David Faiman - Academia.edu (original) (raw)

Papers by David Faiman

Solar Energy, 1999

We describe a computerized microscope system that has been developed for studying the physics of ... more We describe a computerized microscope system that has been developed for studying the physics of dust particles which adhere to various kinds of surfaces such as those of solar collectors. The device enables investigators: (1) to obtain the particle size distribution of dust on a surface; (2) to calculate the fraction of surface area covered by dust; (3) to calculate the reduction of optical efficiency (of the solar collector under study) as a function of particle size; (4) to investigate the effect of various kinds of applied force field on the adhesion of dust particles to the surface. Some examples are given for the use of such a measuring system for the study of photovoltaic and solar-thermal collector surfaces.

Consider the well-known Hotel-Whillier-Bliss equation [1, 2] for the thermal efficiency of a flat... more Consider the well-known Hotel-Whillier-Bliss equation [1, 2] for the thermal efficiency of a flat-plate water-heating solar collector: η = ηo- (U/H) (T- Tamb) (1) where ηo is the optical efficiency, U is the heat-loss coefficient, H is the total solar irradiance incident on the plane of the collector, T is the plate temperature and Tamb is the ambient temperature. If we multiply through by H, we obtain an expression for the useful thermal power ηH that can be extracted from unit area of the collector: ηH = ηoH – U(T – Tamb) (2) If the collector could produce electrical power in addition to thermal power, then the amount of thermal power that could be extracted would be less than that given in eq. (2), namely: ηH = ηoH – U(T – Tamb)- ηe H (3) where ηe is the electrical efficiency of the collector at temperature T. Under conditions of thermal stagnation – i.e., when the useful thermal power drops to zero, the thermal efficiency η becomes zero, and the collector reaches its maximum or ...

Nuclear Physics B, 1976

Abstract We point out that the intersection of the Berkeley-SLAC and Saclay signs of π N→ ϱ N res... more Abstract We point out that the intersection of the Berkeley-SLAC and Saclay signs of π N→ ϱ N resonant amplitudes are consistent with l-broken SU(6) W if both the 70, L P = 1 − and 56, L P = 2 + multiplets choose anti-SU(6) W solutions. The symmetry scheme still fails in that the π N→ πΔ relative signs require an SU(6) W -like solution for the 56, L P = 2 + . This failure however now rests on a single incorrect sign prediction among all N ϱ and Δπ amplitudes.

ABSTRACT The search for a substitute for fossil energy sources, the world-wide improving environm... more ABSTRACT The search for a substitute for fossil energy sources, the world-wide improving environmental awareness and the needs of the growing population in developing countries have increased the interest in photovoltaics as a long term, un-exhaustable, environmentally friendly and reliable energy technology. In the last five years, the production of photovoltaic cells has increased steadily by an average of 25% per year, driven not only by the progress in materials and processing technology, but by market introduction programmes in many countries of the world. This leads to the search for new developments with respect to material use and consumption, device design and production technologies as well as new concepts to increase the overall efficiency. At present solar cell manufacturing based on the technology of crystalline, single junction devices is growing with approx. 30% per year with an increasing tendency. Consistent with the time needed for any major change in the energy infrastructure, another 20 to 30 years of sustained and aggressive growth will be required for photovoltaics to substitute a significant share of the conventional energy sources. This growth will be only possible if a continuous introduction of new technologies takes place, made possible by sound fundamental research. To reach this goal the investigation and research for concepts and techniques to increase the solar cell efficiency above the single-junction efficiency limit are absolutely necessary and are receiving increasing attention. The scope of this workshop was to provide a forum to review and discuss the current status and achievements in high efficiencies for the different kinds of solar cells as well as to foster new concepts and ideas. It is hoped that the results of this workshop will lead in the long run to an increase in research activities and funding possibilities in this field.

1 Ultra high cell efficiency on the path towards fossil-competitive PV economics

This paper addresses the problem of matching the often rapidly changing output of a very large PV... more This paper addresses the problem of matching the often rapidly changing output of a very large PV system to the ability of a power grid to rapidly shut down turbines in order to save fuel. As a first approximation to approaching this problem we have employed a full year of hourly generation data, provided by the Israel Electric Corporation, and the corresponding hourly meteorological data from the Negev Radiation Survey. Four types of calculation are performed: (a) assuming 100% grid flexibility with no PV storage; (b) assuming 65% grid flexibility (as suggested by the IEC data) with no storage; (b) addressing the potential solarization of only the spinning reserve without storage; (d) the latter with the incorporation of storage.

