01. Arab Journal of Basic and Applied Sciences

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e-ISSN 2576-5299

Managing Editor:Prof. Waheeb E. Alnaser
Frequency:3 issues per year

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Arab Journal of Basic and Applied Sciences publishes high-quality, Open Access original research within the natural and applied sciences with a strong focus on discrete mathematics and environmental chemistry.

The journal aims to connect researchers in the region to one another and to the wider, international scientific community.

All published research articles in this journal have undergone rigorous double blind peer review by expert international referees, after initial editor screening. We publish full length original articles, reviews, letters to the editor and short communications scientific articles in English.

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Arab Journal of Basic and Applied Sciences is abstracted and indexed in several databases including Scopus.

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Editor-in-Chief

Prof. Mohammad El-Hilo - General Secretary of Society of Colleges of Science in Arab Universities; and Dean of College of Science, University of Bahrain, Kingdom of Bahrain

Managing Editor

Prof. Waheeb E. Alnaser - Vice President for academic and postgraduate programs, University of Bahrain, Kingdom of Bahrain

Editorial Secretary

Dr. Ali Salman Bin Thani - University of Bahrain, Kingdom of Bahrain

Editorial Board

Prof. Yaseen Al-Soud (Chemistry) - Al al Bayt University, Jordan
Prof. Dumitru Baleanu (Mathematics) - Cankayu University, Turkey
Prof. Belkheir Hammouti (Environmental Chemistry) - University Mohammed Premier, Morocco
Prof. Shoukry S. Hassan (Mathematics) - University of Bahrain, Kingdom of Bahrain
Prof. Ji-Huan He (Mathematics) - Soochow University, China
Prof. M. Ishaque Khan (Chemistry) - Illinois Institute of Technology, USA
Prof. Badiadka Narayana (Environmental Chemistry) - Mangalore University, India
Prof. Xiao-Jun Yang (Mathematics) - China University of Mining and Technology, China
Prof. Haq Nawaz Bhatti (Physical and Environmental Chemistry) - University of Agriculture, Pakistan
Prof. Cemil Tunç (Mathematics) - Van Yuzuncu Yil University, Turkey

International Advisory Editorial Board

Prof. Farouk El-Baz (Geology) - Centre for Remote Sensing, Boston University, USA
Prof. Mustafa Amr El-Sayed (Chemistry) - Georgia Institute of Technology, USA
Prof. Mourad E.H. Ismail (Mathematics) - University of Central Florida, USA
Prof. Ahmed Sameh (Computer Science) - Minnesota University, USA
Prof. Munir H. Nayfeh (Physics) - Illinois University, USA
Prof. Sultan Abu Orabi (Chemistry) - Secretary General of AAU, Jubeyha, Amman, Jordan
Prof. Riyad Y. Hamzah (Biochemistry) - President of University of Bahrain, Kingdom of Bahrain

Distinguished Advisory Editorial Board

Prof. Ahmed H. Zewail (26 February 1946 - 2 August 2016)

