Document
International Conference on th Presented 38 Advanced Ceramics and Composites Daytona Beach, FL , Jan 28, 2014
Electric Aircraft
Presented at OSU Graduate Seminar, April 1, 2013
Dr. Ajay Misra
Cleveland, OH
Material Challenges and
Opportunities for Commercial
NASA Glenn Research Center
NASA Goals for Fixed Wing Aircraft
green system
–
Significantly reduced emission (near zero for certain concepts) Significant reduction in fuel burn due to higher efficiency of electrical systems Reduction in noise Advanced concepts (such as distributed propulsion and boundary layer ingestion) might be enabled by certain electric propulsion concepts
Benefits of Electric Propulsion
• • • •
FAN FAN MOTOR ENGINE TURBINE Energy storage for power mgmt LINE) ELECTRIC BUS (TRANSMISSION p Pr MOTOR MOTOR n ERA Power Non-Prop Energy storage for power mgmt GENERATOR LINE) p ELECTRIC BUS (TRANSMISSION Power Non-Prop N ENGINE TURBINE FUEL PACK BATTERY
Possible Future Commercial Large Transport Aircraft
Turbo Electric Hybrid Electric Both Concepts can use either non-cryogenic motors or cryogenic superconducting motors.
FAN VoltAirs concept – MOTOR MOTOR High temperature Li-Air battery superconducting motor EADS • • LINE) BUSS ELECTRIC (TRANSMISSION CELL FUEL PACK BATTERY
All Electric Propulsion
FUEL 40 Yr Hybrid electric 737-150 PAX Turboelectric 737-150 PAX Turboelectric and hybrid electric distributed propulsion 300 PAX • • • > 10 MW 30 Yr Turboelectric 100 PAX regional Turboelectric distributed propulsion 150 PAX 5-10 MW • • 20 Yr class 2-5 MW Turboelectric 50 PAX regional Turboelectric distributed propulsion 100 PAX regional • • Notional Timeline 10 Yr class All electric and hybrid electric GA 1-2 MW • Today kW class Power Level for Electrical Propulsion System
Progression of Adoption of Electric Propulsion in Aircraft
High power density power electronics Lightweight power transmission cable Energy storage system with high specific energy
Key Challenges for Large Commercial Electric Aircraft
High power density superconducting motor (cryogenic) Lightweight thermal management system High power density non- cryogenic motor Gas Turbine Engine Non-Cryogenic Motor Years From Today 10 Superconducting (Cryogenic) Motor 5 20 25 30 10 15 Power Density, hp/lb Power Density of Gas Turbine Engines Compared to Projected Power Density of Electric Motors The state-of-the-art superconducting motor is limited to application of superconducting materials in rotor coils only Application of superconducting material in stator coils is limited by high ac losses due to the effect of varying magnetic field • • – easy to fabricate in coil form
Fully Superconducting Motors Needed for Electric Aircraft
The challenge for fully superconducting motor is to develop low ac-loss stator coils MgB needs liquid hydrogen for cooling Reducing filament size (state-of- the-art filament size on the order of 70-100 microns, experimental filaments of 30 micron diameter, need to reduce diameter to 10 microns or lower Twisting wire with reduction in twist pitch Increasing resistivity of sheath material and reaction barrier Reduction of ac-loss in superconducting coil requires: • • • Significant manufacturing challenge to develop 10 micron or less diameter MgB filament with superconducting properties and required mechanical properties for stator coil application Cu MgB Nb (reaction barrier) Cu-Ni sheath
Key Materials Challenge for Fully Superconducting Motor
magnets capability energy product conductivity coil Higher electrical Higher temperature Magnets with higher material with high higher temperature Stator coil insulation thermal conductivity and
Material Advancements Needed for High Power Density Non-Cryogenic Electric Motor
CNT fiber with electrical conductivity greater than Cu Fabrication of coils with CNT fiber Motor design with CNT fiber Iodine-doped CNT from Rice University (2011) Challenge: • • • 2013- carbon nanotube fiber with high specific electrical conductivity by Rice Univ.
