cz silicon single crystal growth process

Mathematical simulation results for inert gas (argon) dynamics in the rarefied atmosphere of Redmet-10 Cz single crystal silicon growth furnace chamber have been reported. Gas flows in cold (room temperature) and hot (growth process) chambers have been analyzed. Convective gas flows have been considered for two growth chamber gas supply options: basic supply, i.e., through the top central inlet hole only, and combined, i.e., with additional gas supply through the lateral inlet hole. Gas outlet is through the growth chamber bottom outlet hole for both options. For the cold chamber option, forced convection has been studied using the incompressible ideal gas model. For hot chamber, both the nonisothermal compressible ideal gas model and the weakly compressible gas model in the Boussinesq approximation have been used for studying the vortex structure produced by a joint action of forced and thermal-gravitational convection. The effect of different gas inlet methods on the convective transport of silicon monoxide evaporating from the free melt surface has been discussed.

Drawing of fibres composed of shear-thinning or shear-thickening fluid with internal holes

We explore the drawing of a shear-thinning or shear-thickening thread with an axisymmetric hole that evolves due to axial drawing, inertia and surface tension effects. The stress is assumed to be proportional to the shear rate raised to the $n$ th power. The presence of non-Newtonian rheology and surface tension forces acting on the hole introduces radial pressure gradients that make the derivation of long-wavelength equations significantly more challenging than either a Newtonian thread with a hole or shear-thinning and shear-thickening threads without a hole. In the case of weak surface tension, we determine the steady-state profiles. Our results show that for negligible inertia the hole size at the exit becomes smaller as $n$ is decreased (i.e. strong shear-thinning effects) above a critical draw ratio, but surprisingly the opposite is true below this critical draw ratio. We determine an accurate estimate of the critical draw ratio and also discuss how inertia affects this process. We further show that the dynamics of hole closure is dominated by a different limit, and we determine the asymptotic forms of the hole closure process for shear-thinning and shear-thickening fluids with inertia. A linear instability analysis is conducted to predict the onset of draw resonance. We show that increased shear thinning, surface tension and inlet hole size all act to destabilise the flow. We also show that increasing shear-thinning effects reduce the critical Reynolds number required for unconditional stability. Our study provides valuable insights into the drawing process and its dependence on the physical effects.

Effects of inlet air holes on swirl flow characteristics and outlet temperature distribution in an axial swirl combustor

The air inlet holes on the swirl combustor are crucial for high-performance micro gas turbine (MGT), affecting internal airflow, fuel-air mixing, temperature distribution, and cooling. However, there are seldom studies that pay attention to the influence of the air inlet holes coupled with low volatility macromolecular fuels for fast and better fuel-air mixing and combustion processes in MGT. This study investigates the influence of primary and dilution hole positions on airflow, temperature, emissions, and combustion efficiency. Numerical simulations in ANSYS Fluent examine five inlet hole configurations in a two-stage axial swirl combustor. Simulation validation is conducted under three test conditions. The results showed that the cut-off effect of the primary hole affected the size of the swirl vortex core, and the backward movement of the primary hole resulted in a significant increase in the length of the recirculation zone and the coherence high-temperature zone, accelerated the droplet evaporation rate, and reduced CO and NO emissions. Backward movement of dilution hole alters flow field, affecting swirl vortex stability and reflow intensity. Case 3, with original dilution hole and backward extended primary hole, exhibits optimal outlet temperature distribution and combustion efficiency.

