Omar Rafae Alomar

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• Prof. Dr.-Ing. in Thermal Engineering ( TU Freiberg , Germany)
• PostDoc Position at Northern Technical University

This work involves the numerical simulations of two-phase flow inside porous media and the associated phase change processes in order to investigate the effects of thermal dispersion and variable porosity near the wall boundary. The modified enthalpy formulation has been employed. The mathematical model for the conservation of energy is based on th...

This work involves an experimental study on a trapezoidal Double-Pass Solar Air Heater (DPSAH) to analyse its performance under natural and forced convection cases for the purpose of comparison. The experiments have been conducted in winter and compared for each case in same time and weather conditions. The collector has been carefully designed and...

In this article, a new mathematical model, based on the modified enthalpy formulation of Two-Phase Mixture Model (TPMM), is developed by considering non-Darcy flow and Local Thermal Non-Equilibrium (LTNE) conditions to describe numerically the two-dimensional problems of the complete evaporation process inside an asymmetrically heated porous evapor...

This study numerically presents the characteristics of natural convection induced by a bank of orthogonal heated plates instilled inside porous cavity using the assumption of local thermal non-equilibrium (LTNE) and non-Darcian conditions. In-line and staggered arrangements of heated sections have been investigated for the purpose of comparison. At...

This study numerically presents the transient behaviour of complete evaporation process inside porous channel. Based on the modified enthalpy formulation under non-Darcy flow and Local Thermal Non-Equilibrium (LTNE) conditions, solutions have been obtained utilizing the finite volume method for various relevant parameters. The results have been val...

As a result of the climate changes occurring on the planet and the carbon emissions they cause, solar energy systems must be developed in order to achieve greater efficiency. This study examines the performance of double‐pass solar air heaters (DPSAH) with and without porous media under forced convection. Two types of porous media, glass balls and...

This investigation involves a numerical and experimental work on mixed convective heat transfer inside cavity heated from below and reciprocating moving upper surface. For the experimental work, the smoke method is used for the air flow visualization. The experiments include the measurements of air temperature inside the cavity and upper and lower...

Drinking water requirements are rapidly increasing while the availability of drinking water is decreasing. Overcoming this problem requires a sustainable energy source, such as solar energy, to desalinate untreated water. The most essential and simplest application of brackish water desalination is solar distillation. However, a limitation of the w...

This current investigation involves an experimental inspection of adding porous medium and phase change material (PCM) above the absorber surface to enhance the performance of a single slope and single basin solar water distiller system. To demonstrate the effectiveness of adding porous medium and PCM, the performance of the modified system and con...

This current investigation involves an experimental inspection of adding porous medium and phase change material (PCM) above the absorber surface to enhance the performance of a single slope and single basin solar water distiller system. To demonstrate the effectiveness of adding porous medium and PCM, the performance of the modified system and con...

With growing the world population, the demand on fresh water production is increased. Since solar energy is considered one of the most inexpensive and readily available energy sources, it can be used in several applications, e.g. the purification of water. There are various types of solar still (SS) systems that are designed and used for the purifi...

This study numerically involves the performance of thermal insulation of different types of composite walls and roofs to demonstrate the best model that can be used for energy-efficient building construction in Iraq. The mathematical model is solved by building its code using the Transmission Matrix Method in MATLAB software. The weather data of 21...

The present investigation involves an experimental examination of incorporating rectangular fins, black glass balls as porous media, and phase change material (PCM) above the absorber surface to improve the effectiveness of the single-slope and single-basin solar water distiller system, known as MSS-FPPCM. Data was gathered in November and December...

Improving the performance of solar water distiller system

This work involves an experimental study on the performance of automobile air-conditioning systems by adding Al2O3 nanoparticles to oil compressors to investigate their impacts on the enhancement of the speed cooling of refrigeration systems and to compare it with the system operated using only oil. The Al2O3 nanoparticles have been added to the oi...

The incident solar energy that impinges upon the photovoltaic cells undergoes a conversion process, resulting in the generation of electrical energy and conversion of absorbed energy into heat. This increase in temperature adversely affects the performance of the panel, leading to a decrease in its overall efficiency. This study examines the proper...

