Experimental Test Setup Research Articles

Mathematical modeling of drying characteristics for cylindrical Thompson seedless grapes under natural convection

AbstractThe objective of this paper is to develop a universal diffusion model of drying kinetics that can be applied to a variety of shrinkable products such as fruits and vegetables. The main objective is to examine the physical changes that occur during convective air‐drying process of Thompson seedless type cylindrical grapes. These include changes in the physical properties of the product, such as the moisture content, the temperature of the product, and the size of the product. The authors develop a two‐dimensional transient diffusion model and MATLAB that takes into account convection, radiation, and evaporation phenomena under a variety of operating conditions for simulating grape drying and shrinkage. The differential equations are solved for moisture transfer within a cylinder using the finite difference method. A lab‐scale experimental test setup has also been developed and tests are performed. The results obtained from the mathematical model are compared with experimental results and found to be in agreement with a maximum error of 14%. The model is also validated with the results reported in the literature. Meteorological data are used to determine the time‐dependent radiation flux density (I(t)) on a particular day. For each of the investigated conditions, the effective moisture diffusivity (Deff) is determined using Fick's diffusion equation. Volume reduction of a product due to drying process was assumed to be equivalent to moisture removal. A coefficient of effective diffusivity was calculated using drying data collected at constant cabin air temperatures between 50 and 70°C. The maximum radius and length of the grape were reduced by 40.33% and 42.40%, respectively, when the size of the grape was considered to be 6.5 mm radius and 25 mm length. The results of the present mathematical model may be useful for accurately predicting the temperature, moisture content, and size change of the product.Practical ApplicationDrying food to preserve it is an energy‐intensive process. Solar drying is one of the oldest methods used to preserve agricultural produce. Solar thermal energy has tremendous potential for commercial and industrial drying applications with air temperatures as high as 80°C. Solar drying is prevalent in India because farmers have easy access to solar drying systems. Through the installation of such a system, agricultural products can be dried in agricultural regions. This work provides farmers with added value for their particular products. Solar dryers system ensure significant fossil fuel energy savings. Solar dryers must meet rigorous requirements for dependability and continuous operation. This research contributes to the design, optimization, and control of food drying processes. For each drying time, the extent of moisture distribution, product temperature, and product size are determined. For dryers operating under a variety of operating conditions, this aids in system performance forecasting. In addition, the effect of interior cabin temperature variation is investigated, which aids in identifying drying characteristics.

Modeling and Simulation of Time Domain Reflectometry Signals on a Real Network for Use in Fault Classification and Location

Today, the classification and location of faults in electrical networks remains a topic of great interest. Faults are a major issue, mainly due to the time spent to detect, locate, and repair the cause of the fault. To reduce time and associated costs, automatic fault classification and location is gaining great interest. State-of-the-art techniques to classify and locate faults are mainly based on line-impedance measurements or the detection of the traveling wave produced by the event caused by the fault itself. In contrast, this paper describes the methodology for creating a database and a model for a complex distribution network. Both objectives are covered under the paradigm of the time-domain pulse reflectometry (TDR) principle. By using this technique, large distances can be monitored on a line with a single device. Thus, in this way a database is shared and created from the results of simulations of a real and complex distribution network modeled in the PSCAD™ software, which have been validated with measurements from an experimental test setup. Experimental validations have shown that the combination of the TDR technique with the modeling of a real network (including the real injector and the network coupling filter from the prototype) provides high-quality signals that are very similar and reliable to the real ones. In this sense, it is intended firstly that this model and its corresponding data will serve as a basis for further processing by any of the existing state-of-the-art techniques. And secondly, to become a valid alternative to the already well-known Test Feeders but adapted to work groups not used to the electrical world but to the environment of pure data processing.

