Optimization of Operating Conditions for an SOFC Stack

2015 ◽  
Vol 656-657 ◽  
pp. 119-123 ◽  
Author(s):  
Chang Wei Lu ◽  
Szu Han Wu ◽  
Hung Hsiang Lin ◽  
Wen Hsiu Chung ◽  
Jing Kai Lin ◽  
...  
Keyword(s):  
Single Cell ◽  
Electrical Power ◽  
Performance Testing ◽  
Operating Conditions ◽  
Fuel Utilization ◽  
Flow Rates ◽  
Electrical Efficiency ◽  
Fuel Flow ◽  
Anode Supported Cell ◽  
Electrical Power Output

Performance testing for a single-cell solid oxide fuel cell (SOFC) stack is carried out to optimize its operating conditions. In this study, the Taguchi method is employed to effectively define the test matrix. The single-cell stack is composed of a 10x10 cm2 commercial anode-supported cell, metallic interconnects, current collectors, and glass-ceramic sealant. The major parameters for the experiments include: flow rates of fuel (hydrogen) and oxidant (air) gases, and temperatures. The target indices are the electrical power output, electrical efficiency, and fuel utilization. The fuel flow rates (400, 500, and 600 sccm), air flow rates (1000, 1500, and 2000 sccm) and temperatures (650, 675, and 700°C) are evaluated for different experimental combinations. The results reveal that, the operating temperature is the most crucial factor to the stack performance. The maximum power reaches to 46 W (570 mW/cm2) with a current of 58 A (715 mA/cm2) at test conditions of 700°C and fuel and oxidant flow rates of 600 sccm and 2000 sccm, respectively. As the fuel flow rate decreases to 400 sccm, the electrical efficiency can reach to 53% while the power at 34.6 W (427 mW/cm2) and current 42 A (518 mA/cm2). As the current increases to 44 A (543 mA/cm2), the fuel utilization reaches to 83%, nevertheless concentration polarization is observed in such operating condition.

Application of Taguchi Method to Optimize the Operating Parameters for a Solid Oxide Fuel Cell

2015 ◽  
Vol 656-657 ◽  
pp. 544-548 ◽  
Author(s):  
Jing Kai Lin ◽  
Shin Wei Cheng ◽  
Chang Wei Lu ◽  
Yung Neng Cheng ◽  
Ruey Yi Lee ◽  
...  
Keyword(s):  
Taguchi Method ◽  
Operating Temperature ◽  
Air Flow ◽  
Orthogonal Arrays ◽  
Solid Oxide ◽  
Operating Parameters ◽  
Fuel Utilization ◽  
Flow Rates ◽  
Electrical Efficiency ◽  
Fuel Flow

In this paper, the Taguchi method is employed to systematically optimize the operating parameters of an anode-supported SOFC cell. Effects of cell temperatures (650, 675, and 700°C), fuel flow rates (400, 500, and 600 sccm), and oxidant flow rates (1000, 1500, and 2000 sccm) on electrochemical performance, fuel utilization, and electrical efficiency are investigated. The L27 orthogonal arrays of Taguchi experiments are designed and carried out. The signal-to-noise ratios (S/N) indicate that the electrical efficiency is majorly determined by the hydrogen and air flow rates, while the power output is significantly affected by the operating temperatures. The analysis of variance (ANOVA) reveals that, under the operating temperature at 675°C with hydrogen and air flow rates respectively of 500 and 1500 sccm, the maximum power density is 480 mW/cm2, where the overall electrical efficiency and fuel utilization is 51.9% and 86.1%, respectively.

scholarly journals Design of a Hybrid Photovoltaic Thermal System in Lebanon

2018 ◽  
Vol 171 ◽  
pp. 02002
Author(s):  
Elie Karam ◽  
Patrick Moukarzel ◽  
Maya Chamoun ◽  
Charbel Habchi ◽  
Charbel Bou-Mosleh
Keyword(s):  
Power Output ◽  
Electrical Power ◽  
Hot Water ◽  
Thermal System ◽  
Conduction Model ◽  
Electrical Efficiency ◽  
Pv Module ◽  
Temperature Loss ◽  
Photovoltaic Thermal System ◽  
Electrical Power Output

