Energy

PTC Heater Brings Greater Control for Hand-held Medical Devices and Disposables

Point of Care diagnostics devices, whether handheld or single-use, often require a brief application of tightly controlled heat. The disposable nature of these devices requires a low-cost component capable of delivering that heat reliably and safely. Heatron's new PTC heater solution uses a polymer-based heater technology that controls heat to within ±2°C of the target temperature, and reduces unit cost by eliminating sensors and applied controls.

Posted in: White Papers, Briefs, TSP, Electronics & Computers, Thermoelectrics, Medical, Medical equipment and supplies, Heating, ventilation, and air conditioning systems (HVAC), Polymers
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High-Voltage Supercapacitors for Improved Energy Density Hybrid Power Sources

Both the aerospace and automotive industries depend increasingly on electrochemical energy storage. Reduction in mass, increase in energy, and increase in power can benefit both of these areas dramatically. Supercapacitors are currently under consideration for use in both hybrid electric vehicles (HEV) and electric vehicles (EV) to improve delivery of power (due to their high rate capability), improve the life of the lithium-ion batteries (due to their ability to buffer the detrimental effects of high current pulses or alternating currents on the battery), and implement more efficient capture of regenerative breaking energy (due to their excellent charge acceptance at high rates).

Posted in: Briefs, Energy, Energy storage systems, Lithium-ion batteries, Ultracapacitors and supercapacitors, Electric vehicles, Hybrid electric vehicles
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Fuel Cell Power Management

This technique produces multiple voltages simultaneously from a single fuel cell stack, without the need for converters.

An innovation from NASA Glenn Research Center increases the efficiency and versatility of fuel cell stacks for power generation. To meet the requirements of a fuel cell system, engineers have typically added direct-current-to-direct-current (DC-to-DC) converters that reduce the voltage produced at the ends of the fuel cell stack. This smaller voltage is then used to operate the valves, pumps, heaters, and electronics that make up the fuel cell system. However, adding DC-to-DC converters increases cost, reduces efficiency, adds to the system part count (which reduces reliability), and increases both the mass and volume of the fuel cell system. NASA's innovative technique features multiple power points that connect different numbers of cells in an electrical series, allowing the fuel cell stack to produce electrical power at multiple DC voltages simultaneously. This capability eliminates DC-to-DC converter electronics, thereby reducing cost and simplifying the system.

Posted in: Briefs, Energy, Voltage regulators, Electric power, Fuel cells
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Solid-State Lithium Sulfur Battery

Applications include electric vehicles, consumer electronics, UAVs, and wind and solar energy storage.

Sulfur is a promising cathode for lithium batteries due to its high theoretical specific capacity (1673 mAh/g), low cost, and environmental friendliness. With a high specific energy density of 2500 Wh/kg, which is a five times greater energy density than a conventional Li-ion battery, Li-S batteries hold great potential for next-generation high-energy storage systems. However, wide-scale commercial use has been limited because some key challenges, such as the dissolution of the intermediate discharge product (Li2Sx, 2<X<8) in conventional liquid electrolytes, remain unsolved. On the other hand, all-solid-state batteries (SSBs) are considered to be the ultimate power supply for pure electric vehicles (EVs). SSB systems demonstrate a new approach for novel Li-S batteries. Replacing the organic electrolyte with solid-state electrolytes (SSEs) will intrinsically eliminate the dissolution of polysulfide. However, all of the solidstate Li-S batteries incorporating current state-of-the-art SSEs suffer from high interfacial impedance due to their low surface area.

Posted in: Briefs, Energy, Battery cell chemistry, Lithium-ion batteries, Electrolytes, Electric vehicles
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Standardized Heating Method to Trigger and Prevent Thermal Runaway Propagation in Lithium-Ion Batteries

Lithium-ion (Li-ion) cells are increasingly used in high-voltage and high-capacity modules. The Li-ion chemistry has the highest energy density of all rechargeable battery chemistries, but associated with that energy is the issue of catastrophic thermal runaway with a fire. With recent incidents in the commercial aerospace and electronics sectors, methods are required to prevent cell-to-cell thermal runaway propagation. The goal of this work was to achieve a common method for triggering a single cell in a Li-ion battery module into thermal runaway, determine if one can consistently obtain this thermal runaway event, and design mitigation measures to address propagation of the thermal runaway to other cells in the module.