Fabrication of organic thin films using slit nozzle with a wide viscosity spectrum

A slit nozzle with a broad viscosity spectrum is highly demanded for slit coating of various materials with different viscosities without a compromise on the film quality. To this end, we have fabricated a multi-cavity slit nozzle with the inlet and vent holes for each cavity. Compared with a slit nozzle with a high-volume single cavity, such a multi-cavity slit nozzle further reduces the dead volume and thus material waste. As a design parameter in computational fluid dynamics (CFD) simulations for the multi-cavity slit nozzles, we have calculated the coefficient of variation in the internal pressure (Pcv) of the cavity and investigated the correlation between the simulated Pcv value and the measured thickness uniformity of low-viscosity (tens of cPs) poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), medium-viscosity (5000 cPs) polydimethylsiloxane (PDMS), and high-viscosity (18,000 cPs) hard-PDMS films. It is addressed that the Pcv value that can ensure the thickness non-uniformity of less than 5 % is of the order of 1 %, and the internal pressure of the nozzle should not exceed a specific upper limit to protect a coating system against overload. Based on the design guideline provided, we have found that the upper limit of the viscosity spectrum of the triple-cavity slit nozzle with the 800-μm-thick shim is 79,000 cPs when the flow rate is 50 ml/min. Using the multi-cavity slit nozzle, we have fabricated a highly uniform PDMS film exhibiting the tensile strain as high as 180 %, which can be used as a substrate for stretchable displays. Furthermore, we have successfully fabricated flexible OLED stripes on the slit-coated conductive PEDOT:PSS stripes, showing the average luminance of 72.8 cd/m2 at 5 V and inter-stripe luminance non-uniformity as low as 8.2 %.

Enhancing the aerodynamic performance of large-span roof using a ‘breathable’ optimization tube: A parametric study

In wind engineering community, large-span roofs are widely acknowledged to be wind-sensitive, and oftentimes aerodynamic optimization is needed to enhance its wind-resistance. For such purpose, we proposed a “breathable” aerodynamic optimization tube in this study, the performance of which was experimentally examined via a series of wind tunnel tests. The results showed that, the proposed aerodynamic optimization tube is capable to significantly reducing the wind loads on the large-span roof, the effectiveness of which varies with different tube parameters. On this account, the effect of six key parameters, namely section shape, inlet-outlet angle, hole size, in-out ratio, hole distance and inlet hole length were examined independently. Overall, the outcomes are expected to provide important implications regarding the wind-resistance design of large-span roof structures.

A Visual Measurement Method for Deep Holes in Composite Material Aerospace Components.

The visual measurement of deep holes in composite material workpieces constitutes a critical step in the robotic assembly of aerospace components. The positioning accuracy of assembly holes significantly impacts the assembly quality of components. However, the complex texture of the composite material surface and mutual interference between the imaging of the inlet and outlet edges of deep holes significantly challenge hole detection. A visual measurement method for deep holes in composite materials based on the radial penalty Laplacian operator is proposed to address the issues by suppressing visual noise and enhancing the features of hole edges. Coupled with a novel inflection-point-removal algorithm, this approach enables the accurate detection of holes with a diameter of 10 mm and a depth of 50 mm in composite material components, achieving a measurement precision of 0.03 mm.

Evaluation of gunshot injuries to long bones from pneumatic weapons using a human thigh model. Part II. Presentation and discussion of the detailed results of tests of gunshots of the anterior surface of the femur with 5.5 mm and 6.35 mm caliber shot.

The development of pneumatic shooting has led to the construction of technologically advanced devices with discharge energies similar to those of firearms. The pneumatic weapons ammunition market offers a variety of shot which varies in penetration properties and the extent of gunshot damage. In view of the ease of "tuning" of air rifles, a study was conducted of the inlet damage to the anterior femoral surface after pneumatic gunshots. The paper shows the differences in damage parameters depending on the type of shot. In the study, Air Arms Hi-Power Xtra FAC cal. 5.5 mm and FX Bobcat Mk II cal. 6.35 mm pneumatic carbines were used and lead shot by Haendler&Natterman's Spitzkugel type, Hollow Point and Baracuda cal. 5.5 mm and 6.35 mm, as well as lead-free shot Excite Apollo cal. 5.5 mm and Black Max Lead-Free cal. 6.35 mm. Measurements were taken of the extent of inlet damage to the anterior surface of the femoral shaft with X-ray and CT imaging. HollowPoint shot caused the greatest range of gunshot penetration damage in both bone and periosteum, Apollo lead-free shot caused the least. At the same time, HollowPoint shot showed the greatest susceptibility to ricocheting. 1. The type of shot used influences diversified morphology of the holes and the nature of gunshot damage to the femoral shaft. The differences concern both the gunshot holes and the nature, course and extent of associated fractures. 2. The smallest inlet holes and damage to the periosteum with a regular shape are caused by gunshots with pointed and pointed tip pellets. The greatest extent of bone and periosteum inlet damage was observed in gunshots with Hollow Point type shot due to its predisposition to deformation and fragmentation. 3. Radio-imaging studies are a valuable complement to macroscopic visual assessment providing a useful value for identifying the type of shot used.

