scholarly journals Next-Generation Cryo-Electric Hydrogen-Powered Aviation

2021 ◽  
Author(s):  
Jonas Kristiansen Nøland ◽  
Christian Hartmann ◽  
Runar Mellerud
Keyword(s):  
Co2 Emissions ◽  
Liquid Form ◽  
Design Choice ◽  
Higher Power ◽  
Overall Performance ◽  
Hydrogen Cooling ◽  
Power Densities ◽  
Important Design ◽  
Space Occupation ◽  
Cooling Ability

Hydrogen-powered airplanes have recently attracted a revitalized push in the aviation sector to combat CO2 emissions. However, to also reduce, or even eliminate, non-CO2 emissions and contrails, the combination of hydrogen with all-electric solutions is undoubtedly the best option to move toward the ambitious goal of climate-neutral aviation. Another important design choice is to store hydrogen cryogenically in its liquid form (LH2) to reduce space occupation compared to storage as compressed gas. However, the LH2 fuels cannot be utilized directly in fuel cells. It needs to be brought from liquid to a gas at about 350 K, where large amounts of heat must be added. Thus, a synergy can be made from this otherwise wasted cryogenic refrigeration power where superconducting machines (SCMs) and cold power electronics (CPE) are low-hanging fruits that could lead to radical space and weight reductions onboard the aircraft. These opportunities can be realized without having to pay the price, nor the volume occupation and mass needed for the cooling ability usually needed to achieve these extraordinary performances. In fact, this ground-breaking synergy makes cryogenic energy conversion relevant in a whole new way for aviation. The SCMs’ more than five times higher power densities than their conventional counterparts are exceptionally significant. This article introduces the recently proposed cryo-electric drivetrain initiatives and explores the opportunities of using direct hydrogen cooling as a potential heating solution to enhance the overall performance and scalability of zero-emission propulsion systems in future regional aircraft.

scholarly journals Next-Generation Cryo-Electric Hydrogen-Powered Aviation

2021 ◽  
Author(s):  
Jonas Kristiansen Nøland ◽  
Christian Hartmann ◽  
Runar Mellerud
Keyword(s):  
Co2 Emissions ◽  
Liquid Form ◽  
Design Choice ◽  
Higher Power ◽  
Overall Performance ◽  
Hydrogen Cooling ◽  
Power Densities ◽  
Important Design ◽  
Space Occupation ◽  
Cooling Ability

Hydrogen-powered airplanes have recently attracted a revitalized push in the aviation sector to combat CO2 emissions. However, to also reduce, or even eliminate, non-CO2 emissions and contrails, the combination of hydrogen with all-electric solutions is undoubtedly the best option to move toward the ambitious goal of climate-neutral aviation. Another important design choice is to store hydrogen cryogenically in its liquid form (LH2) to reduce space occupation compared to storage as compressed gas. However, the LH2 fuels cannot be utilized directly in fuel cells. It needs to be brought from liquid to a gas at about 350 K, where large amounts of heat must be added. Thus, a synergy can be made from this otherwise wasted cryogenic refrigeration power where superconducting machines (SCMs) and cold power electronics (CPE) are low-hanging fruits that could lead to radical space and weight reductions onboard the aircraft. These opportunities can be realized without having to pay the price, nor the volume occupation and mass needed for the cooling ability usually needed to achieve these extraordinary performances. In fact, this ground-breaking synergy makes cryogenic energy conversion relevant in a whole new way for aviation. The SCMs’ more than five times higher power densities than their conventional counterparts are exceptionally significant. This article introduces the recently proposed cryo-electric drivetrain initiatives and explores the opportunities of using direct hydrogen cooling as a potential heating solution to enhance the overall performance and scalability of zero-emission propulsion systems in future regional aircraft.