The aim of the work is to develop a mathematical model which has capability to analyses the design parameters as a function of operations conditions for single and multi-stage Joule Thomson Cryocooler System JTCS. The operations conditions are inlet and outlet pressure, precooling temperature, and mass flow rate. The design parameters are expansion...

Free convective heat transfer created from two aligned cylinders immersed inside a vented air duct is experimentally investigated. The experiments include the measurements of cylinders temperature and the air temperature inside the enclosure under steady, turbulent, and incompressible flow properties by using steady‐state heat equations. The studie...

The performance of discharge coefficient (Cd) and wall pressure of Venturi meter under various convergent and divergent cone angles have been experimentally investigated. Several models of tubes have been examined, where the tubes have been manufactured with two convergent angles (20° and 40°) and three divergent angles (7°, 11° and 15°). A pipe sy...

A new design of a Solar Vortex Engine integrated with a PV panel is designed. The system with a horizontal PV panel has the highest efficiency reaching 52.4%. The novel design forms an artificial vortex convenient for energy production.

This work involves an experimental investigation of a Compound Parabolic Concentrator (CPC) solar air flat plate collector with adding Phase Change Material (PCM). To explore the best model performance, the structure of CPC has two symmetric giant parabolic mirror reflectors, a concentration ratio of 1.7, similar flat plate receiver with 12 tubes f...

This work involves an experimental investigation of a Compound Parabolic Concentrator (CPC) solar air flat plate collector with adding Phase Change Material (PCM). To explore the best model performance, the structure of CPC has two symmetric giant parabolic mirror reflectors, a concentration ratio of 1.7, similar flat plate receiver with 12 tubes f...

The atmospheric vortex engine (AVE) model is one of the major objectives of this study; it is a new model that has been recently developed. There includes a presentation and discussion of the system's design and implementation, as well as thermodynamic measurements and analysis. Whereas the AVE consists of a Solar Air Collector (SAC) with an area o...

The main problem of gas generating units that operate in the simple cycle system is their relatively low thermal efficiency, which results in a large waste of heat energy resulting from the fuel combustion process. The current research is aimed to study the economic evaluation of the different types of fuel in the Qayyarah gas power plant. Gas turb...

The present study aims to evaluate the performance of SI engine using GT-Power simulation software with local gasoline fuel (LG) under different compression ratios (CR8, CR8.5, CR9) compared to standard gasoline fuel (SG) under a compression ratio of (8.5) as a base for comparison. A single-cylinder four-stroke (SI), engine (Robine EH17) with a con...

An experimental study on the performance of a single slope and single basin solar water distiller by adding extended fins above the absorber surface. To determine the effectiveness of adding fins, the results of modified collector has been compared with the traditional collector without using fins under identical operating conditions. The experimen...

In this research, the design of a low-cost modified anaerobic digester that contributes to improving biogas production in cold winter climates has been investigated. A laboratory biogas production plant consists of two anaerobic fermentation systems has been constricted, the first is conventional and the other is modified. Tests and measurements we...

It is common knowledge that phase-change materials are used for the purpose of thermal storage because of the characteristics that are exclusive to these materials and not found in others. These characteristics include a large capacity for absorbing heat and a large capacity for releasing heat when the phase changes; however, these materials have a...

This study covers a simulation on conjugate free convective in a porous enclosure containing a side wall thickness and partially heated and cooled from sides under the considerations of local thermal nonequilibrium (LTNE) and non‐Darcy flow. Interest has been focused on how the side wall thickness and the locations of cooled and heated parts affect...

This study involves an investigation on fully evaporation process inside annular porous heat exchanger using Cu/distilled water nano-fluid. Emphasis has been placed on how the use of Cu/distilled water affected two-stage flux predictions. Two-phase mixture model, based on the considerations of Local Thermal Equilibrium (LTE), has been reformulated...

This work involves a numerical investigation on free convection heat transfer occurred by a hot cylinder immersed in a square duct cooled from one side under different temperatures. Simulations have been done for a large ranges of Rayleigh number (10 3 ≤ Ra ≤10 7) and right wall temperature (0≤Tr ≤0.75). The results displayed that Nu is enhanced wi...

