scholarly journals An Ultrasonic Rheometer to Measure Gas Absorption in Ionic Liquids: Design, Calibration and Testing

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3544
Author(s):  
Michele Schirru ◽  
Michael Adler
Keyword(s):  
Thermal Cycling ◽  
Lead Zirconate Titanate ◽  
Tungsten Bronze ◽  
Hydrogen Gas ◽  
Operating Conditions ◽  
Gas Absorption ◽  
Time Duration ◽  
Suitable Material ◽  
Lead Metaniobate ◽  
Titanate Lead

The first goal of this study is to identify the ideal piezoelectric material for the manufacturing of rheological reflectance ultrasonic sensors. The second goal is to integrate the ultrasonic rheometer within a gas absorption reactor and to measure viscosity changes in an ionic liquid (IL) caused by gas absorption. To achieve the objectives, bismuth titanate, lead titanate, lead metaniobate and lead zirconate titanate materials in layer, tungsten bronze and perovskite structures were assembled on aluminum delay lines and tested under thermal cycling between room temperature and 150 °C. The results showed that lead metaniobate in tungsten bronze structure is the most suitable material for long time duration thermal cycling. Therefore, the ultrasonic rheometer was assembled using this material and installed in a pressurized reactor to test a reference IL at the operating conditions of 50 °C and at a pressure of 80 bar. The reference IL was saturated with nitrogen as well as hydrogen gas. Viscosity signals remained constant under the hydrogen atmosphere, while in nitrogen atmosphere the absorption of the gas lead to a rise in the value of viscosity.

Relationships Between Microstructure and Reliability in Pzt Mems

2001 ◽  
Vol 666 ◽  
Author(s):  
B.W. Olson ◽  
L.M. Randall ◽  
C.D. Richards ◽  
R.F. Richards ◽  
D.F. Bahr
Keyword(s):  
Grain Size ◽  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Electrical Energy ◽  
Lead Zirconate ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Processing Route ◽  
Bulge Testing ◽  
Sol Gel Process

ABSTRACTPiezoelectric oxide films, such as lead zirconate titanate (PZT), are now being integrated into MEMS applications. Many PZT derived systems are deposited using a sol-gel process, which can be used in a microelectronics processing route using spin coating as the deposition method. An application of interest for PZT films is in power generation, where a flexing membrane is used to transform mechanical to electrical energy. The current study was undertaken to identify the relationships between the processing, microstructure, and mechanical reliability of these films. Films were deposited onto both monolithic and bulk micromachined platinized silicon wafers using standard sol-gel chemistries, with roughness and grain size tracked using electron and scanning probe microscopy. Mechanical properties were evaluated in a dynamic bulge testing apparatus. Grain size variations in the Pt film between 35 and 125 nm are shown to have little effect on grain size of the subsequent PZT film and the adhesion of the PZT to the Pt film. Only the Pt film with 125 nm grains was shown to undergo any significant interfacial fracture. Fatigue tests suggest film lifetime is primarily limited by the number of pre- existing flaws in the film from processing. Reducing the microcrack density has been shown to produce films and devices that fail at strains of 1.4% and have mechanical fatigue lifetimes in excess of 100 million cycles at strains simulating the operating conditions.

scholarly journals Dynamic Mechanical Fatigue Behavior of Polymer Electrolyte Membranes for Fuel Cell Electric Vehicles Using a Gas Pressure-Loaded Blister

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4177
Author(s):  
Jun Hyun Lim ◽  
Jian Hou ◽  
Chang Hyun Lee
Keyword(s):  
Proton Conductivity ◽  
Hydrogen Gas ◽  
Gas Pressure ◽  
Operating Conditions ◽  
Mechanical Resistance ◽  
Dynamic Mechanical ◽  
Mechanical Fatigue ◽  
Aging Test ◽  
Short Period ◽  
Mechanical Aging

This study reports on an innovative press-loaded blister hybrid system equipped with gas-chromatography (PBS-GC) that is designed to evaluate the mechanical fatigue of two representative types of commercial Nafion membranes under relevant PEMFC operating conditions (e.g., simultaneously controlling temperature and humidity). The influences of various applied pressures (50 kPa, 100 kPa, etc.) and blistering gas types (hydrogen, oxygen, etc.) on the mechanical resistance loss are systematically investigated. The results evidently indicate that hydrogen gas is a more effective blistering gas for inducing dynamic mechanical losses of PEM. The changes in proton conductivity are also measured before and after hydrogen gas pressure-loaded blistering. After performing the mechanical aging test, a decrease in proton conductivity was confirmed, which was also interpreted using small angle X-ray scattering (SAXS) analysis. Finally, an accelerated dynamic mechanical aging test is performed using the homemade PBS-GC system, where the hydrogen permeability rate increases significantly when the membrane is pressure-loaded blistering for 10 min, suggesting notable mechanical fatigue of the PEM. In summary, this PBS-GC system developed in-house clearly demonstrates its capability of screening and characterizing various membrane candidates in a relatively short period of time (<1.5 h at 50 kPa versus 200 h).

