scholarly journals Studies on Influence of Cell Temperature in Direct Methanol Fuel Cell Operation

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 353 ◽  
Author(s):  
R. Govindarasu ◽  
S. Somasundaram
Keyword(s):  
Real Time ◽  
Power Density ◽  
Flow Rate ◽  
Fossil Fuels ◽  
Process Variable ◽  
Methanol Concentration ◽  
Optimum Operating ◽  
Membrane Electrode ◽  
Cell Temperature ◽  
Optimum Operating Temperature

Directmethanol fuel cells (DMFCs) offer one of the most promising alternatives for the replacement of fossil fuels. A DMFC that had an active Membrane Electrode Assembly (MEA) area of 45 cm2, a squoval-shaped manifold hole design, and a Pt-Ru/C catalyst combination at the anode was taken for analysis in simulation and real-time experimentation. A mathematical model was developed using dynamic equations of a DMFC. Simulation of a DMFC model using MATLAB software was carried out to identify the most influencing process variables, namely cell temperature, methanol flow rate and methanol concentration during a DMFC operation. Simulation results were recorded and analyzed. It was observed from the results that the cell temperature was the most influencing process variable in the DMFC operation, more so than the methanol flow rate and the methanol concentration. In the DMFC, real-time experimentation was carried out at different cell temperatures to find out the optimum temperature at which maximum power density was obtained. The results obtained in simulation and the experiment were compared and it was concluded that the temperature was the most influencing process variable and 333K was the optimum operating temperature required to achieve the most productive performance in power density of the DMFC.

scholarly journals Thermal Profile of a Low-Concentrator Photovoltaic: A COMSOL Simulation

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Maryam M. Alqurashi ◽  
Reem M. Altuwirqi ◽  
Entesar A. Ganash
Keyword(s):  
Wind Speed ◽  
Temperature Gradient ◽  
Solar Radiation ◽  
Fossil Fuels ◽  
Electrical Power ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
Thermal Profile ◽  
Ambient Temperatures ◽  
Pv Panel

With the gradual reduction of fossil fuels, it is essential to find alternative renewable sources of energy. It is important to take advantage of substitutes that are less expensive and more efficient in energy production. Photovoltaic concentrators (CPVs) are effective methods through which solar energy can be maximized resulting in more conversion into electrical power. V-trough concentrators are the simplest types of low-CPV in terms of design as it is limited to the use of two plane mirrors with a flat photovoltaic (PV) plate. A consequence of concentrating more solar radiation on a PV panel is an increase in its temperature that may decrease its efficiency. In this work, the thermal profile of the PV plate in a V-trough system will be determined when this system is placed in different geographical locations in Saudi Arabia. The simulation is conducted using COMSOL Multiphysics software with a ray optics package integrated with a heat transfer routine. The 21st of June was chosen to conduct the simulation as it coincides with the summer solstice. The employment of wind as a cooling method for V-troughs was investigated in this work. It was found that with the increase in wind speed, the PV panel temperature dropped significantly below its optimum operating temperature. However, due to the mirrors’ attachment to the PV panel, the temperature distribution on the surface of the panel was nonuniform. The temperature gradient on the PV surface was reduced with the increase of wind speed but not significantly. Reducing the size of the mirrors resulted in a partial coverage of solar radiation on the PV surface which helped in reducing the temperature gradient but did not eliminate it. This work can assist in testing numerous cooling models to optimize the use of V-troughs and increase its efficiency especially in locations having high ambient temperatures.

scholarly journals Performance Analysis of a PEM Fuel Cell Stack Having 150 cm2 Active Layer by Using Design of Experiments (DOE)

2020 ◽  
Vol 162 ◽  
pp. 01004
Author(s):  
Elif Eker Kahveci ◽  
Imdat Taymaz
Keyword(s):  
Fuel Cell ◽  
Power Density ◽  
Active Layer ◽  
Flow Rate ◽  
Polymer Electrolyte Membrane ◽  
Operating Conditions ◽  
Cell Temperature ◽  
Fuel Cell Stack ◽  
Electrolyte Membrane ◽  
Optimization Study

