Yousif Abdalla Abakr

Theoretical and Experimental Investigation of a Novel Multistage Evacuated Solar Still

Solar desalination is an ideal source of fresh water for both drinking and agriculture. A lot of research was conducted on solar desalination systems, but most of the available systems have low production, are expensive, and are not reliable for long term use. In this work a new multistage evacuated solar desalination system was proposed and designed.The objective of this work is to increase the productivity and improve the low efficiency of the traditional solar desalination systems. The new system works by virtue of the higher evaporation rate under vacuum condition inside the solar still. A model for the system was developed and used to optimize the system design. The new model was subjected to a Finite Element Analysis (FEA) structural analysis using MSC/NASTRAN™ FEA software. A Computational Fluid Dynamics (CFD) simulation of the evaporation and condensation process inside one stage of the new solar still was conducted using FLUENT™ software. The system prototype was fabricated and tested at the actual outdoor ambient conditions for a period of 3 months. The productivity of this new system was found to be 14.2 kg/m2/day, which is about threefold of the maximum productivity of the basin type solar still. The cost of produced still water is estimated as 0.20 US

Effect of vegetation and waterbody on the garden city concept: An evaluation study using a newly developed city, Putrajaya, Malaysia

/gal. The results show that the multi-stage evacuated solar still might be a good option as a solar desalination system.

Design and development of a low-cost, electricity-generating cooking Score-Stove™

The garden city concept was adopted in the development of a new tropical city, Putrajaya, aimed at mitigating the effect of urban thermal modification associated with urbanisation, such as urban heat island (UHI). WRF/Noah/UCM coupled system was used to estimate the urban environment over the area and the individual thermal contributions of natural land use classes (vegetation and waterbody). A control experiment including all land use types describing the urban conditions of Putrajaya city agreed well with the observations in the region. A series of experiments was then conducted, in which vegetation and waterbody were successively replaced with an urban land use type, providing the basis for an assessment of their respective effect on urban thermal mitigation. Surface energy components, 2-m air temperature (T2m) and mixing ratio (Q2m), relative humidity (RH) and UHI intensity (UHII) showed variations for each land use class. Overall, an increase in urban surfaces caused a corresponding increase in the thermal conditions of the city. Conversely, waterbody and vegetation induced a daily reduction of 0.14 and 0.39 °C of T2m, respectively. RH, UHI and T2m also showed variations with urban fractions. A thermal reduction effect of vegetation is visible during mornings and nights, while that of water is minimally shown during daytime. However, during nights and mornings, canopy layer thermal conditions above waterbody remain relatively high, with a rather undesirable effect on the surrounding microclimate, because of its high heat capacity and thermal inertia.

Development of Thermoacoustic Engine Operating by Waste Heat from Cooking Stove

A design of the thermo-acoustic engine to combustion interface of an electrically generating clean cookstove is presented. Social surveys carried out by the SCORE project have indicated that adding electrical generation to a clean cookstove should increase their uptake considerably above the current 8% level (outside China) as electricity is perceived as high value and so wanted by the communities. This work discusses the development process, using elements of the formal design methodology BS 7000 to design a mass-producible, easy-to-manufacture, low-cost cooking stove that uses a thermo-acoustic engine to produce electricity whilst cooking. The iterative design process is discussed with analyses made of predicted cost and performance at each iteration and compared with the targets set from social surveys. With currently available technology and suitable investment in tooling and production facilities, estimated production costs are £100. An independent audit by engineers and cost estimators from a large international blue chip company made a prediction of £150. At this stage of the design, this is considered a quite good correlation. Proposals for bringing this cost down to £60 are made. To obtain lower costs would require more research. SCORE market evaluations indicate that at the upper-cost target of £60 (2007 prices), 60 million people would afford the stove. A wood-burning Score-Stove™2 prototype successfully developed 22.7 W of electricity based on the presented planar thermo-acoustic engine design, indicating that the new Score-Stove™2 design may have the potential, when manufactured in volume, to meet the social and cooking requirements of rural people in developing countries.

Optimization of cooling systems in data centre by Computational Fluid Dynamics model and simulation

There are about 1.5 billion people worldwide use biomass as their primary form of energy in household cooking[1]. They do not have access to electricity, and are too remote to benefit from grid electrical supply. In many rural communities, stoves are made without technical advancements, mostly using open fires cooking stoves which have been proven to be extremely low efficiency, and about 93% of the energy generated is lost during cooking. The cooking is done inside a dwelling and creates significant health hazard to the family members and pollution to environment. SCORE (www.score.uk.com) is an international collaboration research project to design and build a low-cost, high efficiency woodstove that uses about half amount of the wood of an open wood fire, and uses the waste heat of the stove to power a thermoacoustic engine (TAE) to produce electricity for applications such as LED lighting, charging mobile phones or charging a 12V battery. This paper reviews on the development of two types of the thermoacoustic engine powered by waste heat from cooking stove which is either using Propane gas or burning of wood as a cooking energy to produce an acceptable amount of electricity for the use of rural communities.There are about 1.5 billion people worldwide use biomass as their primary form of energy in household cooking[1]. They do not have access to electricity, and are too remote to benefit from grid electrical supply. In many rural communities, stoves are made without technical advancements, mostly using open fires cooking stoves which have been proven to be extremely low efficiency, and about 93% of the energy generated is lost during cooking. The cooking is done inside a dwelling and creates significant health hazard to the family members and pollution to environment. SCORE (www.score.uk.com) is an international collaboration research project to design and build a low-cost, high efficiency woodstove that uses about half amount of the wood of an open wood fire, and uses the waste heat of the stove to power a thermoacoustic engine (TAE) to produce electricity for applications such as LED lighting, charging mobile phones or charging a 12V battery. This paper reviews on the development of two types of the thermo...