Due to global warming and the high toxic gas emissions of traditional power generation methods, renewable energy has become a very active topic in many applications. This study focuses on one versatile type of solar energy: Hybrid Photovoltaic Thermal System (hybrid PV/T). Hybrid PV/T combines both PV and thermal application and by doing this the efficiency of the system will increase by taking advantage of the temperature loss from PV module. The solar radiation and heat will be harnessed to deliver electricity and hot water simultaneously. In the present study a solar system is designed to recycle the heat and improve the temperature loss from PV module in order to supply both electricity and domestic hot water. The project was tested twice in Zouk Mosbeh - Lebanon; on May 18, 2016, and June 7, 2016. The average electrical efficiency was around 11.5% with an average electrical power output of 174.22 W, while with cooling, the average electrical efficiency reaches 11% with a power output of 200 W. The temperature increases by about 7 degrees Celsius from the inlet. The 1D conduction model is also performed in order to design the hybrid PV/T system.

scholarly journals Photovoltaic Panels Temperature Regulation Using Evaporative Cooling Principle: Detailed Theoretical and Real Operating Conditions Experimental Approaches

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 145
Author(s):  
Zeyad A. Haidar ◽  
Jamel Orfi ◽  
Zakariya Kaneesamkandi
Keyword(s):  
Electrical Power ◽  
Evaporative Cooling ◽  
Operating Conditions ◽  
Bottom Surface ◽  
Transfer Model ◽  
Solar Pv ◽  
Pv Panel ◽  
Better Regulation ◽  
Steady State Heat ◽  
Electrical Power Output

Solar photovoltaic (PV) applications are gaining a great interest worldwide and dominating the renewable energy sector. However, the solar PV panels’ performance is reduced significantly with the increase in their operating temperature, resulting in a substantial loss of energy production and poor economic scenarios. This research contributes to overcoming the PV performance degradation due to the temperature rise. This work involves experimental and theoretical studies on cooling of PV panels using the evaporative cooling (EC) principle. A new EC design to cool the bottom surface of a PV panel was proposed, fabricated, tested, and modeled. A series of experimentation readings under real conditions showed the effectiveness of the method. A steady state heat and mass transfer model was implemented and compared with the experimental data. Fair agreement between the results of the modelling and experimental work was observed. It was found that the temperature of the PV panel can be decreased by 10 °C and the power improvement achieved was 5%. Moreover, the EC helps to stabilize the panels’ temperature fluctuation, which results in a better regulation of electrical power output and reduces the uncertainty associated with solar PV systems.

The Effect of the Fuel-Cell Unit Size on the Efficiency of a Fuel- Cell-Topped Rankine Power Cycle

1993 ◽  
Vol 115 (2) ◽  
pp. 105-107 ◽  
Author(s):  
W. R. Dunbar ◽  
N. Lior ◽  
R. A. Gaggioli
Keyword(s):  
Fuel Cell ◽  
Fuel Consumption ◽  
Power Plants ◽  
Electrical Power ◽  
Operating Conditions ◽  
Unit Size ◽  
Power Cycle ◽  
Fuel Flow ◽  
The Relationship ◽  
Plant Efficiency

Dunbar, Lior and Gaggioli (1991) proposed a configuration of a fuel-cell-topped electrical Rankine power generating station and analyzed its performance. That study revealed that the fuel-cell topping improved plant efficiency to values up to 62 percent, versus the conventional plant efficiency of 41.5 percent. This work lays the foundation for a thermoeconomic analysis of such systems by relating exergy consumption to fuel-cell unit size, as follows: 1) the relationship between system efficiency (and hence fuel consumption) and fuel-cell unit size is presented for a number of fuel-cell operating conditions; 2) the relationship between fuel flow rate and fuel-cell unit size is shown; and 3) the exergetic effects of the major plant components are discussed as a function of fuel-cell unit size. The results reveal that specific fuel consumption may be reduced by as much as 32 percent when incorporating fuel-cell units into electrical power plants.

scholarly journals Management of the Output Electrical Power in Thermoelectric Generators

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1514 ◽  
Author(s):  
Elisabetta Dimaggio ◽  
Francesco Rossella ◽  
Giovanni Pennelli
Keyword(s):  
Conversion Efficiency ◽  
Power Output ◽  
Electrical Resistance ◽  
Electrical Power ◽  
Operating Conditions ◽  
Maximum Power ◽  
Thermoelectric Generators ◽  
Power Transfer ◽  
Electrical Load ◽  
Electrical Power Output

