حمزة عاشور ميلاد محمد


عضو هيئة تدريس قار

المؤهل العلمي: دكتوراه

الدرجة العلمية: محاضر

التخصص: انتقال الحرارة بالإشعاع - انتقال الحرارة Heat Transfer

الهندسة الميكانيكية والصناعية - الهندسة

المنشورات العلمية
HVAC System Design by Using Geothermal Heat Pump
Journal Article

A design of a geothermal heat pump heating, ventilating, and air conditioning system has been done for XYZ Indianapolis School by using renewable energy. Geothermal energy is one of the important energies that has proved itself in air conditioning systems all over the world. The design was classified in three points as follows. Using borehole heat exchanger (BHEs) vertical type, heat pump and all its equipment such as mechanical room, pipes, and fitting design to cover the total load of the school the results were 20 boreholes and a total flow rate of 60 gpm (3 gpm/bore) of 20 % propylene solution, and spacing 20 ft with 1.1 Hp and 6.5 in impeller size. For individual borehole design, the results were 15 boreholes and a total power consumption 1.1 kW. For the ventilation design, the peak load for heating is 42779 Btu/hr, and for cooling, it is 47779 Btu/hr. There are 4 boreholes, a 0.5 hp electric pump with a flow rate of 10 gpm a 40ft of H2O pressure drop, and a 10 hp fan integrated with a water-to-water heat pump. The total load we assumed for the heating supply in class 6 and the corridor are 10% and 25 %, respectively. The thermal resistance was calculated for each case according to the fluid flow rate. The ventilation load of the school is designed separately from the heating and cooling loads and connected to a water-water heat pump that will make the system work with high efficiency. Finally, we designed this project using Geothermal Energy, which is cleaner than conventional energy.


Hmza Ashur Milad Mohamed, (01-2025), ليبيا: AlQalam Journal of Medical and Applied Sciences (AJMAS), 1 (8), 277-291

DESIGNING SOLAR ENERGY SYSTEMS WITH THE INTEGRATION OF NET ZERO ENERGY BUILDING TECHNOLOGY
Journal Article

Solar energy, known for its abundance and sustainability, stands out as a preferred renewable energy source. Net-zero energy buildings (NZEBs) technology for an elementary school in Dayton, Ohio, was implemented using the f-chart, phi method, photovoltaic system, and the CombiSystem TRNSYS executable. The solar fraction achieved for the system was 56% utilizing the f-chart and phi method. The project required 181 collectors for heating and cooling loads and 578 photovoltaic collectors for electricity generation. Using the f-chart and phi method, the simple payback period was calculated to be 5 years. The optimal storage tank design was determined to be a 120-60 gallon configuration, achieving a solar fraction of 62.45%. The photovoltaic system generated energy valued at $191,135 annually, meeting the requirements for a net-zero energy building. This design provides clean energy without environmental pollution or CO₂ emissions. The total project cost amounted to $275,393.99, making it the most cost-effective design compared to alternative designs incorporating photovoltaic systems for cooling loads. 

Hmza Ashur Milad Mohamed, (12-2024), ليبيا: مجلة العلوم التقنية, 2 (8), 2959-3298

VERTICAL RECTANGULAR FINS ARRAY DESIGN EXPERIMENTAL AND THEORITICAL COMPARISONS
Journal Article
  • Experimental and theoretical comparisons have been performed for natural convection heat transfer over rectangular fins array at different fin parameters. This investigation includes the effect of fin length, fin spacing, fin height, orientation angle, and temperature difference between the heat sink and the surrounding environment. To understand the general flow patterns dominating flows from the heat sink, the three dimensionless elliptic governing equations were solved using finite volume computational fluid dynamics (CFD) code, and the experimental work was carried for the system at different orientations. A new empirical correlation (modified of McAdam's correlation) was derived to correlate the mean Nusselt number as a function of the Rayleigh number. The average heat transfer coefficient has a maximum value at an orientation angle equal to zero degrees, and it decreases with an increasing orientation angle. The heat transfer rate per unit base area increases as fin spacing increase until it reaches a maximum value (6.5 mm), then it decreases with a further increase of fin spacing. The results of these investigations between the experimental and theoretical study were showing good agreements with similar international works.