МОДЕЛЮВАННЯ ПРОЦЕСУ ЗАПОВНЕННЯ В’ЯЗКОЮ РІДИНОЮ ПОРОЖНИНИ ПРЕС-ФОРМИ ДЛЯ ЛИТТЯ ДЕТАЛЕЙ ВЗУТТЯ

The article considers the determination of the optimal structural and technological parameters of injection molding, which are necessary to simulate the process of filling the mold cavity with a viscous liquid, which involves the construction of a numerical model of the flow of a viscous liquid in the mold cavity. The simulated process of the movement of a viscous liquid in the mold cavity using the finite element method. The implementation of the finite element method in the presented form leads to a symmetrical system of linear algebraic equations relative to the unknown nodal values of the velocity and pressure vector components. The use of the Moldex3D software complex made it possible to visualize the process of filling the cavity of the mold during the manufacture of the sole. The complex includes tools that provide automatic discretization of the initial area into triangular elements, formation of the matrix of finite elements taking into account the boundary conditions and solving the system of linear equations. By varying the location of the inlets and their diameters (that is, the initial values of the melt velocities in each inlet), it is possible to achieve the optimal location of the joining lines (places where the polymer solution flows are welded). Thus, simulating the process of filling the mold cavity with PVC material through the four inlet holes, it is possible to observe the process of formation of joints. The proposed mathematical model of the flow of a viscous liquid in the cavity of the mold and the method of its implementation using the Moldex3D software complex will allow determining the optimal design of the molds and the technological modes of the process of filling them with polymer material.

Gear-Shaped High-g Combustion Chamber for Micro Turbojet Engine Applications.

Enhancing combustion efficiency and optimizing the thrust-to-weight ratio are critical technical challenges encountered in the development, application, and growth of micro turbojet engines. The high-centrifugal (high-g) combustion chamber, as an innovative combustion chamber system, has the capability to replace the primary combustion chamber of the traditional turbojet engine, reducing the length of the combustion chamber while maintaining engine performance. Previous studies on the structure of the high-g combustor (HGC) have shown problems such as uneven temperature distribution of the turbojet rotor. To improve the feasibility of HGC integration into micro turbojet engines, this study conducts relevant experiments on a 120 N thrust engine. Subsequently, the results of these experiments were used to analyze the structural design of HGC through a simulation approach. Including six main configurations, the first four structural designs focused on establishing a suitable highly centrifugal environment to stabilize and improve the combustion performance, which was successfully achieved by designing the outer ring gear-shaped inlet with four different angles. Subsequent structural designs were based around improving the uniformity of the temperature distribution at the combustion chamber outlet. The final design of the HGC combustion efficiency is not much different from the original combustion chamber, and it can shorten the axial length of the combustion chamber by nearly 30%. The design of the air inlet holes and the baffle plate effectively improves the temperature uniformity at the outlet of the combustion chamber. Moreover, without changing the combustion chamber material, the corresponding engine weight can be reduced by about 10.7%, and the engine thrust-to-weight ratio can be improved by up to 12% with the same thrust, which provides design ideas for further lightweight applications.

