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Go to Editorial ManagerAn energy-harvesting hydraulic regeneration suspension system is described in this article, which includes a hydraulic motor, a spool valves, and a hydraulic cylinder. Regenerative actuators are built using a hydraulic transmission system as their inspiration. The proposed regenerative actuator is implemented in the vehicle's non-linear suspension system for a complete model. MATLAB Simulink is utilized to generate and simulate the entire vehicle's regenerative suspension system, which has force properties which are nonlinear with hydraulic actuators equations with energy harvesting from regenerative actuators. During the mathematical simulation, the effect of pressure differential on the spool valve's operation is also taken into account. The quantity of captured energy is compared to the energy expended on the active actuator and the energy generated with the electromagnetic actuator at three distinct input signals at three different pressure level (10, 30 and 50 bars) (random, sinusoidal, and square). The energy generated in the regenerative hydraulic actuator at three pressure levels behaves the same as the active actuator in terms of response, plus the highest pressure of 50 bar is closely comparable to the active system in terms of energy harvest and gradually decreases as the output pressure drops in addition to the behavior of the electromagnetic and its comparison with the wasted energy of the active system.
The present work is aimed to reduce the annual electric energy consumption in a residential building in Basrah city through introducing a standardized rule for the annual electrical consumption for the cooling and heating purposes. This work will concentrate on all parameters which help to go toward the optimum use of thermally efficient house. The building energy analysis program e-Quest was used to simulate the annual energy consumption for a typical residential house built with different types of building materials. Transfer function cooling load calculation was used. The results showed that for the Base- House, the thermal transmission through the walls and roof constitutes more than half of the total peak cooling load. It was found that a house built with thermo-stone causes 5.9% reduction of the annual cooling energy consumption, and 12.4% in the annual heating energy consumption. However, insulating the Base- House causes a significant reduction in the air conditioning equipment capacity and consequently reduction in cooling energy consumption by 23%, and reduces the heating energy consumption by 42.8%. Finally this work presents a useful planning to developed building design which reduces the electrical energy consumption.
This paper presents an extensive review of energy harvesting from the column vibrations of wind turbines under the influence of wind. The study investigates the underlying theories, mechanisms, and potential applications of such a system. By tapping into the vibrational energy otherwise dissipated in wind turbines, the study proposes an innovative approach to enhance renewable energy generation. Furthermore, the potential benefits of the technology, such as powering remote sensors, vibration damping, structural health monitoring, and increasing wind turbine efficiency and lifespan, are discussed. While the study acknowledges the promise of such an approach, it also emphasizes the need for further research to optimize and integrate these systems effectively into the renewable energy landscape.
The goal of this study is to evaluate the mechanical characteristics and energy absorption capabilities of both closed-cell pure Aluminum foam and closed-cell A356 foam. A portion of the lightweight pure foam samples (17.12, 17.77 and 15.27 g) is produced through casting of raw material (99.9 % pure aluminum) using Titanium Hydride (TiH 2 ) as a foaming agent, which lead to (7.5, 7 and 8) Pores Per Inches (PPI); and samples of A356 foam (38.24, 38.18 and 35.88 g) is produced through casting of A356 alloyed material with same procedure which lead to (11, 10 and 12) PPI. In order to determine the maximum compressive strength, strength-to-weight ratio, energy absorption density, complementary energy, and energy absorption efficiency, a uniaxial compression test is conducted. The results indicate that compression of pure foam structure smashed in a ductile manner and shows a lamellar eutectic structure while A365 foams under compression are crashed with brittle character with complex phases distribution inside (polyhedral and globular morphologies), A noticeable enhancement is observed in the mechanical characteristics of the A356 foam. The maximum compressive strength and specific energy absorption of alloyed foam are increased by a factor nearly of 4 and 2 respectively for all tested samples. Also, the result shows a significant decreasing in compressive strength with increasing of PPI for both pure and alloyed foam. The notable enhancements in the properties of alloyed closed cell foam render these advanced materials a viable option for high-strength applications.
