Perforated Tube Research Articles

A modular, human body-mimicking phantom with active thermoregulation capabilities for validation and verification of convective hyperthermia devices

Objectives This study aims to design and fabricate a modular phantom for hyperthermia applications, addressing interpatient variability in thermal regulation mechanisms like sweating rate, metabolic heat production, and blood redistribution. Materials & methods The phantom can be constructed in various weights and dimensions by connecting identical units. Each unit consists of an agar-based block, an ethyl cellulose-based top layer, a heat source, deep and superficial water circulation, and a sweating mechanism. Agar and ethyl cellulose gels mimic the thermal properties of human tissues and fat respectively. The blocks are wrapped in PVC foil to prevent water evaporation. A heating wire, coiled around an embedded aluminum tubing simulates metabolic heat production. A superficial water circulation mimics skin capillaries. A water pump ensures a steady flow rate throughout the tubing system. Sweat production is simulated using a water pump and perforated tubing. A programmed controller maintains core temperature in a normal operating mode and simulates an anesthetized patient in anesthesia mode. Results Temperature uniformity and regulation were assessed under varying environmental conditions. The phantom effectively regulated its core temperature at 37.0 °C +/- 0.7 °C with an ambient temperature ranging between 21 °C and 30 °C. Activating the water circulation reduced the maximum temperature gradient within the phantom from 4.70 °C to 1.92 °C. Conclusion The versatile phantom successfully models heat exchange processes. Its thermal properties, dimensions, and heat exchange rates can be tuned to mimic different patient models. These are promising results as an effective tool for hyperthermia device validation and verification, representing human physiological responses.

Structural Performance Analysis and Optimization of Small Diesel Engine Exhaust Muffler

In recent years, the optimization of diesel engine exhaust mufflers has predominantly targeted acoustic performance, while the impact on engine power performance has often been overlooked. Therefore, this paper proposes a parallel perforated tube expansion muffler and conducts a numerical analysis of its acoustic and aerodynamic performance using the finite element method. Then, a Kriging model is established based on the Design of Experiments to reveal the impact of different parameter couplings on muffler performance. With transmission loss (TL) and pressure loss (PL) as the optimization objectives, a multi-objective optimization study is carried out using the competitive multi-objective particle swarm optimization (CMOPSO). The optimization results indicate that this method can simplify the optimization model and improve optimization efficiency. After CMOPSO calculation, the average TL of the muffler increased from 27.3 dB to 31.6 dB, and the PL decreased from 1087 Pa to 953 Pa, which reduced the exhaust noise and improved the fuel economy of the engine, thus enhancing the overall performance of the muffler. This work provides a reference and guidance for the optimal design of mufflers for small agricultural diesel engines.

Experimental investigation on axial quasi-static compression and low-velocity impact behaviors of perforated thermoplastic composite cylindrical shells

Perforation in cylindrical shells is commonly a typical technique to fulfill relevant functional requirements. However, how the perforation influence the mechanical performance of thermoplastic composite cylindrical shells (TPCCS) is incompletely understood. Hence, a systematic investigation through quasi-static compression and low-velocity impact (LVI) experiments was carried out in this paper. The full-field strain distributions of TPCCS intact tubes (IT) and perforated tubes (PT) were monitored by using 3D-DIC, and the residual properties were also characterized by compression-after-impact (CAI) tests. The results show that under quasi-static compression, the structural stiffness decreases significantly with increasing perforation diameter. The perforation reduces the interference of internal random defects on the structural deformation mode, which leads to a significant strain concentration in PT. The peak force and initial stiffness under LVI are smaller than those under quasi-static compression, with IT displaying higher sensitivity to dynamic loading compared to PT. At the impact energy of 100 J, IT and PT exhibit “S”- and “X”-shaped deformation modes, respectively. CAI tests indicate that although PT has a poorer residual load-carrying capacity than IT, it retains good structural integrity and secondary energy absorption capacity. This study provides a valuable reference for the assessment and application of perforated TPCCS.