A Novel Experimental Testing Setup and Calibration Procedures for Cylindrical Cell Thermal Models

Temperature is known to have a significant impact on the performance and ageing of Li-ion batteries. Because of it, their temperature is monitored and controlled implementing a Battery Thermal Management System (BTMS) in which lumped-parameter thermal models are commonly used to estimate the cells’ thermal behavior, due to their low computation effort. In this regard, it is important to plan a proper calibration procedure able to accurately assess the cell’s thermal properties. While literature presents several methodologies with different levels of accuracy and complexity, there is a lack of a systematic approach. Furthermore, only a few works take into account the heat lost through the cell holder by conduction. In this work, a re-designed cell holder is introduced to minimize its thermal interaction with the cell during testing, then it provides a better understanding of thermal models calibration by comparing two simple, but effective, testing procedures. The specific heat capacity of a cylindrical cell is evaluated by carrying out two testing procedures in which heat flow direction is inverted. In the first procedure, heat is actively generated from the cell, while in the second procedure it is externally provided using a flexible polyimide heater. This has led to two different formulations of the energy balance equation that differ from the internal thermal dissipation modeling. At the end, a validation has been carried out implementing a current profile generated from the UDDS drive cycle. Both formulations have shown to have the similar temperature prediction with a RMSE of 0.484 °C.

Endotracheal Tube Cuffs for Neonates: Novel cuff design to minimise tracheal damage

Neonatal mechanical ventilation (MV) is complex and its efficiency is limited due to leakage of air around the endotracheal tube (ETT). Adult ETT cuffs cannot be used in neonatal patients to block reverse flow as they cause damage to delicate throat tissues. A novel design and testing method for a non-contact neonatal ETT cuff was developed and validated. The goal was to minimise cuff surface area and contact, while creating resistance to airflow using turbulence to reduce ventilator leakage and increase efficacy of treatment for neonatal patients. Several cuff designs were generated based on testing results. Cuffs were tested using flow visualisation methods to assess leak performance in a fluid dynamically scaled experimental test setup. Final cuff designs utilised successful elements from several cuff design iterations. Overall, leakage was reduced by an average of 77.8% from an uncuffed baseline. By increasing the efficacy of healthcare solutions for neonatal patients it is hoped the burden on New Zealand's NICUs will be reduced, and quality of care increased to improve overall patient outcomes.

Strain distribution at the transition from bent to unbent regions in tube rotary draw bending: an in-situ, real-time measurement study

In tube bending processes, accurate control of springback is of crucial importance as this affects the dimensional accuracy of the final product and overall equipment efficiency. The distribution of stress and strain during bending is one of the most fundamental issues determining the springback magnitude of the product. In conventional analyses of rotary draw bending, the deformation behaviour along the bending direction is normally assumed to be uniform for constant-radius bends, following the contour of the die configuration. In practice, however, the stress-strain distribution is non-uniform, particularly at the transition between the bent and unbent regions of the formed component. The distribution makes a significant contribution to springback and its variations, especially for low bend-angle components. This research focuses on exploring the strain distribution at the end transition of the bend of aluminium tubes in rotary draw bending. An experimental test setup for strain measurements with a strain gauge glued to the unbent area has been designed and conducted to measure the strain distribution during bending. The characteristics of non-uniform strain distribution during tube bending, including the evolving transition behaviour at the transition between bent and unbent areas, are studied. The results enhance the understanding of deformation characteristics of bent tubes, and contribute to improved physically-based models and springback control routines in industrial practice.

Investigations of Hydrodynamic Force Generated on the Rotating Cylinder Implemented as a Bow Rudder on a Large-Scale Ship Model

This paper presents experimental studies of the force generated on the rotating cylinder implemented as a bow rudder on a large-scale ship model. The research focused on the maneuverability of the unit equipped with a rotating cylinder (RC) in the front part of the model and its future use as a steering device on small draft river barges. The study presented in this paper is a continuation of the research carried out using the small physical model of a river push train in 1:20 geometric scale equipped with two bow RCs and open water tests of separated rotating cylinders carried out in a flume tank. The experimental test setup with RC installed on the model in 1:24 geometric scale allowed to compare the parameters of standard maneuvers performed with the use of RC and without it. The proposed method based on the measurement of the ship model trajectory during maneuvers allowed to compare the hydrodynamic steering force generated by RC with the steering force generated by the conventional stern spade rudder. The results of the experiments compared with empirical models show a similar trend. RC dynamics was tested for rotational speeds up to 570 RPM (revolutions per minute) and ship model velocity up to 1 m/s. The rotating cylinder generated velocity field is presented and phenomena influencing the generated hydrodynamic force are discussed.