Hmza Ashur Milad Mohamed, (09-2021), USA: IJSRED, 4 (5), 937-953

OPTIMUM DESIGN OF VERTICAL RECTANGULAR FIN ARRAY
Journal Article

Experimental and numerical investigations have been performed to study the natural convection heat transfer from a vertical rectangular fin arrays at different orientation angles.An experimental setup was constructed and calibrated to test different fin configurations. It basically consists of base plate, an array of parallel longitudinal fins, heating unit and layers of thermal insulation. Fin length (L) and fin thickness (t) were kept fixed at 187 and 6.5 mm respectively, while fin spacing (S) was varied from 3 to 16 mm and fin height (H) was varied from 15 to 45 mm. The orientation angle (β) was changed from 0° to 60°, and temperature difference between fin and surrounding (∆T) from 30 to 95 o C.Base-to-ambient temperature difference was also varied through a calibrated wattmeter ranging from 10 to 180W. To understand the general flow patterns dominating flows from the heat sink, the three-dimensionless elliptic governing equations were solved using finite volume computational fluid dynamics (CFD) code. A comparative study between the experimental and numerical results was performed to verify the numerical code. It was found for the configuration tested that the heat transfer rate per unit base area increases with the increase in the fin spacing and reaches a maximum value then decreases with farther increase in the fin spacing. The maximum heat dissipation occurs at optimal spacing S opt =7 mm. Empirical correlations between Nussult number, Rayleigh number, fin spacing, fin height, orientation angle, temperature difference between the fin and surroundings were derived. Finally the present work general empirical formula is given in the form =. .. .. Where , 15 mm ≤ H ≤ 45 mm, 3mm ≤ S ≤ 16 mm, °0 ≤ β ≤°60, t = 6.5 mm, L = 187 mm.

Hmza Ashur Milad Mohamed, (07-2021), USA: IJSRED, 4 (4), 1110-1133

NATIRT – Model of the Loss of Flow Transient for Tajoura Research Reactor with LEU Fuel
Journal Article

Design parameters are presented for Tajoura reactor core utilizing the new fuel assemblies with low enriched uranium (LEU, using IRT-4M fuel assemblies) in the steady state safety operational parameters and Loss of Flow transient mathematical models (NATIRT - computer program. The calculated results of the model are presented in the cases of forced convection steady state, transient during emergency tank filling and natural convection after emergency tank filling modes at different reactor core thermal power level. The results of NATIRT for all cases of flow were in good agreement with the PARET and PLTEMP computer programs.

Hmza Ashur Milad Mohamed, (01-2021), USA: IJSRED, 4 (5), 1-9

Mie MODEL OF RADIATION HEAT TRANSFERIN ISOTHERMAL SPHERICAL MEDIUM
Journal Article

In certain extremely low probability, severe accident scenarios which have been postulated for liquid metal cooled fast reactors,large bubble cavities containing fuel vapor and fission products transit a layer of coolant and release this material to the cover gas thereby presenting a contribution to an accident-specific source term [5].Mie model in radiation heat transfer has been investigated to analysis and interpret the experiments that conducted during 1980's for oxide UO 2 fueled reactors in Fuel Aerosol Simulant Test (FAST) facility at Oak Ridge National Laboratory (ORNL).These analyses are applied to estimate the bubble collapse of Liquid Metal reactors (LMR's) during a hypothetical core disruptive accident (HCDA).InMie scattering model the particle size was 0.07 µm [6]. The scattering coefficient of UO 2 particles (σ = 1.24 m-1), was calculated by using Mie theory,at the same number of stable nuclei's N (2.9 E15 nuclei/m 3) that resulted from theabsorbed coefficientk = 0.082 m-1 [7].P 1 approximation method was used to solve the radiative heat transfer equation (RTE) in spherical coordinates of participating medium confined between the two concentric spheres.The surfaces of the spheres are assumed to be gray, diffusely emitting and diffusely reflecting boundaries, and an isothermal boundary conditions were assumed at these surfaces.Marsak's boundary condition was to computed, the net radiative heat flux q(τ), and the incident radiation G(τ), to analyze and interpret the CVD experiments data that were conducted in the FAST facility at ORNL [8] and Fast Flux Test Facility reactor (FFTF) in Argonne National Laboratory ANL.The conclude that extracted from this study is greater margin of safety when the bubble rising time is greater than the bubble collapse time since the bubble collapses (UO 2 condenses) before it can reach the top of the vessel therefore there is less chance of release of aerosol as in Oak Ridge National Laboratory (ORNL) FAST experiments and Argonne National Laboratory (FFTF) reactor.