Coils With High Electrical Conductivity
Breakthrough needed to significantly increase maximum energy product of magnets
Development of Advanced Magnets
over the last decade capability of magnets increasing temperature No major improvement in C required o
High Temperature Magnets
Challenge is to develop high temperature magnets with high maximum energy product (BH) and temperature capability greater than 400 C or o Polymer composite with conductive fillers Polymer composite stator coil insulation materials with order of magnitude increase in thermal conductivity Temperature capability of 400 higher Challenge: • • Improved polymer SOA polymer
Advanced Stator Coil Insulation Material
[112 0] [1 10 0] 0 0 0 [000 1] ~ 15 mm Long Crystal Defect-free SiC for large wafers is a technical challenge High temperature packaging is a major barrier C o ~ 600 C o SiC theoretical ~ 250 SOA SiC C o Si ~ 150
Power Electronics Semiconductor
Need temperature capability beyond the current state-of-the-art (SOAA) Increase in power density by increasing temperature capability of semiconductor From AFRL
Capacitors for Power Electronics
Capacitors with higher energy density and higher temperature capability are required for increasing power density of power electronics Polymer-nanoceramic composite with energy storage capability greater than 20 J/cm High temperature ceramic capacitors with high breakdown strength Challenge: • • Polymer- ceramic nanodielectric C, but have low breakdown strength o
Advanced Capacitors for High Power Density Power Electronics
Ceramic capacitors with temperature capability beyond 200 Higher temperature and compact power electronics will enable placement of power electronics on motor Year Projected power density improvements for power electronics
Material Advances Critical for Increasing Power Density of Power Electronics
1980 10 0.1 100 0.01 Power Density, kW/L Materials advances (higher temperature SiC semiconductor, high temperature packaging, and higher temperature capacitor with high energy density) are critical for 10-fold increase in power density of power electronics High voltage transmission Higher temperature electrical insulation with high thermal conductivity (enables more current to pass through wire, allowing for use of fewer wire) Iodine-doped CNT from Rice University (2011) High electrical conductivity carbon nanotube (CNT) 140 miles of Cu electrical wiring in Boeing 747 contributing to 3500 lb of wiring between generators and motors –
Lightweight Power Transmission
Superconducting transmission lines Electrical cables contribute to significant weight in commercial aircraft Transfer of MW of power in turboelectric and hybrid electric aircraft will require significantly large diameter of Cu cables, adding significant weight Lightweight power transmission system required • • • Corona discharge problem at high voltage
Material Challenges with Higher Voltage Power Transmission
Require materials with high relative permittivity and high breakdown voltage IBM Engineered porous cathode structure 30 yr Li-Air 15 yr 30 yr Dendrite growth on Li anode Li-S 15 yr 30 yr Li-ion Requirements for hybrid electric aircraft 15 yr 200 400 600 800 1000 1200 1400 Energy Density, watt-hr/kg
High Energy Density Batteries Require Significant Advances in Materials
Lightweight recuperator materials for cryocooler Aligned nanotube as thermal interface material Graphite foam heat exchanger Material advances critical for lightweight thermal management system motors, – Flexible and mechanically strong aerogel insulation
Thermal Management Challenge
10 MW power system with 1% loss = 100 kW of heat to be rejected; 3 % loss = 300 kW of heat to be rejected Thermal management of each component power electronics, power transmission Integrated thermal management strategy required Lightweight thermal management system required • • • • Multifunctional battery with load-bearing capability Batteries incorporated inside structure Conformal thin film battery
Multifunctional Structures Enabling for Reducing Weight of Commercial Electric Aircraft
Multifunctional structure with load-bearing and thermal management capability 5X increase in power density of electrical motors 10X increase in power density of power electronics 10X reduction in weight of power transmission 10X reduction in weight of thermal management system • • • •
Summary
max Materials with electrical conductivity higher than that of Cu High temperature electrical insulation materials with high relative permittivity and high breakdown voltage strength Magnets with high maximum energy product (BH) Higher temperature magnets Higher temperature power electronics semiconductor and packaging technology Materials to enable orders of magnitude increase in energy density and power density of energy storage system Lightweight thermal management materials Multifunctional materials Material advances critical for future large commercial electric aircraft: • • • • • • • •