Thermoelectric Generators (TEGs) are devices for direct conversion of heat into electrical power and bear a great potential for applications in energy scavenging and green energy harvesting. Given a heat source, the conversion efficiency depends on the available temperature difference, and must be maximized for optimal operation of the TEG. In this frame, the choice of materials with high thermoelectric properties should be accompanied by the identification of criteria for an optimal exploitation of the electrical power output. In this work, we briefly review the main properties of TEGs, focusing on the electrical power output and the thermal-to-electrical conversion efficiency. Besides, we discuss principles of operation of TEGs enabling the optimization of the electrical power output, based on the suitable choice of the electrical load. In particular, we comparatively present and discuss the conditions for matching the electrical load—yielding to maximum power transfer—and those for maximizing the conversion efficiency. We compare the two conditions applying them to the exploitation of a heat reservoir for energy storage and to the recovery of heat from a heat exchanger. We conclude that the difference between the two conditions is not significant enough to justify the complexity required by the implementation of the maximum efficiency. In addition, we consider the effect of the thermal contact resistance on the electrical power output. Using a simple thermal-electrical model, we demonstrate that the equivalent electrical resistance measured between the terminals of the TEG depends on the thermal exchange. Hence, for maximum power transfer, the electrical load of the TEG should not match its parasitic resistance, but the equivalent electrical resistance in each specific operating conditions, which determine the thermal fluxes. The model can be applied for the development of efficient alternative algorithms for maximum power point tracking.

scholarly journals Power Performance Measurements of the NREL CART-2 Wind Turbine Using a Nacelle-Based Lidar Scanner

2014 ◽  
Vol 31 (10) ◽  
pp. 2029-2034 ◽  
Author(s):  
Andreas Rettenmeier ◽  
David Schlipf ◽  
Ines Würth ◽  
Po Wen Cheng
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Shear ◽  
Electrical Power ◽  
Performance Testing ◽  
Performance Measurements ◽  
Power Performance ◽  
Lidar System ◽  
Scanning Lidar ◽  
Electrical Power Output

Abstract Different certification procedures in wind energy, such as power performance testing or load estimation, require measurements of the wind speed, which is set in relation to the electrical power output or the turbine loading. The wind shear affects the behavior of the turbine as hub heights and rotor diameters of modern wind turbines increase. Different measurement methods have been developed to take the wind shear into account. In this paper an approach is presented where the wind speed is measured from the nacelle of a wind turbine using a scanning lidar system. The measurement campaign was performed on the two-bladed Controls Advanced Research Turbine (CART-2) at the National Wind Technology Center in Colorado. The wind speed of the turbine inflow was measured and recalculated in three different ways: using an anemometer installed on a meteorological mast, using the nacelle-based lidar scanner, and using the wind turbine itself. Here, the wind speed was recalculated from turbine data using the wind turbine as a big horizontal anemometer. Despite the small number of useful data, the correlation between this so-called rotor effective wind speed and the wind speed measured by the scanning nacelle-based lidar is high. It could be demonstrated that a nacelle-based scanning lidar system provides accurate measurements of the wind speed converted by a wind turbine. This is a first step, and it provides evidence to support further investigations using a much more extensive dataset and refines the parameters in the measurement process.

Nitrogen Removal from Anaerobically-Treated Leachate

1984 ◽  
Vol 19 (1) ◽  
pp. 87-100
Author(s):  
D. Prasad ◽  
J.G. Henry ◽  
P. Elefsiniotis
Keyword(s):  
Nitrogen Removal ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Anaerobic Filter ◽  
Ph Values ◽  
Wide Range ◽  
Ammonia Desorption ◽  
Effects Of Ph

Abstract Laboratory studies were conducted to demonstrate the effectiveness of diffused aeration for the removal of ammonia from the effluent of an anaerobic filter treating leachate. The effects of pH, temperature and air flow on the process were studied. The coefficient of desorption of ammonia, KD for the anaerobic filter effluent (TKN 75 mg/L with NH3-N 88%) was determined at pH values of 9, 10 and 11, temperatures of 10, 15, 20, 30 and 35°C, and air flow rates of 50, 120, and 190 cm3/sec/L. Results indicated that nitrogen removal from the effluent of anaerobic filters by ammonia desorption was feasible. Removals exceeding 90% were obtained with 8 hours aeration at pH of 10, a temperature of 20°C, and an air flow rate of 190 cm3/sec/L. Ammonia desorption coefficients, KD, determined at other temperatures and air flow rates can be used to predict ammonia removals under a wide range of operating conditions.

scholarly journals Near-field thermophotovoltaics for efficient heat to electricity conversion at high power density