Integrating Weather Research and Forecasting Model, Noah Land Surface Model and Urban Canopy Model for Urban Heat Island Effect Assessment

Development of information technology drives the increase demand of data centre and the invention of high performance of computer facilities which will impact to the increasing of heat dissipation from equipment. The environmental condition in data centre must be designed and maintained strictly to avoid disruption and thermally shut down that caused by overheat and loss of cooling. This paper primarily focuses on the optimization cooling system in data centre by arrangement of racks position and airflow management. Models and simulation of Computational Fluid Dynamics (CFD) are developed for the room and equipment of data centre where the effect to temperature and airflow profiles will be observed. A case study of data centre design in Kuala Lumpur with 30 racks of equipment and combination of raised floor cooling and spot cooling was carried out. Results of CFD simulation show the issues of data centre cooling and improvement was suggested to improve the distribution of cooling and reduction of hot spots.

Element characteristic tolerance for semi-batch fixed bed biomass pyrolysis

Despite increased interest on the urban heat island (UHI) phenomenon, there are limited UHI studies on cities built using the green-city concept of Sir Ebenezer Howard [1]. The administrative capital of Malaysia, Putrajaya is one of such cities built using the green-city concept. The objective of this study was to confirm the effectiveness of the green city concept using the National Centre for Atmospheric Research (NCAR) numerical technique. Numerical mesoscale Weather Research and Forecasting (WRF) Model was coupled with Noah land surface model and a single layer urban canopy model (UCM) to investigate the existence and distribution of UHI, and the behavior of urban canopy layer (2-m) temperature of Putrajaya city. Few studies have been conducted using the NCAR numerical technique (WRF) to explore Malaysian climatology. Suitability of the model employed in studying UHI phenomenon of Putrajaya city was determined using in-situ study of the area, and observational data from AlamSekitar Malaysia SdnBhd (ASMA). Contribution of urban fabrics on the spatial and temporal variations of UHI was also investigated. Comparison with ASMA and in-situ data revealed a satisfactory performance of the model.UHI intensity (UHII) of Putrajaya exhibits a diurnal profile; increasing during the night to a peak value and then diminishing towards morning with a negligible value in the mid-day. In the night time, the UHII ranges from Original Research Article

PIV wave propagation investigation of non-linear losses through 90 degree bends in a thermoacoustic engine's feedback loop

Biomass pyrolysis to bio-oil is one of the promising sustainable fuels. In this work, relation between biomass feedstock element characteristic and crude bio-oil production yield and lower heating value was explored. The element characteristics considered in this study include moisture, ash, fix carbon, volatile matter, C, H, N, O, S, cellulose, hemicellulose, and lignin content. A semi-batch fixed bed reactor was used for biomass pyrolysis with heating rate of 30 °C/min from room temperature to 600 °C and the reactor was held at 600 °C for 1 h before cooling down. Constant nitrogen flow (1bar) was provided for anaerobic condition. Sago and Napier glass were used in the study to create different element characteristic of feedstock by altering mixing ratio. Comparison between each element characteristic to crude bio-oil yield and low heating value was conducted. The result suggested potential key element characteristic for pyrolysis and provide a platform to access the feedstock element acceptance range.

Mechanical Oscillator in a Magnetic Field

Thermoacoustic engine technology has recently been applied to renewable energy to convert heat energy into acoustic energy for the purpose of electricity generation. One of the vital components of the engine is its feedback loop which is sensitive to geometrical changes that can cause system losses. We previously postulated that a critical Acoustic Dean Number exist above which the Acoustic Power Transmission Loss increases drastically for a wave propagating though a bend. This paper investigates the wave propagation through the bend using Particle Image Velocimetry(PIV). This technique has not been used in this field of investigation and allows the flow visualization as well as the planar velocity field measurement of the system. The PIV results confirmed earlier pressure measurements that a critical Dean number does exist, and describes visualizations of the flows causing the losses.

Minimum volume fraction of vapor for liquid-vapor interphase transfer of flow boiling in microchannel

An analytical solution for a system exhibiting oscillations of a conductor in magnetic field which is controlled by a discrete waveform is developed by means of multiple scales. The solution provides a guideline to design an effective control strategy so as to guide the system to a desirable attractor. Initial tests were also conducted to investigate the effect of hydrodynamic forces on an inertia excited by this mechanism.