Using a solar energy in water desalination system is regarded as one of the most effective ways to resolve the problem of freshwater shortages in this world. Experimental and theoretical approaches were carried out to design and test multistage solar still. The experimental tests were conducted for five months in the city of Kirkuk, north of Iraq, at 43.39° longitudinal and 35.17° latitude. The performance requirement of the design is dependent on many factors such as circumstances, work and designation variables. Designating variables, mainly length, width, height and volume of each stage besides the number of all stages, are determined via theoretical analysis approach. The results obtained by both approaches have shown that there is a 10% deviation in still water productivity. Also, the results indicated that the minimum and maximum daily average of still water productivity is 1.7 and 3.8 kg. MATLAB software was employed to model and simulate the experimental processes of evaporation and condensation. The simulation model results were found to agree well with the experiments carried out in many other papers and studies. The test results reported that the system produces about 5 kg of clean water per day with 87% distillation efficiency and 26% of the overall efficiency due to heat losses in the system. Such system is not only promising, but can offer a new technology that can particularly be used in remote and rural areas. The theoretical calculations were compared with the experimental results, and there is a good agreement between the two .

الهدف الأساسي للألواح الكهروضوئية هو توليد الكهرباء ، وتعتمد كفاءة هذه العملية على درجة حرارة سطح تشغيل اللوحة. تؤدي درجات الحرارة المنخفضة إلى أداء أعلى ، مما يجعل من الضروري الحفاظ على الخلية الكهروضوئية باردة قدر الإمكان. يمكن تحقيق ذلك من خلال نظام التبريد ، الذي لا يعزز الكفاءة الكهربائية للوحدة الكهروضوئية فحسب ، بل يقلل أيضًا من معدل تدهورها بمرور الوقت ، وبالتالي يطيل من عمرها. بالإضافة إلى ذلك ، يمكن استخدام الحرارة الزائدة التي يتم إزالتها بواسطة نظام التبريد في العديد من التطبيقات. هناك العديد من تقنيات التبريد المتاحة ، بما في ذلك استخدام الهواء أو الماء كسوائل عمل ، مع الحركة الناتجة عن دوران الماء ، أو مبادل حرارة الماء القسري ، أو رش الماء ، أو المروحة. تقدم هذه الورقة مراجعة للأدبيات ذات الصلة حول التبريد النشط للتنظيم الحراري وتعزيز الكفاءة الكهربائية للوحدات الكهروضوئية. أظهرت الأبحاث التي أجريت في هذا المجال أن هذه التقنيات قد تم تطبيقها بنجاح لتحسين كفاءة الخلايا الكهروضوئية في ظل ظروف مختلفة.

Experimental and numerical investigations to study the effect of adding slots to the blades on the rotating stall phenomenon and pressure fluctuations in centrifugal blower. The experimental test rig which concludes a centrifugal blower, pressure sensors and measurement instrumentations are design and constructed for the present work. The experimental study has been carried out by measuring the static pressure variation and pressure fluctuation for two cases of impeller (with and without slots). Measuring of static values has been completed at various points prepared on the front-wall of the volute casing along one path for two cases of impeller. Enhancement in pressure distribution adds slots to the blades comparison with cases without slots at values of mass flow rate between non-flow and 0.02254 kg/s. The pressure fluctuations increase with decrease values of mass flow rates. We concluded also that pressure fluctuations decrease with adding slots to blades. This led to decrease occur of rotating stall phenomenon and increase stability of centrifugal blower. Numerical simulation has been carried out on present centrifugal blower to analyze both flow field and pressure fluctuations by using FLUENT 14 package. The numerical simulation has been completed by solving the continuity and momentum equations with moving reference frame technique inside the blower. The results of numerical simulation give a good agreement with the experimental results.

A major problem with any combustion system of any design, whether external or internal, is pollution emissions. The pollution emissions from combustion processes have also been found to cause geographical changes due to flooding as a result of high temperatures caused by global warming. An experimental investigation was thus undertaken to study the effect of utilising a palm oil and Iraqi conventional diesel blend on such emissions. Palm oil was mixed with diesel a volumetric percentage of 5, 10, 15, and 20%, and engine BTE, BSFC, and emissions tested in each case. The test results suggested that the operation of biodiesel in CI engine increases specific fuel consumption by up to 11.72% while reducing emission rates of carbon monoxide and unburned hydrocarbon to 27.81% and 44.6%, respectively. The biofuel operation process led to increases in nitrogen oxides and increased carbon dioxide emissions by about 39.6%, however.

In the current study, to enhance the characteristics and forced convection performance in the horizontal annular in the case of the presence of porous material and without porous material, energy analyses were performed. Many types of porous material, porosities, and diameters were used. Computational fluid dynamics was used to simulate an annuli tube in case of the presence of porous material and without porous material by utilization of ANSYS FLUENT software 17.2. The working fluid utilized was water with Reynolds number from 100-500 and constant wall heat flux at 150 kW/m2. Two types of porous media glass and steel balls, two different porosities (0.6 and 0.7), and two different porous material diameters (12 and 24mm) were utilized. Investigations occurred under the study state for studying heat transfer properties and flow of fluid in the annuli tube. The energy analysis outcomes showed that there is a relationship between Nu and Reynolds number. The highest enhancement of Nu number happened at 12mm diameter and 0.6 porosity for bolls of glass and 0.7 for bolls of steel. The pressure drop rising occurs with the rising of Re for all cases and the diameter of 12mm gives the maximum pressure drop for both steel and glass pellets and the uppermost pressure drop occurs at a porosity of 0.6. As compared with those in the annulus in the absence of a glass sphere as porous material at the same ball volumes.