نبيل عبد الهادي غياض المجثومي

In the present research, experimental and theoretical work is carried out using ecofriendly refrigeration as working fluid in the absorption system. The working pair is considered in the analysis, namely, acetone and zinc bromide. The system is designed to work under outdoor conditions in Hila city-Iraq. In the test, the outdoor conditions are varied and the hot water is used as heat source. To check the performance of the system, various operating conditions are included in this study. These varied conditions include heat source, absorber, condenser, and evaporator temperatures. The system is tested during September 2019. The results show that the COP of the absorption cooling system ranged from 0.13 to 0.487, while the temperature drop in evaporator is 16 °C. Condensation and absorption temperatures are under 41 °C, while the maximum temperature of the driving water is 80 °C. The steady-state model is analyzed by using EES program. Energy and mass balance achieved on absorption system to predict some parameters such as temperature, pressure and (COP) to compare it with the measured parameters. The results of the model satisfied the experimental results for temperatures as well as the coefficient of performance. The results also show that the generator temperature had a great effect on the system performance

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.

Integrating solar assisted plant with a carbon capture unit to provide the required reboiler heat duty has been recently investigated extensively to reduce the negative impact of carbon capture unit on plant performance. However, using solar assisted plant to provide the required energy in the reboiler of the stripper leads to increase plant’s condenser duty unfavorably. In the present study, two novel configurations have been proposed for a concentrated solar assisted power plant to generate the required reboiler duty in the stripper of a post-combustion carbon capture unit (PCCC-SAPP) in a (630 MWe) natural gas combined cycle (NGCC) power plant to reduce both the condenser duty and power penalty of the plant simultaneously. In the present study, both the solar plant and plant’s low-pressure steam (LPS) are contributing to deliver the required reboiler thermal energy in the first method while the extraction is from the cooling system load in addition to the solar plant in the second method. Solar contribution factor (SCF) is the main criteria which has been used to evaluate the findings. Condenser duty with its associated water requirements, power penalty, and the required solar field land area are the parameters which have been investigated in the preset study.

In the present study, a solar collector is designed and constructed. The collector consists of parabolic trough of mild steel sheet and a helical coil receiver fabricated using copper tube positioned at the focal line of the trough. The copper tube is coated with black paint to increase its absorptivity. The system is fabricated and tested at Babylon University site in Hila city Iraq (32.4olatitude, 44.4o longitudinal) using water as working fluid under outdoor condition. The system is operated as a closed loop water circulation with a storage tank of 30 liter capacity contains 8 liters of water. Tests are carried out during the period from October to November 2018 . The tests are performed with different circulation flow rate (1,1.5,2) l/min . Results show that the maximum helical coil surface temperature with non-circulation is 107.2 °C at 1.00 PM from 25th September and 75 °C with circulation at flow rate 1.5 l/min at 2.00 PM from 9th October . The maximum mean storage water temperature is 73.8 °C for flow rate 1.5 l/min at 2.00 PM from 9th October , 70.5°C for flow rate 1 l/min at 2.00 PM from 8th October and 69.1 °C for flow rate 2 l/min at 1.50 PM from 24th October.

Abstract: The cycle performance of absorption cooling cycles depends not only on their configuration, but also on thermodynamic properties of working pairs regularly composed of refrigerant and absorbent. A review of potential working fluids used in the absorption cooling technologies presented in this work in order to determine the availability of viable working fluid that can give high cooling power while maintaining efficient system performance. In recent years the interest in absorption refrigeration has increased as a complementary refrigeration system that can utilize the low-grade heat for cooling. Absorption cycles contain absorption heat pumps, absorption chillers, and absorption transformers. Therefore, seeking more advantageous working pairs with good thermal stability, with minimum corrosion, and without crystallization has become the research focus last decades. Many reviewers have studied in the work to review the viable working fluids that can be used in the system and concluding that there is a number of fluids that show good working characteristics, which has been studied theoretically and studied experimentally shows potential for being good working fluids. Keywords: Absorption , Refrigeration, Coefficient of Performance, working pairs.

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 swept back 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 Gauss-elimination to determine quadrilateral doublet singularity strength distribution. Finally finite difference formula was used to predict aerodynamic loads calculation.

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.

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

In this study heat transfer and thermal performance characteristics in the pipe flow with three types of ribs tubes (square, circular, elliptic) at constant wall flux condition was studied for Reynolds number ranges from 5000 to 15000 to investigate the effect of the rib shapes on heat transfer. The renormalization group k-ε model is used to simulate turbulence in ANSYS - FLUENT 6.3. Results of temperature and velocity distribution along the tube for the case of tube with internal ribs were compared with that of smooth tube, these results show that the use of internal ribs enhance the heat transfer rate and found to possess the highest performance factors for turbulent flow.

In this research, study was conducted and analytical process was used for complex tubes inside stockist governor Fund tends several angles on the horizon and facing south .The main features of this complex are low cost and ease of transportation and simplicity of design. Practically, study included an experiment on the system according to the circumstances in the city of Najaf on Thursday, 05.23.2013 The study examines the performance of the complex, as well as the study of the performance of the entire complex of different experiences and different operational conditions . Rely the heater solar principle of thermal gradient in the process of storage where the highest temperature on the sixteenth of March amounted to (67C°) and minimum temperature is (37C°) with an average temperature of (50C°) where the average temperature primary when running is (19C°), Results shows that when water is pulled from the heater at the highest temperature the change in temperature reach's 2 ° C at 10 liter pulled from the top of the heater and 5 degrees Celsius at the lowest point in the geyser.

Experiments were carried out to evaluate the influence of the addition of hydrogen to the inlet air on the performance of a single cylinder direct injection diesel engine. Hydrogen was injected in the inlet manifold. The addition of hydrogen was done on energy replacement basis. It was found that the addition of hydrogen improves the combustion process due to superior combustion characteristics of hydrogen in comparison to conventional diesel fuels. It was also found that 10% energy replacement improves the engine thermal efficiency by about 40% and reduces the sfc by about 35% however the volumetric efficiency was reduced by about 35%.

The problem of pollutants emitted from internal combustion engines becomes increasingly important since it affects directly and indirectly human life on earth through air pollution, global warming, acid rains.. etc. The concentration of these pollutants must be reduced. One approach to reduce these concentrations is by blending hydrogen gas with hydrocarbon fuels used in internal combustion engines. In this paper an experimental research is carried out to study the effect of hydrogen blending. A four stroke air cooled diesel engine is used in this program. The engine is run at different loads, speeds and hydrogen blending percentages. It is found that increasing the blending percentage reduces the emitted concentration of carbon oxides and smoke. However it is found that nitrogen oxides concentration is increased with increasing hydrogen blending percentage due to higher cylinder temperatures. The results showed that 10% hydrogen blending reduces smoke opacity by about 65%, increases the nitrogen oxides concentration by about 21.8% and reduces CO2 and CO concentrations by about 27% and 32% respectively. This trend is found at all tested speeds and loads.