Prediction and analysis for airflow generated noise inside mufflers based on large eddy simulation and Morhing acoustic analogy

The airflow generated noise inside a simple expansion chamber muffler is predicted by combining large eddy simulation and Morhing acoustic analogy in the present work, and a good agreement is observed between the prediction and measurement. Research indicates that wall pressure fluctuations are dominated by hydrodynamic pressure fluctuations at the distance of first three pipe diameters in the outlet pipe, and wall pressure fluctuations at the distance of six pipe diameters downstream are dominated by sound pressure fluctuations. The airflow generated noise is mainly attributed to the vortex generated by structural change in the muffler, and one observes strong influences at the longitudinal resonance frequency and antiresonance frequency of the expansion chamber. In addition, the effects of expansion chamber lengths, extensions of inlet/outlet, filleted structure, conical tube, and perforated tube on airflow generated noise are studied. Predicted results show that the filleted structure, conical tube, and perforated tube structure may reduce the airflow generated noise effectively.

Numerical simulation of flow distribution characteristics in carbon dioxide microchannel evaporator

Microchannel heat exchangers find widespread use in household and automotive air conditioning due to their compact structure and high efficiency. However, two-phase refrigerant flow mal-distribution in microchannels limits their application. For the CO2 heat pump, the performance reduction by flow mal-distribution could be as large as 20%. This study proposed an approach to mitigate flow mal-distribution by inserting a perforated tube into the header of a microchannel evaporator in CO2 heat pump. Numerical simulations were carried out to investigate the impact of perforated tube parameters and CO2 inlet conditions on flow distribution. Results show a 24.4% increase in total non-uniformity (S) of flow distribution with a perforated tube. A higher number of openings and smaller diameters enhance uniformity, with the 10-hole, 2 mm diameter perforated tube proving most effective. Additionally, the most uniform flow distribution was achieved at an inlet CO2 mass flow rate of 30 g/s and a vapor quality of 0.2. And the flat tubes with an insertion depth of 5 mm and a cross-section of 16 × 2 mm is the most beneficial for uniform flow distribution.

Nonlinear Acoustic Behavior Prediction and Analysis of Straight Through Perforated Tube Silencer With Flow

Straight through perforated tube silencers are widely used in intake and exhaust noise control, and their acoustic behaviors are influenced by the gas flow and high amplitude sound remarkably. To investigate the acoustic attenuation performance of straight through perforated tube silencers in the presence of flow and high amplitude sound, an approach based on the three-dimensional (3D) time-domain computational fluid dynamics (CFD) simulation is employed and validated by comparing predictions and measurements. Transmission loss of the straight through perforated tube silencer under pure tone and multi-tone sound excitations is predicted. Results show that, under the pure tone sound excitations, the acoustic attenuations are affected remarkably by the high amplitude sound, and the nonlinear effects turn to weaken as flow velocity increases. With the sound pressure level (SPL) decreasing along the axis of the silencer, the acoustic nonlinearity in the orifice weakens gradually. The shedding vortices are restricted to the region near perforations because of the transport of flow. When the multi-tone sound excitation is enforced on the inlet, transmission loss of the silencer is different from the pure tone excitation at the same SPL of every compositional frequency.

Experimental Assessment of PV Panels Front Water Cooling Strategy

The electrical performance and reliability of flat type photovoltaic (PV) modules can be severely affected by elevated cell operating temperature due to elevated ambient temperatures. In this work the free flow front water cooling solutions to enhance flat-type PV module electrical performance is experimentally explored on laboratory scale module operated outdoors under natural light luminance. Water-cooling is implemented using a perforated tube disposed on the top of the panel and a chilled water source, both attached to the module active surface. The cooling water directly wets the module active surface, thereby decreasing the light reflection loss and cleaning the panel surface in the same time. For given meteorological conditions, the efficiency of free water cooling was measured and the corresponding additionally electrical energy yield was determined. The equivalent electric circuit of the PV panel cooling system is developed and an appropriate algorithm for its parameters experimental determination is proposed.

