Power density

About: Power density is a research topic. Over the lifetime, 9534 publications have been published within this topic receiving 197264 citations. The topic is also known as: volumic power & volume power density.

UNIFORM ELECTRICAL EXCITATION OF LARGE‐VOLUME HIGH‐PRESSURE NEAR‐SONIC CO2–N2–He FLOWSTREAM

Abstract: Aerodynamic techniques are described whereby continuous electric discharges may be produced uniformly over large volumes in near‐sonic CO2–N2–He flowstreams. Experiment shows that discharge input power scales with pressure for the range 30–150 Torr thereby maintaining a fixed specific power load of ≃ 270 kW/lb(mass)/sec, while diffuse discharges at 1‐atm pressure have been achieved at much lower specific power levels. Discharges occupying 4.5‐ and 43‐liter volumes with the corresponding flowrates 2700 and 28 000 cfm are each uniform over their entire volumes, indicating that volume‐flowrate scaling is not affected by wall diffusion. Using these discharge techniques, a closed cycle 28 000‐cfm 5.6 × 76 × 100‐cm3 CO2 laser amplifier channel has been designed to produce in excess of 20 kW laser power, continuous. In preliminary experiments small‐signal gains reaching 1.9%/cm have been measured transversely across both cold and hot extremities of this device.

Very low emission hybrid electric vehicle incorporating an integrated propulsion system including a fuel cell and a high power nickel metal hydride battery pack

Abstract: A very low emission hybrid electric vehicle incorporating an integrated propulsion system which includes a fuel cell, a metal hydride hydrogen storage unit, an electric motor, high specific power, high energy density nickel-metal hydride (NiMH) batteries, and preferably a regenerative braking system. The nickel-metal hydride battery module preferably has a peak power density in relation to energy density as defined by: P>1,375−15E, where P is greater than 600 Watts/kilogram, where P is the peak power density as measured in Watts/kilogram and E is the energy density as measured in Watt-hours/kilogram.

Heat dissipation at a graphene–substrate interface

Abstract: The development of nanoelectronics faces severe challenges from Joule heating, leading to high power density and spatial localization of heat, which nucleates thermal hot spots, limits the maximum current density and potentially causes catastrophic materials failure. Weak interfacial coupling with the substrate is a major route for effective heat mitigation in low-dimensional materials such as graphene and carbon nanotubes. Here we investigate the molecular-scale physics of this process by performing molecular dynamics simulations, and find that significant heating in graphene supported by a silicon carbide substrate cannot be avoided when the areal power density exceeds PG = 0.5 GW m−2. A steady state will be established within 200 ps with a significant temperature difference built up across the interface, and the interfacial thermal conductivity κc increases at higher power densities from 10 to 50 MW m−2 K−1. These observations are explained by a two-resistor model, where strong phonon scattering at the interface may perturb the ballistic heat transport and lead to a diffusive mechanism. Nanoengineering the interfacial thermal coupling by intercalating guest atoms shows potential for designing thermally transparent but electronically insulating interfaces, which paves the way for simultaneously optimizing thermal management and charge carrier mobility in nanoelectronics.

Neutral bremsstrahlung measurement in an atmospheric-pressure radio frequency discharge

Abstract: Neutral bremsstrahlung emission spectrum is measured in an atmospheric-pressure radio frequency (rf) capacitive discharge for a gas mixture of helium (99.5%) and oxygen (0.5%) using a high resolution triple monochromator between 450 and 1000 nm. Good agreement is obtained for spectral variation and absolute intensity between the observed neutral bremsstrahlung and theoretical emissivity calculated using electron–neutral momentum cross sections. Based on a theoretical fitting, the discharge is characterized by a time averaged electron density of 2.9×1011 cm−3 and an electron temperature of 1.9 eV for an input power density of 28 W/cm3.

Power architecture design with improved system efficiency, EMI and power density

Abstract: The optimized design of power architecture is discussed in this paper. The paper first discusses the asymmetrical interleaved multi-channel PFC technique and its benefits to system power density and the reduction of differential mode noise. A balance technique is then proposed to minimize the common mode noise of asymmetrical interleaved multi-channel PFC. Greatly reduced EMI leads to the size reduction of EMI filters. System power density is therefore improved. For DC/DC stage, a 1 MHz, LLC resonant converter with novel synchronous rectifier is proposed to reduce body diode conduction time. Both conduction loss and reverse recovery loss can be reduced. The whole system's efficiency, EMI and power density can be greatly improved by applying the techniques proposed in this paper.