Iraqi journal of mechanical and material engineering

Due to conventional energy sources shortage and higher prices and to global environmental pollution problem researches for clean and sustainable sources are intensified worldwide. This paper is tries to explore the potentials of renewable energy sources in Iraq specially solar and wind energies. Measurements of solar flux and wind speed in Hilla (32° 28' 45" N, 44° 25' 58" E, centre of Babylon Province /IRAQ) is performed during the year 2011. It is found that there is a very good potential for solar energy since the maximum incident flux reaches to about 1000 W/m2 specially during summer months and the maximum monthly average is about 562 W/m2. The wind speed is not so promising for electrical power generation since the maximum monthly averaged recorded speed is about 5.1 km/hr (1.4178 m/s). However this might not be true for all parts of Iraq specially in the western parts where there is large areas of open Sahara.

The main aim of this research is to study the effect of fluid lubricant on the properties of soap greases, such as lithium, calcium, sodium, and lithium – calcium.Base stock oils 40, 60, and 150 have been added with different concentrations to grease to obtain the best concentration that improves the properties of greases such as load carrying, wear resistance, corrosion resistance, drop point, and penetration.Decrease in grease properties has been noticed when adding 20 % of base sock oil 40, and 30 % of base stock oil 60, but no significant change being observed of base stock oil 150.Also, it is noticed that as the viscosity of base stock increases the effect of oil on changing grease properties will decrease.

The simultaneous deposition of Cr and Si into austenitic stainless steel 316L alloy using a halide-activated pack-cementation process is described, using a pack mixture containing (67 wt. % Cr, 8 wt. % Si, 2 wt. % NH4Cl, 23 wt. % Al2O3). The diffusion coating process is carried out at 950oC for 6hrs under Ar atmosphere. It was found that diffusion coating time produce coating thickness of 80-100µm, the corrosion resistant properties of austenitic stainless steel can be improved by enriching the surface composition in Cr and Si using pack cementation process, this study compare the hot corrosion performance of uncoated and coated austenitic stainless steel 316L with chromized-siliconized diffusion coating specimens in the presence of molten mixture of Na2So4and V2O5at 850oC and compare the micro-hardness between them. In the case of coated austenitic stainless steel 316L alloy with chromized-siliconized diffusion coating, specific weight gain will be observed while specific weight lose can be observed in the case of uncoated austenitic stainless steel 316L alloy. Diffusion coated austenitic stainless steel 316L alloy has shown excellent corrosion resistance and higher micro hardness than uncoated austenitic stainless steel 316L alloy because the coated layer that consisted mainly of CrSi2 and Cr3Si phases.

Surge is an unstable operating mode of compression systems which occurs at low mass flow where the pressure delivered by the compressor is less than the plenum pressure. This instability is global, one- dimensional and nonlinear. It is characterized by a limit-cycle oscillation in mass flow and pressure rise. This paper presentedapplication of active surge control in centrifugal compressor, with measurement and evaluation of the thermodynamic operational parameters of the compressor system. In experimental work investigation the surge phenomenon by measuring and calculating mass flow rate and outlet pressure from sensors and manometers and designing plenum to move the surge line to the left side of the compressor map. Thevariable speed compressor characteristic is derived based on energy losses in a compressor components. Active control of surge in connection with varying speed is studied.

This paper presents an effort aimed at developing a new formula to calculate compression factor within acceptable error range. A formula has been generalized to permit calculation of the compression factor as a function of reduced properties: reduced temperature TR and reduced pressure PR. The new correlations show improvement in temperature and pressure range which offers flexibility for estimating compression factor for a wide range of reduced temperature; TR=1-5 and reduced pressure ;PR=0.5- 6.5. This correlation provides accurate and computationally reliable prediction of the compression factor (Z) with an average absolute error (AAE) 4.6 % for 169 data points.

The objective of this study was to develop a back-propagation artificial neural network (ANN) model that could be distinguished the microstructure of metals instead of the traditional methods which are cost and need more time in addition some time give wrong results . Although the colour indices associated with image pixels were used as inputs, it was assumed that the ANN model could develop the ability to use other information, such as shapes that are implicit in these data. The 504x504 pixel images were taken in the field in standard situations and were then cropped to 10x10-pixel images depicting only one microstructure metal. The metals images with size 10x10 which is sufficient for recognizing by ANN. There are four images of different materials.

This paper investigated experimentally the friction factor reduction and heat transfer enhancement processes over staggered perforated pin fins in a rectangular channel with air cross flow. The channel had a duct cross section width of 62 mm, cross section depth of 167 mm and duct length of 1200 mm. The experiment covers the following ranges: Reynolds number 28000-113000, and pin fin shapes (solid, horizontal/vertical (HV) perforation and horizontal/vertical/lateral (HLV) perforation). Results show that the Nusselt numbers of pins with horizontal/vertical (HV) perforations are about 11% higher than those for solid pins and with horizontal /vertical/lateral (HLV) perforations are about 21% higher than those for the solid pins.. In addition, experimental results show that pins with horizontal/vertical/lateral (HLV) perforations, have good enhancement of heat transfer in addition to a significant reduction in weight compared with solid pin case performance.

The present paper aims at studying the possibility of using sequencing technique in implementing required works done by student with the Application schedule, and determining the mean of flow time to do exercise on lathe machine to make the utmost use of time and skill of students.The results reached that have shown there is a noticeable waste of time used to produce exercises due to the unavailability of a flow chart for the work in addition to weaknesses in the students skills through consuming a great deal in raw materials in exercises more than once. It is noteworthy that the technique used in analyzing results is (LPT&SPT).