The recent study encompasses a practical inspect on adding porous material above absorber flat plate having fins to improve the effectiveness of solar air heater (SAH) collector along with forced air circulation process. The efficiency of the altered model and conventional SAH system is compared at the same time to display the impacts of adding por...

The current work focuses on the experimental research of a vapor compression cycle using Polyol Oil Ester (POE) with nano copper oxide (CuO) and a fluidized bed for condenser cooling to enhance its performance. The efficiencies of the modified and normal systems using only POE oil have been compared to present the actions of using nano CuO and a...

The current work deals with the numerical investigation of mixed convection occurring from two hot cylinders placed inside vented ducts under different sizes of inflow and locations of outflow opening vents. The mathematical formulation is solved based on the finite volume approach. The location of the outflow section is changed to left, center, an...

The current work involves an experimental investigation of a modified v-corrugated absorber plate to get a better performance of the Solar Air Heater (SAH) collector. The thermal efficiencies of the modified and the normal v-corrugated collector having a jet plate blown systems are compared to present the actions of the modified system. The modifie...

Energy, economic and environment performances of 1 MWp photovoltaic power plant has been numerically investigated under climatic condition of Zakho city/Iraq using the reality metrological measurements. Results of PV system have been compared with other available power plants that used fossil fuel under identical power value. The findings displayed...

In this article, a technical–economic study has been displayed to evaluate the productivity of grid-connected photovoltaic (PV) solar system in a campus of University of Zakho, Iraq. The feasibility of this study is based on performance ratio, capacity factor, cost of energy and yield factor. The analysis of the system has been performed using Syst...

Scientific progress in any country is measured by the importance that is given to scientific research. Recently, the interest in scientific research has increased by the local and international universities in various fields of sciences, given its importance in achieving sustainable development goals, where several countries and universities have i...

In this article, an experimental work has been carried out to examine the effect of varying operating conditions on performance of Pelton turbine. The experiments have been performed for various nozzle jet diameters (d), volume flowrate (Q) and pressure head (H). The experimental results display that the rise in d leads to reduce the input power du...

Thermal energy is transferred in the atmosphere from a high-temperature zone to a low-temperature zone via convective vortices that generate mechanical energy. There are two ways to generate vertical flow in the core of a vortex: (1) through the direct effect of buoyancy on hot air. (2) Core growth, which spreads the vortex's lateral spread with he...

The current study implements a numerical investigation on natural convection inside non-Darican porous duct to analyse the actions of using a single heated obstacle attached horizontally/vertically at the heated surface under Local thermal non-equilibrium (LTNE). Importance has been given on how the heated obstacle length and its position manipulat...

The current review focuses on the utilization of heavy fuel in operating gas turbine and their effect on the power plant performance. The literature survey includes a comparison of the different studies to reveal the effect of the fuel property on the combustion efficiency and fuel consumption. the most important of which is the generation of elect...

An experimental investigation on the performance of a solar air heater (SAH) system has been performed using a new model of v-corrugated absorber plate having perforations jets. The effectiveness of new model has been compared with the conventional v-corrugated absorber plate under identical operating conditions to display the effectiveness of new...

In this article, the fully boiling process inside pipe filled with porous media has been numerically investigated using Cu/water nanofluid. Two-Phase Mixture Model (TPMM) has been modified to include the impacts of adding nano-fluid instead of pure water under Local Thermal Equilibrium (LTE) model. The mathematical formulation have been solved util...

Present work involves a theoretical energetic and exegetic analysis on the thermal efficiency of the flat plate solar system under variables water inlet temperature and heat loss coefficient. The experimental analysis has been performed based on experimental data that conducted under outdoor conditions of Duhok city at north of Iraq in May 2019. Th...

Fuel quality is an important indicator for the suitability of alternative fuel for the utilization in internal combustion (IC) engines. In this paper, light naphtha and fusel oil have been introduced as fuel additives for local low octane gasoline to operate a spark ignition (SI) engine. Investigated fuel samples have been prepared based on volume...

