University of Khartoum Engineering Journal
The University of Khartoum Engineering Journal (UofKEJ) is an open access journal published in English and/or Arabic by the Faculty of Engineering, University of Khartoum.
University of Khartoum Faculty of Engineering
The Effect of Radiometric Resolution on Information Sharing Between Landsat8 Bands
The technological revolution that the world is witnessing also included the development of the characteristics of remote sensing devices, which had a direct impact on increasing the accuracy of the data obtained through these devices. For example; the radiometric resolution of Landsat satellite sensors increased from 7 bits in the first Landsat sensors to 16 bits in Landsat-8. In this study, the effect of this improvement in radiometric resolution was measured to find the amount of change in the mutual information at several dynamic ranges. The study area was the state of Khartoum, and the study was conducted on four different types of land cover (agricultural, urban, water, and desert) to determine the amount of shared information between several dynamic ranges based on the land cover unit. The image obtained from the Landsat-8 satellite for the study area had a 16-bit dynamic range. However, it was down sampled to 8bits, 9 bits, 10 bits, 11 bits, 12 bits, 13 bits and 14 bits, and the amount of information shared between these dynamic ranges and the original image was calculated for the first seven bands of Landsat-8. The results showed that the amount of shared information varies based on the type of land cover, however, this amount reaches its lowest value on the water cover between the 8-bit image and the 16-bit image which is 80%. The study ended with a recommendation that the effect of change in radiometric resolution should be examined in the stage classification of images.
الحقوق الفكرية (c) 2023 University of Khartoum Engineering Journal
Historically Acacia seyal gums in the Sudan is ranking as a second important gum product after A. senegal in terms of quantities 10% in average until 2011. Thus the contribution percentages within the last four years (2012-2015) jumped to almost 60% in average. A. seyal trees coverage extend in an area of 36,000 square kilometers (3.6 million ha) in a latitude ranging between 10 to 140North. The distribution of the A.seyal stand is extensively on the clay soil plains where an average rainfall is ranging between 300 to 400 mm. Two infraspecific variants of A. seyal widely distributed in Sudan separated on the basis of the presence and absence of the ant-galls and the colour of the bark. Ant-gall and white colored bark are the characteristics of variety fistula, while the bark of variety of seyal is green or red. Despite the significant contribution of A. seyal in the exports market in the Sudan, farmers have slightly a poor knowledge of post- harvest cultural practices of A. seyal of which proper methods of storage conditions and gum stacking. Nevertheless, this paper is trying to review the existing research in the areas of pre- and post-harvest cultural practices including tree husbandry, tapping, gum collection, handling and storage. Exudation mechanisms (tapping and natural exudation) are also been highlighted coupled with physical and chemical properties of A. seyal (characterization) as well as moisture content, colour, tannins etc., aiming at establishing a clear protocol of the A. seyal tree in the Sudan.
الحقوق الفكرية (c) 2022 University of Khartoum Engineering Journal
Causes and Effects of Delays in Road Construction Projects in Sudan
Construction delay is one of the serious concerns of the road industry in Sudan. The study aims to identify the causes of delays that have adverse effects on road projects in terms of time, cost and quality. Literature of different types of delays, their causes and effects on road construction projects were intensively reviewed. The study identified a number of causes of delays at great risk and have adverse effects on construction of road projects. A questionnaire based on 15 causes and 5 effects was sent to the clients, consultants and contractors. The collected data were analysed using the Relative Importance Index (RII). The results showed that the contractor is most commonly responsible for project delay (37%), followed by the client (33%) and the consultant (30%). The study findings reveal that the top five main delay causes are payment delay by client, funding problems, conflicts among the project parties, suspension of work due to the client or consultant, and project schedule changes. On the other hand, cost and time overrun, poor quality of work due to rush, and disputes are the main effects of delays. The study concluded that adequate construction budget and payments on time should be the main factors for the project success.