Hmza Ashur Milad Mohamed, (09-2020), USA: IJSRED, 3 (5), 402-420

Rayleigh Model of Radiation Heat Transfer in Spherical Medium
Journal Article

In certain extremely low probability, severe accident scenarios which have been postulated for liquid metal cooled fast reactors, large bubble cavities containing fuel vapor and fission products transit a layer of coolant and release this material to the cover gas thereby presenting a contribution to an accident-specific source term [5]. Rayleigh model in radiation heat transfer has been investigated to analysis and interpret the experiments that conducted during 1980's for oxide UO 2 fueled reactors in Fuel Aerosol Simulant Test (FAST) facility at Oak Ridge National Laboratory (ORNL).These analyses are applied to estimate the bubble collapse of Liquid Metal reactors (LMR's) during a hypothetical core disruptive accident (HCDA). In Rayleigh non-scattering model the particle size was 0.01 µm [6],and according to Mie theory principle, the absorption coefficient for small particle-size distribution was estimated (k = 10 m-1 was used) from reference [7] at complex refractive index of UO 2 at λ = 600 µm and x = 0.0785.A MATLAB code was used to solvethe radiative heat equation (RTE) in spherical coordinates. The mixture is in local thermodynamic equilibrium inside the bubble which has a black body surface boundary.The mixture in the cavity contains three components: the non-condensable gas Xenon, Uranium dioxide vapor, and fog.To simulate fuel bubble's geometry as realistically as possible, according to experimental observation, the energy equation in a spherical coordinate system has been solved with the radiative flux heat transfer equation (RTE) to obtain the effect of fuel bubble's geometry on the transient radiative heat flux and to predict the transient temperature distribution in the participating medium during a hypothetical core disruptive accident (HCDA) for liquid metal fast breeding reactor (LMFBR) for FAST. The transient temperature distribution in fog region was utilized to predict the amount of condensable UO 2 vapor = − ! " ! #. The conclusion that can be drawn from the present study, is that the Fuel Aerosol Simulant Test (FAST) facility at Oak Ridge National Laboratory has a larger margin of safety since the bubble rising time is greater than the bubble collapse time.

Hmza Ashur Milad Mohamed, (09-2020), USA: IJSRED, 3 (5), 421-437

RADIATION HEAT TRANSFER ANALYSIS IN TWO-PHASE MIXTURE ASSOCIATED WITH LIQUID METAL REACTOR ACCIDENTS
PhD Thesis

Analytical study associated with liquid-metal fast breeder reactor (LMFBR) has been investigated by using scattering and non-scattering mathematical radiation models. In the nonscattering model, the radiative transfer equation (RTE) was solved together with the continuity equations of mixture components under local thermodynamic equilibrium. A MATLAB code was used to solve these equations. This application employed a numerical integration to compute the temperature distribution within the bubble and the transient wall heat flux. First, in Rayleigh nonscattering model the particle size was 0.01 µm [6], and according to Mie theory principle, the absorption coefficient for small particle –size distribution was estimated (k = 10 m-1 was used) from reference [7] at complex refractive index of UO2 at λ = 600 µm and x = 0.0785. A MATLAB code was used to solve the radiative heat equation (RTE) in spherical coordinates. The mixture is in local thermodynamic equilibrium inside the bubble which has a black body surface boundary. The mixture in the bubble contains three components: the non-condensable gas Xenon, Uranium dioxide vapor, and fog. To simulate fuel bubble’s geometry as realistically as possible, according to experimental observation, the energy equation in a spherical coordinate system has been solved with the radiative flux heat transfer equation (RTE) to obtain the effect of fuel bubble’s geometry on the transient radiative heat flux and to predict the transient temperature iv distribution in the participating medium during a hypothetical core disruptive accident (HCDA) for liquid metal fast breeding reactor (LMFBR) for FAST. The transient temperature distribution in fog region was used to predict the amount of condensable UO2 vapor. The conclusion that can be drawn from the present study, is that the Fuel Aerosol Simulant Test (FAST) facility at Oak Ridge National Laboratory has a larger margin of safety since the bubble rising time is greater than the bubble collapse time. Second in the scattering model, the spherical harmonics method was used to solve the radiative heat transfer equation (RTE) in spherical coordinates, and the particle size was 0.07 µm [6]. The scattering coefficient of UO2 particles (σ = 1.24 m-1 ), was calculated using Mie theory at the same number of stable nuclei N (2.9 E15 nuclei/m3 ) that resulted from the absorption coefficient k = 0.082 m-1 [7]. The P1 approximation method was used to solve the radiative transfer equation (RTE) in spherical coordinates of participating medium confined between two concentric spheres. The surfaces of the spheres are assumed to be gray, diffusely emitting and diffusely reflecting boundaries, and isothermal boundary conditions were assumed at these surfaces. Marsak’s boundary condition was used to compute the net radiative heat flux, q(τ), and the incident radiation, G(τ), to analyze and interpret CVD experiments data that were conducted in the FAST facility at ORNL [8] and Fast Flux Test Facility reactor (FFTF) at ANL. From this study, it can be concluded that there is greater margin of safety when the bubble rise time is a greater than the bubble collapse time since the bubble collapses (UO2 condenses) before it can reach the top of the vessel. In addition, the work transfer by itself can’t completely eliminate the super-heated vapor, as the bubble contains noncondensable species which hinder condensation. However, it is reasonable to assume that work transfer could decrease the amount of UO2 vapor contained in the bubble as it reached the covergas [63].


