University of Thi-Qar Journal for Engineering Sciences

A numerical study of three – dimensional, steady, laminar and incompressible natural convection of air (Pr=0.72) within a rectangular solar chimney is presented. Partial differential equations for conservation of mass, momentum and energy equations are solved by finite volume method with staggered grid arrangement. SIMPLE algorithm is applied to solve the set of discretization equations. The numerical results are compared with those of previous published work under the same conditions and gives a good agreement. The influence of changing in chimney dimension (thickness and height) and the inlet air temperature on the amount of induced flow rate is studied. From the presented results the optimal design for the chimney can be achieved

In this article experimentally investigations have been carried out to study the effect of the size and type particles on the thermal conductivity of micro and nanofluids. The study investigated nanofluids and microfluids which containing copper (Cu) and titanium oxide (TiO2) as well as in the size and type of micro and nanoparticles in distilled water as base fluid with different particles size and concentrations. The experimental results emphasized the enhancement of the thermal conductivity due to the nanoparticles presence in the fluid greater than microfluids, also shown the effect of the particle size and concentration on the thermal conductivity. It has been recognized that the addition of highly conductive particles can significantly increase the thermal conductivity of heat – transfer fluids. Particles in the micro and nano – size range have attracted the most interest because of their enhanced stability against sedimentation and, as a result, reduction in potential for clogging a flow system. Furthermore the results showed that, they obtained thermal conductivities doubtlessly revealed that a size and type particle was a key factor affecting conductive heat transport in suspensions. These results show noticeable enhancement in the thermal conductivity were evaluated to be (7.66 %, 2.35 %) for the Cu, TiO2 – distilled water nanofluid while reaches to (3.23 %, 1.02 %) for the Cu, TiO2 – distilled water micro fluids at the concentration of (5 vol. %) and at the room temperature. Moreover thermal conductivity was increased for the nanofluids and microfluids which contains large particle size compared with that contains small particle size. A good agreement was found between the experimental obtained data for this paper and other results from published papers

A water chiller air-conditioning system has been completed. Energy savings was estimated using different variables: calculation power consumption, electricity consumption, the cooling load of the testing room. The system tested during the environment of Al- Muthanna province (Al-Rummaitha city), Iraq. The measurements were taken during the summer months (May - June – July and August). The results indicated a difference in energy saving during the daily operating hours, the highest reduction rate was obtained of cooling loads, which were based on the change in evaporator temperatures and also the highest percentage was achieved during August by 23% and the lowest percentage during May by 5%. Thus, the study concluded that the percentage of electricity consumption during the months of May and August was 56% and 41%, respectively. This paper concludes the power electricity was 14.7 amperes in conventional air conditioners whereas the chiller air-conditioning was up to 1.07 amperes. Also, the electricity saving was effected with lower storage tank water

The process of deep drawing of complex shapes is a difficult process compared to the process of drawing simple shapes such as cylindrical, square and rectangle because of the complex shape is subjected to the higher stresses concentration compared to simple shapes. This work aims to study the effect of the wall corner radius of punch and radial clearance on deep drawing operation using the experimental work and numerical simulation. In this work, an analysis of the deep drawing process is performed for process design of stellar cup drawing. A deep drawing die was designed and manufacturing to perform the experimental procedure required to produce a stellar cup with inner dimensions (major axis equal to 43.7 mm and minor axis equal to 36.64 mm) formed from a circular flat sheet (80 mm diameter) comprised of low carbon steel of (0.08%) carbon content, without any intermediate annealing. A commercially finite element program code (ANSYS 18.0) is utilized to simulate the stellar deep drawing operation. From the comparison between the results, it has been found that the thinning at cup corner increases by decreasing the wall corner radius of the punch and the maximum thinning with the wall corner radius of the punch equal to ( 16Rcp'> = 2 mm) at the corner of the minor axis of completely drawn cup

Recently, hybrid structure graphene / organic nano composite have been studied for low cost photovoltaic devices (P3HT/Graphene ) can be formed by solution process at room temperature, in this study, we demonstrate a hybrid solar cells composite of (Graphene-P3HT/TiO2 Nanowire to allowed for distributed the organic materials among the nanorode, the organic which cover by spin coating to provide higher mobility and conductivity of (G-P3HT) where employed as P-type or Hole transparent materials with TiO2 NW as a photoanode. The nanocoposite of P3HT (G-P3HT, 10% wt graphene) deposited on TiO2 NW by spin couter technique. The solar cells based on vertical TiO2 NW nanowire arrays by utilizing a spin couter spin speed. The initial results showed the power conversion efficiency of 0.5 %. The cells with G-P3HT showed different performance. The power conversion efficiency was improved from 0.3 for spin couter speed 300 rpm to 1.3 at 500 rpm for G-P3HT among different spin speed solar cells. It exhibited tunable power conversion efficiency with spin speed, with very thin materials and in expensive processing ,hybrid G/P3HT /Nanorod solar cells are promising as an economically viable alternative energy solution