Experimental and simulation studies of oxygen-blown, steam-injected, entrained flow gasification of lignin

This article presents results from experimental and simulation studies on a laboratory-scale pressurized O2-blown Entrained Flow biomass gasification Reactor (EFR) using pulverized commercial lignin pellets as feedstock. The primary focus lies in the assessment of the EFR’s performance indicators such as the H2/CO ratio, the Cold Gas Efficiency (CGE), and the Carbon Conversion Efficiency (CCE). The gasifier was operated at an absolute pressure of 8.2 bars, with varying amounts of O2 and steam. In the first series of experiments, the O2 equivalence ratio varied between 0.2 and 0.8, with no steam injection. This yielded a maximum CGE of 47%, a CCE of 94%, and an H2/CO ratio within the range of 0.4–0.7. In the last series of experiments, a perforated horizontal steam tube was installed allowing for a variation of the steam-to-biomass ratio (S/B), between 0.5 and 1.5. At a S/B of 1.5, the CGE and the CCE were at their highest levels of 91% and 99%, respectively. Based on the experimental setup, a 3D multiscale Eulerian-Lagrangian computational particle fluid dynamics (CPFD) model for the reactor was developed and validated against the experimental data. This model was then employed to explore the impacts of reactor temperature, S/B, equivalence ratio (λ), and the lignin particle size distribution (PSD) on the gasification process. The findings show that increased reactor temperature enhances H2 and CO production. Higher S/B ratios lead to greater H2 production but reduced CO production. Increased S/B ratios improve both CGE and CCE. Larger particles and higher λ values decrease CO and H2 production. Without steam injection, the peak CGE occurs at λ ≈ 0.45, corresponding to complete CH4 conversion. Beyond this point, as λ increases, reactor temperatures rise while CGEs decrease. Simulations reveal the optimal λ range for steam injection is 0.15–0.35. A sensitivity analysis highlights the significant impact of reactor temperature on H2 and CO production. While λ shows high sensitivity for H2 production, the S/B ratio exerts a greater impact on CO production.

Reducing temperature difference of a direct ammonia tubular SOFC to 1K

In this study, a three-dimensional direct ammonia solid oxide fuel cell (DA-SOFC) was numerically modeled to investigate the effects of ammonia inlet flow velocity, tube structure, and catalyst filling on the internal temperature distribution of the cell. The results show that shortening the length of the ammonia inlet tube and increasing the inlet flow velocity leads to an increase in the temperature difference inside the cell. By perforating the ammonia inlet tube, the temperature difference can be further reduced, and the low-temperature zone inside the cell gradually decreases with the perforated area percentage increasing. In addition, placing ammonia decomposition catalyst inside the perforated inlet tube can further improve the temperature difference between the electrodes inside the cell, reducing it from 30 K to about 1 K. Furthermore, the temperature distribution pattern inside the fuel cell with metal supports was investigated, and it was found that the metal support can better export the heat generated inside the fuel cell. This study provides a new idea to improve the temperature distribution of DA-SOFC and enhance the stability and reliability of cell operation.

Acoustic Attenuation Prediction of Perforated Reactive and Dissipative Mufflers With Flow by Using Frequency-Domain Linearized Navier-Stokes Equations

To comprehensively consider the impact of complex airflow on sound propagation, a numerical approach by solving the three-dimensional (3-D) frequency-domain linearized Navier-Stokes equations (LNSEs) is proposed to accurately predict the transmission losses of perforated tube reactive and dissipative mufflers in the presence of complex airflow. The numerical computations are performed in two steps: (1) solve the time averaged flow by steady-state computational fluid dynamics (CFD) simulation and then map the results into acoustic mesh; (2) treat sound-absorbing material as an equivalent fluid and obtain acoustic perturbation variables by solving the frequency-domain LNSEs. The transmission losses of perforated tube reactive and dissipative mufflers are measured in the presence of flow and compared with the numerical predictions. The excellent consistencies between predictions and measurements validate the present approach. The influence of Mach number on acoustic attenuation performance of perforated tube reactive and dissipative mufflers is then investigated. With Mach number increases, the transmission loss of perforated tube reactive muffler increases somewhat, while the transmission loss of dissipative mufflers decreases obviously in the lower frequency range and change is limited at higher frequencies.

