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.

Conversion of carbon dioxide to value-added chemicals in atmospheric pressure dielectric barrier discharges

Abstract: The aim of this work consists of the evaluation of atmospheric pressure dielectric barrier discharges for the conversion of greenhouse gases into useful compounds. Therefore, pure CO2 feed flows are administered to the discharge zone at varying discharge frequency, power input, gas temperature and feed flow rates, aiming at the formation of CO and O2. The discharge obtained in CO2 is characterized as a filamentary mode with a microdischarge zone in each half cycle of the applied voltage. It is shown that the most important parameter affecting the CO2-conversion levels is the gas flow rate. At low flow rates, both the conversion and the CO-yield are significantly higher. In addition, also an increase in the gas temperature and the power input give rise to higher conversion levels, although the effect on the CO-yield is limited. The optimum discharge frequency depends on the power input level and it cannot be unambiguously stated that higher frequencies give rise to increased conversion levels. A maximum CO2 conversion of 30% is achieved at a flow rate of 0.05Lmin −1 , a power density of 14.75Wcm −3 and a frequency of 60kHz. The most energy efficient conversions are achieved at a flow rate of 0.2Lmin −1 , a power density of 11Wcm −3 and a discharge frequency of 30kHz. (Some figures in this article are in colour only in the electronic version)

High power rechargeable batteries

Abstract: Energy and power density are the key figures of merit for most electrochemical energy storage systems. Considerable efforts worldwide have been made to improve the energy density of rechargeable (secondary) batteries, as this is critical for most applications. As the penetration of batteries into ever more demanding applications has increased, power density, the allowed rate of energy transfer per unit volume or mass, is becoming equally important. High power density batteries have the potential to be rapidly charged, possibly in a few minutes or less, and can also deliver high peak discharge powers. Normally increases in power density are only possible through significant reductions in energy density, however emerging materials research is showing this needs not to be the case. Here we discuss emerging concepts in high power batteries, with a particular focus on Li-ion based chemistries.

Pulsed Nanogenerator with Huge Instantaneous Output Power Density

Abstract: A nanogenerator (NG) usually gives a high output voltage but low output current, so that the output power is low. In this paper, we developed a general approach that gives a hugely improved instantaneous output power of the NG, while the entire output energy stays the same. Our design is based on an off-on-off contact based switching during mechanical triggering that largely reduces the duration of the charging/discharge process, so that the instantaneous output current pulse is hugely improved without sacrificing the output voltage. For a vertical contact-separation mode triboelectric NG (TENG), the instantaneous output current and power peak can reach as high as 0.53 A and 142 W at a load of 500 Ω, respectively. The corresponding instantaneous output current and power density peak even approach 1325 A/m(2) and 3.6 × 10(5) W/m(2), which are more than 2500 and 1100 times higher than the previous records of TENG, respectively. For the rotation disk based TENG in the lateral sliding mode, the instantaneous output current and power density of 104 A/m(2) and 1.4 × 10(4) W/m(2) have been demonstrated at a frequency of 106.7 Hz. The approach presented here applies to both a piezoelectric NG and a triboelectric NG, and it is a major advance toward practical applications of a NG as a high pulsed power source.