Comparative Study on Some Chemical and Mechanical Stabilizations of Expansive Soils
This paper studies the differences between effects of chemical and mechanical stabilizations on the engineering properties of expansive soil. Undisturbed soil samples were collected form Abu-Gameem in South Sudan. The soil sample was very high expansive in accordance to the primary test conducted. Laboratory tests were undertaken to study the effect of chemical and mechanical additives individually on soil properties. Atterberg’s limits, compaction, California bearing ratio, free swell and swelling pressure tests were conducted on natural and treated soil. Quicklime was used as chemical stabilizer agent, while fine sand was used as mechanical. The lime was collected from Sabol industrial area in south of Khartoum while the sand was obtained from Omdurman in Sudan. The soil was first treated by quicklime contents as 3%, 5% and 7% by weight. Then separately was treated by fine sand contents as 5%, 10% 15% by weight. Comparing the results obtained from chemical and mechanical stabilizations, it can be reported that both of them are effective in improving the engineering properties of expansive soils. Notwithstanding, chemical stabilization improved the soil with less contents of additive. Addition of only 3% quicklime reduced soil plasticity from 45% to a suitable value (18%) while addition of 15% fine sand reduced soil plasticity to 24%. Addition of quicklime resulted in reduction of free swell index almost 4 times of its initial value, whereas slight reduction was observed when fine sand used. Significant improvement on the swelling pressure was obtained when using lime. But, the compaction characteristics were improved further when fine sand used. It could be concluded that based on the result of this study, chemical stabilization is more effective than mechanical. However, a combination of them can be used for further investigations.
Design and Implementation of a Universal Integrated Wi-Fi Controller for Smart Buildings
Internet of things (IoT) technologies deal with the control over communication networks for different applications of different fields, such as residential buildings, commercial buildings, agricultural farms, transport vehicles, and manufacturing industries. Wi-Fi is a family of protocols for wireless local area networks, based on the IEEE 802.11 standards. Recently, a microcontroller with a built-in Wi-Fi module can be considered one of the most recent technologies of IoT. Nevertheless, most of the available research on Wi-Fi controllers is dedicated to a specific application. This paper aims to design and implement a universal hardware platform for a Wi-Fi controller that can be integrated with multiple applications for residential and commercial buildings. The proposed system is based on Ep8266 NodeMCU with a built-in WiFi module. Input modules and output modules of the proposed system are designed to be suited for various voltage levels. The proposed system was implemented and evaluated for multiple applications. The first application deals with controlling residential building loads with an embedded web server on the Wi-Fi controller and web browser on smartphones. The second one is related to integration with the remote access control application of commercial buildings, which is based on Radio Frequency Identification (RFID) cards with Wiegand protocol and based on User Datagram Protocol (UDP) with Internet Protocol (IP).
Banana Extract Lateritic Soil Stabilization in Sudan
Soil stabilization otherwise known as soil modification or improvement, is the process of modifying soil properties to render them durable building and road construction materials by using various admixtures, the well-known being cement and lime. The aim of this study, however, to examine the stabilizing effect of banana extract on selected Sudanese lateritic soils. The objective of this study is to develop a new process for stabilizing lateritic soils. The three soil samples were blended with banana raw extract at 17% by weight of the dry soil at optimum extract content (soil + banana solution). High degree of improvement was obtained in both dry (12.60 – 30.54 N/mm²) and wet (1.03 – 5.03 N/mm²) compressive strength. It was concluded that, banana extract has a profound modifying effect over lateritic soils.
Mohammed Salih Mohammed Khalid M.Elmadni
Impact of Grand Ethiopian Renaissance Dam (GERD) on Manufacturing of the Traditional Fired Clay Bricks in Sudan
The Grand Ethiopian Renaissance Dam (GERD), one of the largest dam projects in the world is currently under construction on the Blue Nile River reach in Ethiopia. Such a massive project will have positive and negative impacts on downstream countries like Sudan. These impacts include impounding sedimentation and avoiding flood occurrence. Previous researches indicated that GERD is expected to impound up to 86% of the Blue Nile annual sediment yield. This is expected to adversely affect the manufacturing of traditional fired clay brick (TFCB) at the banks of both the Blue Nile and the Main Nile rivers. The aim of this paper is to study the impact of GERD on TFCB industry which utilizes the sediment as the main raw material in brick manufacturing. Based on the literature and brick market survey, it has been found from this study that the produced TFCB could be reduced by 68.8% following GERD. This reduction in TFCBs is expected to affect more than 170,000 workers around the country. Future studies and market plans are needed to fill the gap of the TFCB shortage.
