دكتور صاحب شهاب احمد الدليمي

The presented study is considered as a review related to early researches on heat transfer enhancementby means of ribs mounted in duct. One of the considerable topics used for developing highly-effective, inexpensive and light-weight heat exchangers is the heat transfer enhancement. With regard to the energy saving purposes, different techniques of heat transfer enhancement like rib tabulators, dimples, pin fin and swirl chamber were utilized in various industrial heat exchanger devices. Ribs’ attachment to flow passage is the majorly utilized technique of heat transfer enhancement. In addition, the ribs can be constructed easily and thoroughly utilized in various industries. There were various types of ribs for enhancing the heat transfer rate like circular and segmented ribs, rectangular and triangular ribs, and V-ribs (broken and simple v-ribs). The rib’s shape is of high importance in the heat transfer enhancement since it is affecting the bubbles’ separation behind the ribsas well as the amount related to turbulent kinetic energy productions. With regard to utilizing many rib types, the enhancement of the heat transfer is on the basis of height and number of ribs and many arrangements of ribs. This study is showing a review regarding various non-conventional, conventional rib shape as well as the combined effect related to ribs arrangements on the force convection heat transfer in the duct.

The rapidly rising issue of declining the non-renewable resources available has focused the world attention on how renewable resources can be better used and harvested. Solar energy is one of the essential sources of renewable energy. Solar energy is a source of renewable energy for various applications in the world today. The present study is regarded as a summary of early studies on utilizing phase-change material in the use and storage of solar power. Due to its high thermal density, the isothermal nature and the easy power, the late thermosetting with the material is an advantageous way to store thermal energy. This paper summarizes how thermal energy can be efficiently stored via PCM in thermal energy storage systems of solar collectors. PCMs are isothermal, have higher density energy storage and are capable of operating in varying temperature environments. Therefore, an attempt was made in this paper to summarize an analysis of the various applications of phase change material (PCM), even solar collection device integrating PCMs.

omputational Fluid Dynamics (CFD) is the science of predicting fluid flow, heat transfer, mass transfer, phase change, chemical reaction, mechanical movement, stress or deformation of related solid structures, and related phenomena by solving the mathematical equations that govern these processes using a numerical algorithm on a computer. The results of CFD analyses are relevant in: conceptual studies of new designs, detailed product development, troubleshooting, and redesign. CFD analysis complements testing and experimentation, by reduces the total effort required in the experiment design and data acquisition. CFD complements physical modelling and other experimental techniques by providing a detailed look into our fluid flow problems, including complex physical processes such as turbulence, chemical reactions, heat and mass transfer, and multiphase flows. In many cases, we can build and analyze virtual models at a fraction of the time and cost of physical modelling. This allows us to investigate more design options and "what if" scenarios than ever before. Moreover, flow modelling provides insights into our fluid flow problems that would be too costly or simply prohibitive by experimental techniques alone. The added insight and understanding gained from flow modelling gives us confidence in our design proposals, avoiding the added costs of over-sizing and over-specification, while reducing risk. The use of Computational Fluid Dynamics to simulate engineering phenomena continues to grow throughout many engineering disciplines. On the back of ever more powerful computers and graphical user interfaces CFD provides engineers with a reliable tool to assist in the design of industrial equipment often reducing or eliminating the need for performing trial-and-error experimentation. In summary, much progress has been made in engineering applications of CFD. The chapters in this book testify to the vitality of engineering CFD research and demonstrate the considerable potential for use of these techniques in the future. The book is intended to serve as a reference for both researchers and postgraduate students. I thank the work and commitment of all of the authors who submitted chapters according to my requests and dealt with my numerous comments.

In the present investigation Low order panel method with Dirichlet boundary condition conjugated with Kutta condition, was used to calculate pressure coefficients for potential flow about isolated curved wings at different aspect ratios and different angles of attack. Also both local and total lift coefficients were calculated for the same wings, with detailed streamline behavior on both upper and lower surface. Constant strength quadrilateral doublet element and Constant strength quadrilateral source element were placed on each panel, except on wake sheet only constant strength quadrilateral doublets were placed to satisfy Kutta condition at trailing edge. A set of linear algebraic equations were established by setting inner potential equals to free stream potential. These equations were solved using Gausselimination to determine quadrilateral doublet singularity strength distribution. Finally finite difference formula was used to predict aerodynamic loads calculation.

This paper investigates mechanical and thermal stresses that arise in the exhaust valve due to its operating with and without thermal coating layer (ceramic) on face exhaust valve. Three dimensional models of an exhaust valve four cylinders, four stroke, and direct injection diesel engine have been presented. The governing equations were discretized using a finite-volume method (FVM) and solved using multi-physics COMSOL® package Version 5. The engine’s exhaust valve crown is coated with various materials in different thermal conductivity such as (Gd2Zr2O7), over a 150μm thickness of bond coat. The maximum thickness of coating is about 300 μm. Results indicate that after creating a coating layer exhaust valve the temperature distribution, temperature gradients distribution, von-Mises stress distribution and displacement distribution are decreased.