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Now showing 1 - 20 of 229

Survey of Low Background Radiation in the Kingdom of Bahrain
(University of Bahrain, 2005-01-01) Alnaser, W. E.; Aldallal, S.M.S; Zein, M.M.; Alnaser, Y. E.
A survey of the α (Alpha) and β (Beta)low background radiation level (LBRL) at the Kingdom of Bahrain is reported herein.2 grams samples were collected from the soil at the surface and at a certain depth of terrestrial and coastal areas. The possibility of the existence of nuclear pollution or radioactive sources is investigated. The weighted average for α - LBRL was 22.63 pCi, for samples taken from the terrestrial surface, and 21.21 pCi, for samples taken from a certain depth. For the coastal areas the LBRL was 14.17 pCi and 10.86 pCi, respectively. The weighted average for β- LBRL was 51.63pCi, for samples taken from the terrestrial surface and 47.10 pCi, for samples taken from a certain depth. For samples taken from the coastal areas it was 32.7 pCi and 28.47 pCi, respectively. The unweighted average of α -LBRL was 25.78 pCi, for samples taken from the terrestrial surface, and 23.85 pCi, for samples taken from a certain depth; For β-LBRL the average values were 55.56 and 51.30 pCi, respectively. Isa Town region had the highest average measured terrestrial α- LBRL (68.36 pCi for surface samples and 78.97 pCi at a certain depth), while the lowest was in Sitra (12.98 pCi and 12.75pCi, respectively). Meanwhile, the highest terrestrial average β- LBRL was measured in Isa Town (123.48 pCi for surface samples and 137 pCi for samples taken from a certain depth), while the lowest was in Sitra (30.42 pCi and 28.67pCi, respectively). The highest measured coastal α- LBRL was in Hidd beach (27.98pCi for surface samples and 18.21 pCi for samples taken from a certain depth), while the lowest was in Belajaljazair (4.99 and 6.38pCi ,respectively).The highest measured coastal β- LBRL was in Hidd region (52.14pCi for surface samples), but the highest for samples taken at a certain depth was in Manama port(55.18pCi).The lowest coastal average β- LBRL was in Halat Alsalath (5.33pCi for samples taken from surface ), while its in Hidd for samples taken from a certain depth(0.236 pCi). The ratio of αsur to α dep as well as βsur to βdep in terrestrial region in Bahrain was found equal to 1.08 for both, when it was unweighted and 1.06 and 1.09 respectively, when they are weighted. This indicates that no major nuclear fallout on the kingdom or no nuclear emission from underground.
Rural Photovoltaic Electrification Program In Jordan
(University of Bahrain, 2005-01-01) AL-Soud, M. S.; Hrayshat, E. S.
The photovoltaic (PV) technology potential in Jordan is high, based on the fact that many remote and isolated sites are located far away from the national electric grid and can not be connected to it in the near future. Therefore, a rural PV electrification program - driven by quality-of-life improvement for the users - was launched in Jordan in 2002. An important element of the program is the access of low-income, rural consumers to essential electricity. This paper discusses and analyses the first stage of this program that is the electrification of a remote and small Jordanian village. Nine PV solar home systems (SHS) were installed in this village in order to provide lighting and power for radio and television. Feed back from the users of the installed systems indicates that the PV based electricity has been providing very satisfactory service to the consumers, and that it is an appropriate technology suitable for dissemination in the rural Jordanian areas.
The Role Of Hydrogen Energy In Sustainable Development
(University of Bahrain, 2005-01-01) Sahin, Ahmet Z.
In this paper, the role of hydrogen energy for the sustainable development is discussed considering its production, storage and utilization. In addition, the environmental impacts in using hydrogen energy base technology and possible adverse consequences that may arise in the production, transportation, storing and use of hydrogen are carefully studied from both environmental and economical perspective towards sustainable development.
Wind Resource Assessment Of Eastern Coastal Region Of Saudi Arabia
(University of Bahrain, 2005-01-01) Elhadidy, M.A.; Shaahid, S.M.
In the present study, the hourly mean wind-speed data of the period 1986-1997 recorded at the solar radiation and meteorological station, Dhahran (Eastern coastal plain of Saudi Arabia), has been analyzed to present different characteristics of wind speed in considerable depth such as: yearly, monthly, diurnal variations of wind speed, etc. The long-term monthly average wind speeds for Dhahran range from 4.2 to 6.4 m/s. More importantly, the study deals with impact of hub height on wind energy generation. Attention has also been focussed on monthly average daily energy generation from different sizes of commercially available wind machines (150 kW, 250 kW, 600 kW) to identify the optimum wind machine size from energy production point of view. It has been found that for a given 6 MW wind farm size, at 50 m hub height, array of 150 kW wind machines yields about 48 % more energy as compared to 600 kW wind machines. Literature shows that commercial/residential buildings in Saudi Arabia consume an estimated 10 - 40% of the total electric energy generated. So, concurrently, as a case-study, attempt has been made to investigate/examine the potential of utilizing hybrid (wind-diesel) power systems to meet the load requirements of hundred typical 2-bedroom residential buildings (with annual electrical energy demand of 3512 MWh). The hybrid systems considered in the present case-study consist of different combinations of wind machines (of various capacities), supplemented with battery storage and diesel back-up. The deficit energy generated from the back-up diesel generator and the number of operational hours of the diesel system to meet a specific annual electrical energy demand of 3512 MWh have also been presented. The evaluation of hybrid system shows that with seven 150 kW WECS (wind energy conversion systems) and three days of battery storage, the diesel back-up system has to provide 17.5 % of the load demand. However, in absence of battery storage, about 37 % of the load needs to be provided by the diesel system