Forecasting of Data Traffic in Sudan Internet Exchange Point Using Autoregressive Integrated Moving Average Model
Network traffic prediction is an important issue that has received much interest recently from computer network community. The network traffic prediction is one of the typical issues useful for monitoring network, network security, avoid congestion and increase speed of networks. Different techniques are used for network traffic prediction; first are linear time predictors such as Last Value (LV) Predictor, Windowed Moving Average (MA), Double Exponential Smoothing (DES), Auto Regressive (AR), Autoregressive Moving Average (ARMA) and Autoregressive Integrated Moving Average (ARIMA). The Second techniques are nonlinear time predictor such as generalized autoregressive conditional heteroscedasticity (GARCH) and the last one is hybrid model techniques, and it is combination between two or more models. From literature review, the ARIMA model is the best model to predict data traffic that has time series specification and linear growth. Data traffic collected from Sudan Internet Exchange Point (SIXP) and ARIMA is used to model data and forecast the next five years values. In addition to forecasting values, upper, and lower values are also founded. Furthermore, ARIMA model findings are compared with Monte Carlo forecast and it is found that the results are nearly typical. Finally, when the forecasted results are compared to actual data traffic on January 2020, the predicted values are shown to be very close to the measured ones.
Economic Analysis and Policy-Related Recommendations to Promote Distributed Solar Photovoltaic Systems in Sudan
Distributed solar photovoltaic (DSPV) is a practical and reliable solution in the case of Sudan, considering the vast and remote off-grid rural areas and the insufficient electricity generation in the parts powered by the national provider. This research outlines the scientific processes to work out the economic appraisal of an off-grid PV system with and without storage units that could be deployed within Greater Khartoum. The provided financial assessment, which relies on the PV price, the annualized monthly bill savings, the Levelized cost of energy, the simple payback period, and the national and regional kilowatt-hour tariffs, delivers an insight into the cost affordability of solar-generated electric power in Sudan. Accordingly, the analysis concluded that approximately 1.6 $/Wp is the PV price for a system with a battery bank and 1.2 $/Wp for the on-grid option, both to be fixed in the residential sector. However, the designed system here will not pay back the initial cost considering the low local electricity price. Also, considering the status quo, the investment will not attract investors in the energy sector, although it compensates for the frequent power deficiency in times of need. On the other side, the effort presents local experts and leaders in energy research and planning recommendations to encourage the governmental facilitation of DSPV use as viable renewable energy (RE) technological option. These recommendations hover around the issuance of country-level PV energy policies and are categorized into financial, policy, social, and technical. This work's novelty is its contribution to developing and supporting the Sudanese literature in the energy field, in which the lack of resources and content specific to the republic, especially RE, is evident.
Design and Construction of an Absorption Cooling System Driven by Solar Energy
The objective of this work is to design and construct a lithium bromide–water (LiBr-H2O) absorption cooling system with a nominal capacity of approximately 1 TOR driven by solar energy which uses Lithium Bromide as absorbent and Water as refrigerant. The proposed absorption cooling system comprises a roof-mounted vacuum tubes solar collector, a single-effect LiBr–H2O absorption chiller (generator, a solution heat exchanger, an evaporator, a condenser, and an absorber),fan coil unit, a cooling tower, pumps, flow throttling and controlling valves. A thermodynamic analysis of the absorption cooling cycle has been performed to study the effect of various operating conditions on the thermal performance. Results from experimental work carried out in Khartoum City during October 2015show that the COP of the absorption cooling system ranged from 0.57 to 0.64 while the Chilled water temperatures mostly ranged between 17°C to 19.5°C. Condensation and absorption temperatures were under 45°C while the maximum temperature of the driving water is 83°C. The results also show that the generator temperature had a great effect on the performance of absorption and solar collector systems.