The main goal of this paper are equate behavior of the piston with and without different thermal coating layer on the piston head under thermal and mechanical loads that arise in the piston due to its operating. Three dimensional model of a piston heavy diesel engine has been presented. The governing equations have been discretized using a finite-volume method (FVM) and solved using multiphysics COMSOL package version 5. The results of the numerical model are showing the distribution of temperature, temperature gradients, Von-Mises stresses, and displacement in the diesel engine piston with and without 200 µm of thermal coating layer as (La2Zr 2O7) which have low thermal conductivity. The results show great improving in the performance of the piston with thermal coating layer.

This paper investigates mechanical and thermal stresses that arise in the exhaust valve due to its operating with and without thermal coating layer (ceramic) on face exhaust valve. Three dimensional models of an exhaust valve four cylinders, four stroke, and direct injection diesel engine have been presented. The governing equations were discretized using a finite-volume method (FVM) and solved using multi-physics COMSOL® package Version 5. The engine’s exhaust valve crown is coated with various materials in different thermal conductivity such as (Gd2Zr2O7), over a 150μm thickness of bond coat. The maximum thickness of coating is about 300 μm. Results indicate that after creating a coating layer exhaust valve the temperature distribution, temperature gradients distribution, von-Mises stress distribution and displacement distribution are decreased.

Recent technology to use the reclaimed rubbers (RR) in the virgin polymer materials has attracted many rubber industries. Most work in the field have investigated the cure characteristics and the products properties obtained by the incorporation of the reclaimed rubber, in various forms, into different virgin materials. The aim of this work was to study the influence of Alkylphenol Disulfide in preparation reclaim rubber. Tow compositions of Alkylphenol Disulfide with loading of [0.2 and 0.15 %], the compositions were prepared in Laboratories Inc. Tires Babylon. The tests included the tensile, hardness, Chloroform and Acetone and Rheometric. To determine the tensile strength, and elongation at break a tensile test device called (Tensilmete) was used According to ASTM D412, operating at strain rates of 500 mm/min. Finally, by using a device (Hardness), to determine the Hardness IRHD of reclaim compound. Andy Rushton says "RECLAIMED RUBBER A new life for an old product".

This study discusses the performance and exhaust emissions of a vehicle fueled with low content alcohol (methanol) blends and pure gasoline. In this study, experiments have been done to measure the performance and emissions of a 4-stroke S.I. Engine, one by using the commercial imported gasoline, another by using the gasoline-methanol blends. The engine is run at different loads and methanol blending percentages . It is found that increasing the blending percentage reduces the emitted concentration of carbon oxides and HC . However it is found that break power and break thermal efficiency are increased with increasing methanol blending percentage due to higher cylinder temperatures. The results showed that use of 10% volume of methanol blending with the gasoline appears to be a good option for replacing any oxygenate additives in the gasoline, where the CO, CO2, and HC are minimum and the fuel consumption of the blend is lower than of the commercial gasoline.

الوصف In the present work a numerical analysis includes modeling of separation flow of a two-dimensional, incompressible, steady and turbulent flow around (NACA 0012) airfoil. The study includes the numerical solution of the continuity and momentum equations with the two equations of the (k-İ) turbulence model. Grid generation with Body Fitted Coordinates System (BFCS) has been used. The grid generation technique based on differential equations which it solve by finite difference method and the clustering of the grid was used in the numerical solution. The Finite Volume Method (FVM) is adapted to solve Navier-Stokes equation by transferring these equations from differential forms to algebraic forms which can be solved according to the (SIMPLE algorithm) procedure with collocated grid arrangement The flow variables(aerodynamic characteristics) such as the velocity vector and stream function are computed. Beside, pressure, lift and drag coefficients. The present study gives a detail description of separation flow and its effects under different flow conditions. Separation point at the airfoil surface is predicted at high angles of attack. It is found that increase the angle of attack will lead to increases all of separation occurrence, recirculation, reversed flow also, pressure, lift and drag coefficients are highly influenced by the angle of attack and the Reynolds number before stall angle. The numerical results were compared with other pervious experimental and theoretical results. The agreement was good, confirming the reliability of the proposed computational algorithm in calculating the turbulent separation flow around (NACA 0012)

Analyzing the double diffusive mixed convection inside a triangular enclosure with moving lid and involving a wavy porous cylinder emitting a concentration is addressed in this paper. Such a problem simulates various processes such as crystallization, absorption, and distillation where both heat and mass transfer are involved. The horizontal wall of the lid-driven cavity maintains a constant temperature, while the inclined walls of the triangle cavity are thermally insulated. The wavy wall of the inner porous cylinder releases a constant species and kept colder than the moving wall. This study presents a novel way for improving heat transmission from a surface utilizing porous cylinders. Using a porous cylinder with e porosity can improve the performance of heat transfer. The governing equations are transformed to a non-dimensional form and solved with the finite element method. The study examines how porosity (ε), Darcy number (Da), undulation number (N), and wave amplitude (A) affect fluid flow, heat transfer and concentration distribution. More improvement in the porous cylinder performance is discovered to be possible with increasing (ε), (N), (Ri), and (Re), particularly at large (Da) levels. It is discovered that the average Nusselt number rises by the porous cylinder wall’s waviness. The results indicate that in certain cases, increasing N from 1 to 5 raises the Nusselt number by 6 % while increasing the Darcy number from 10− 3 to 10− 2 could improve convective heat transmission in the liquid by 7.5 %

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