Predication of entropy generation rate in a concentrating photovoltaic thermal system with twisted tube turbulator using Boosted regression tree algorithm

Efficient energy conversion and utilization remain paramount in addressing the growing energy demand and environmental concerns. Concentrating photovoltaic thermal (CPVT) systems have emerged as promising solutions by integrating photovoltaic (PV) cells with thermal components for simultaneous electricity and heat generation. In this paper, we propose the application of the Boosted Regression Tree (BRT) algorithm to predict the entropy generation rate in a CPVT system equipped with a perforated twisted tube turbulator. Brief introduction of numerical analysis of local and global rates of frictional (S˙fr) and thermal (S˙th) irreversibilities in a CPVT system equipped with a perforated twisted tube turbulator. The results approve the efficacy of the BRT algorithm in predicting the entropy generation rate. Through comprehensive simulations and data analysis, we establish a predictive model that considers factors such as solar irradiance, fluid flow rate, tube geometry, and turbulator characteristics. The BRT model exhibits remarkable accuracy in capturing the nuanced interplay of these factors, enabling reliable estimations of entropy generation rate.

Environmental assessment of several scenarios of active and passive radon control measures

In buildings, radon gas mainly enters through cracks in the floors and gaps around pipes and cables in contact with the soil, thereby increasing indoor radon levels. Like other building components or systems, the radon control measures have embodied and operational environmental impacts that have been neglected to a certain extent. While many actions have been taken recently to achieve carbon-neutral yet energy-efficient buildings, even radon control measures should be investigated not only for protecting human health since radon gas is the major source of ionising radiation for humans but also for the environment. This paper aims to undertake a comparative analysis of the embodied and operational impacts of variant radon-protective measures installed at the floor foundation level (both active and passive solutions) for new and existing buildings. In particular, this analysis includes four different measures based on radon venting from i) floor air gap created from plastic components, ii) flexible perforated pipes embedded in the gravel layer under the floor, iii) radon sump placed in the sub-floor layer, and iv) perforated tubes drilled horizontally into the subsoil under the house. In all cases, radon will be removed through a vertical exhaust pipe terminated above the roof or by a roof fan. The impacts are calculated for the life cycle assessment (LCA) stages A1-A3 (production phase) and B6 (operational energy) to determine whether future research should be focused on the reduction of environmental impacts on the production stages or the operational ones.

Simulation study on flexural behaviour of perforated aluminium tubes

A numerical investigation was conducted to compare the flexural capacity of AA6063-T5 aluminum alloy tubes with perforations of different hole diameters (4, 6, 8, and 10 mm), hole spacing (13-26-39-52 mm) and tube wall thickness (0.5, 1, 1.5 and 2 mm) by the finite-element analysis (FEA). As the tube thickness increases, the load-carrying capacity decreases, while the LCC increases as the hole diameter increases. It was observed that the LCC increased as the distance between the holes increased. ANOVA test was used to analyze the influence of hole diameter, hole spacing, and tube wall thickness on tube load-carrying capacity. It is found from the statistical analyses that the most significant factor on maximum load is tube thickness (97.2 %) between parameters of hole diameter, hole spacing, and tube wall thickness. As a result of the second statistical analysis, the most significant factor on maximum load is hole diameter (73.14 %) between parameters of hole diameter and hole spacing. A second important factor is hole spacing on maximum load.

Evaluation of sound localization and speech recognition with a sound enhancing connection tube for non-linear earplugs

Noise-induced hearing-loss (NIHL) can occur when an individual is exposed to high-intensity acoustic stimuli. To prevent NIHL, individuals may use non-linear-earplugs (NLEPs) that provide some attenuation, substantially within the frequency range of 1–4 kHz. Wearing NLEPs can reduce speech recognition as well as sound localization. As weapon noise is mostly present in the 1–4 kHz range and is therefore partly attenuated by NLEPs, there is a downside to the reduced ability of a soldier using them to localize the source of enemy gunfire. A perforated sound-enhancing connection tube (SECT) was designed to connect to NLEPs for improving the user’s ability to localize sound and speech recognition in noise while retaining the NLEPs's noise attenuation benefits of protecting one's hearing. A previous experiment examined the effect of the SECT with NLEPs on the Head Related Transfer Function (HRTF) of a head-and-torso-simulator (HATS) (manikin). The obtained HRTF demonstrated a 3–10 dB difference in the 1–4 kHz frequency range relative to the HRTF with the NLEPs alone, implying that sound stimuli in that frequency range might be more audible to the user. The presented work will demonstrate the speech recognition in noise and sound localization of participants when using the SECT with NLEPs.