Estimating Precipitation Recycling in Sudan using a BulkModel
The objective of this study was to estimate precipitation recycling ratio (PRR) in Sudan. The numerical bulk model of Eltahir and Brass was used. It was adopted to fit the moisture flux in the domain. The data was retrieved from the European Re-Analysis (ERA-40) of the European Centre for Medium and long-range Weather Forecast (ECMWF) archive. Surface evaporation, horizontal wind speed and specific humidity for 11 levels between the ground surface and the tropopause were used. The grid resolution was 2.5° 2.5° latitude by longitude. The period was the rainy season for the years 1984, 1988 and 2001. These years represent a dry, a wet and a normal year respectively. By calculating the vertical integrals for moisture fluxes the troposphere was reduced to a 2-dimansional domain. PRR values indicated a strong coupling between the ground surface characteristics and the rain patterns. Precipitation recycling ratio was found to be 19% in July, 21% in August and 27% in September. The contribution of the evaporation in South Sudan to the local rains exceeded 25%. It approached zero north of latitude 15°N. While evaporation from South Sudan was recycled, evaporation from North Sudan was not entrained in rain-producing systems due to air subsidence. This raised the question about the benefit of storing water in the desert.
Moisture Flux over Sudan during the Rainy Season
The objective of this study is to evaluate the tropospheric moisture fluxes into and out of Sudan during the rainy season. The data was retrieved from the European Re-analysis (ERA-40) of the European Centre for Medium and long-range Weather Forecast (ECMWF) archive. Horizontal wind speed and specific humidity for levels of significance between the ground surface and the tropopause were used. Vertical integrals for moisture fluxes between the ground surface and the tropopause were calculated at spacing of 2.5°. The moisture fluxes were calculated around the box bound by 2.5°N, 20.0°N, 22.5°E and 37.5°E. Depending on the moisture flux three distinct layers were found within the troposphere. The bulk of moisture entered Sudan from south and west. In the dry year of 1984 the moisture out flux of moisture nearly balanced the influx, leaving the area in a situation of weak convergence which did not favor rain production. The drought of 1984 was attributed to the absence of rain-producing systems rather than to lack of atmospheric moisture. The study concluded that high moisture content is necessary but is not sufficient to produce rain in the absence of converging wind flows. To improve rain predictions and forecast, adequate monitoring of tropospheric moisture and winds is needed
Towards better Management of Sediment and Water in Gezira Irrigation System, Sudan
The one dimensional numerical model Fine Sediment Transport (FSEDT) was developed to simulate the fine sediment transport in irrigation canals of the Gezira Scheme in Sudan. The model was used to understand the sedimentation processes in Gezira canals, as well as for possible wider application. The approach applied to estimate the transport and deposition rates of fine sediment suspensions, for sediments in the cohesive size range has been presented. The model was calibrated and validated using field measurement data at selected canals in the Gezira Scheme during 2011 and 2012 flood seasons. The simulated bed profile of the Zananda Major Canal shows good agreement with the bathymetric survey. The hydro-dynamic part of the model was checked by comparing the water surface profile of the model with that obtained by the DUFLOW model. The results of the two models show good agreement. The analysis demonstrates that the model is a useful tool that can be applied to study the mechanism of sediment transport under different operation and maintenance scenarios not only in Gezira Scheme but also in similar cases.
