This study investigates numerically heat transfer augmentation using water-based Al 2 O 3 nanofluid flowing in a circular cross-sectional tube under constant inlet temperature in laminar flow conditions. The Al2O3/water nanofluid with different volume fractions (3% and 5%) and twisted tape twist ratio of (H/D =1.85) are employed, and Reynolds numbers of 678 to 2033 in a laminar flow are considered. The numerical analysis is used to solve the governing partial differential equations in three dimensions. Results of the flow structure, velocity vector, and temperature field are reported. The numerical results indicate that the heat transfer rate becomes more remarkable when employing nanofluid. The maximum 46% enhancement is obtained in the convective heat transfer coefficient by using Al 2 O 3 /water nanofluid at 5% particle volume fraction and Reynolds number of 678, comparing with pure water. It is also found that heat transfer enhancement increases with an increase in the particle volume concentration and Reynolds number.

In this work, a system of heat pipe is implemented to improve the performance of flat plate solar collector. The experiment rig consists of sun light simulator, flat plate, heat pipe (wickless), heat exchanger, and measurement instruments. The model is represented by twisting portion of the evaporator section and also inclined by an angle of 30° with a constant total length of 1140 mm. In this model the evaporator, adiabatic and condenser lengths are 780mm, 140mm and 230mm respectively. The omitted energies from sun light simulator are 200, 400, 600, 800 and 1000 W/m2 which is close to the normal solar energy in Iraq. The working fluid for all models is water with fill charge ratio of 30% and the efficiency of the solar collector is investigated with three values of condenser inlet water temperatures, namely (12, 16 and 20° C). The experimental result showed an optimum volume flow rate of cooling water in condenser at which the efficiency of collector is a maximum. This optimum agree well with the ASHRA standard volume of flow rate for conventional tasting for flat plate solar collector. When the radiation incident increases the thermal resistance of thermosyphon is decreases, where the heat transfer from the evaporator to condenser increases. The experimental results showed the performance of solar collector with twisted evaporator greater than other types of evaporator as a ratio 13.5 %.

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.

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Solar distillation occurs within a device called the (solar still). There are many types of solar still. In this study, the addition of modern technology for solar still was used. Experimental tests have conducted in (Baghdad), the capital of (Iraq). On the other hand, (MAT LAB) program was used to formulate mathematical formulas. The study was conducted during (July) and (August) and extended during the testing day from (5:30 am) to (10:00 pm). Coarse and fine gravel added to the solar still basins to develop its product. The percentage of increase in the production of solar still with the presence of gravel was (47%), the percentage increase in night productivity was (64%).