Neural Fuzzy Networks for Optimal MPPT Control in PV Powered AC Loads
(University of Bahrain, 2005-01-01) Della, K. M.; Midoun, A.
Renewable energies are being more popular and viewed in some cases as a viable alternative to conventional sources of energy. A great number of renewable based applications have been developed to satisfy energy demand in different fields. This paper deals with the application of artificial intelligence in photovoltaic powered AC loads. Neural fuzzy networks are applied in order to optimize the energy produced by photovoltaic generators (PVG) and successfully improving the maximum power point tracking (MPPT) control. Simulation and experimental results will be given to demonstrate the efficiency and performance of the proposed control system.
Calculation of Sky Turbidity in the Kingdom of Saudi Arabia
(University of Bahrain, 2005-01-01) Al-Mostafa, Z. A.
The atmospheric turbidity has been calculated using data from 29 locations around the Kingdom of Saudi Arabia, using a nine years solar radiation data covering the period from 1971 to 1980. The turbidity values were found to range from 0.1 to 0.4, and the long-term average of the turbidity was 0.281±0.056. The minimum value was in Sirr-Lasan (0.168±0.028) and the maximum value was in Riyadh 0.474±0.090. The low value of the turbidity indicates that the sky of Sirr-Lasan (2100 meter above sea level) may be the clearest in the country, when considering the turbidity as the main factor in preliminary site selection for astronomical observatory. Correlations between the turbidity and geographical coordinates have been investigated here, and have shown a weak relation between them. Also, seasonal variations studies have shown no significant distribution, which means that each station has its own trend. The low values of the turbidity indicate that the sky of Saudi Arabia has relatively slight polluted atmosphere in the period of study.
Nile Flooding fluctuations and its possible connection to the long solar variability
(University of Bahrain, 2005-01-01) Basurah, H. M.
In the present paper, data of the Nile River flooding, from mid of the seventh century to the end of the ninth century, which collected from different Islamic history books, has been used to investigate the cycles of its level variability. This is considered as the longest direct instrumental climatic record available up to now. It also could provide information, dating back to hundred years, which make it suitable for analyzing climate variations and their possible correlation with the solar activities. The most significant periods were found corresponding to the Gleissberg and Schwabe solar cycles. Also centennial and multidecadal cycles have been found, but at low confidence level. We had found some of these cycles are similar to the solar variability cycles, while others are typical for terrestrial climate that may be considered as possible indication of solarclimate relationship. The results obtained in the work are consistent with other work (Hameed 1984, Shaltout and Tadros 1990, Putter et al 1998) where they had used different version of Nile river flood-level time series.
Mineralogical and Geochemical Study of the Subsurface Acidification Products Ninivite, Alunite and Jarosite, Northern Iraq
(University of Bahrain, 2006-01-01) Al-Juboury, Ali Ismail; Al-Naqib, Salim Qassim; Al-Traif, Abdul-Salam Mehdi
Petrographic, mineralogical and chemical analyses of marl were investigated to verify the formation processes of many alteration products under low temperature -pressure conditions, where an ample source of sulphate exists. Marl (calcareous claystone) comprising about one third of the lithological constituents of the Middle Miocene Fat'ha Formation (previously named Lower Fars Formation) in northern Iraq in addition to evaporites and limestones. The extensive reduction of its sulphate members produces economically significant deposits of sulphur as well as sulphate and salt. Oxidation of H 2S produces sulphuric acid due to the effect of Thiobacillus bacteria. The interaction of H2SO4 with marl, leaching of K, Na, Al, Fe and Ca leaves behind a porous silica -rich (ninivite) center of the zoning pattern due to the alteration- precipitation processes, followed outwards by alunite, which is, in turn, surrounded by a narrow zone of jarosite and finally iron oxides in the rim. Secondary gypsum (selenite) is precipitated in shrinkage cracks as veins or as.floating crystals in the ninivite.
Statistical magnitude analysis and distance determination of the nearby GOV stars
(University of Bahrain, 2006-01-01) Sharaf, M.A.