Performance Improvement of an Air Cooled Air Conditioning System Using an Evaporative Cooled Condenser
The aim of this paper is to investigate the performance improvement of an air-cooled air conditioning system utilizing an evaporative cooled condenser. Air-cooled condensers in many refrigeration and air conditioning systems when used in hot climate are less efficient and have technical, economical, and environmental constraints. As an alternative, the use of evaporative air-cooled condensers, seem to be a unique option to mitigate the limitations above and improve the energy performance of such systems. Another advantage of using evaporative air-cooled condensers is to protect the compressor and keep the system working without interruptions at high outdoor temperatures.To characterize this energy benefit, a model was developed and applied to predict the performance of a variable refrigerant flow (VRF) system under various ambient air temperatures up to 42 °C using an engineering equation solver (EES) software. The results show that the application of the evaporative precooled air in an air-cooled condenser has significant effect on the performance improvement of the air conditioning system. In Khartoum’s hot and dry climate, the rate of improvement is increased as ambient air temperature increases. It is also found that, compared to an air-cooled condensers system, the refrigerant effect and the coefficient of performance of evaporative cooled condensers could be increased by 23% and 60%, respectively. In addition, the compressor work is decreased by 35% followed by a considerable reduction of the operational costs of the system.
Effect of Fly Ash on the Characteristics of Expansive Soils in Sudan
This paper discusses the effect of Fly ash on the engineering properties of expansive soils. As reviewed in literature, many previous investigations have shown promising results for improvement of expansive soil after stabilization with Fly ash. Laboratory tests have been conducted on expansive soils obtained from three different regions in Khartoum state. Various percentages of Fly ash such as 0%, 10%, 20%, 25%, and 30% by weight of soil were added to the three soils and their influence on the soil plasticity, swell characteristics and unconfined compression strength are discussed. Additions of Fly ash to the three soils resulted in significant improvement in the strength and reduction in plasticity and swell properties of soils. The unconfined compression strength of soils treated with 10% Fly ash showed almost 2 times improvement compared with untreated soils. For the addition of 10% fly ash, the reduction in free swell, swell pressure and swell potential is in the range 50% to 70%. Further addition of fly ash caused a reduction in the swell characteristics of 90% at 25% fly ash. Hence, it is concluded that the fly ash has a good potential to be used as a additive for improving the engineering properties of expansive soil.
Importance of Deep Excavation Support and Its Influence on Adjacent Buildings
This paper aims to investigate the important role of deep excavation support and its effect on nearby existing buildings, especially those founded on shallow foundations. Excavation of basement or foundations induces movements as a consequence of stress-release from earthwork and an increase in overburden pressure in the retained ground. Ground movements throughout excavation result in damage to existing structure located nearby. An intensive literature of previous experiences on supporting deep excavation and their impact on neighboring structures reviewed. This paper presents three case histories and two local current cases of excavations, which caused damages either on their own projects or on adjacent buildings. The results revealed that there are numerous sources of risk associated with performing deep excavations in urban areas, they must be considered in the design and execution of the excavation works for a minimum cost. General conclusions have been drawn from the study findings.
Sudan and the Water Sciences Programmes of UNESCO
UNESCO's contribution to enhance the knowledge base, research and capacity to sustainably manage water resources of the world is continually growing for a period close to seventy years (1948 to date). This paper summarizes the initiation of this programme in 1948, leading to the major project in Arid Zone which was followed by the IHD and then the famous current IHP which was enforced by the UNESCO water family that included as well as the UNESCO-IHE and WWAP. The paper gives a brief introduction of these initiatives and examples of the benefits gained by Sudan in the various stages of these initiatives. It also encourages further enhancement in Sudan’s interaction with the UNESCO water family.
An Efficient FPGA-based Design and Implementation of AES Algorithm
This paper presents an FPGA based hardware design and implementation of a 128 bit AES encryption processor. Synthesis is achieved using Verilog code implemented on the FPGA. Two different architectures are presented, the basic iterative architecture which achieves low FPGA resources requirements, 347 slices and 10 BRAM and a maximum throughput is 1.3988Gbps. And the fully pipelined architecture of AES encryption processor for higher speed applications. The second architecture achieved 31.4574 Gbps as maximum throughput and using 30 Block RAM. These designs utilize the low cost and low power Spartan3E(TM) FPGA. Hardware verification has been performed on the Spartan-3E starter board (xc3s500e-4) and the results were similar to simulation results.