An Investigation of Methane Combustion in a Rectangular Shaped Meso Chamber

2014 ◽  
Author(s):  
Mahbub Ahmed ◽  
Cheng Zhang ◽  
Scott McKay ◽  
Vivek Shirsat ◽  
Jobaidur Khan
Keyword(s):  
Cfd Simulation ◽  
Methane Combustion ◽  
Ansys Fluent ◽  
Flamelet Model ◽  
Power Generators ◽  
Rich Condition ◽  
Higher Power ◽  
Fluent Software ◽  
Finite Volume Approach ◽  
Power Densities

Hydrocarbon-based miniature power generators are promising any many application since hydrocarbon based fuels have higher power densities compared to conventional lithium batteries. A 40mm long meso-combustor of two different configurations, two-inlet and three-inlet, were used to investigate the combustion of methane in the meso-chamber. A non-premixed combustion of methane and oxygen was simulated numerically using a steady laminar flamelet model. The mesh generation and the CFD simulation were performed using ANSYS FLUENT software. A a finite volume approach was used for the simulation. The fuel-oxidizer mixing, thermal behavior and fuel burning efficiency were studied. An adequate mixing that supports the combustion was observed in certain locations. The exhaust gas was analyzed experimentally. The temperature distributions were also observed to predict the flame locations. According to the numerical analysis it was apparent that the flame would be anchored in the well mixed regions of the chamber the flames were found to be attached in two distinct locations. One in the upstream zone and the other one in the downstream zone. Another important finding was that the fuel lean condition produced higher efficiency than the fuel rich condition.

Design and Preliminary Testing of a Prototype Thermophotovoltaic System

2003 ◽  
Author(s):  
Chris J. Astle ◽  
Gary J. Kovacik ◽  
Ted R. Heidrick
Keyword(s):  
The Sun ◽  
Solar Pv ◽  
Pv System ◽  
Solar Photovoltaics ◽  
Compact Size ◽  
Higher Power ◽  
Close Proximity ◽  
Solar Pv System ◽  
Additional Improvement ◽  
Power Densities

Thermophotovoltaics (TPV) is technology similar to conventional solar photovoltaics, which have been in existence for over 50 years. The main difference between traditional solar photovoltaics and TPV is that, instead of the sun, an “emitter” is used to produce light, which is then converted into electricity by the TPV system. This emitter is heated via combustion or some other method until photons are ejected. Although the light utilized in the TPV system is not as energetic as that from the sun, the fact that the TPV cells can be placed in close proximity to the source (compared with the distance to the sun) increases the intensity of the light received by the cells. This results in a higher power production density than is possible with traditional solar photovoltaic systems. One estimate of maximum achievable output power density for TPV systems is 5W/cm2, approximately 500 times that of a traditional solar PV system. Researchers in this field have already demonstrated power densities of 1.5W/cm2. Other attractions of TPV systems include fuel versatility, compact size, silent sun-independent operation, and low maintenance costs. A TPV test station has been assembled at the Alberta Research Council in Canada. A general overview of the background technology and system components will be presented, as well as preliminary experimental results. Areas that require additional improvement in order to increase system efficiency will also be addressed.

Performance of micropiled raft in sand subjected to vertical concentrated load: centrifuge modeling

2015 ◽  
Vol 52 (1) ◽  
pp. 33-45 ◽  
Author(s):  
A.M. Alnuaim ◽  
H. El Naggar ◽  
M.H. El Naggar
Keyword(s):  
Contact Pressure ◽  
Bending Moment ◽  
Centrifuge Modeling ◽  
Design Parameters ◽  
Concentrated Load ◽  
Centrifuge Testing ◽  
Geotechnical Centrifuge ◽  
Piled Raft Foundation ◽  
Overall Performance ◽  
Important Design

Initial applications of micropiles have involved retrofitting foundations of existing buildings. In these applications, the overall performance of the micropiles–raft (MPR) foundation system is similar to a piled raft foundation where the load is transmitted through both the raft and micropiles. However, there is no guidance available regarding the performance of MPR foundations. In this study, geotechnical centrifuge testing was conducted to investigate the behavior of MPR foundations in sand and evaluate their performance characteristics. The study investigated the effect of raft flexibility on a number of important design parameters, including raft total and differential settlements, raft contact pressure, raft bending moment, and load sharing between the raft and micropiles. In addition, the use of micropiles as settlement reducers was investigated. The results showed that the micropiles carried 42%–59% of the applied load for the MPR configuration considered, which resulted in redistribution of the raft contact pressure. It was found that the Poulos–Davis–Randolph (PDR) method can be used to evaluate the performance of MPR systems with relatively stiff rafts; however, it is not applicable for MPR with flexible raft. A correction factor was proposed to account for the raft flexibility in the PDR method.