Using Numerical Models to Accelerate Electrolyte Transport Parameter Identification

A new electrolyte transport parameter identification methodology, based on the numerical solution of a symmetric Li–Li cell model, is presented. In contrast to available techniques in the literature, where small concentration perturbations are generated in testing setups and linearization is assumed to identify transport properties for the initial salt concentration, large currents are used here to excite nonlinear dynamics able to reveal concentration dependent transport properties. This approach allows a significant reduction in the experimental effort. The proposed methodology is applied to two synthetic experiments. Firstly, an ideal case (where all difficulties associated to stripping and plating dynamics on Li metal surface are neglected) is considered in order to show both the details of the proposed methodology and its performance (specially its robustness, including the effect of the noise level in the voltage measurements in the experiment). A second case considers the effect of complex stripping and plating dynamics to show that, provided (macroscopic) modelling/identification of this dynamics is carried out, the proposed methodology is still able to accurately identify electrolyte transport properties using a simple experimental test setup.

Simulation Model for Digital Twins of Pneumatic Vacuum Ejectors

AbstractIncreasing productivity, as well as flexibility, is required for the industrial production sector. To meet these challenges, concepts in the field of “Industry 4.0” are arising, such as the concept of Digital Twins. Vacuum handling systems are a widespread technology for material handling in industry and face the same challenges and opportunities. In this field, a key issue is the lack of Digital Twins containing behavior models for vacuum handling systems and their components in different applications and use cases. A novel concept for modeling and simulating the fluidic behavior of pneumatic vacuum ejectors as key components of vacuum handling systems is proposed. In order to increase the simulation accuracy, the concept can access instance‐specific data of the used asset instead of object‐specific data. The model and the data are part of the Digital Twins of pneumatic vacuum ejectors, which shall be able to be combined with other components to represent a Digital Twin of entire vacuum handling systems. The proposed model is validated in an experimental test setup and in an industrial application delivering sufficiently accurate results.

Non-condensable gas in the refrigerant of air-source heat pumps: Interactions between detection features, charge level, and temperature

Non-condensable gas (NC) can be introduced into a vapor compression refrigeration cycle through improper installation or service, and decrease system efficiency, increase burden on the compressor, and reduce the compressor life span. Therefore, detecting this fault early can prevent energy waste and prolong the operating life of the system. However, diagnostic methods are not widely available, and neither are methods to quantify NC amounts based on easily measured variables. Therefore, an experimental test apparatus was built to provide data to improve understanding of NC-refrigerant interactions. Two NC fault intensities (50%, 100%), each at four charge levels (70%, 80%, 100%, 120%), were tested under five different ambient temperatures (0-40°C). Dry nitrogen gas was used for the NC. The results showed that the theoretical estimation method is inaccurate. The trends of the results from experimental tests are consistent with those from theoretical calculations, but the thresholds obtained from experimental tests are larger than those from theoretical calculations. This paper explains these differences, and provides a model to quantify the NC fault intensity using easily-measured variables. The specific model is applicable to typical residential air-conditioner and heat pump systems that use R410A refrigerant, but the general findings are applicable to other refrigerants.

Experimental Investigation on the Thermal Performance of a Conical Solar Water Heater Using Mixed Asphalt Absorber Plate

Abstract In the present research, an investigational study on thermal performance of a mixed asphalt conical solar water heater (MACSWH) was analyzed under field conditions. The key target of the present research is to evaluate the dynamics of heat and performance of a conical solar collector with an attached mixed asphalt as an absorber plate. In the current experimental test setup, the mixed asphalt as an absorber plate with a diameter of 0.20 m and thickness of 0.05 m was set in the middle of the focal area for accumulating the solar radiation, reflecting from a polished zinc conical reflector. The aperture diameter of the MACSWH was 0.45 m with a concentration ratio of 2.20. The copper pipe had a total length of 2 m, and the inclination angle of the conical was fixed at 15 deg. The experimental results provide evidence that the mixed asphalt set as an absorber plate at the center of the focal area was an effective practical approach to improve the performance of a conical solar collector. This method raises the maximum percentage difference between inlet water temperature and outlet water temperature by approximately 47.27%, while the maximum temperatures of absorber plate, copper pipe, and efficacy are at 82 °C, 62 °C, and 72%, respectively.