In this study, the effects of operating parameters on power density of a 3-cell PEMFC (Polymer Electrolyte Membrane Fuel Cell) stack with serpentine flow channels having 150 cm2 total active layer have been examined experimentally. Desing Expert, which is the experimental design program (trial version) was used, and the data obtained as a result of the experiments were analyzed by entering this program. A total of 25 experiments were carried out according to the design created with the data entered into the program within the specified operating conditions range. The independent variables were entered which are cell temperature, humidification temperature, H2 flow rate and O2 flow rate, and the response is the power density. In this study, the hydrophobic cell stack which has the highest cell performance of which was previous studies results was used. In the optimization study, keeping the power density and maximum H2 flow to a minimum, the most suitable values are cell temperature 57.826°C, humidification temperature 56.151°C, O2 flow 1.587 L/min. Finally 432.398 mW/cm2 power density value was obtained under these operating conditions.

scholarly journals New Comparative Study of High-Sensitivity H2Gas Sensors at Room Temperature Based on ZnO NWs Grown on Si and PS/Si Substrates without Catalyst by Wet Thermal Evaporation Method

2021 ◽  
Vol 2114 (1) ◽  
pp. 012087
Author(s):  
H. I. Abdulgafour ◽  
Thamer A.A. Hassan ◽  
F.K. Yam
Keyword(s):  
Gas Sensor ◽  
Flow Rate ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Specific Area ◽  
Hydrogen Gas ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
High Quality ◽  
Thermal Evaporation Method

Abstract A novel approach for growing high-quality ZnOnano-structures with no catalyst using an inexpensive technique that is called wet thermal evaporation has been investigated for gas sensor applications. For a novel comparative investigation of H2 gas sensors, large regions regarding the well-aligned coral reef-like ZnOnano-structures on the porous Si (PS) and flower-like nano-rods on Silicon were successfully utilized. In the presented study, a Pd/ZnO/Pd metal-semiconductor-metal was efficiently created for H2 gas sensor device employing high-quality ZnOnano-structures that are grown on a variety of the substrates. At room temperature, the sensitivity related to ZnO/PS and ZnO/Si is evaluated at various flow rate values (25sccm, 50sccm, 100sccm, and 150sccm) of 2% H2 gas. The I-V characteristics revealed that ZnO/Si has a larger hydrogen gas barrier height than ZnO/PS. At room temperature, the ZnO/Si sensitivity was about 105% and 190% for ZnO/PS at 150sccm flow rate. The sensors’ sensitivity and optimum operating temperature for ZnO/PS at 150sccm of H2 gas are 350% (at 100 Celsius), which is higher compared to double the maximal sensitivity with regard to ZnO/Si device at a temperature of 150 Celsius. This research concluded that because ZnO/PS has a large specific area, it has a greater possibility of reacting with gases and increasing sensitivity at the temperature of theroom.

scholarly journals Dynamic Modelling and Simulation of a Multistage Flash Desalination System

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 522
Author(s):  
Qiu-Yun Huang ◽  
Ai-Peng Jiang ◽  
Han-Yu Zhang ◽  
Jian Wang ◽  
Yu-Dong Xia ◽  
...  
Keyword(s):  
Real Time ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Dynamic Change ◽  
Seawater Temperature ◽  
Dynamic Modelling ◽  
Optimal Operation ◽  
Simultaneous Solution ◽  
Time Optimal

As the leading thermal desalination method, multistage flash (MSF) desalination plays an important role in obtaining freshwater. Its dynamic modeling and dynamic performance prediction are quite important for the optimal control, real-time optimal operation, maintenance, and fault diagnosis of MSF plants. In this study, a detailed mathematical model of the MSF system, based on the first principle and its treatment strategy, was established to obtain transient performance change quickly. Firstly, the whole MSF system was divided into four parts, which are brine heat exchanger, flashing stage room, mixed and split modulate, and physical parameter modulate. Secondly, based on mass, energy, and momentum conservation laws, the dynamic correlation equations were formulated and then put together for a simultaneous solution. Next, with the established model, the performance of a brine-recirculation (BR)-MSF plant with 16-stage flash chambers was simulated and compared for validation. Finally, with the validated model and the simultaneous solution method, dynamic simulation and analysis were carried out to respond to the dynamic change of feed seawater temperature, feed seawater concentration, recycle stream mass flow rate, and steam temperature. The dynamic response curves of TBT (top brine temperature), BBT (bottom brine temperature), the temperature of flashing brine at previous stages, and distillate mass flow rate at previous stages were obtained, which specifically reflect the dynamic characteristics of the system. The presented dynamic model and its treatment can provide better analysis for the real-time optimal operation and control of the MSF system to achieve lower operational cost and more stable freshwater quality.

