Reliability, Durability, and Safety
This is the October 2014 issue of the Transportation and Hydrogen Newsletter.
CNG Vehicle Fueling Animation
When fueling a vehicle with compressed natural gas (CNG), the amount of fuel in a "full tank" will vary according to a number of factors, including the ambient temperature, type of fueling equipment, vehicle design, and the type of vehicle fuel tank. This is because CNG expands and contracts substantially depending on its temperature. An online animation developed by NREL helps explain these variables and the fill results obtained in different scenarios. The animation serves as a useful tool to help fleet owners and drivers learn more about how temperature and fill speeds affect the final volume in CNG vehicle tanks.
October 29, 2014
Thermoplastics Show Promise as BIMs
NREL is characterizing the thermal performance and reliability of emerging bonded interface materials (BIMs) with the objective of improving them for use in power electronics packaging. BIMs are being considered for state-of-the-art power electronics packages for electric-drive vehicle applications. However, thermal cycling can cause reliability concerns. After analyzing packaging with large-area bonded interfaces based on solder, sintered silver, and thermoplastics, thermoplastics demonstrated excellent reliability with no defects while maintaining good thermal performance after accelerated thermal analysis (2,500 thermal cycles).
BIMs Incorporating Nanomaterials Show Good Reliability
NREL is supporting the development of mechanically compliant, low-resistance BIMs through thermal performance and reliability characterization. The low thermal resistance of the BIMs, some of which incorporate nanomaterials, is gaining interest from the power electronics packaging industry due to their potential as replacements for traditional thermal interface materials, which have limitations from a performance and reliability perspective. Evaluation results for three different BIMs indicate that BIMs based on copper nanosprings have promising reliability.
Fueling Robot Automates Hydrogen Hose Reliability Analysis
NREL is using an automated robot to analyze the reliability of hydrogen dispensing hoses under simulated field conditions. Accelerated analysis performed with the robot will reveal the hoses' durability over time in a real-world environmenthelping to reduce costs and increase reliability and safety. View the video of the robot, which mimics the repetitive stress of a person bending and twisting a hose to dispense hydrogen into a fuel cell vehicle's onboard storage tank.
Nanomaterials Boost Battery Performance and Lifespan
Carbon nanotubes and nanorods are being used by NREL scientists to boost power and durability of lithium-ion batteries for transportation and other applications. The nanotubes not only increase the conductivity of active materials, but also strengthen the binding of electrode particles, making them more durable through many charge-discharge cycles. The technology has quickly attracted interest from industry and is being licensed to NanoResearch, Inc., for volume production.
Independent Analysis Supports Hydrogen Sensor Developers and End Users
NREL is evaluating the performance and reliability of hydrogen sensor technologies to support the needs of emerging hydrogen infrastructure. Researchers at the Safety Sensor Testing Laboratory independently analyze and verify the performance of commercial sensors and prototypes under controlled conditions. Information gained from the analysis assists in development and helps end users select and deploy appropriate sensors for different hydrogen and fuel cell applications.