This work displays a numerical investigation on free convection inside non-Darcy porous cavity having a vertical triple adiabatic obstacles under conditions of Local thermal non-equilibrium (LTNE). Interesting has been focused on how the obstacles lengths arrangements manipulates the enhancement of free convection. Based on obstacles lengths, seven...

Present study involves an exhaustive analysis on hybrid photovoltaic thermal (PVT) system to display the actions of climate and operating conditions on its thermal and electrical efficiencies. The performances of the system have been evaluated based on energy and exergy analysis using the experimental data for the purpose of comparison. Experimenta...

This paper presents an experimental work on two trapezoidal double-pass solar air heaters (DPSAH) having double glass covers under natural and forced air circulation conditions to investigate their performances by adding packed beds above the absorber surface on one them for target of comparison. The DPSAH-1 has been operated with adding porous med...

Mixed convective induced by two aligned horizontal heated cylinders embedded in a square enclosure with symmetrical openings at lower and upper surfaces of the enclosure has been numerically investigated. Navier- Stokes and energy equations have been employed to simulate the behaviours of heat and fluid flow fields. The flow has been considered to...

Scientific progress in any country is measured by the importance that given to the scientific research. Recently, the interest in the scientific research has increased by the local and international universities in various fields of sciences, given its importance in achieving sustainable development goals, where several countries and universities h...

This study experimentally investigates the influence of adding SiC on microstructure and mechanical properties of the aluminium alloys welded joints. The SiC particles have been directly added into a zone of Friction Stir Welding (FSW) to make (AA 6061 – AA 2024) SiC composites material. Results show that the effect of adding SiC particles on micro...

This article displays a numerical investigation on natural convection within non‐Darcy porous layer surrounded by two horizontal surfaces having sinusoidal temperature profiles with difference in phase and wave number. The Darcy–Brinkman–Forchheimer model and local thermal nonequilibrium condition have been employed. Simulations have been performed...

Complete evaporation process inside diffuser filled with porous medium has been numerically investigated. The flow has been considered steady and one-dimensional. The governing equations have been made dimensionless form and discretised using Finite Volume Method (FVM). Effects of the relevant parameters on the temperature distribution and liquid s...

The prediction accuracies of friction factor correlations in turbulent pipe flow have remained unsatisfactory due to Colebrook equation is characterized as an implicit correlation. Thus, this works deals with numerical simulation for optimization the correlation of friction factor (fD) in turbulent pipe flow. Genetic Algorithms (GAs) method has bee...

In this article, two triple-pass solar air heater (TPSAH) collectors have been experimentally investigated to analyse their performances through adding a net of tubes below the absorber surface and double glass cover on one of them for purpose of comparison. The first collector (TPSAH-1) has been covered with a single glass, whereas the second coll...

In this article, two-phase flow in a double-pipe porous heat exchanger and associated phase change processes has been numerically analysed to investigate the impacts of the relative permeabilities. The modified h-formulation along with the assumption of Local Thermal Equilibrium condition has been employed. Finite Volume Method (FVM) has been used...

In this paper, the hybrid photovoltaic/thermal solar domestic hot water (PVT-SDHW) has been numerically investigated to determine its thermal and electrical performance of a house consists of 5 persons in Iraq climate environment. A detailed mathematical formulations of PVT-SDHW system have been developed. To validate the feasibility of the develop...

This work involves a study on the convective heat transfer over a two perpendicular plates embedded inside a square porous cavity using non-Darcian flow and Local Thermal Non-Equilibrium (LTNE) assumptions. The problem has been assumed to be steady and two-dimensional coordinates. For non-Darcy flow, the effects of inertia and boundary layer have b...

In this paper, an experimental work has been performed to investigate the performance of a new Compound Parabolic Concentrator (CPC) with a flat plate receiver model. The CPC structure has been designed based on the two offset large parabolas reflector surfaces with a concentration ratio equal to 1.5. The experiments have been carried out in winter...

In this work, numerical simulations of thermal processing in a uniform fin geometry have been investigated to evaluate the effect of adding the heat loss by radiation on the fin effectiveness. The heat transfer through the fin has been considered to be one-dimensional and under steady state condition.

In this work, numerical simulations of thermal processing in a uniform fin geometry have been investigated to evaluate the effect of adding the heat loss by radiation on the fin effectiveness. The heat transfer through the fin has been considered to be one-dimensional and under steady state condition. The mathematical formulations have been convert...

