Renewable Energy Alternatives

Permanent URI for this collection

https://repository.nrf.go.ke/handle/123456789/11

Browse

Browsing Renewable Energy Alternatives by Funder "Kenyatta University"

Now showing 1 - 2 of 2
  • Publication
    Publication
    Electron Impact Elastic Scattering of Strontium Using Distorted Wave Method
    (Kenyatta University, 2018-11)
    Differential and integral cross sections for electron-atom are useful for interpretation and understanding of electron contact with the targets and for determining dynamics of the collision processes. They are useful in X-ray photoelectron spectroscopy (XPS), upper atmosphere dynamics, Monte-Carlo simulation (MCS), Auger-electron spectroscopy (AES), in gaseous-exchange, laser development, plasma physics and fluorescent lighting. For elastic scattering of strontium very few calculations have been performed and currently there are no known results using the present method. Also the available theoretical results do not have other results to be compared with so it makes it important to obtain results to compare them and to be compared with future experimental results. In calculation of differential and integral cross section for elastic scattering of electron by strontium atom, first-order distorted wave born approximation method has been used to determine DCS and ICS at impact energies of 10eV to 200eV and scattering angles ranging from 00 to 1800. Also in this study at the initial state, both initial and final channel distortion potential of elastic scattering of electron by a strontium atom are taken as the static potentials since it is an elastic scattering. The distorted waves are expanded in terms of radial wavefunctions and spherical harmonics, Numerov method was then used to solve the radial equations to obtain the radial wavefunctions. The Madison and Bartschat computer program DWBA1 for e- - H scattering was modified to perform the mathematical computations for e - - Sr scattering and the results for differential and integral cross sections are calculated and compared with the available results. The integral cross sections (ICS) results agree well qualitatively with the other theoretical results. At lower incident energies (10-30 eV), the present differential cross section (DCS) results disagree with results obtained from optical potential method. This is because the first order distorted wave method gives poor results at low impact energies and also the nature of the distortion potential used. At intermediate and higher energies (60-200 eV), the present DCS results agree well with the results obtained from optical potential method. In conclusion, the DWBA was developed and applied to 𝑒− - Sr scattering, changes on the DWBA1 computer program were made for strontium, differential cross section (DCS) and integral cross section (ICS) at impact energies 10-200eV for elastic scattering of electron-strontium were determined using DWBA at intermediate and high energies and the results compared with the other available results. From this work it was recommended that some experimental studies on electron impact elastic scattering of strontium should be made to give results for comparison with the calculated results, more theoretical studies using other methods should be conducted on DCS and ICS for purposes of comparison with the present results, a distortion potential that incorporates the polarization potential, exchange potential and absorption potential should be used in the calculation and the present method incorporating all the distortion potentials should be extended further for electron impact elastic scattering of other alkaline earth metals such as beryllium, cesium, ytterbium, and radium.
  • Publication
    Publication
    Performance Evaluation of Silicon-Based Photovoltaic Modules Found in the Kenyan Market
    (Kenyatta University, 2015) Njeru, Elosy Gatakaa
    Various kinds of photovoltaic (PV) modules have been developed and practically deployed as PV systems over time. The performance of PV modules found in the Kenyan market has not been documented and therefore their reliability and stability in providing an alternative source of energy has not been sufficiently established. In this study the I-V data of Silicon-based mono crystalline, poly crystalline and amorphous modules was collected. The choice of the modules was done randomly depending on their availability, the cost of the modules and their power rating. They were selected randomly from PV module vendors within Nairobi Central Business District (CBD). The manufacturers’ specifications were taken. The modules were then mounted at an optimum fixed tilt angle of 15 degrees. Initial measurements of short circuit current Isc, open circuit voltage Voc, ambient temperature and module temperature were taken immediately on mounting the modules. Measurements of current and voltage to obtain I-V data was done daily at solar noon for four months. The back of the module temperature and ambient temperature at the time of measurement was measured using thermocouple while the irradiance at the time of measurement was measured using a pyranometer. The pyranometer was mounted at the plane of array of 15 degrees as the modules. The collected I-V data was normalized and I-V curves were plotted. Performance parameters of the modules were then calculated from the I-V curve. There was a decrease in Voc of the modules with time with the amorphous modules clearly showing the Staebler-Wronski effect. The Isc of the modules showed little variation while Pmax of the modules had reduced significantly. The Pmax of most of the modules was found not to match with the manufacturers specifications provided in their data sheet. On inspection of the modules, the 10W polycrystalline module revealed a defect which was as a result of overheating of the cells that contributed greatly to its poor performance in comparison to the other polycrystalline modules. The efficiency of the amorphous modules ranged between 3%- 5% while that of mono crystalline and polycrystalline was above 10%.