Hydropower Generation in Merowe Dam in response to Grand Ethiopian Renaissance Dam (GERD)
This paper aims to quantify the influence of Grand Ethiopian Renaissance Dam (GERD) on Merowe Dam (MD) in the context of hydropower generation. MD is located on River Nile (RN) in the North Sudan, about 800 km downstream Khartoum with a total storage capacity of 12.4 Km3. It worth mentioning that, RN annual runoff is estimated to an average of 85 Km3, formed from Blue Nile (57%), White Nile (29%) and Atbara River (14%).GERD reservoir capacity is estimated to be 74 Km3, with installed capacity of about 6000 Megawatts, while the installed capacity of MD is 1250 Megawatts; the average annual energy output is about 6000 Giga-watts 85% of the required water for the generation in MD comes from the runoff river, while the reservoir provides 15% of water per year.The two main objectives of this study are to quantify the impacts of GERD during first filling and long term run. Comprehensive study for the RN Hydrological system was performed, using Excel Sheets designed with Visual Basic for Applications VBA, calibrated and tested. Boundary conditions were established and different operation policies were applied. It should be noted that, five different scenarios were studied, for the first impounding during 6 years with a total retaining of water between 10-50% of the Blue Nile yield; the impacts were limited to a deficit of 10% max.In summary, the effects of GERD on MD are quantified by decreasing in energy by 10% during first impounding and, increasing in energy by 27% annually for long run.
Incorporation of Fluoride into Coating Process of Aluminium Oxide Coated Charcoal to Enhance Its Adsorption Capacity
Fluoride removal from water is one of the topics that researchers have discussed frequently in the recent period. Many techniques were invented; however; adsorption is considered the most preferred one due its high efficiency low cost. Aluminum Oxide Coated Charcoal AOCC is the one of the most promising fluoride adsorbent. Different researchers found that; AOCC are not only recovering its adsorption capacity after regeneration; but amazingly the adsorption capacity is further increase. The aim of this study is to investigate the reason behind the enhancement of AOCC adsorption capacity after regeneration and to optimize its coating process. Different coating conditions were applied then batch experiments were performed to determine the isotherms and kinetics of fluoride adsorption onto AOCC. Moreover, different techniques were used to characterize the adsorbent such as SEM, EDX and pH point of zero charge methods. The results show that incorporation of fluoride into coating process resulted in formation of aluminum hydroxide precipitates inside the charcoal pores. This precipitated aluminum hydroxide particles lead to enhance the specific surface area and increase the aluminum contents in adsorbent which consequently improve fluoride adsorption capacity.
Experimental study of heat and mass transfer of Solar Powered liquid desiccant regeneration system
Liquid desiccant regeneration has an important effect on the performance of a liquid desiccant air conditioning system. Instead of a conventional packed regenerator an internally heated regenerator is proposed to achieve better regeneration performance. This paper presents an experimental investigation on the performance of the internally heated counter flow desiccant regeneration system. Triethylene Glycol (TEG) solution is used as the working desiccant material in this system. The structured packing used in this system was a finned tube heat exchanger. The effects of inlet parameters such as air flow rate, relative humidity, desiccant solution flow rate and desiccant solution concentration on the performance of the system are studied. The performance of the system is evaluated using the water evaporation rate, regenerator effectiveness, and enthalpy effectiveness.