In this paper, an experimental study has been performed to investigate the performance of varying diameter of orifice that made from acrylic plastic on the flow characteristics. A colour water has been used as a working fluid to flow through a PVC pipe system. The orifice has a sharp-edged with 30° angle and the pipe system has thirty tapping point...

This work deals with modelling and numerical simulation of complete evaporation process inside anisotropic porous media. Based on the modified enthalpy formulation of Two-Phase Mixture Model (TPMM) along with the assumption of Local Thermal Non-Equilibrium (LTNE), a modified formulation has been proposed that can easily accommodate the anisotropy i...

Two-Phase flow in an inclined rectangular porous media, under unsteady-state condition, has been numerically investigated in this article, based on the modified h-formulation of Two-Phase Mixture Model (TPMM). The governing equations have been discretised using Finite Volume Method (FVM) and solved iteratively in a SIMPLE-like manner. Effects of va...

In this paper, the emissions characteristics and performance of a direct four-stroke diesel engine fueled by three different kinds of biodiesel oils and normal diesel oil (DF) has been experimentally investigated. Biodiesel fuels of Palm, Coconut and Sunflower have been separately used as an alternative fuels and the results obtained have been comp...

The complete evaporation process inside an asymmetrically heated porous channel, under steady-state condition, has been numerically investigated in this article, based on the modified enthalpy formulation along with the assumption of Local Thermal Non-Equilibrium (LTNE). The governing equations have been discretised using finite volume method on bo...

Two-Phase flow in an inclined rectangular porous media, under unsteady-state condition, has been numerically investigated in this article, based on the modified h-formulation of Two-Phase Mixture Model (TPMM)

Two-Phase flow in an inclined rectangular porous media, under unsteady-state condition, has been numerically investigated in this article, based on the modified h-formulation of Two-Phase Mixture Model (TPMM)

The Complete liquid-vapour phase change process inside an asymmetrically heated porous channel has been numerically investigated in this article, based on the Two-Phase Mixture Model (TPMM), while employing both Local Thermal Equilibrium (LTE) and Non-Equilibrium (LTNE) conditions. For the latter condition, four different models have been considere...

This work deals with modeling and numerical simulation of the complete liquid–vapor phase change process inside porous media, based on the Two-Phase Mixture Model (TPMM) along with the assumption of Local Thermal Equilibrium (LTE) and Non-Equilibrium (LTNE) conditions. In particular, it demonstrates the necessity and usefulness of a newly proposed...

In the present article, after critically analysing the drawbacks of the existing h-formulation based on Two Phase Mixture Model (TPMM), a modified formulation has been developed that can easily accommodate substantial density variations in the single phase regions. The results for steady one-dimensional complete liquid-vapour phase change problems...

The present article demonstrates the necessity and the usefulness of a newly proposed smoothing algorithm for the effective diffusion coefficient in order to avoid non-physical “jump” in the predicted properties during numerical simulations of the complete liquid–vapour phase change process within porous media. The formulation is based on the two-p...

The present study deals with numerical simulations of the complete liquid-vapour phase change process inside an annular porous evaporator. The employment of a newly proposed smoothing algorithm for the effective diffusion coefficient has been found to be essential in order to avoid the occurrence of non-physical “jump” in the predicted properties d...

The present paper deals with numerical simulations of complete phase change process inside porous media, based on the two-phase mixture model, using finite volume method for discretisation. The investigation proposes a successful remedy in order to eliminate the occurrence of “jump” in predicted properties, by introducing an efficient smoothing alg...

Complete phase change process within a divergent porous evaporator is numerically investigated in this paper. A smoothing algorithm, proposed by the present authors, is used in order to deal with the discontinuity in effective diffusion coefficient. Effects of various parameters on the temperature distribution are carefully investigated, which clea...

In this paper, Non–Darcian steady flow two-dimensional natural convective heat transfer in an rectangular and square porous cavities with two parallel walls kept at constant different temperatures, while the other two parallel walls were well insulated, had been studied numerically. The governing equations had been solved using finite difference me...