Grinding Force Model and Experimental Study on Ultrasonic Assisted Spiral Grinding of Silicon Carbide Ceramic Materials

In order to reveal the mechanical properties of silicon carbide ceramic materials during the drilling process, based on the indentation fracture mechanics theory, a grinding force model of ultrasonic assisted spiral grinding for hole making was established, and the experimental results of ultrasonic assisted spiral grinding for hole making verified the mechanical model. The results showed that the experimental results had the same change trend as the predicted results of the established mechanical model, and the values were close to each other, indicating the accuracy of the established prediction model. The influence of different process parameters on the size accuracy of the hole inlet and outlet aperture after machining is analyzed. It is found that it should be selected as large rotation speed, moderate axial feed speed and small feed pitch to ensure the accuracy of the aperture and effectively suppress the aperture defects during ultrasonic assisted spiral grinding.

Hydrophobic barrier-free laminated paper-based analytical device (LPAD) using a diameter-based measurement for determination of iodide in pharmaceutical products

This work presents, for the first time, an exploitation of an argentometric Mohr's method for iodide detection using diameter-based measurement on laminated paper-based analytical device (LPAD). Our LPAD is simplified fabricated with no required hydrophobic barrier for patterning a detection flow channel. In the absence of a flow channel, the liquid is imbibed radially into the filter paper outward from the small center inlet hole. This imbibition leads to the measurement of diameter after the formation of the precipitation product. For LPAD, a rectangular piece of Whatman filter paper is cut and positioned between a top laminating sheet, which has a hole punched for inlet, and a bottom laminating sheet. The central inlet hole enables access to the liquid on the paper. For iodide analysis, silver nitrate is dispensed first, followed by the iodide standard/sample. This process leads to the formation of pale-yellow silver iodide solids on the paper. The chromate indicator solution is subsequently loaded to the paper. The color of the chromate solution imparts a tint to the circular band of silver iodide solids, resulting in an intense yellow color. When the silver iodide precipitates are stained, the chromate solution typically serves as an indicator, chemically reacting to an excess silver nitrate solution moistened on paper. This reaction generates an outer reddish-brown ring of silver chromate. The distinct color contrast between the intense yellow (tinted silver iodide) and reddish-brown (silver chromate) allows for clear observation of the measurement boundary, facilitating diameter-based measurements of the circular band of silver iodide. We demonstrate the applicability in analysis of pharmaceutical KI tablets. The quantitative results obtained from diameter-based measurement LPAD show good agreement with those obtained from the potentiometric method. Our hydrophobic barrier-free LPAD is rapid, cost-effective, low liquid consumption and applicable for onsite analysis.

A novel numerical modeling of microsecond laser beam percussion micro-drilling of Hastelloy X: experimental validation and multi-objective optimization

The paper investigates the characteristics of the laser beam percussion micro-drilling (LBPMD) process in aerospace nickel-based superalloy Hastelloy X using microsecond pulses. The quality of the drilled hole is crucial in laser beam micromachining, and selecting appropriate process parameters significantly impacts the hole’s quality. The objective is to achieve predefined hole dimensions with minimal taper angles. Additionally, the study focuses on the alteration of pulse width, which is a combination of laser pulse frequency and duty cycle. Laser power (P), duty cycle % (D), focal plane position (FPP), and laser frequency (f) are considered input parameters, while geometric features such as inlet and outlet diameters, hole taper angle, and inlet circularity are examined as process responses. ANOVA is employed to establish significant relationships between process parameters and response variations based on experimental tests. Creating a precise simulation model that accurately accounts for the moving boundary of the target material’s receding surface is a crucial and challenging task in formulating the laser heat conduction problem. It is necessary to simultaneously capture the material’s dynamic front movement and update the boundary conditions of the laser source. To model the micro-drilled hole with LBPMD, the UMESHMOTION and DFLUX subroutines, along with the arbitrary Lagrangian-Eulerian (ALE) adaptive remesh algorithm in the Abaqus™ software, are utilized. Notably, no previous numerical study has predicted the geometry of micro-drilled holes using this technique. The proposed procedure is validated through the predictions of inlet and outlet hole diameters. Special emphasis is placed on the validation of models. Consequently, the numerical model and statistical model are compared as well as the need to define model applicability. The study demonstrates that all input parameters significantly influence the inlet hole diameter, while the pulse width notably affects the taper angle and circularity. The interaction between high laser frequency and low duty cycle results in reduced pulse duration. Multi-objective optimization is performed to determine the optimal process parameter settings for desired quality characteristics, considering minimum hole taper angle, precise inlet diameter, and maximum inlet circularity of the hole as optimization criteria. The findings show that with the optimized predicted results obtained from the optimal input variables, a composite desirability of 92% can be achieved.

