Effect of dimensions on the efficiency of radiant energy cells

Effect of dimensions on quantum and photovoltaic energy conversion efficiency of germanium p-n semiconducting cell

Technical limits for energy conversion efficiency

To reach climate targets, unprecedented levels of energy efficiency improvements are required. To prioritise investments, it is necessary to know the energy saving potential associated with each action. Understanding the potential of technical improvements, requires knowledge on the highest technically achievable efficiency of a technology – the technical efficiency limit. When focusing on technical efficiency improvements, two distinct types of technical systems are recognised: conversion devices and passive systems. Previous research has analysed the technical efficiency limits of passive systems, in this study, the technical efficiency limits of major conversion devices are quantified using physical models. The resulting limits are used to calculate stochastically the energy saving potential of each device and design parameter for the United Kingdom. The UK's final energy demand could be reduced by 25% if conversion devices were operated at their technical limit and two thirds of these savings are in transport. The analysis suggests that a) improvements in conversion efficiencies are insufficient to reach energy reduction targets, except in transport and b) that for most technologies it is more important to focus on converging towards the efficiency level of the best available technologies rather than on research pushing the boundaries of conversion efficiency

Energy conversion efficiency of pulsed ultrasound

Energy characterization of a pulsed ultrasonic system was carried out using a modified calorimetric method. Sonochemical efficiency (SE) for the oxidation of Fe+2 and the formation of H2O2 was determined for selected on:off ratios (R) and different power levels. The measured efficiency of the pulsed ultrasonic system of 60-70% in converting electrical energy into calorimetric energy was found to be constant for all Rratios and equivalent to that for continuous operation. SE of Fe+2 and H2O2 for pulsed ultrasound was higher than that of continuous ultrasound. The ratio R=0.2:0.1 had the highest SE values overall, while for long off-timeratios,R=0.1:0.6 recorded the highest value of SE. These results were supported by the production rates results for Fe+2 and H2O2

Energy conversion efficiency from a high order soliton to fundamental solitons in presence of Raman scattering

We formulate the energy conversion efficiency from a high-order soliton to fundamental solitons by including the influence of interpulse Raman scattering in the fission process. The proposed analytical formula agrees closely with numerical results of the generalized nonlinear Schrodinger equation as well as to experimental results, while the resulting formulation significantly alters the energy conversion efficiency predicted by the Raman-independent inverse scattering method. We also calculate the energy conversion efficiency in materials of different Raman gain profiles such as silica, ZBLAN and chalcogenide glasses (As2S3 and As2Se3). It is predicted that ZBLAN glass leads to the largest energy conversion efficiency of all four materials. The energy conversion efficiency is a notion of utmost practical interest for the design of wavelength converters and supercontinuum generation systems based on the dynamics of soliton self-frequency shift.Comment: To be published in JOSA

Surface-emitting circular DFB, disk-, and ring-Bragg resonator lasers with chirped gratings. III: gain saturation effects and above-threshold analysis

As Part III of this series, this paper focuses on an above-threshold modal analysis which includes gain saturation effects in the surface-emitting chirped circular grating lasers. We derive an exact energy relation which states that, in steady state, the net power generated in the gain medium is equal to the sum of peripheral leakage power and vertical emission power. This relation is particularly useful in checking the accuracy of numerical mode solving. Numerical simulations demonstrate the dependence of required pump level on the vertical emission power and compare the laser threshold and energy conversion efficiency under uniform, Gaussian, and annular pump profiles. A larger overlap between the pump profile and modal intensity distribution leads to a lower threshold and a higher energy conversion efficiency. Finally the dependence of required pump level on device sizes offers us new design guidelines of these lasers for single-mode, high-efficiency, high-power applications

Linear and Nonlinear Mesoscopic Thermoelectric Transport with Coupling to Heat Baths

Decades of research on thermoelectrics stimulated by the fact that nano- and meso-scale thermoelectric transport could yield higher energy conversion efficiency and output power has recently uncovered a new direction on inelastic thermoelectric effects. We introduce the history, motivation, and perspectives on mesoscopic inelastic thermoelectric effects.Comment: Invited by Comptes Rendu

Diffused quantum well solar cell

An alternative multi-bandgap solar cell made of diffused quantum well (DFQW) as the absorber is proposed here. The modeling of the spectral response and energy conversion efficiency of the solar cell will be shown. Significant enhancement in energy conversion efficiency is demonstrated when compared to that of the single bandgap cells.published_or_final_versio