scholarly journals Experimental Verification of Real-Time Flow-Rate Estimations in a Tilting-Ladle-Type Automatic Pouring Machine

2021 ◽  
Vol 11 (15) ◽  
pp. 6701
Author(s):  
Yuta Sueki ◽  
Yoshiyuki Noda
Keyword(s):  
Real Time ◽  
Molten Metal ◽  
Flow Rate ◽  
Kalman Filters ◽  
Estimation Method ◽  
Estimation Methods ◽  
Liquid Volume ◽  
Model Parameters ◽  
Rate Estimation ◽  
Time Flow

This paper discusses a real-time flow-rate estimation method for a tilting-ladle-type automatic pouring machine used in the casting industry. In most pouring machines, molten metal is poured into a mold by tilting the ladle. Precise pouring is required to improve productivity and ensure a safe pouring process. To achieve precise pouring, it is important to control the flow rate of the liquid outflow from the ladle. However, due to the high temperature of molten metal, directly measuring the flow rate to devise flow-rate feedback control is difficult. To solve this problem, specific flow-rate estimation methods have been developed. In the previous study by present authors, a simplified flow-rate estimation method was proposed, in which Kalman filters were decentralized to motor systems and the pouring process for implementing into the industrial controller of an automatic pouring machine used a complicatedly shaped ladle. The effectiveness of this flow rate estimation was verified in the experiment with the ideal condition. In the present study, the appropriateness of the real-time flow-rate estimation by decentralization of Kalman filters is verified by comparing it with two other types of existing real-time flow-rate estimations, i.e., time derivatives of the weight of the outflow liquid measured by the load cell and the liquid volume in the ladle measured by a visible camera. We especially confirmed the estimation errors of the candidate real-time flow-rate estimations in the experiments with the uncertainty of the model parameters. These flow-rate estimation methods were applied to a laboratory-type automatic pouring machine to verify their performance.

Pre-Excitation, Catalytic Oxidation of Analytes over Hopcalite in Flame/Furnace Infrared Emission (FIRE) Spectrometry

1992 ◽  
Vol 46 (4) ◽  
pp. 631-639 ◽  
Author(s):  
Yunke Zhang ◽  
Marianna A. Busch ◽  
Kenneth W. Busch
Keyword(s):  
Detection Limit ◽  
Soot Formation ◽  
Vibrational Excitation ◽  
Infrared Emission ◽  
Optimum Operating ◽  
Air Flow Rate ◽  
Linear Calibration ◽  
Furnace Temperature ◽  
Optimum Operating Temperature ◽  
Pure Acetone

Gas-phase infrared emission measurements made with the use of a new, specially designed, electrically heated furnace or a small hydrogen/air flame have shown that oxidation of a variety of carbon-based analytes to CO2 over the catalyst hopcalite prior to vibrational excitation in the furnace or flame markedly improves the response of the FIRE radiometer. Calibration curves obtained with the use of the furnace alone were generally nonlinear, while those obtained with the flame alone had slopes that were compound dependent. By the use of hopcalite in conjunction with the furnace, conversion to CO2 was significantly improved, and the FIRE response to pure acetone, benzene, dichloromethane, 1-chloro-2-methylpropane, heptane, methanol, and toluene became directly proportional to the number of moles of carbon introduced. In the case of the flame, as little as 0.1 g of hopcalite was sufficient to give a single, linear calibration curve (based on moles of carbon) for injection volumes of 0.2–1.0 μL of a test mixture composed of equal volumes of acetone, benzene, hexane, propanol, and tetrahydrofuran. With the use of hopcalite at its experimentally determined, optimum operating temperature of 380°C, an air flow rate of 45 mL min−1, and a furnace temperature of 600°C, the detection limit for hexane was found to be 518 ng C s−1. The use of hopcalite in conjunction with the flame (900°C) improved this detection limit by two orders of magnitude, due to the combined effects of an increase in excitation temperature and a decrease in source background noise. Injection of chlorinated compounds was found to temporarily poison the hopcalite, resulting in soot formation and loss of catalytic activity for periods of approximately ten minutes.

