Numerical simulations of flow and suspended sediment transport in open-channel flows over smooth-rough bed strips

Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732The flow and transport of suspended sediment in open-channel flows over smooth-rough bed strips were simulated numerically. For the flow, the Reynolds-averaged Navier-Stokes equations were solved with the aid of the Reynolds stress model. Simulated mean flow structures are provided and compared with experimental data available in the literature. The sediment transport of suspended sediment in such flows was also simulated. The transport equation for suspended sediment was solved using the eddy diffusivity concept. The simulation resulted that the sediment concentration changes periodically in the transverse direction, showing higher concentration over the smooth strips. This is consistent with the previous field during the floods. The eddy diffusivity profile was also given and discussed

Impedance Spectroscopic Study of p-i-n Type a-Si Solar Cell by Doping Variation of p-Type Layer

We investigated p-i-n type amorphous silicon (a-Si) solar cell where the diborane flow rate of the p-type layer was varied and the solar cell was measured static/dynamic characteristics. The p/i interface of the thin film amorphous silicon solar cells was studied in terms of the coordination number of boron atoms in the p layer. p-type layer and p/i interface properties were obtained from the X-ray photoelectron spectroscopy (XPS) and impedance spectroscopy. One of the solar cells shows open circuit voltage (oc)=880 mV, short circuit current density (sc)=14.21 mA/cm2, fill factor (FF)=72.03%, and efficiency ()=8.8% while the p-type layer was doped with 0.1%. The impedance spectroscopic measurement showed that the diode ideality factor and built-in potential changed with change in diborane flow rate

Simulation of Silicon Heterojunction Solar Cells for High Efficiency with Lithium Fluoride Electron Carrier Selective Layer

In this work, to ameliorate the quantum efficiency (QE), we made a valuable development by using wide band gap material, such as lithium fluoride (LiFx), as an emitter that also helped us to achieve outstanding efficiency with silicon heterojunction (SHJ) solar cells. Lithium fluoride holds a capacity to achieve significant power conversion efficiency because of its dramatic improvement in electron extraction and injection, which was investigated using the AFORS-HET simulation. We used AFORS-HET to assess the restriction of numerous parameters which also provided an appropriate way to determine the role of diverse parameters in silicon solar cells. We manifested and preferred lithium fluoride as an interfacial layer to diminish the series resistance as well as shunt leakage and it was also beneficial for the optical properties of a cell. Due to the wide band gap and better surface passivation, the LiFx encouraged us to utilize it as the interfacial as well as the emitter layer. In addition, we used the built-in electric and band offset to explore the consequence of work function in the LiFx as a carrier selective contact layer. We were able to achieve a maximum power conversion efficiency (PEC) of 23.74%, fill factor (FF) of 82.12%, Jsc of 38.73 mA cm−2, and Voc of 741 mV by optimizing the work function and thickness of LiFx layer

HF etched glass substrates for improved thin-film solar cells

A hemisphere-array textured glass substrate was fabricated for the development of an improved thin-film (TF) silicon solar cell. The HF-H2SO4-etchant system influenced the light path owing to the formation of the strong fluorine-containing HSO3F acid. In particular, the etching system of the various HF concentration with a constant H2SO4 solution is related to make an improvement of optical transmittance and light trapping structure without a uniform pattern. According to the specular transmittance measurements, the haze ratio was maintained for the glass sample etched with 35% HF in the longer-wavelength region. The proposed substrate was implemented in a TF-Si solar cell, and an improved conversion efficiency was observed according to the short-circuit current density owing to the increase in the haze ratio. This morphology, therefore, induces more scattering at the front side of the cell and leads to an improvement of the open circuit voltage gain for the HF 25% cell. It will be helpful to understand the application of thin film solar cell based on the HF-H2SO4 etching system for the readers