scholarly journals A Simulation and Optimization Study of the Swirling Nozzle for Eccentric Flow Fields of Round Molds

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 691
Author(s):  
Peng Lin ◽  
Yan Jin ◽  
Fu Yang ◽  
Ziyu Liu ◽  
Rundong Jing ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Rotation Angle ◽  
Steel Slag ◽  
Submerged Entry Nozzle ◽  
Operating Conditions ◽  
Gas Absorption ◽  
Simulation And Optimization ◽  
Bias Flow ◽  
The Impact

In continuous casting, the nozzle position may deviate from the center under actual operating conditions, which may cause periodic fluctuation of the steel-slag interface and easily lead to slag entrapment and gas absorption. Swirling nozzles can reduce these negative effects. A mathematical simulation method based on a round mold of steel components with a 600 mm diameter is applied to study the flow field of molten steel in a mold. The swirling nozzle is optimized through the establishment of a fluid dynamics model. Meanwhile, a 1:2 hydraulic model is established for validation experiments. The results show that, when the submerged entry nozzle (SEN) is eccentric in the mold, it results in serious bias flow, increasing the drift index in the mold up to 0.46 at the eccentric distance of 50 mm. The impact depth of liquid steel and turbulent kinetic energy can be decreased by increasing the rotation angle of the nozzle. The nozzle with one bottom hole, which significantly decreases the bottom pressure and turbulent kinetic energy, greatly weakens the scour on nozzle and surface fluctuation. In the eccentric casting condition, using the optimized swirling nozzle that employs a 5-fractional structure, in which the rotation angle of 4 side holes is 30° and there is one bottom outlet, can effectively restrain bias flow and reduce the drift index to 0.28, a decline of more than 39%.

scholarly journals A Novel Self-Deployable Solar Sail System Activated by Shape Memory Alloys

Aerospace ◽  
2019 ◽  
Vol 6 (7) ◽  
pp. 78 ◽  
Author(s):  
Gianluigi Bovesecchi ◽  
Sandra Corasaniti ◽  
Girolamo Costanza ◽  
Maria Elisa Tata
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Environmental Conditions ◽  
Solar Sail ◽  
Operating Conditions ◽  
Small Scale ◽  
Space Vehicles ◽  
Solar Sails ◽  
Suitable Material ◽  
Transfer Mechanisms

This work deals with the feasibility and reliability about the use of shape memory alloys (SMAs) as mechanical actuators for solar sail self-deployment instead of heavy and bulky mechanical booms. Solar sails exploit radiation pressure a as propulsion system for the exploration of the solar system. Sunlight is used to propel space vehicles by reflecting solar photons from a large and light-weight material, so that no propellant is required for primary propulsion. In this work, different small-scale solar sail prototypes (SSP) were studied, manufactured, and tested for bending and in three different environmental conditions to simulate as much as possible the real operating conditions where the solar sails work. Kapton is the most suitable material for sail production and, in the space missions till now, activated booms as deployment systems have always been used. In the present work for the activation of the SMA elements some visible lamps have been employed to simulate the solar radiation and time-temperature diagrams have been acquired for different sail geometries and environmental conditions. Heat transfer mechanisms have been discussed and the minimum distance from the sun allowing the full self-deployment of the sail have also been calculated.

A Simulation of the Solid Oxide Fuel Cell Electrochemical Light Off Phenomenon

2005 ◽  
Author(s):  
Comas L. Haynes ◽  
J. Chris Ford
Keyword(s):  
Fuel Cell ◽  
Thermal Cycling ◽  
Solid Oxide Fuel Cell ◽  
Heat Generation ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Cell Potential ◽  
Start Up ◽  
Electrochemical Transport

During latter-stage, “start-up” heating of a solid oxide fuel cell (SOFC) stack to a desired operating temperature, heat may be generated in an accelerating manner during the establishment of electrochemical reactions. This is because a temperature rise in the stack causes an acceleration of electrochemical transport given the typical Arrhenius nature of the electrolyte conductivity. Considering a potentiostatic condition (i.e., prescribed cell potential), symbiosis thus occurs because greater current prevalently leads to greater by-product heat generation, and vice versa. This interplay of the increasing heat generation and electrochemistry is termed “light off”, and an initial model has been developed to characterize this important thermal cycling phenomenon. The results of the simulation begin elucidating the prospect of using cell potential as well as other electrochemical operating conditions (e.g., reactants utilization) as dynamic controls in managing light off transients and possibly mitigating thermal cycling issues.