The objective of IEA PVPS Task8 is to examine and evaluate the potential of Very Large Scale Phot... more The objective of IEA PVPS Task8 is to examine and evaluate the potential of Very Large Scale Photovoltaic Power Generation (VLS-PV) Systems on desert areas, which have a capacity ranging from multi- Megawatt to Gigawatt, and to develop practical project proposals for implementing the VLS-PV systems in desert regions. The Task8 started in 1999. Based on these results since 1999, we've been in Phase-3 activity (2006-2008). In Phase-3, specific case studies from viewpoints of local, regional and global aspect are carried out, and financial and institutional scenarios and a general instruction for practical project proposals are developed. Also, considerable future technical options implementing VLS-PV system are analysed. Through the activities, Task8 will show the feasibility and the impact of VLS-PV projects, and propose our recommendations for the future.

AIP Conference Proceedings, 1998

A possibility to produce a Schottky barrier at the Ag/C60 thin film interface has been demonstrat... more A possibility to produce a Schottky barrier at the Ag/C60 thin film interface has been demonstrated. The device structure exhibited rectifying behavior in the dark and photovoltaic properties.

AIP Conference Proceedings, 2012

We have constructed a 7-node, 1-dimensional model of the heat flow in a water-cooled CPV receiver... more We have constructed a 7-node, 1-dimensional model of the heat flow in a water-cooled CPV receiver. The model is validated against data from a module exposed to solar irradiance at various concentrations up to 1,000X at the PETAL solar dish facility at Sede Boqer.

Solid State Communications, 1997

... Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (348). 4. S. Kazaoui, R. ... more ... Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (348). 4. S. Kazaoui, R. Ross and N. Minami. Solid State Commun. 90 (1994), p. 623. ... 117, Springer-Verlag, Berlin-Heidelberg (1993), p. 418. 7. S. Gonda, M. Kawasaki, T. Arakane and H. Koinuma. ...

3 sets of PV modules, each set having Si cells of a different morphological structure (a-, mc- an... more 3 sets of PV modules, each set having Si cells of a different morphological structure (a-, mc- and pc- ), were operated side-by-side as grid-connected systems, and continuously monitored for one year. The resulting hourly data were re-normalized in a number of alternative ways so as to permit meaningful efficiency comparisons. In particular, comparisons were made with respect to (1)

Fullerene Science and Technology, 1998

Fullerene solar cells are demonstrated. Illuminated, C60 drives oxidation of redox couples in sol... more Fullerene solar cells are demonstrated. Illuminated, C60 drives oxidation of redox couples in solution. a photoelectrochemical solid/liquid, rather than a solid state, junction, improves photocurrent, and a C60 single crystal, and not polycrystalline film, decreases dark current, and thereby light driven charge transfer dominates.

Energy Policy, 2007

The paper first reviews some recently introduced ideas concerning the feasibility of realizing co... more The paper first reviews some recently introduced ideas concerning the feasibility of realizing concentrator photovoltaic systems on a very large (state-wide) scale. In particular, energy and cost assumptions are re-discussed, the concepts of double and triple sustainability are recalled and used to perform a sensitivity study of the various assumed parameter values. The model is then applied to each of

Journal of Fermentation and Bioengineering, 1998

The relationship between the tilt angle of a flat-plate photobioreactor and productivity of Spiru... more The relationship between the tilt angle of a flat-plate photobioreactor and productivity of Spirulinaplatensis was evaluated along with the annual seasons under the climatic conditions of south Israel (latitude approx. 31"). The reactor tilt angle exerted a significant effect on the optimal population density and thus on the productivity of cell mass, owing to its control over the amount of solar radiation entering the reactor. A direct relationship between solar energy and productivity was observed: the higher the amount of solar energy that was admitted by varying the reactor tilt angle according to season, the higher was the productivity that could be sustained in the culture. Small tilt angles of loo to 30° in summer and larger angles in the vicinity of 60° in winter resulted in maximal productivities for these seasons. Photosynthetic efficiency was calculated for the diierent tilt angles for all seasons. Efficiency was low in the winter due to temperature limitations. In summer it was highest in the !W reactors, indicating that for optimal tilt angles in this season (in regards to productivity) a significant amount of radiation could not be effectively used by the culture. The results suggest a potential benefit in orientating and tilting reactors at various appropriate angles to the sun on a seasonal basis: up to 35% enhancement in annual output rate is estimated to be achievable.

Israel journal of technology, 1981

... 1 1 \ 1 1 1 -\ _ \ \ \ \ \ N - W 4 \ ~ \ \ .Flat plat« V v v\. / EvuCuatid / Parabolic trough... more ... 1 1 \ 1 1 1 -\ _ \ \ \ \ \ N - W 4 \ ~ \ \ .Flat plat« V v v\. / EvuCuatid / Parabolic trough N \\ - ч ~-v \ -.X V ~,- X N¡ ii 1 t 1 Oc »rotino ... collector area for the no-dump system design is obtained from Ас = Р/(ОСг(Гош-Г„,)), 6) and the annual utilizatile energy delivered by the solar retrofit is ...