Ahmed A. Abdel-Rehim

Effect of Nano-Graphite Dispersion on the Thermal Solar Selective Absorbance of Polymeric-Based Coating Material

The basic part of solar water heaters is the collector and the main functional part of the collector is the absorber layer. In this work, a commercial locally available black painting (PACEN code 10382 colour 890), used for swimming pools solar heating, was modified by adding nano-graphite dispersion. The effect of nano-graphite particles percentage on the spectral absorbance of the material was examined on samples containing two values of 1.5 and 2.5% nano-graphite particles by weight. Fourier transform spectroscopy (FTIR) analysis was also used to identify the functional groups in the developed material. A simple experimental setup was designed to evaluate the performance of the developed nanodispersed selective coating polymeric based material, by measuring the increase in temperature of circulating water. It was shown that adding 1.5–2.5% nano-graphite particles to a polymer based black coating causes an increase in the optical absorptance, and an increase in the circulating water temperature.

Thermoelectric Behaviour of Polyvinyl Acetate/CNT Composites

In this work an organic polymer/carbon nanotubes composite is introduced for low cost, versatile, nontoxic, light weight and high performance thermoelectric materials. Organic polymers have low thermal conductivity which is desirable for thermoelectric field. Composite films of polyvinyle Acetate and multi wall carbon nanotubes (MWCNT) are demonstrated as a new candidate material for thermoelectric application. MWCNT wt. percentage ranging from 1 to 70 wt% were manufactured and tested for thermopower and electrical conductivity. Dioctyl sodium sulfosuccinate is used as the wetting agent in ratios of 2, 25 and 100% of CNT weight content. A study of the effect of the dispersantto CNT ratio on the electrical conductivity and thermopower of the composite was also carried out. The composite thermoelectric properties were measured as a function of CNT concentration at room temperature.

Comparative Analysis Between Water and Nanofluids as Working Fluids in Photovoltaic Thermal Collectors

Photovoltaic thermal collectors (PV/T) are devices that produce both electrical and thermal energies simultaneously. Water acts as the working fluid that cools down the PV cells, thus improving their electrical efficiency, and at the same time hot water is produced due to the heat exchange process. As a consequence heat transfer augmentation is an important issue that affects the performance of such a hybrid system. The objective of the current study is to evaluate the effect of using a nanofluid on the performance of a photovoltaic thermal (PV/T) collector. The performance of the water cooled PV/T collector without nanofluid is first evaluated and then additional correlations are incorporated to include the nanofluid properties. Results showed that the use of nanofluid enhanced the rate of heat transfer which resulted in improvement in the performance of the PV/T collector. However, such improvement was not found to be significantly high to shift for nanofluids as working fluids in PV/T collectors.Copyright

Condition Monitoring of a Single Cylinder Engine Running on Gasoline and Gasoline-Ethanol Blend Using Wear Particle Analysis Technique

Analytical techniques performed on oil samples for lubricated machines can be classified in two categories; used oil analysis and wear particle analysis. Used oil analysis determines the condition of the lubricant itself, determines the quality of the lubricant, and checks its suitability for continued use. Wear particle analysis determines the mechanical condition of machine components that are lubricated. Through wear particle analysis, you can identify the composition of the solid material present and evaluate particle type, size, concentration, distribution, and morphology, thus indicating the machine condition and its predictive maintenance.The above mentioned techniques are suitable methods for the detection of abnormal wear occurring in internal combustion engines, especially for engines running on different fuels. These techniques provide cheap, fast and easy to use predictive maintenance methods which can replace other conventional methods.The objective of the present study is to apply wear particle analysis technique as an engine monitoring technique to compare two new and identical engines running on gasoline (Engine 1) and gasoline-ethanol blend (Engine 2). The two engines were tested for a total running period of 850 hours. Spectrometric and ferrographic analysis were used for the comparison where quantitative and qualitative changes in the concentration and size distribution of different particles were analyzed and compared to baseline values.Results showed an increase of wear rate for the engine running on gasoline-ethanol blend compared to the engine running on gasoline only. Two contents of ethanol were used where 10% content showed a moderate increase of wear rate; however 20% content showed a dramatic increase of wear rate.The predominant wear particles were the ferrous particles and aluminum particles indicating the wear of piston elements and piston rings. Corrosive wear was also highly remarked which indicates a chemical reaction in the presence of ethanol.Copyright

Comparative Analysis of Fuel Cell and Photovoltaic Panels as Electrical Sources for RO Desalination Domestic Scale Systems

Fuel cells and photovoltaic cells are two promising technologies for green sustainable societies. Both are technologies that are capable of producing electricity but with different techniques. A solar cell converts light directly into electricity by the photovoltaic effect. On the other hand, a fuel cell converts the chemical energy from the reaction between oxygen and a fuel into electricity and water. The fuel used is hydrogen which can be produced using solar energy. Both devices have different working principles, operation requirements, and efficiencies. However, they share the end goal of producing electricity from a non-fossil clean energy source. The main objective of this work is to investigate whether fuel cells or solar cells are more feasible for domestic use by considering the available technologies and information. The comparison is based on the electricity produced by the two technologies provided the same input of energy from the sun. The research focuses on the electrical output, their efficiencies, and the cost of purchasing, operation, and thus the cost of energy produced from the whole system. A desalination domestic scale system based on Reverse Osmosis (RO) technique was proposed as an application to consume this energy.© 2012 ASME