Fluorometric setup and method for studying the functional activity of corneal endotheliocytes

Subject of study. Experimental methods for investigating the state of preservation and functionality of the corneal endothelium, which is determined by the water permeability of the cells and activity of ion pumps, mainly by sodium–potassium adenosine triphosphatase, were considered. Aim of study. The aim of this study was to identify significant measurable parameters such as the fluorescence intensity integrated over the entire cornea preparation and the temporal dynamic of this fluorescence. Additionally, a specialized experimental fluorometric setup was designed based on fiber optics. Method. Modifications were introduced to the composition and design of a universal experimental setup for the measurement of cell functions that enabled implementation of a fluorescence-based method for determination of the intracellular sodium concentration without processing the digital image of the cornea preparation. Main results. The specialized experimental setup and method were developed for investigating functions of the corneal endothelial cells and the intracellular signaling mechanisms whose activation or disfunction under conditions of a traumatic inflammation and after a hypothermic preservation can be related to the development of a corneal edema and a corneal graft disease. Practical significance. The specialized experimental setup and methods for functional testing of the corneal endothelial cells developed in this study can be applied to determine the degree of suitability of the cornea as a transplantation material. They can also be used as a system of tests for determining the effectiveness of the cornea preservation methods.

Numerical model for solar drying mechanism of grapes using double glazed cabinet type solar dryer

AbstractA development of an integrated mathematical model based on heat and mass transfer process was used to predict the shrinkage, moisture content, and thermal properties of grapes under different climatic conditions. A lab‐scale experimental test setup has also been developed, and tests are performed. The results obtained from the mathematical model are compared with experimental results and found to be in agreement with a maximum error of 14%. The moisture content evaluated from the model showed a fair agreement with the experimental results. An energy balance equation is used to obtain the cabinet temperature. A time‐dependent radiation flux density (I(t)) at a certain day is obtained through meteorological records. The effective moisture diffusivity (Deff) is obtained using Fick's diffusion equation for all the investigated conditions. The model is also validated with the results reported in the literature. Moisture is reduced from the initial moisture content of 4.88 kg of water per kg of dry matter to the final moisture content of approximately 0.38 kg of water per kg dry matter. The average radius of the grape decreased by 34.67% at the end of drying process (moisture content ~13%). The maximum water activity is 0.37 for the highest moisture content. The maximum radius change was found 4.9 mm from 7.5 mm for 50°C case. The maximum temperature increase of grapes with respect to drying time is 18°C. The results obtained using the proposed mathematical model can be used to predict product temperature, moisture content, and drying time for cylindrical‐shaped products.

Experimental Setup for Fatigue Testing of Additively Manufactured Specimens

Poor fatigue life is a huge issue of additively manufactured parts, despite the unique qualities characterizing this manufacturing process (such as low waste of material and geometry freedom). Fatigue life is strongly affected by both surface defects and internal defects, metal AM is characterized by extremely poor surface quality, internal porosities and lack of fusions. For this reason, many researchers investigated methods to improve manufacts quality. The most promising methods are surface finishing treatments and thermal treatments which provide an enhancement of fatigue behavior. A focal point of the research should be evaluating the respective contribution of surface treatments and thermal treatments. In order to evaluate the effectiveness of surface treatment, it is necessary to highlight the surface quality contribution in terms of fatigue life thus a specific testing method is necessary. Rotating beam fatigue test fits this requirement because each point of the specimen’s surface is subjected to the maximum stress. The aim of this work is to present the experimental setup for rotating beam fatigue testing that has been used to evaluate the fatigue behavior of AM SLM IN718 specimens.