The present paper has three folds: first, to provide some basic descriptive statistical parameters for the apparent and absolute magnitudes of the nearby stars of spectral type GOV stars Second, to establish the frequency functions o(m) and W(m) of the absolute and apparent magnitudes for these stars. Third , to compute the distance r of these stars as a system assuming that they scatter around a mean absolute magnitude in a Gaussian distribution. The accuracy of the numerical results is satisfactory in that, the percentage error between r and the mean value is less than 3%.
New Theoretical Approach of Flat Plate Solar Collector Considering the Glass Cover as a Participating Media Subjected to Solar and Thermal Radiations
(University of Bahrain, 2006-01-01) Khoukhi, Maatouk
A new theoretical approach of black flat platesolar collector considering the glass cover as a participating media and taking into account the absorption and emission within a glass cover is presented. Two kinds of glasses commonly used as cover for such system, clear and low iron, have been studied. The glass material is analyzed as a non-gray plane parallel medium subjected to solar and thermal irradiations in one-dimensional case using the Radiation Element Method represented by Ray Emission Model. The optical constants of the complex refractive index, considering 160 values the pair of real part (n) and imaginary part (k), of a clear and low iron glasses reported by Rubin covering the range of interest for solar and thermal calculation have been used. The CPU times for predicting the thermal behavior of a solar collector using non-gray models were found to be prohibitively long. Therefore, suitable semi-gray (SG) models have been proposed for rapid calculation. We should mention that the results presented here are related to the low-iron glass. However, the instantaneous efficiency of the solar collector with low iron glass cover was compared with that obtained with clear one using SG models. It has been shown that the effect of the non-linearity of the radiative heat exchange, between the black plate absorber and the surroundings on the shape of the instantaneous efficiency curve is important. Indeed, the thermal loss coefficient is not constant but is function of temperature; due primarily to the radiative transfer effect. Therefore, when the heat exchange by radiation is dominant compared with the convective mode, the profile of the efficiency curve is not linear. It has been also shown that the instantaneous efficiency of the solar collector with a low iron glass cover is higher than the efficiency of the system with clear glass cover. It increases by approximately 8%.
Some Statistical Characteristics of Solar Radiation and Sunshine Variations in Tropical Area. A Case Study of the Kiang Valley Region, Malaysia
(University of Bahrain, 2006-01-01) Yaseen, Mohamed Elnour; Jahi, Jamaluddin MD
The purpose of this study is to investigate the variations and trends in monthly, seasonal and annual solar radiation in the Kiang Valley Region for the period 1975-2002. The least square method was used for the trend analysis. The linear trend is used mainly to test the change in solar radiation and sunshine to set limits on the rate of change. Trend line and values and significance levels of the slopes have been found The seasonal and the annual average values were computed from the monthly average radiation data. The seasonal and annual average solar radiation and sunshine values were designated as dependent variables, and thus, were fitted linearly for season and annual means for each station. The results showed that the mean of maximum incoming global radiation in September with a value of 21.1 MI M-2 at Petaling Jaya, while the mean minimum in November and December with values of 10.7 and 10.9 MJ ni2 at Petaling Jaya. The low amounts of solar radiation received in November and December are due to greater cloudiness during the period coinciding with the northeast monsoon season. On rainy days, very little global solar radiation is received The overall average rate of change in global solar radiation during 1975-2002 and 1977-2000 is represented by the slope of the linear regression was small (-0.126 and -0.314 MI m-2 per year for Subang Airport and Petaling Jaya respectively). The sunshine results revealed that there is a maximum in May of 7.0 hours at Subang Airport and a minimum in November with a value of 4.5 hours at Universiti Kebangsaan Malaysia. The coefficient of variation (C. V.) ranged from 4.7% in April to 22.3% in December. The coefficient of variation has a wide range during April and December, suggesting large variations from month to month. The statistically fitted linear trend at Subang Airport and Petaling Jaya over the period 1970- 1999 were -4.30 and 0.22 hour per year and statistically not significant. At Universiti Kebangsaan Malaysia the linear trend over the shorter period of measurement available, 1979-2000 was -13.57 hour per year, and was significant at 0.05 level.
Design, Sizing & Simulation of Solar Powered Desalination Unit for Brackish Water in Jordan
(University of Bahrain, 2006-01-01) Muhaidat, Ahmet H.
In the framework of a regional scientific cooperation project between USA, Israel, Jordan, and the Palestinian Authority, Jordan (represented by the National Energy Research Center — NERC) has received two desalination units. The first unit is a US-military RO-desalination unit (ROWPU), producing 16 gpm of fresh water and operated with diesel generator. The second unit designed for brackish water also produces 16 gpm fresh water, and is accompanied by a complete sixteen KWp - PV system. This paper describes the water situation in Jordan, the potential of solar radiation in the area, site selection criteria, and the designing, sizing and simulation of a photovoltaic power supply system for the second RO-desalination unit. Also the paper contains measurement and evaluation data concerning the water quality, energy consumption and efficiency of the (ROWPU), which has been installed and operated by NERC in the village of Qatar in Jordan.