In this paper, study and design of double acting Stirling engine with one piston conducted .The thermodynamic analysis was developed by using MATLAB program for predict the periodic variation of pressure, specific volumes. The performance prediction of the double-acting Stirling engine was developed using ANSYS 18.2 program. This theoretical study mainly studies the influence of the engine parameter (charge pressure) on the engine performances (engine speed, torque, and power output). The performance of the engine was examined for different values ??of the charge pressures (1, 3, 6 bar). The results indicated the maximum power and torque 117.8 W, 2.5404 N.m at 443 rpm when the charge pressure was 6 bars

This paper includes an experimental study of the effect of dynamical vibration (harmonic waves) or wind on the deformation of the ship hull when it is in the case of pitching motion and rolling. The aim of this paper is to calculate the strains of the ship as a result of the effect of waves on it. Aluminum alloy was used to build the frame of the model with suitable dimensions, and then fixed the model on the vibrating system which consists of number of springs with limiting stiffness. Vibrating system supported with means to generate waves with (0.75Hz, 1Hz, 1.25Hz) frequencies. The deformations are measured at the pitching and rolling motion of the model. The results showed that the strains of the model in the pitching motion greater than the rolling motion. When the frequency increases, the strains are increases

The present 3D numerical study was performed to show the effects of the length of central cut twisting tape (CCTT) on the characteristics of thermodynamic and hydrodynamic fields when this tape is inserted inside a tube in which, air is flows in turbulent pattern. Central cut twisting tapes of the same cut ratio (c = C/D) of 0.4 and four different length ratio (LR = l/L) of 0.25, 0.5, 0.75 and 1 were inserted in the tested tube that subjected to a uniform heat flux. The range of Reynolds number of air flow was 10000 ? Re ? 40000. Fluent in ANSYS 15 was used for problem designing, formulation and results obtaining in the present study. Finite volume method was the discretization method and tetrahedral type of mesh element was used. RNG k-? was chosen as the turbulent model. The obtained results showed that the increasing in Reynolds number leads to an increasing in Nusselt number and a decreasing in both friction factor and thermal performance factor. Also, these results cleared that the increasing in the length ratio of the studied type of twisting tape gives higher Nessult number, friction factors and thermal performance factor of 171.172, 0.0932 and 1.432 respectively

In present paper, a three dimensional turbulent flow; and heat transfer inside a rectangular channel equipped with array of winglet vortex generators has been investigated experimentally and numerically. Three pairs array of winglet vortex generators of different geometrical configuration as rectangular, triangular, semi circle and parabolic are considered. The array of winglet vortex generators is formed and distributed on the bottom hot surface with a facility for changing the angle of attack from (0° to 60°). ANSYS Fluent Code (15.0) based on a finite volume method is used to get the numerical results while a k-w turbulence model is used to model the turbulent . The Reynolds number range is from 10000 to 50,000 under a constant heat flux boundary condition. The spin wise between the vortex generators are set to 1 cm and 1.5 cm while the stream wise between the vortex are 9cm,12cm and 18 cm respectively. The results indicated that the rectangular winglet vortex generators array indicated the optimum thermal performance with considerable penalty of the pressure drop while the parabolic vortex generator stated the minimum performance among the considered vortex generators shapes. The overall efficiency for rectangular, triangular, semi circle and parabolic winglet vortex generators is enhanced by (166%), (130%), (165%) and (121%) respectively as compared with plane channel.

In this work, the photovoltaic panel performance has been investigated theoretically and experimentally where using an array of pin fins as a cooling system. Trying to satisfy the ideal operation conditions of the solar panel, heat sink was fixated on the back of the PV panel to use as a passive technique. An Analytical thermal model based on the steady state and one dimension analysis condition was built to transfer the excess heat from PV panel with the heat sink existing to predict the operation temperature of PV panel. Theoretical results were compared with experimental results of solar panels cooled by heat sink, in order to validate the suggested thermal model. Also, the effect of the solar cells temperature on the panel performance has been studied experimentally. The results displays that using pin fins array as a cooling technique led to drop in the average panel's temperature nearly 5.9°C and an enhancement of the average output power nearly 13.5%.

In this investigation using (PCMs), the phase change materials in the electrical transformer is numerically analyzed by CFD. In this paper used oil transformer and PCMs (Wax, RT44 and P116), the cooling as mediums which are represented the heat storage assistance the oil. Ten kilogram of PCMs used as shield around the windings and coils. A (25, 37, 45 and 55 Co) represented surrounding temperatures that are taken. Because of, absorbed the heat by the latent heat that got it from PCM, the PCM added at transformer temperature shows clear decreasing the average temperature. The boundary condition represented with mixed (convection and radiation), heat generation applied on the transformer. The results displayed that, temperature reduction of the transformers is about 4 Co due to use of different types of PCM.