			Home About us Contact

Effective Efficiency (effective + efficiency)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

Effective Efficiency as a Tool for Sustainable Water Resources Management,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2008
Naim Haie
Abstract:, The sufficiency and usefulness of Effective Efficiency (EE) as a water resources index is shown through conceptual formulation of a generalized EE and practical applications. Two EE models are proposed: one is based on water quantity and the other on quantity and quality, with the possibility of considering water reuse (recycling) in both. These models were developed for two scales: the first is called Project EE and the second Basin EE. The latter gives the influence of the project on the water resources systems of the basin while the former does not make such connection to the whole basin. Such considerations give proper signals as to the adequacy of any intervention to increase efficiency. A crucial distinction is made between depletion and diversion water savings. Classical Efficiency (CE) models are analyzed and compared with the various EE models. CE results in values that are less than EE because of not considering water reuse and water quality in its calculation. Some authors, pointing to these problems , particularly the first problem , have advocated the use of hydrological "fractions" instead of efficiency concepts. This paper defends the use of a proper efficiency model such as EE and suggests putting an end to the use of the CE indicators. To test the models, they are applied to five cases of irrigation and city water use in the United States and Egypt. The analysis of the results demonstrates all the points mentioned above and the potential of the EE models to adequately describe the water resources efficiency and sustainability at a location. [source]

Effective efficiency of PV modules under field conditions

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2007
Marko Topi
Abstract The conversion efficiency of photovoltaic modules varies with irradiance and temperature in a predictable fashion, and hence the effective efficiency averaged over a year under field conditions can be reliably assessed. The suggested procedure is to define the efficiency versus irradiance and temperature for a specific module, collect the local irradiance and temperature data, and combine the two mathematically, resulting in effective efficiency. Reasonable approximations simplify the process. The module performance ratio is defined to be the ratio of effective efficiency to that under standard test conditions. Variations of the order of 10% in this factor among manufacturers, primarily the result of the differences in effective series resistance and leakage conductance, are not unusual. A focus on these parameters that control the effective efficiency should provide a path to PV modules with improved field performance. Copyright © 2006 John Wiley & Sons, Ltd. [source]