Spatial Hydrological GIS Analysis and Estimations of Runoff in Khor Gowb Drainage Basin in the Red Sea State –Sudan
The magnitude and availability of surface waters in Khor Gwob of the Red Sea State was examined using spatial hydrological analysis in Geographical Information Systems (GIS). As a system with advanced geo- modelling capabilities, GIS is used to integrate spatial analysis with hydrological modelling. Several levels of spatial hydrological modelling such as parameterization, spatial integration, regionalization and assessment of hydrologic problems were made. Four physical / deterministic and stochastic models were developed and applied at both catchment‟s and regional scales to estimate the water volume of many drainage basins in the area. The results evaluated using the general error term to compute the differences between the estimated areal runoff and the observed runoff in the Khor Gwob drainage basin in Erkowit area of the Red Sea State. Accordingly, one stochastic model has been tested and regionalized. The significance of the catchment and regional runoff estimates was evaluated in relation to errors inherent in the spatial database, GIS analysis, and hydrological modelling (e.g., the Rational Formula). Finally, it is concluded that Khor Gwob basin and the Red Sea State at large, contributes an annual surface runoff that exceeds the human and animal needs with a considerable surplus that can be used for agriculture (i.e., the region is water sufficient). Conversely, this sufficiency is limited by the problem of spatial distribution and related storage difficulties. With regard to human, animal and agricultural water supply, only few catchments can support the proposition of water sufficiency in the State.
Determining the Thermodynamic Properties of Fuel Blends from those of their Components For Air-Fuel Models of IC Engines
The paper presents an Excel-based procedure for determining the coefficients in the polynomials that describe the thermodynamic properties of fuel blends. The procedure is meant for use in conjunction with air-fuel computer models of internal combustion engines. It enables such models to deal with fuel blends just as they deal with pure fuels without modifying the main computer program. To obtain the mixture properties, the procedure applies the ideal-gas mixture relationship, which is already inherent in the formulation of existing air-fuels models. Excel has been chosen as computational platform for developing the procedure because of its simplicity and wide availability. The procedure is applied to determine the coefficients for binary mixtures of gasoline-ethanol, gasoline-hydrogen, and methane-hydrogen
Experimental Investigation of the performance of a Desiccant Wheel
Desiccant cooling systems have the potential to make a major contribution to the reduction of both CFC’s emissions and electricity peak load. An experimental investigation on the sensible effectiveness of a desiccant wheel is conducted. Measurements were made for a range of rotational speeds (0-5 rpm), regeneration temperatures (50 to 60oC). A computer based calculation procedure using Excel worksheet was built, and applied to estimate the effect of the desiccant wheel speed on the moisture removal and the sensible effectiveness. The calculations were based on the experimental data obtained during the experiment. The results succeeded in determining the optimum rotational speed for the desiccant wheel, the sensible effectiveness, the moisture removal efficiency and the dehumidification coefficient of performance. It was found that the lower speeds gave better results than the higher ones.
Using Dynamic Facade for IAQ, Thermal Comfort and Energy Efficient air Conditioning
:The built environment has a direct impact on Qatar's natural environment, the economy and human health. Qatar is the largest consumer of energy per capita in the world, the fourth country in the world that produces less water from freshwater resources and so relies essentially on desalination for domestic water supplies. Qatar Sustainability Assessment System (QSAS) is a performance-based sustainability rating system which aims to create a sustainable urban environment that reduce environmental impacts while satisfying local community needs. In addition to addressing all locally relevant aspects of sustainability, ecological impact, and green building design criteria, QSAS developed a standalone building energy standard to support Qatar’s building energy ratings. QSAS adopted the EPC CEN standard and EPC approach for the Qatar energy code development and some normative parameters used in CEN standards were changed for the use in the Qatar local environment. It complies with the global trend towards performance-based code; using standardised normative calculation methods. The simplified calculation is preferred as it requires less input data, no deep simulation expertise and leads to transparent readily understandable calculations. Buildings, new and old, account for 50% of global energy consumption and related emissions. This figure rises to more than 70% for the Gulf Region. Estimates of the cut in carbon emissions needed within our lifetime to avert catastrophic climate change range from 60% to 80% of current demand. Buildings thus present both a major impediment to reducing our reliance on the burning of dwindling reserves of fossil fuel and a real opportunity for achieving significant reduction in global carbon emissions. Dynamic facade, using Dynamic Insulation (DI), is an energy-efficient method of supplying pre-tempered, filtered ventilation air to a building through an air-permeable, dynamically insulated envelope or facade. One of the important features of DI is that it effectively decouples ventilation rate from energy use. In theory, it should work well with all buildings, including homes, schools, offices and sports facilities where high occupancy is the norm. Our paper investigates the use of DI in a building facade for zone local insulation and ventilation. The savings in energy and CO2 reduction are quantified against existing standards in the Gulf Region. The results show that DI can provide tempered fresh air, raise energy efficiency and reduce air conditioning energy demand without compromising Indoor Air Quality (IAQ) or thermal comfort level.