MmNi5 and MmNi4.85Fe0.15 as Hydrogen Storage Medium

2012 ◽  
Author(s):  
Anwar Johari ◽  
Rosli Mohd. Yunus ◽  
Mohd. Suffian Noordin ◽  
Mohd. Nazlee Faisal Md. Ghazali ◽  
Tuan Amran Tuan Abdullah
Keyword(s):  
Hydrogen Storage ◽  
Plateau Pressure ◽  
Absorption Capacity ◽  
Hydrogen Gas ◽  
Operating Conditions ◽  
Activation Process ◽  
Hydride Hydrogen ◽  
Temperature And Pressure ◽  
Pressure Hydrogen ◽  
Hydrogen Storage Medium

Ciri–ciri MmNi5 dan MmNi4.85Fe0.15 sebagai medium gas hidrogen telah dilakukan di dalam penyelidikan ini. Keupayaan penyerapan logam tersebut adalah dipengaruhi oleh faktor suhu dan dan tekanan. Julat suhu yang dipilih adalah di antara 298K dan 323K manakala tekanan diubah–ubah dari 2 hingga 30 bar. Dalam penyelidikan ini didapati bahawa jumlah gas hidrogen yang diserap oleh MmNi5 adalah berkadar songsang dengan suhu. Jumlah penyerapan maksimum NmNi5 telah dicapai pada suhu 298K dan pada tekanan plateau 10 m bar. Nilai penyerapan hidrogen pada suhu dan tekanan tersebut adalah 1.20 peratus berat. Bagi penyerapan MmNi5 pada 313K dan 323K, keputusan menunjukkan nilai 0.9 dan 0.8 peratus berat. Masing–masing menunjukkan tekanan plateau didapati pada 20 dan 24 bar. Penyelidikan ke atas MmNi4.85 menunjukkan keputusan yang tidak menepati dengan teori. Hasil daripada rujukan dan penyelidikan yang menyeluruh, didapati bahawa proses pengaktifan sampel yang dilakukan adalah tidak mencukupi untuk mengaktifkan MmNi4.85Fe0.15. Kata kunci: Logam hidrid; penyimpanan gas hidrogen; proses pengaktifan; tekanan plateau; jumlah penyerapan hidrogen The characteristics of MmNi5 and MmNi4.85Fe0.15 in storing hydrogen gas were examined in this study. The absorption capacity of the metal was monitored under the influence of temperature and pressure. Due to the limitation on its operating conditions, the range of the temperature chosen was from 298K to 323K while pressure was varied from 2 to 30 bar. Study conducted on MmNi5, showed that the amount of hydrogen absorbed was inversely proportional to the operating temperature. In the study of MnNi5 the maximum absorption was achieved at 298K and exhibited the plateau pressure of 10 bar. The hydrogen content was expressed as weight and the value was calculated to be at 1.20 wt%. As for MmNi5 at 313K abd 323K, the results are pointed at 0.9 wt% and 0.8 wt% whilst the plateau was encountedered at 20 and 24 bar, respectively. Study conducted on MmNi4.85Fe0.15 showed inconsistent findings with theory. After thorough examination, it was realized that the misbehavior of the sample was due to the insufficient agrresiveness activations method employed. Key words: Metal hydride; hydrogen storage; activation process; plateau pressure; hydrogen absorbed content

Hierarchical Control System with Fuzzy Supervisory System and PID Controller and Application to Large-Scale Hydrogen Gas Purity Control

1999 ◽  
Vol 3 (2) ◽  
pp. 126-130 ◽  
Author(s):  
Tetsuji Tani ◽  
◽  
Takahiro Kobayashi ◽  
Sadaaki Miyamoto ◽  
Keyword(s):  
Large Scale ◽  
Control Function ◽  
Hierarchical Control ◽  
Hydrogen Gas ◽  
Operating Conditions ◽  
Function Block ◽  
Plant Operations ◽  
Function Blocks ◽  
Human Supervisory Control ◽  
Purity Control

We present hierarchical control that combines conventional PID controllers and their supervisory fuzzy control designed based on human knowledge. Hierarchical control consists of 2 control function blocks, where we use (1) a statistical model using multiregression with an updating factor for the function block to estimate parameters of plant operations and (2) fuzzy logic for the control function block to compensate for operating conditions. Hierarchical control has been applied to hydrogen gas purity control in large-scale petroleum-refining plants. It has been verified that this control shows better performance than conventional human supervisory control and (1) reduces operator interaction, (2) cuts energy consumption, and (3) lowers CO2 generation.

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