Environmentally Friendly and Sustainable Source of Energy from Photovoltaics and Fuel Cells
(University of Bahrain, 2006-01-01) Stamouli, A. Boudghene; Larbi, N.; Traversa, E.
Several definitions of sustainable development have been put forth, including the following common one: development that meets the needs of the present without compromising the ability of future generations to meet their own needs. A recent World Energy Council (WEC) study found that without any change in our current practice, the world energy demand in 2020 would be 50 to 80% higher than 1990 levels. According to a recent U.S. Department of Energy (DoE) report, annual energy demand will increase from a current capacity of 363 million kilowatts to 750 million kilowatts by 2020. The world's energy consumption today is estimated to 22 billion kWh per year, 53 billion kWh by 2020. Such ever increasing demand could place significant strain on the current energy infrastructure and potentially damage world environmental health by CO, CO2, 502, NOx effluent gas emissions and global warming. Achieving solutions to environmental problems that we face today requires long-term potential actions for sustainable development. In this regard, renewable energy resources appear to be the one of the most efficient and effective solutions since the intimate relationship between renewable energy and sustainable development. More rational use of energy is an important bridge to help transition from today's fossil fuel dominated world to a world powered by non-polluting fuels and advanced technologies such as photovoltaic (PV) and fuel cells (FC). This paper discusses the potential for such integrated systems in the stationary and portable power market in response to the critical need for a cleaner energy technology. Anticipated patterns of future energy use and consequent environmental impacts (acid precipitation, ozone depletion and the greenhouse effect or global warming) are comprehensively discussed in this paper. Throughout the paper several issues relating to renewable energies, environment and sustainable development are examined from both current and future perspectives.
Short Circuit Currents Improvements of In-doped Silicon (n) Structure
(University of Bahrain, 2006-01-01) Mohamad, Wagah F.
Theoretical and practical calculations of short circuit currents of In-doped Silicon (n) structure have been calculated. Theoretically maximum value of generated current was 5.25 mA at 0.5x1017 cm-3 indium concentrations. Practically the ideal I-V characteristic of the structure is obtained with indium thickness of 1500 °A annealed at 1100 r for an hour. This structure has a knee voltage at 0.8 V with very small value of reverse saturation current and 1.6 ideality factor. The maximum photogenerated current about 2.3 mA is obtained at 0.396x1017 CM-3 of indium concentration. Theoretical & practical results agree that the maximum photo generated current occurs at zero cell output voltage.
A simplified method for infrared and ultraviolet solar radiation analysis in Riyadh, Saudi Arabia
(University of Bahrain, 2006-01-01) Al-Salhi, Mohammed S.
The present work describes a simplified method for field data which include total, direct, infrared (IR) and ultraviolet (UV) solar radiation in Riyadh for the period from 1982 to 1992. Four dimensionless parameters namely A A1,B and B are considered to study the d' d daily, monthly and yearly variations. Two normalized parameters for UV and IR are also introduced The observed variations in UV and IR together with their implicit and normalized parameters enable us to a better understanding of some environmental effects in the region such as UV/IR scattering, UV/IR reflection, clouds, ozone, and temperature.
Environmentally Friendly and Sustainable Source of Energy from Photovoltaics and Fuel Cells
(University of Bahrain, 2007-01-01) Stamouli, A. Boudghene; Larbi, N.; Traversa, E.
Several definitions of sustainable development have been put forth, including the following common one: development that meets the needs of the present without compromising the ability of future generations to meet their own needs. A recent World Energy Council (WEC) study found that without any change in our current practice, the world energy demand in 2020 would be 50 to 80% higher than 1990 levels. According to a recent U.S. Department of Energy (DoE) report, annual energy demand will increase from a current capacity of 363 million kilowatts to 750 million kilowatts by 2020. The world's energy consumption today is estimated to 22 billion kWh per year, 53 billion kWh by 2020. Such ever increasing demand could place significant strain on the current energy infrastructure and potentially damage world environmental health by CO, CO2, 502, NOx effluent gas emissions and global warming. Achieving solutions to environmental problems that we face today requires long-term potential actions Jiff sustainable development. In this regard, renewable energy resources appear to he the one of the most efficient and effective solutions since the intimate relationship between renewable energy and sustainable development. More rational use of energy is an important bridge to help transition from today's fossil fuel dominated world to a world powered by non polluting fuels and advanced technologies such as photovoltaics (PV) and fuel cells (FC). This paper discusses the potential for such integrated systems in the stationary and portable power market in response to the critical need for a cleaner energy technology. Anticipated patterns of future energy use and consequent environmental impacts (acid precipitation, ozone depletion and the greenhouse effect or global warming) are comprehensively discussed in this paper. Throughout the paper several issues relating to renewable energies, environment and sustainable development are examined from both current and future perspectives.