Posted in: Briefs, Energy, Battery cell chemistry, Lithium-ion batteries, Fire prevention, Risk assessments
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Method of Forming Textured Silicon Substrate by Maskless Cryogenic Etching

NASA’s Jet Propulsion Laboratory has developed an advanced energy-storage device to accommodate portable devices, minimize emissions from automobiles, and enable more challenging space missions. The use of silicon for the anode of lithium ion (Li-ion) batteries is attractive because silicon has the highest theoretical charge capacity of any material when used as an anode in a Li-ion battery. Conventional silicon anodes undergo large-volume expansions and contractions with the absorption and desorption of Li-ions, however, and this results in pulverization of the anode after several charge and discharge cycles. JPL’s innovative Li-ion battery anodes are made of micro-textured silicon, which is able to accommodate the stress of expansion and contraction during the charging cycle. These robust silicon anodes make high-capacity, rapid-charge-rate Li-ion batteries practical.

Posted in: Briefs, Power Management, Energy, Battery cell chemistry, Energy storage systems, Lithium-ion batteries, Silicon alloys
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Fully Premixed, Low-Emission, High-Pressure, Multi-Fuel Burner

Applications include use in aircraft, spacecraft, and heating and boilers for commercial and residential systems.

NASA’s Glenn Research Center has developed a novel design for a fully premixed, high-pressure burner capable of operating on a variety of gaseous fuels and oxidizers, including hydrogen-air mixtures, with a low pressure drop. The burner provides a rapidly and uniformly mixed fuel-oxidizer mixture that is suitable for use in a fully premixed combustion regime that has the benefits of low pollutant emissions (when operated at fuel lean conditions) and freedom from harmful flashback effects, combustion instabilities, and thermal meltdown problems that are normally associated with premixed combustion systems operating at high pressures.

Posted in: Briefs, Aerospace, Aviation, Energy, Low emission vehicles (LEV) and Zero emission vehicles (ZEV), Hydrogen fuel, Gases, Combustion and combustion processes
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Selenium Interlayer for High-Efficiency Multi-Junction Solar Cell

This technology can be commercialized for terrestrial applications such as power plants and smart grid systems.

Innovators at NASA’s Glenn Research Center have developed a low-cost, high-efficiency solar cell that uses a thin layer of selenium as the bonding material between wafers. Selenium is a semiconductor, and it is also transparent to light at photon energies below the band gap. The innovation allows a multi-junction solar cell to be developed without the constraint of lattice matching, and uses a low-cost, robust silicon wafer as the supporting bottom substrate and bottom cell. This enables a cell that is simultaneously lower in cost, more rugged, and more efficient than existing space solar cell designs. This technology has the potential to be used in next-generation solar cells in space, and it can be commercialized for terrestrial applications such as power plants and smart grid systems.

Posted in: Briefs, Energy, Solar Power, Solar energy, Joining, Semiconductors, Silicon alloys, Durability, Reliability
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Tethered Vehicle Control and Tracking System

The system enables effective operation of airborne wind energy (AWE) generation systems.

NASA’s Langley Research Center has developed hardware and software to track the flight of tethered vehicles, including kite-like, airborne wind energy (AWE) generation systems. The control system consists of a pan-tilt platform and a visible-spectrum digital camera, combined with tracking control software running on a standard PC. The system controls the flight of the vehicle to keep its position on a power-producing trajectory, maximizing velocity (but within limits). This trajectory produces tension, which turns the ground-based generator, producing the energy. The NASA system enables effective operation of groundgen or flygen types of AWE systems. NASA has a working prototype and pre-beta software, and is seeking development partners to make it more robust and user-friendly by testing it in real-world systems.

Posted in: Briefs, Aerospace, Aviation, Energy, Trajectory control, Computer software and hardware, Imaging and visualization, Autonomous vehicles
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Preventing Cell-to-Cell Thermal Runaway in Lithium-Ion Battery Modules

Lithium-ion (Li-ion) cells are increasingly used in high-voltage and high-capacity modules. The Li-ion chemistry has the highest energy density of all rechargeable battery chemistries, but associated with that energy is the issue of catastrophic thermal runaway with a fire. With recent incidents in the commercial aerospace and electronics sectors, it was necessary to find methods to prevent cell-to-cell thermal runaway propagation.

Posted in: Briefs, Batteries, Energy, Scale models, Battery cell chemistry, Lithium-ion batteries, Fire prevention
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