Hmza Ashur Milad Mohamed, (05-2020), USA: University of Dayton,

THE ENERGETICS OF COOLANT-BUBBLE-COVERGAS INTERACTIONS ASSOCIATED WITH LMR OUT-OF-REACTOR SOURCE TERM EXPERIMENTS
Conference paper

In certain extremely low probability, severe accident scenarios which have been postulated for liquid metal cooled fast reactors, large bubble cavities containing fuel vapor and fission products transit a layer of coolant and release this material to the cover gas thereby presenting a contribution to an accident-specific source term. So that a more mechanistic assessment of these types of events can be developed, analyses have recently been performed to account for the heat and work transfer observed in out-of-reactor source term experiments conducted during the 1980’s for oxide fueled reactors in the Fuel Aerosol Simulant Test (FAST) facility at Oak Ridge National Laboratory. In ten experiments, UO2 specimens were vaporized in pools of sodium, and for an additional number of benchmarking tests, in pools of water, for purposes of experimentally assessing the bubble transport characteristics of both types of pools. The current analyses present several firsts for these experiments: (a) a comparison of the bubble-to-coolant transfer rates; heat versus work, (b) a bubble-to-coolant heat transfer model accounting for how condensation and radiation heat transfer are affected by coolant selection; sodium versus water, and (c) an assessment of how both types of heat transfer influence the movement of aerosol-laden bubbles through the coolant pool. These analyses significantly extend previous evaluations of FAST experimental results by providing a more comprehensive model for determining how bubble-coolant interactions affect aerosol transport and, in this way, contribute to data base development associated with mechanistic assessments of the source term.


Hmza Ashur Milad Mohamed, (08-2015), USA: NURETH-16 Chicago IL, 7372-7385

Orientation Effect on Natural Convection Performance of Longitudinal Fin Arrays Heat Sink
Journal Article

Experimental and numerical investigations have been performed to study the natural convection heat transfer from a longitudinal fin arrays at different orientation angles. For such purpose, an experimental test rig was manufactured to be used for these investigations. It basically consists of base plate, an array of parallel longitudinal fins, heating unit and layers of thermal insulation. During the experiments, the fin spacing (S) was varied from 3.375 to 33 mm, while the fin height (H) from 15 to 60 mm. The orientation angle (Ф) was changed from 0° to 180°, and temperature difference between fin and surrounding (∆T) from 35 to 95 °C. To understand the general flow patterns dominating flows from the heat sink, the three-dimensionless elliptic governing equations were solved using finite volume computational fluid dynamics (CFD) code. A comparative study between the experimental and numerical results was performed to verify the numerical code. It was found for the configuration tested that the heat transfer rate per unit base area increases with the increase in the fin spacing and reaches a maximum value then decreases with farther increase in the fin spacing. The maximum heat dissipation occurs at optimal spacing 5. 6 S opt = mm. Moreover, the average heat transfer coefficient was found to have a maximum value at Ф = 0° and decreased with the increase of (Ф) to reach a minimum value at Ф = 90°. Empirical correlations between Nussult number, Rayleigh number, fin spacing, fin height, orientation angle, temperature difference between the fin and surroundings were derived.


Hmza Ashur Milad Mohamed, (06-2008), مصر القاهرة: مجلة جامعة عين الشمس, 1 (1), 1687-8612

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