Fabrication and Characterization of Anode-Supported SDC Film Electrolyte and its Single Cell

2010 ◽  
Vol 177 ◽  
pp. 407-410
Author(s):  
Xi Bao Li ◽  
Jian Wang ◽  
Xiao Hua Yu ◽  
Hong Xing Gu ◽  
Gang Qin Shao
Keyword(s):  
Single Cell ◽  
Power Density ◽  
Flow Rate ◽  
Current Density ◽  
Tape Casting ◽  
Threshold Value ◽  
Interface Layer ◽  
Open Circuit ◽  
Discharge Performance ◽  
Film Electrolyte

NiO-YSZ (NiO-yttria stabilized zirconia, 3:2, wt.%) and samaria doped ceria (SDC) tapes were prepared by aqueous tape casting. NiO-YSZ anode-supported SDC film electrolyte half-cell was fabricated by laminating and co-sintering at 1400°C for 2 h. The single cell was prepared after LSCF-SDC (lanthanum strontium cobalt ferrite-SDC, 1:1, wt.%) cathode was coated on the electrolyte surface and sintered at 1300 °C for 2 h. The discharge performance of the single cell was tested from 500 °C to 800 °C at different H2 flow rate. Results showed that the relationship between current (I) of and H2 flow rate (ν) was I = 8 × 106 ν. Before reaching the threshold value of H2 flow rate, the current density of single cell increased with the increasing of H2 flow rate. However, the current density did not change with increasing of H2 flow rate over the threshold value. The open circuit voltage (OCV) of single cell at 500°C, 600°C, 700°C, 800°C was 0.978, 0.921, 0.861, 0.803 V, respectively. The maximum power density reached 93.03 mW/cm2 at 800°C. The resistance of interface layer between Ni-YSZ anode and SDC electrolyte was the key impact on the power density.

Electrostatic Sensor for Real–Time Mass Flow Rate Measurement of Particle Conveying in Pneumatic Pipeline

2012 ◽  
Author(s):  
Mohd. Fua’ad Rahmat ◽  
Wee Lee Yaw
Keyword(s):  
Real Time ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cross Correlation ◽  
High Accuracy ◽  
Industrial Processes ◽  
Rate Measurement ◽  
Flow Rate Measurement ◽  
Controlled Flow

This paper discussed the electrostatic sensors that have been constructed for real–time mass flow rate measurement of particle conveying in a Pneumatic pipeline. Many industrial processes require continuous, smooth, and consistent delivery of solids materials with a high accuracy of controlled flow rate. This requirement can only be achieved by installing a proper measurement system. Electrostatic sensor offers the most inexpensive and simplest means of measuring solids flows in pipes. Key words: Electrostatic sensor, cross-correlation, peripheral velocity

scholarly journals Titanium Dioxide-Based64∘YXLiNbO3Surface Acoustic Wave Hydrogen Gas Sensors

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
A. Z. Sadek ◽  
D. Buso ◽  
A. Martucci ◽  
P. Mulvaney ◽  
W. Wlodarski ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Acoustic Wave ◽  
Gas Sensors ◽  
Sol Gel ◽  
Hydrogen Gas ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
Helium Atmosphere ◽  
Gas Detectors ◽  
Hydrogen Gas Sensors

Amorphous titanium dioxide (TiO2) and gold (Au) dopedTiO2-based surface acoustic wave (SAW) sensors have been investigated as hydrogen gas detectors. The nanocrystal-dopedTiO2films were synthesized through a sol-gel route, mixing a Ti-butoxide-based solution with diluted colloidal gold nanoparticles. The films were deposited via spin coating onto64∘YXLiNbO3SAW transducers in a helium atmosphere. The SAW gas sensors were operated at various temperatures between 150 and310∘C. It was found that gold doping onTiO2increased the device sensitivity and reduced the optimum operating temperature.

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