The Texas Cryogenic Oxy-Fuel Cycle (TCO): A Novel Approach to Power Generation With CO2 Options

2012 ◽  
Author(s):  
Jason Gatewood ◽  
Jeff Moore ◽  
Marybeth Nored ◽  
Klaus Brun ◽  
Vishwas Iyengar
Keyword(s):  
Co2 Emissions ◽  
Oil Recovery ◽  
High Pressures ◽  
Fuel Cycle ◽  
Thermodynamic Cycle ◽  
Liquid Form ◽  
Power Requirement ◽  
Long Term Storage ◽  
Novel Approach ◽  
The Individual

A novel oxy-fuel based power cycle is presented that combines conventional oxy-fuel cycle technology with novel mixed gaseous compression and liquid pumping of CO2 to produce both useable power and provide transportable CO2 for transportation via pipeline for use in sequestration or enhanced oil recovery (EOR). CO2 emissions reduction is a central focus of climate change initiatives. Therefore, it is desired to have a power plant process cycle that reduces CO2 emissions associated with producing power. Once captured CO2 must be transferred to a sequestration site for long term storage or utilized in EOR operations. Recent research has demonstrated that CO2 is most efficiently transported as a liquid at high pressures via pipelines. A Cryogenic Oxy-Fuel cycle will be presented that captures all CO2 produced during combustion and inherently converts that CO2 to a sequestration-ready state that can be immediately placed into transportation pipelines and stored at the desired sequestration site. The proposed cycle deviates from conventional cycles in that during part of the process the CO2 is in cooled liquid form which allows; 1) Decreased power demand to increase the CO2 pressure because pumping has lower power requirement than compression, 2) The take-off of the CO2 is optimized for pipeline transport and no further compression or expansion is required, and 3) A high overall thermodynamic cycle efficiency can be reached with relatively low firing temperatures in the oxy-burner (around 1000°F). This significantly simplifies the combustor and expander designs required for the process. Additional benefits of the cycle include predicted efficiencies near state of the art IGCC’s, applicability to multiple fuel sources, and cost reduction associated with reduced component sizes utilized in the cycle. This presentation will focus on the overall operational and technological requirements of the novel cycle, a breakdown of the individual components utilized, and simulations demonstrating predicted performance. Technological challenges of implementing a working version of the cycle will be discussed and suggested development required for overcoming the challenges will be presented. This paper will include recent research and development of an oxy-fuel combustor utilized in the cycle as well as implementation of compression and pumping apparatus of recent development.

scholarly journals Solving the Large-Scale TSP Problem in 1 h: Santa Claus Challenge 2020

2021 ◽  
Vol 8 ◽  
Author(s):  
Radu Mariescu-Istodor ◽  
Pasi Fränti
Keyword(s):  
Large Scale ◽  
Computing Time ◽  
Real Life ◽  
Problem Instance ◽  
Santa Claus ◽  
Design Choice ◽  
Long Time ◽  
Problem Instances ◽  
The Given ◽  
Important Design

The scalability of traveling salesperson problem (TSP) algorithms for handling large-scale problem instances has been an open problem for a long time. We arranged a so-called Santa Claus challenge and invited people to submit their algorithms to solve a TSP problem instance that is larger than 1 M nodes given only 1 h of computing time. In this article, we analyze the results and show which design choices are decisive in providing the best solution to the problem with the given constraints. There were three valid submissions, all based on local search, including k-opt up to k = 5. The most important design choice turned out to be the localization of the operator using a neighborhood graph. The divide-and-merge strategy suffers a 2% loss of quality. However, via parallelization, the result can be obtained within less than 2 min, which can make a key difference in real-life applications.