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rohith Mittapally ◽  
Byungjun Lee ◽  
Linxiao Zhu ◽  
Amin Reihani ◽  
Ju Won Lim ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
High Efficiency ◽  
Near Field ◽  
Electrical Power ◽  
Photovoltaic Cells ◽  
High Power Density ◽  
Pv Cell ◽  
Electrical Power Output ◽  
Power Densities

AbstractThermophotovoltaic approaches that take advantage of near-field evanescent modes are being actively explored due to their potential for high-power density and high-efficiency energy conversion. However, progress towards functional near-field thermophotovoltaic devices has been limited by challenges in creating thermally robust planar emitters and photovoltaic cells designed for near-field thermal radiation. Here, we demonstrate record power densities of ~5 kW/m2 at an efficiency of 6.8%, where the efficiency of the system is defined as the ratio of the electrical power output of the PV cell to the radiative heat transfer from the emitter to the PV cell. This was accomplished by developing novel emitter devices that can sustain temperatures as high as 1270 K and positioning them into the near-field (<100 nm) of custom-fabricated InGaAs-based thin film photovoltaic cells. In addition to demonstrating efficient heat-to-electricity conversion at high power density, we report the performance of thermophotovoltaic devices across a range of emitter temperatures (~800 K–1270 K) and gap sizes (70 nm–7 µm). The methods and insights achieved in this work represent a critical step towards understanding the fundamental principles of harvesting thermal energy in the near-field.

Heat transfer characteristic modelling and the effect of operating conditions on re-cooled cycle for a scramjet

2011 ◽  
Vol 115 (1164) ◽  
pp. 83-90 ◽  
Author(s):  
W. Bao ◽  
J. Qin ◽  
W. X. Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Transfer Characteristic ◽  
Cooling Capacity ◽  
Sensitivity Study ◽  
Performance Model ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Fuel Flow ◽  
Temperature And Pressure

Abstract A re-cooled cycle has been proposed for a regeneratively cooled scramjet to reduce the hydrogen fuel flow for cooling. Upon the completion of the first cooling, fuel can be used for secondary cooling by transferring the enthalpy from fuel to work. Fuel heat sink (cooling capacity) is thus repeatedly used and fuel heat sink is indirectly increased. Instead of carrying excess fuel for cooling or seeking for any new coolant, the cooling fuel flow is reduced, and fuel onboard is adequate to satisfy the cooling requirement for the whole hypersonic vehicle. A performance model considering flow and heat transfer is build. A model sensitivity study of inlet temperature and pressure reveals that, for given exterior heating condition and cooling panel size, fuel heat sink can be obviously increased at moderate inlet temperature and pressure. Simultaneously the low-temperature heat transfer deterioration and Mach number constrains can also be avoided.

Performance Analysis of Near-Field Thermophotovoltaic With a Multilayer Metallodielectric Emitter

2016 ◽  
Author(s):  
Y. Yang ◽  
J. Y. Chang ◽  
L. P. Wang
Keyword(s):  
Heat Flux ◽  
Power Output ◽  
Indium Tin Oxide ◽  
Effective Medium Theory ◽  
Near Field ◽  
Electrical Power ◽  
Electrical Contacts ◽  
Alumina Layer ◽  
Photon Transport ◽  
Electrical Power Output

The photon transport and energy conversion of a near-field thermophotovoltaic (TPV) system with a selective emitter composed of alternate tungsten and alumina layers and a photovoltaic cell sandwiched by electrical contacts are theoretically investigated in this paper. Fluctuational electrodynamics along with the dyadic Green’s function for a multilayered structure is applied to calculate the spectral heat flux, and photocurrent generation and electrical power output are solved from the photon-coupled charge transport equations. The tungsten and alumina layer thicknesses are optimized to match the spectral heat flux with the bandgap of TPV cell. The spectral heat flux is much enhanced when plain tungsten emitter is replaced with the multilayer emitter due to the mechanism of surface plasmon polariton coupling in the tungsten thin film. In addition, the invalidity of effective medium theory to predict photon transport in the near field with multilayer emitters is discussed. Effects of a gold back reflector and indium tin oxide front coating with nanometer thickness, which could practically act as the electrodes to collect the photon-generated charges on the TPV cell, are explored. Conversion efficiency of 23.7% and electrical power output of 0.31 MW/m2 are achieved at 100 nm vacuum gap when the emitter and receiver are respectively at temperatures of 2000 K and 300 K.

Sign in / Sign up

Export Citation Format

Share Document