Resistance bias estimation of a liquid column in a cylindrical conductivity cell with lateral liquid supply

The article shows a physical model of a cylindrical two-electrode conductivity cell with inlet and outlet holes for filling located perpendicular to the cell axis. Based on the finite element method (FEM), the non-uniformity of the current density distribution inside the cell was determined. For a range of geometrical parameters of the cell, the resistance biases of the liquid column with respect to the idealized model—a cell with a uniform current density distribution (without holes) are calculated. A mathematical expression is given that describes calculating the electrolytic conductivity value using the geometrical parameters of a conductivity cell, taking into account the field distortion caused by holes for filling. It has also been found that at the ratio of the cell diameter to the hole diameter D/d ≥ 5, the entire field distortion inside the cell is provided by a liquid column in the holes with a length of only (h ≤ d) mm. Theoretical estimates and mathematical models covered in this article were used to create the primary differential conductivity cell. Structurally, such a cell consists of two tubes of the same diameter but of different lengths, at the edges of which platinized electrodes are placed.

Evaluation Method and Analysis on Performance of Diffuser in Heat Storage Tank

The diffuser is a critical component in a heat storage tank, and its structure has an important influence on the thermal performance of the heat storage tank. At present, research on the structure of diffusers often focuses on the change of one single parameter, which results in the need for a comprehensive structure analysis of diffusers in heat storage tanks. This paper comprehensively considers the inlet diameter, hole distance, and hole diameter of the diffuser and the inlet conditions of the heat storage tank. Then, a new evaluation index, namely the non-uniformity coefficient of the diffuser, is proposed. The experiments verify the accuracy of numerical calculation, and the related empirical formula is summarized finally. The results show that the diffuser with a small non-uniformity coefficient can achieve thin temperature stratification and higher exergy efficiency. In other words, the non-uniformity coefficient is in good agreement with temperature stratification and the exergy efficiency of the heat storage tank. When the flow rate of the inlet device is 0.5 m/s, the exergy efficiency increases by nearly 30 percentage points and the non-uniformity coefficient of the No. 4 diffuser is 3.39%. In contrast, that of the No. 8 diffuser is 75.17%. This evaluation index is suitable for different diffuser types with high accuracy. It provides the theoretical and experimental basis for the structural design and selection of diffusers for heat storage tanks.

Simultaneous detection of multiple spoilage bacteria using a fluorogenic loop-mediated isothermal amplification-based multi-sample microfluidic chip

Spoilage bacteria, which ubiquitously contribute to food spoilage, pose a global public health risk. In this study, we developed a centrifugal microfluidic chip integrating fluorogenic loop-mediated isothermal amplification (LAMP) to detect six important spoilage bacteria: Bacillus cereus, Clostridium botulinum, Photobacterium phosphoreum, Pseudomonas putida, Streptococcus agalactiae, and Shewanella putrefaciens. The LAMP reaction components were pre-mixed (primers pre-embedded in each reaction chamber of the chip) and evenly pipetted into the two inlet holes, enabling the simultaneous analysis of six genetic targets from a single sample. This facilitates the automated detection of up to four samples simultaneously using a single chip. The LAMP reactions were conducted in a 5-μL volume at 65 °C for 60 min, achieving limits of detection ranging from 10−1 to 10−2 pg/μL of bacterial genomic DNA. Almost all coefficients of variation for time-to-positive values consistently remained under 10% when genomic DNA was used at concentrations within the limits of detection for the six bacteria. This demonstrated excellent reproducibility across replicates. The clinical sensitivity and specificity for field sample detection were 93.3% and 97.5%, respectively. This method offers ease of operation, rapid analysis, and minimal reagent usage and has great potential for the on-site detection of multiple spoilage bacteria.