Effect of Temperature on the Solar Module Performances
(University of Bahrain, 2007-01-01) Benatiallah, A.; Kadi, L.; Dakyo, B.
Photovoltaic system is established as a reliable and economical source of electricity in rural and Sahara areas, especially in developing countries where the population is dispersed, therefore requiring low energy consumption. Among solutions of producing decentralized electricity, the present renewable energies presents many advantages comparing to the classic sources (nuclear, oil, gas, etc). The solar energy is the most promising among other renewable energies and especially. for developing countries where irradiance is very strong (Arabian countries). The results, which are illustrated by curves, are analyzed. The analysis qf the performance concluded that this electrical parameters decrease with the temperature. A decrease of the output power (4 wIcK), of the open voltage (0.2 VI°C) and of the conversion efficiency (0.59 x10-3 % PK) of the PV module with the temperature increase has been observed. The current increases approximately linearly with the temperature with 1.2 mA PC.
Mycoflora of Herbal Drug Plants from Bahrain
(University of Bahrain, 2007-01-01) Mandeel, Qaher A.
Mycoflora profile were evaluated in crude unstored samples of twenty herbal drug plants, in which half were collected from cultivated habitats and the rest from desert locations. Micro/1mgal colonies were singled out from a total of 130 samples using standard dilution plate method on several media. The highest fungal spectra and diversity was encountered in materials of cultivated habitats with a total of 2707 isolates, representing 39 species compared to only 965 isolates and 25 species .from desert locations. The most heavily contaminated herbal drug samples examined .from cultivated and desert habitats were observed in parts of Atriplex leucoclada and Erodium laciniatum var pulverulentum, with an average of 636 and 259 cfitIg„ respectively. The maximum relative contamination frequency from five random samples infected with > 5 fungi was also found associated with A. leucoclada (93.2%) followed by Trigonella anguina (86.7%) in cultivated and desert habitats, correspondingly. Moreover, among both habitats, the medicinal herb A. leucoclada from the cultivated habitat exhibited the highest species diversity based on the SIMPSON (0.930) and SHANNON-WIENER (2.856) indices. The most predominant mould genera detected from both habitats, based on relative density values (> 5%), were Chaetomium, Aspergillus, Rhizopus and Cladosporium. Moreover, these taxa revealed an overall frequency of occurrence rates > 70% and hence contributed substantially to the total population density load of the recovered fungi in this study. The incidence of toxigenic moulds represented mainly by A. flavus in ? 5 random samples fluctuated between 31.3 —1.9`% in cultivated habitat plants and 11.7 — 3.2% in desert habitat plants. Similarly, data are consistent with previously reported .findings that mould spoilage incidence of herbal drug plants investigated in this study constitute a health hazard, especially if destined for human consumption. Thus, there is an urgent need for quality control and hygienic measures before the, finished products are channeled to consumers or end up in drug preparations.
An Investigation of the Wall Heat Transfer in Fixed Bed Reactor at Atmospheric and High Pressure
(University of Bahrain, 2007-01-01) Al-Meshragi, M.; Hughes, R.
A wall heat transfer parameters in fixed bed in a radial direction using air, carbon dioxide and helium has been measured. In addition, the radial wall heat coefficient in the same fixed bed was investigated under high pressure (up to 20 bar). The temperature gradients obtained from the experimental data were analyzed by the two-dimensional pseudo-homogeneous model to determine the wall heat transfer coefficient. The results obtained, rom experimental data for atmospheric and high pressure indicates that the wall heat transfer coefficient increase with increasing Reynolds number at both pressures. However, the effect of pressure upon wall heat transfer coefficient as function of Reynolds number indicates that pressure higher than atmospheric cause a decrease in the wall heat transfer and the values of atmospheric pressure were found to lie well above those at high pressures.
Designing a Heat Pipe to Improve the Exhaust Emissions from Petrol Engines
(University of Bahrain, 2007-01-01) Elmabrouk, Ali. M.; Gashoot, Saleh R.
The national engineering Laboratory and the Shell research Laboratory have co-operated in applying the heat pipe to the problem of exhaust emission .from petrol engine. In this paper, a complete design of heat pipe is carried out, taking into account the necessary criteria to decide various geometrical parameters. The design has been carried out using basic formulas in thermodynamics, heat transfer and physics. The results of this design have been checked for various practical limits.