a b s t r a c tAn experimental and numerical model of a solar chimney was proposed in order to predict its performance under varying geometrical features in Iraqi environmental conditions. Steady, two dimensional, turbulent flow was developed by natural convection inside an inclined solar chimney. This flow was investigated numerically at inclination angles 15 to 60 , solar heat flux 150e750 W/m 2 and chimney thickness (50, 100 and 150) mm. The experimental study was conducted using a single solar chimney installed on the roof of a single room with a volume of 12 m 3 . The chimney was 2 m long; 2 m wide has three gap thicknesses namely: 50, 100 and 150 mm. The performance of the solar chimney was evaluated by measuring the temperature of its glass cover, the absorbing wall and the temperature and velocity of induced air. The results of numerical model showed that; the optimum chimney inclination angle was 60 to obtain the maximum rate of ventilation. At this inclination angle, the rate of ventilation was about 20% higher than 45 . Highest rate of ventilation induced with the help of solar energy was found to be 30 air changes per hour in a room of 12 m 3 volumes, at a solar radiation of 750 W/m 2 , inclined surface angle of 60 , aspect ratio of 13.3 and chimney length of 2 m. The maximum air velocity was 0.8 m/s for a radiation intensity of 750 W/m 2 at an air gap of 50 mm thickness. No reverse air flow circulation was observed even at the largest gap of 150 mm. The induced air stream by solar chimney can be used for ventilation and cooling in a natural way (passive), without any mechanical assistance.

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An experimental and numerical investigation is carried out for the heat transfer from a cube faces subjected to impinging jet which centrally strikes the top face of the cube. The cube is subjected also to a comparatively low velocity cross flow through the duct occupying the cube. Different factors affecting the cooling characteristics of the cube are studied as orifice size, jet velocity and orifice to cube top distance. The results show that cross flow increases heat rates from the cube for small size orifices and low impinging jet velocities. Orifice sizes equal or bigger than cube size will isolate the cube from cross flow effect especially at high impinging jet velocities.

The fresh water reserves on the earth are finite. The brackish water can be converted tothe fresh water by solar water distillery. A theoretical investigation to investigate the effect ofthe turning hollow-cylinder within the solar still equipped with flat plate solar water collectoron the output of distillate water and its thermal efficiency. The numerical analysis was carriedout by using FORTRAN 90, program. The numerical analysis is used for complex phenomenawithout resorting to expensive prototypes and difficult experimental measurements. The studyconsidered several parameters which are; solar radiation intensity, ambient air temperature,ambient wind velocity, basin plate temperature, basin water temperature, glass covertemperature and hollow cylinder surfaces temperature. The cumulative of distillate wateroutput from the modified solar still increased compared with the conventional solar still by afactor not less than 240%

This paper presents an experimental and numerical analysis of the effect of the geometric parameter on the two-phase flow (white kerosene-water) flow pattern system. The investigation was carried out using three lengths (1, 2 and 3) m of rectangular horizontal smooth channel and three channel heights of (5, 7.5 and 10) cm respectively. The flow conditions for the input water velocity (0.2 m/s) and the input kerosene velocity (0.1 m/s) for both measurements have been investigated. Two-inlet techniques have been employed. Firstly, at the inlet, the kerosene was on top of the bath. Then, second, from the center, the kerosene inlets (water is above and below the kerosene). A numerical verification analysis was introduced using the ANSYS software using the method of volume of fluid (VOF) and mixture multiphase flow modeling coupled with the normal k-ε turbulence schemes. A collection of seven methods of CFD types is explored by running 224 instances. Comparisons were made between numerical and experimental works.

An experimental investigation involves the effect of the turning hollow-cylinder within a solar water distillation on the output of distillate water. This study is to be conducted in order to validate the optimum productivity of purification water by turning hollow-cylinder. The experiments were carried out in Kirkuk city, Iraq, 2018.Experimental results demonstrated that a basin water height is (1 cm) gives the better productivity of (1225 ml/ m2.day) for the conventional solar water distillation, and (2 cm) basin water height for the modification solar water distillation gives the optimum productivity which is (3540 ml/m2.day) which represent an increase of 188% when compared with the productivity of the conventional solar water distillation. 0.5 rpm and 1rpm are the optimum rpm for the hollow cylinder for the modification solar water distillation without and with flat plate solar water collector. The maximum percentage of productivity obtained from the modification solar water distillation which connected to a solar water heater with automatically varying speed according to the solar radiation intensity (Auto turning + Collector) gives more than (310%) enhancement. The estimated cost of one litre distillate water output for modification and conventional solar water distilleries were 136 ID and 175 ID respectively.

Poppet valve development requires study of the complex flow inside it. This needs an advanced technology, such as particle image velocimetry (PIV) technique and CFD flow simulation. The main keys of this work are experimental investigation of the flow structure through a truncated conical poppet valve by using PIV technique. A numerical model of the valve is validated using experimental results. This validation gives the ability to modify the valve geometry and improve the flow structure, furthermore, and minimize the energy losses. The experiments have been done using the three flow rate values (Q) (25, 35, 45) L/min, each of them with three poppet displacements (Xv) (3.5, 5.5, 7.5) mm. The vortex radius and intensity, which is an indicator of losses magnitude, increased with the increasing of flow rate and decreasing of poppet movement Xv. The experimental results showed a good agreement with the numerical one, beyond some difference for flow out of the metering area. The three-dimensional effects may be the reason of this difference. The results provide good information to design process.