Development of Smart Material-Hydraulic Pumps and Actuators

Aerospace ◽  
2006 ◽  
Author(s):  
Ryan C. Sneed ◽  
Roland R. Smith ◽  
Michael F. Cash ◽  
Gregory L. Bales ◽  
Eric H. Anderson
Keyword(s):  
Smart Materials ◽  
Smart Material ◽  
Hydraulic Systems ◽  
Electromagnetic Actuators ◽  
Higher Power ◽  
Pump Stage ◽  
Material Power ◽  
Power Densities ◽  
Design And Testing ◽  
Magnetostrictive Devices

Smart materials such as piezoelectrics and magnetostrictives produce mechanical power in a form that is improperly matched to many applications. When packaged in typical ways, these stiff materials have excess force but are deficient in displacement. Recent research has suggested that smart materials can be used for the pressurization and pump stage in electrohydrostatic actuators (EHAs). EHAs offer advantages over traditional centralized hydraulic systems by providing local pressurization in a closed fluid system and eliminating the need for distributed, high-pressure fluid lines. Given inherent material power densities, smart material-based EHAs could produce higher power output compared to electromagnetic actuators. High frequency, low displacement smart material actuation, typically operated in the range of 500 Hz, but in some cases much higher, is rectified via fluid flow to produce larger output displacements at lower frequencies. Valve limitations, mechanical compliances, and fluid compressibility account for significant losses in the pumps. Continuing previous research, this paper describes design approaches that address and attempt to minimize losses. Piezoelectric and magnetostrictive devices are compared, and the design and testing of magnetostrictive pumps is described in greater detail, with special considerations given to heat generation and improved efficiency.

scholarly journals Large Planar Na-β″-Al2O3 Solid Electrolytes for Next Generation Na-Batteries

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 433
Author(s):  
Samuel Clark Ligon ◽  
Marie-Claude Bay ◽  
Meike V. F. Heinz ◽  
Corsin Battaglia ◽  
Thomas Graule ◽  
...  
Keyword(s):  
Solid Electrolytes ◽  
Large Diameter ◽  
Tape Casting ◽  
Casting Process ◽  
Hydraulic Press ◽  
Tubular Cells ◽  
Base Materials ◽  
Higher Power ◽  
Power Densities ◽  
Binder Burnout

Large diameter (> 100 mm) planar Na-β″-Al2O3 solid electrolytes (BASE) with thickness from 1.0 to 1.5 mm have been prepared. Na-β″-Al2O3 was processed as a slurry and cast to give several meters of tape. One hundred and forty mm diameter discs were punched from the tape, stacked, and laminated with a large hydraulic press. Binder burnout and sintering were performed in 150 mm diameter MgO spinel encapsulations to mitigate the loss of Na2O vapor. Conductivity and flexural strength were measured on smaller Na-β″-Al2O3 samples produced via the same tape casting process followed by sintering and gave results consistent with BASE materials produced by uniaxial pressing of powders. Planar BASE membranes enable new cell designs, which are predicted to have higher power densities and better stacking efficiency compared to currently manufactured tubular cells.

Challenges for High Temperature Silicon Carbide Electronics

2003 ◽  
Vol 764 ◽  
Author(s):  
C.-M. Zetterling ◽  
S.-M. Koo ◽  
E. Danielsson ◽  
W. Liu ◽  
S.-K. Lee ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
High Power ◽  
High Frequency ◽  
Process Technology ◽  
High Temperature Electronics ◽  
Higher Power ◽  
Device Structures ◽  
Power Densities

AbstractSilicon carbide has been proposed as an excellent material for high-frequency, high-power and high-temperature electronics. High power and high frequency applications have been pursued for quite some time in SiC with a great deal of success in terms of demonstrated devices. However, self-heating problems due to the much higher power densities that result when ten times higher electrical fields are used inside the devices needs to be addressed. High-temperature electronics has not yet experienced as much attention and success, possibly because there is no immediate market. This paper will review some of the advances that have been made in high-temperature electronics using silicon carbide, starting from process technology, continuing with device design, and finishing with circuit examples. For process technology, one of the biggest obstacles is long-term stable contacts. Several device structures have been electrically characterized at high temperature (BJTs and FETs) and will be compared to surface temperature measurements and physical device simulation. Finally some proposed circuit topologies as well as novel solutions will be presented.

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