Effectiveness and Economic Feasibility of Gas Turbine Inlet-Air Cooling by Air Washing in the Hot and Dry Climate of Sudan
This paper studies the effectiveness and economic feasibility of cooling the gas-turbine's inlet-air by air washing (AW) compared to wetted-media evaporative cooling (WMEC) in the hot and dry climatic conditions of Sudan. Measurements were made on an experimental test rig to determine the cooling effect of the WMEV and that of AW with water at ambient temperature and with chilled water. Taken at two seasons of the year with different ambient temperature and humidity levels, the experimental results were used to estimate the revenues that the systems can generate as a result of increased megawatts and reduced heat rate of a typical gas turbine model (GE PG6581B). The calculations indicate that the WMEC system can increase the gas turbine output by 12% and reduce its heat rate by 1.6%. Using un-chilled water, the AW system can increase the output by 16.7% and reduce the heat rate by 2.2%, while with chilled water it can increase the power by 23.3% and reduce the heat rate by 3.1%. Based on these estimates, the WMEC system requires a payback period of 8 months if run for 4 hours daily, which reduces to 4 months if used for 8 hours. AW with un-chilled water has a payback period of about 8 months, but the pay-back period for the chilled-water AW system is about 5 years.
Restartability of Sudanese Nile Blend Crude Oil
The Restartability of the Sudanese Nile Blend crude oil inside Test Loop pipeline was performed to understand the parameters determining the yield stress and describe the process of yielding up to final line clearing. Test Loop is designed to find the relationship between the required restart time and the pressure required and also to find the blend yield stress. The yield stress of the Nile Blend was found to be affected significantly by the shutdown time, static cooling rate after shutdown, and the final temperature after shutdown.
Design and Testing of a solar Parabolic Trough System for Electricity Generation in Sudan
The performance characteristics of a parabolic trough collector system have been characterized using ASHRAE 93 standard. The standard includes collector efficiency test and the incident angle modifier test. The fabricated trough-receiver unit and its down stream system were installed in an open area at the roof of the Mechanical Engineering Department, University of Khartoum. The test result shows that the obtained thermal efficiency is 32%. The output shows that it is possible to generate electricity using parabolic trough system with a considerable efficiency and competitively with the other conventional systems due to high local solar potential through the year and availability of site areas
تأهيل مناهج التعليم لغرس وشحذ أساسيات المقدرة على الابتكار والاستثمارلتحقيق النهضة التكنولوجية والطفرة الاقتصادية
Design, Development and Calibration of an Integrated Thin Ring Drawbar Pull Transducer for an Agricultural Tractor
The objective of this research work is to design, develop and calibrate an integrated thing ring drawbar transducer for measuring the horizontal drawbar pull of an agricultural tractor. The transducer is based on a thin proof ring that forms an integral part of the drawbar element with strain gauges bonded on the inside and the outside curvature of the proof ring. The strain gauges are arranged in a full bridge constant volt circuitry and interfaced to a data acquisition system. Static calibration tests on the transducer showed high degree of linearity between applied load and output volt with coefficient of correlation R2 equal to 0.9968. The transducer measurements accuracy was within the acceptable range limits with measurement errors not more than 0.67% of the measured force magnitudes under the static measurements. The data acquisition system was able to successfully scan and recorded the transducer signals as programmed. The developed transducer can be a part of complete instrumentation system to be used for developing comprehensive information database on power and energy demand of various tractor and implement field operation in Sudan.