منى حميد سعيد الطريحي

Most bacterial contaminants found in operation rooms come from patient’s exhale or from the wound after surgery that make colony forming units. Thus, yearly a lot people suffering from infections acquired during surgical procedures. Removing pollutants from operation room by investigating the influence of different locations and types of entry and exit grills, is the subject of present work. Equations of fluid flow including the continuity, momentum, energy equations and species equation have been numerically solved by using the FLUENT ANSYS v.14 for virtual symmetric operation room taken in this paper. Turbulent flow of mixture material species is applied in the model of operation room. Standard K-epsilon was used for simulating turbulent flow pattern. The present study aims to find a proper arrangement of inlet and exhaust locations to reduce the unfavorable factors in operation room such us, contamination, humidity, temperature and also air velocity. These factors were achieved according to modification in inlet and exhaust grills arrangement and then simulated through FLUENT software program. Six different arrangements of supply and exhaust were studied to determine case of best health and comfort demands. Case no 5, which is using local exhaust ventilation, shows good improvement in removing contaminants. While case no 6, which uses both local exhaust ventilation and like air curtain air supply, shows the optimum removal of contaminants, because it shows lowest contamination mass fraction. While worst contaminant removal in cases 2 and case 1, where source of contaminant exists in low movement zone (dead zones) or region of separating of streamlines. Results showed, using both local exhaust ventilation and like air curtain air supply as in case (6) maintains un average temperature of 21.3 oC , least amount of particles mass fraction of contaminants 6.36E-08 and moisture content of 0.009.

Cooling and ventilation in an occupied spaces by displacement ventilation system is potentially more energy efficient than conventional air conditioning systems. The overall aim of the work described in the thesis has been to develop a suitable model of this type of system for use in an office room. The operating characteristics of displacement ventilation system, used with three types of air supply diffusers, have been studied by making experimental measurements in an office room .Numerical calculations of the flow, temperature fields and relative humidity have been made with (CFD) simulation. In this study experiments and CFD modeling were performed to compare the indoor air quality and thermal performance between three types of air supply diffusers (three direction-square diffuser, semi-circle diffuser and two parts of one direction-square diffuser).Each type were studied with three different locations of return air grills. The experimental study was performed to investigate how the use of the three different arrangement would effect on thermal environment inside tested room of dimensions (4×3.2×4) m used as an office room. The results of the experimental study were used to validate the CFD simulations. The boundary conditions for Computational Fluid Dynamics (CFD) study were obtained from the same set-up measurement with a Reynolds number of 12773, 12239and 9578, respectively for , semi-circle terminal ,three direction-square terminal and two units of one direction-square terminal). The results were analyzed to show how the shape of air supply diffuser and location of return grilles would affect the air quality and thermal environment in the room. Ansys Fluent-14Users guide of a three-dimensional software was used to simulate the complex flow with buoyant inside the models rooms. The present computational program was validated by comparing the numerical results with experimental data of published studies and the comparison showed good agreement. The studied tested rooms was built and meshes by Ansys Fluent14Users guide program. Realizable, k-ε turbulence models are evaluated in predicting the airflow pattern and thermal behavior of DV devices in an office room.The supply air velocity and temperature for each case study was calculated depending on heat gain inside space under Iraqi climate. The different types of the supply air devices have been chosen according to the data provided by manufactures depending on supply airflow rate in order to avoid drafts. The results concluded that the arrangements at an office room for both the air supply diffuser and return air grille on the same side wall orientation gives accepted thermal human comfortable depending on the magnitude of Air Distribution Performance Index (ADPI) and effectiveness temperature(ɛt) ,in addition, to the percentage of relative humidity . Lastly, from the research according to different geometries of displacement ventilation devices, it was found due to Iraqi cooling code and ASHRAE standards and according to (ADPI) and (ɛt) values. The three direction-square diffuser was the best type compared with the others two types since it gives(66.76 %) and(1.82) respectively ,and the semi-circle type were gives (62.3) % and (1.55) respectively .Also the measured of relative humidity gives approximated converged values between all the three devices.

ABSTRACT: In the present study, heat transfer in a square cavity filled by a fluid and a saturated porous media has been numerically analyzed to investigate the effect of void (ε) and thermal conductivity ratio (porous to fluid thermal conductivity ratio kr) of the material on flow and thermal field characteristics. A circular bar with a uniform heated surface is inserted into the middle of the cavity. The sides and upper walls of the cavity are maintained at a uniform cold temperature. Results are presented in terms of streamlines, isotherms, pressure distribution, average Nusselt number at several parameters values such Grashof number, material porosity, and thermal conductivity ratio. It is observed that these conditions have a significant effect on the flow and temperature field inside the cavity. It is found that porosity increment has a major influence for improving natural heat transfer and increasing average Nusselt number. In addition, the increment of thermal conductivity ratio of ten times leads to increase the average Nusselt number due to more heat transfer through the conduction the aid the natural convection to improve the overall heat transfer inside the cavity. In this work, Darcy number and Prandtl number are selected as 0.01 and 0.7, respectively. The analysis is accomplished for five porosity values, ɛ = 0.4, 0.5, 0.55, 0.6 and 0.65 and different values of Grashof numbers Gr and thermal conductivity ratio kr.

Numerical investigation was performed to investigate the convection heat transfer in a square cavity that have been vented vertically. Different values of Reynolds number used (50, 100, 200, and 250) with three different opening to side length ratio (S/L) in the cavity (0.1, 0.2, and 0.3). Richardson number varied between (1, 5, and 10). Galerkin finite element utilized for the numerical simulations, the numerical model was validated and the result obtained was acceptable. The results showed that as Reynolds number increase inside the cavity, the Nusselt number is also increased. From the inlet opening of the cavity to the exit, Nusselt number seamed to decrease. Increasing the value of Richardson number at the same value of Reynolds number increases the Nusselt number within the cavity. Streamlines patterns and isothermal patterns were also shown for the mixed convection flow inside the cavity.

This study represents an investigation of the critical thermal buckling load in columns consist of two different materials for the case of fixed-fixed and fixed pinned loading in order to choose the suitable compound ratio. The finite element model using ANSYS APDL 17.2 was built to simulate the compound column consist of two different materials of different compound column length, different materials and different lengths of the fixed part. Analytically, four analytical models were suggested to describe the effects of moduli of elasticity and thermal expansion factors of the used materials on the critical thermal buckling load. The results showed that the fourth analytical model is the suitable analytical model described the effects of elasticity and thermal expansion factors of the used materials in a fixed – fixed compound column. In fixed – pinned compound column, all analytical models suggested in this work cannot describe the effects of elasticity and thermal expansion factors along the length of the compound column.