Multiscale Shear Properties and Flow Performance of Milled Woody Biomass

One dominant challenge facing the development of biorefineries is achieving consistent system throughput with highly variant biomass feedstock quality and handling performance. Current handling unit operations are adapted from other sectors (primarily agriculture), where some simplifying assumptions about granular mechanics and flow performance do not translate well to a highly compressible and anisotropic material with nonlinear time- and stress-dependent properties. This work explores the shear and frictional properties of loblolly pine at multiple experimental test apparatus and particle scales to elucidate a property window that defines the shear behavior over a range of material attributes (particle size, size distribution, moisture content, etc.). In general, it was observed that the bulk internal friction and apparent cohesion depend strongly on both the stress state of the sample in granular shear testers and the overall particle size and distribution span. For equipment designed to characterize the quasi-static shear stress failure of bulk materials ranging from 50 to 1,000 ml in test volume, similar test results were observed for finely milled particles (50% passing size of 1.4 mm) with a narrow size distribution (span between 10 and 90% passing size of 0.9 mm), while stress chaining and over-torque issues persisted for the bench-scale test apparatus for larger particle sizes or widely dispersed sample sizes. Measurement of the anisotropic particle–particle friction ranged from coefficients of approximately 0.20 to 0.45 and resulted in significantly higher and more variable friction measurements for larger particle sizes and in perpendicular alignment orientations. To supplement these laboratory-scale properties, this work explores the flow of loblolly pine and Douglas fir through a pilot-scale wedge-shaped hopper and a screw feeder. For the gravity-driven hopper flow, the critical arching distance and mass discharge rate ranged from approximately 10 to 30 mm and 2 to 16 tons/hour, respectively, for both materials, where the arching distance depends strongly on the overall particle size and depends less on the hopper inclination angle. Comparatively, the auger feeder was found to be much more impacted by the size of the particles, where smaller particles had a more consistent and stable flow while consuming less power.

Failure analysis of POM ternary nanocomposites for gear applications: Experimental and finite element study

The main purpose of the present study is to assess the failure behavior of polyoxymethylene/carbon black/CaCO3 ternary nanocomposite gears by employing an experimental gear test setup and a gear renewal technique. The failure-related factors including surface temperature, tooth wear, and failure analysis at macro- and micro-scales were studied. The tooth surface temperature was measured continuously based on an online-measuring approach. The tooth wear was calculated using microscopic images and software analysis. The maximum contact stress on meshing teeth surfaces was specified by finite element analysis. According to SEM micrographs, the application of both nanostructures contributed to a more uniform distribution of each nanophase within the POM matrix. The gear test results indicated an enhanced tooth resistance and service life of up to 58% and 125%, respectively, for ternary nanocomposites relative to neat POM gears. The tooth surface temperature was reduced for nanocomposite gears due to the promoted heat transfer and thermal stability. The tooth deformation and cracking were highly suppressed for ternary nanocomposite gears at failure. The evaluation of teeth surface damages at micro-scale revealed the suppression of plastic flow and material adhesion for ternary nanocomposites.

Experimental analysis of steering wheel vibrations of an agriculture tractor for reduction of hand-arm vibrations

Steering wheel vibration is one of the most important factors in determining the operator comfort in agricultural tractors. It is important to investigate steering wheel vibrations in an agricultural tractor in order to improve the operator’s comfort and decrease the negative health impacts on the operator’s hand. The Mahindra 575 DI tractor was selected for further investigation and development as the maximum vibration acceleration was found in the Mahindra 575 DI tractor while measuring the amplitude of vibration on various tractors. The experimental test setup was designed with a solution to reduce steering wheel vibrations. The experimental analysis of steering wheel vibration of an agriculture tractor for the reduction of Hand-Arm Vibration Syndrome (HAVS) is presented in this research article. The vibration level was decreased effectively after establishing a tuned mass damper between the steering gearbox and the vibration exciter.