Some technical and economic indicators for operating an irrigation pump using natural gas

This paper presents the experimental study of the types of mixers used in mixing natural gas with air to operate the irrigation pump to save energy; many measurements were carried out in the 2021 year in workshops of the Agricultural Engineering Department, Faculty of Agriculture, Ain Shams University, Egypt. Used engine single-cylinder, air-cooled. A new pump with a discharge diameter of 2 inches, which was an Egyptian manufacturer. Before entering the engine, several mixers were manufactured to mix natural gas with air. Three types of mixers were used using iron pipes of different diameters: Mixer with a perforated inner tube of 8, 10. Using the engine speed measuring device, 12cm (L8, L10, L12) was selected to determine the four shaft speeds (1750, 2300, 2900 and 3500 rpm). The results here dealt with the study of the analysis of technical indicators for the types of mixers used in mixing natural gas with air to operate the irrigation pump where the actual power (Braking power) is superior to all types when operating with gasoline (3.07 kW). A comparison with natural gas, where the mixer type (L10) (2.69 kW) was 10% less than gasoline. The lowest Specific fuel consumption (s. fc) for gasoline was (219.025 gm/Kw.h) at an engine speed of (2900 rpm). The lowest (S.fc) for the types of mixers was the mixer (L10) (340.144 gm/Kw.h) at an engine speed of (2900 rpm). The highest pump discharge was with the L8 mixer (32.98 m3/h), an increase of 1.8% over gasoline at an engine speed of (3500 rpm). The highest actual hydraulic power with the L10 type mixer compared to other type L mixers (0.782 kW) was 12 % lower than gasoline. As for the economic indicators, the lowest Internal Rate of Return (IRR) was gasoline ( 0.44), and the highest (IRR) when carrying the mixer type (L8) was (0.60), an increase of 26.6 % over gasoline. The lowest payback period was for the type of mixer (L8) (1.66 years), and the highest payback period was When the Gasoline was (2.27 years). Keywords: Irrigation pump, natural gas, gasoline, mixer, Engine speed, power, economic.

Clinical experience and complications with limited pleural dissection combined with a novel, simplified technique for thoracic Redon-like drain in vertebral body tethering

PurposeTo report on our experience with a simplified, suction-bottle-drain technique of thoracic drain (Redon-like) combined with fully thoracoscopic vertebral body tethering (VBT) and a limited pleural approach, with particular focus on the rate of pulmonary complications.MethodsA retrospective study was performed on all consecutive patients who underwent VBT for adolescent idiopathic scoliosis. For all subjects, a 10G Redon drain, an active drain system consisting of a perforated tube and a suction bottle, was placed intrathoracically and tunneled under the skin. All drains were removed on the first postoperative day. Perioperative and postoperative data such as type of access, length of surgery, amount of fluid collection in the drain, and length of hospital stay were collected. The type and number of pulmonary complications occurring in the first 3 months after surgery, along with their symptoms and management, were recorded.ResultsOne Hundred eighty-two patients were included in the analysis. The mean length of surgery was 97 min (75–120). The average fluid collection in the drain was 30 ml (5–50), the mean length of hospital stay was 3 days (2–4). During the observation period, pulmonary complications occurred in five patients (2%). Two patients presented an aseptic right pleural effusion; for two patients, a residual pneumothorax was diagnosed on the X-rays in the recovery room and one patient developed a chylothorax. All patients recovered without sequelae.ConclusionThe simplified, Redon-like drain combined with a fully thoracoscopic VBT and limited pleural approach seems a safe and effective alternative to the chest drain. This technique allows to remove the drain on the first postoperative day, thus simplifying the management of the patients and improving their comfort.

Experimental investigation on the axial compression behaviour of perforated glass fibre reinforced plastic medium-length tubes

This paper aims to investigate the axial compression behaviour of perforated glass fibre reinforced plastic (GFRP) circular tubes. A total of 12 GFRP medium-length tubes with and without circular holes were tested under axial compression. The influence of hole size and hole quantity on the failure mode and mechanical behaviour of perforated GFRP tubes were carefully evaluated. The overall buckling failure and material strength failure, mainly determined by the hole size, were observed in the axial compression tests. The critical load and axial stiffness of the perforated tubes decreased further with the increase of hole sizes and quantities, compared to those of the intact GFRP tubes. To reveal the damage mechanism of perforated GFRP tubes, three-dimensional digital image correlation (3D-DIC) technique was used to analyse the evolution of full-field strain around the hole. It was demonstrated that the damage mechanisms of the overall buckling failure and material strength failure were respectively compression-shear destruction and tension-shear destruction in the high strain concentration regions around the hole. Finally, design-oriented equations were proposed to predict the critical load and axial stiffness of perforated GFRP tubes under axial compression, and 95% confidence interval was used for interval estimation. The proposed equations were in good agreement with the test results. In addition, the prediction results of axial stiffness are generally more accurate than that of critical load.

Nb3Sn CIC for Outsert Windings of Hybrid Dipoles

A Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn Cable-in-Conduit (CIC) conductor is being developed for use in the outsert winding of a hybrid dipole for a future hadron collider. The CIC provides several significant benefits for use in a hybrid dipole: Lorentz stress is managed at the cable level, flared ends can be formed with small bend radius with no degradation to the wires within, and supercritical helium cooling flows through the perforated center tube to provide enhanced wire stability. The Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn outsert is heat-treated as an autonomous assembly, then assembled onto a REBCO insert and preloaded within the dipole yoke structure. The cable and coil technologies of the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn CIC are described, and its incorporation in the 18.5 T hybrid dipole is presented.

Numerical and ensemble machine learning-based investigation of the energy and exergy yields of a concentrating photovoltaic thermal device equipped with a perforated twisted tube turbulator

The current research was carried out with the aim of numerically investigating the effect of employing a perforated twisted tube turbulator on the energy and exergy yields of a concentrating photovoltaic thermal (PVT) device. The simulations were performed in 4 different Reynolds numbers (Re) (i.e. 500, 1000, 1500 and 2000) and considering 4 different twist distance (TD) (i.e. L/25, L/50, L/70, and L/100) for the non-perforated turbulator and three different perforated turbulators (with 1, 2, and 3 holes) with TD = L/100. Among the examined cases, the best and worst performance belonged to the PVT device with perforated turbulator and without a turbulator, respectively. For the PVT device with non-perforated turbulator, the lowest PV panel temperature, the highest water outlet temperature, and the highest energy and exergy efficiencies occurred at the highest Re (i.e. 2000) and the lowest TD (i.e. L/100). Also, it was revealed that among the examined perforated turbulators, the best performance belongs to the turbulator with 3 holes in each pitch. In this case, the temperature of the PV panel, the overall energy efficiency and the overall exergy efficiency of the PVT device are respectively 3 ºC lower, 7.43% higher and 3.21% higher than the case without turbulator. As another novelty, a new ensemble machine learning model, namely boosted regression tree (BRT) was developed to simulation of the overall energy and exergy efficiencies based on the Reynolds number and volume fraction. The outcomes revealed the promising accuracy for both targets in terms various statistical metrics.

Condenser performance in a cylindrical humidification and dehumidification (HDH) system

AbstractIn recent years, humidification and dehumidification (HDH) systems have garnered significant attention due to their enhanced effectiveness with packed beds, particularly for high‐salinity waters. The direct‐contact packed beds HDH system offers a more convenient and efficient installation compared with conventional HDH systems. This paper introduces a novel, compact cylindrical crossflow HDH system design that is easily constructed and scalable for industrial and residential applications. The compact crossflow‐packed bed condenser employs perforated air tubes to distribute humidified air radially while cooling water drips vertically through the packed bed, coming into direct contact with the humidified air. To evaluate the system's performance, two‐dimensional steady‐state energy, and mass conservation equations were developed solving enthalpies instead of temperatures as dependents. The coupled partial differential equations were numerically solved to predict water temperature, air/vapor temperature, humidity ratio, and condenser effectiveness. Multiple designs were proposed, demonstrating that the proposed configuration can achieve effectiveness above 0.80 and a water production rate of 3.85 g/s under ideal operating conditions.