Heat transfer analysis of air-mist evaporative cooling in heat sink

This paper investigates heat transfer enhancement of evaporative air-mist cooling in heat sinks. Heat transfer in heat sink is studied through the development of theoretical equations of mass, momentum, energy, and water droplets evaporation. The flow domain consists of air and water droplets entrained in the primary air phase. An experimental testing setup is built and used to examine the validity of the numerical modeling of the air-mist cooling approach. The influence of mist droplets on heat transfer and the thermal performance of the heat sink is analyzed numerically and experimentally. Investigation is carried out for Reynolds number ranging between 100 and 1500, mist volume fraction ranging between 1 and 10%, and mist droplets diameter of 10 µm. It is found that increasing the inlet mist fraction from 1% to 6% increases the heat transfer coefficient by approximately 158%. Moreover, it is found that increasing Reynolds number from 100 to 1000 increases the heat transfer coefficient by approximately 100%. This numerical investigation illustrates the effectiveness of using two-phase air-mist flow cooling of heat sinks in comparison with a single-phase air flow. This study highlights the importance of using two-phase flow for enhanced heat transfer and it contributes to the development of advanced microelectronic cooling systems.

Experimental study of a liquid metal film flow in a streamwise magnetic field

Continuous wetting of a surface with liquid metal is indispensable in many applications, such as in fusion reactors. In the present study, we provide data on the suppression of free-surface instabilities of liquid metal film flows under the action of strong streamwise magnetic fields in analogy to the poloidal fields used in application. We have designed and built up an experimental test setup which allows studying the influence of magnetohydrodynamics on the dynamic behaviour of liquid metal GaInSn film flows in laminar, transient, and turbulent regimes. While the width and the length of the film are adjusted at w = 23 mm and l = 120 mm, respectively, we are able to apply strong uniform magnetic fields up to B = 5 T over the entire fluid-flow volume. Moreover, the setup allows to vary the Reynolds number within the range 200 ≤ Re ≤ 1700. The corresponding Hartmann and Stuart numbers are Ha ≤ 180 and N ≤ 40, respectively. This study shows that a streamwise magnetic field is capable of suppressing free-surface instabilities even in the turbulent regime of the film flow by dampening any motion perpendicular to the applied magnetic field. Plans for future studies include the quantitative investigation of the parameter space. Figs 4, Refs 8.

A six degree-of-freedom set-up for wind tunnel testing of floating wind turbines

In this paper we present a six-degree-of-freedom (DoF) experimental set-up for wind tunnel testing of floating offshore wind turbines (FOWTs). The system is composed of a 6-DoF Stewart platform that can be used to mimic realistically the motions of a floating turbine at laboratory scale. The platform is specifically made for the Model Wind Turbine Oldenburg 0.6 (MoWiTO 0.6). First, the methodology followed to design the system as well as the scaling issues are depicted. Then, the characterisation of the platform is presented. Finally, limitations of the set-up are discussed.

Data-driven model-based calibration for optimizing electrically boosted diesel engine performance

Engine calibration is a process of optimizing its control variables, which is a crucial step to achieve the desired performance from the engine system. However, its complexity has increased dramatically due to the constant evolution of the engine architecture with multiple control variables interacting with each other, making it difficult to calibrate its control variables with significantly increased experimental costs. System complexity also affects the physics-based modeling process as it makes the system model highly non-linear and difficult to capture system dynamics under all engine operating conditions. To overcome these challenges, the current work proposes a machine learning-based framework to reduce the required calibration effort. The work implements a stochastic surrogate assisted optimization approach on an actual engine experimental test setup, which efficiently looks for the global optimal solution based on only the input-output data set. This work performs a steady-state calibration of a turbocharged diesel engine with an additional external electric-assisted boosting system (eBoost). Three control parameters are considered for this study: Variable Geometry Turbocharger (VGT) vane position, Exhaust Gas Recirculation (EGR) valve position, and eBoost speed to identify the optimal trade-off between engine efficiency (Brake Specific Fuel Consumption) and emissions ( NO x). The addition of eBoost makes the calibration problem difficult because the two control parameters, VGT and EGR, also depend on eBoost speed. Using the proposed data-driven calibration approach, the experimental results showed enhanced engine performance in terms of efficiency and emissions using the eBoost compared with the case without eBoost. At the same time, the experimental cost was reduced significantly due to the reduced number of testing points required to achieve the optimum.