Solar energy can only be used when it's sunny outside. Therefore, solar heating is only efficient during the day and decreases at night or on overcast days. Consumer energy needs have a distinct seasonal structure, and solar energy cannot completely meet those needs. In order to satisfy customer demand, energy storage is essential. In order to maximize the use of solar energy and to increase the energy and efficiency of the solar absorption system, superior thermal properties of sophisticated materials, such as phase change materials, are important [1]. In the current study, 20 kg of phase change material (PCM) is integrated with solar water heating and fed into a storage tank to enhance the solar water heating efficiency. Helical coil heat exchangers were added to the storage tank as an external load. The trials were conducted in four separate months (September 2021, April, May, and June 2022) that were chosen on the first day. The effectiveness, heat gain, and significance of the phase change material in increasing heating efficiency throughout the day were studied using a range of variables, including water volume flow rate (2, 3, 4, 6, and 8 L/min) and inlet water temperature (25, 30, and 35 °C). The results showed that, given an initial temperature of 25 °C, the daily efficiency range, was 0.58 to 0.65, and that the daily final outlet temperature was enhanced outlet temperature over 65 °C. Additionally, on all test days, the heat released by the phase change material was audible in the evening and increased the utilization time.
The hybrid electric vehicle (HEV) is considered an effective technique to reduce fuel consumption and exhaust emissions. The effectiveness of the HEVs in reducing fuel consumption and exhaust emissions is required an accurate division of the total power demand between energy sources. This aim is reached by an accurate design of energy management strategy (EMS) in the HEVs. Dynamic programming is an effective strategy to found the optimal solution for energy management. This technique requires the driving cycle to be known previously, wherefore it's not suitable to implement in real-time. The Equivalent Consumption Minimization Strategy (ECMS) is an effective technique that can be implemented in real-time. This strategy is used to estimate and adapt the equivalent factor (EF) in real-time, which is used to convert the electric energy from the battery to equivalent fuel cost. The value of the (EF) varies with the driving cycle, therefore, the (EF) is suitable for a certain driving cycle and may lead to weak performance to another. This work proposed a technique based on the battery state of charge feedback called adaptive prediction (AP) to estimate and adapt the equivalent factor in real-time. The best-obtained results are ranged between (11.1 to 32.889) % for several different driving cycles.
This paper explores the significance of energy conservation in the context of rising energy consumption and its impact on economic growth. With a focus on cooling systems, particularly evaporative condenser technology, the study aims to investigate its fundamentals, operating principles, and theoretical aspects. The paper delves into the various types of condensers used in cooling systems, emphasizing the role of evaporative condensers in enhancing heat transfer efficiency. The operating principles of evaporative condensers are detailed, considering factors such as air and water flow rates, wet bulb temperatures, and heat transfer coefficients. Theoretical models and mathematical approaches for evaluating evaporative condenser performance are also reviewed. The research includes an extensive review of existing literature on evaporative condenser technology, covering refrigeration models, HVAC systems, and various experimental studies. Theoretical models are discussed, highlighting the challenges in accurately modeling evaporative condenser behavior. The paper also presents achievements and advancements in research, including experiments that demonstrate the positive impact of evaporative cooling on air-cooled condenser systems. Various case studies and experimental validations showcase the potential energy savings and improved performance achieved through the incorporation of evaporative condensers in cooling systems. By switching from an air-cooled to an evaporatively-cooled condenser, one can reduce electricity consumption by 58%, according to research. This alternate condenser type improves performance by 113.4% at from 3 to 3000 kW of cooling power.
Conventional Refrigeration Systems (VCRS) are the most commonly used in industrial buildings and facilities. Conventional refrigeration systems are among the most energy-consuming sources in addition to causing more environmental problems and gas emissions, such as hydrocarbons (HCs) and hydrochlorofluorocarbons (HCFCs), are known to contribute to global warming and ozone depletion. Absorption Refrigeration Systems (VARS) are a good alternative to conventional refrigeration systems because they use low-grade heat sources and operate with environmentally friendly liquids. The most important of these heat sources is the heat wasted from engines, industrial processes and many other sources. The global objective of the study is a literature review on the different ways to operate the absorption refrigeration system using waste heat in engines that include exhaust gases and engine cooling water as well as renewable energy that includes solar energy. Reviews of the literature have demonstrated how the absorption refrigeration system can be used and operated using a variety of thermal sources. This study also supports the usage of ecologically friendly chillers to provide air conditioning and refrigeration, as it shows these systems have a lower performance coefficient when compared to conventional refrigeration systems.
Impact energy prediction of thermal aged cast stainless steel from impact test was studied using artificial neural network (ANN) modeling. Impact energy data for specimens from eleven cast stainless steel alloys at different aging times and temperatures, were used to evaluate possible artificial neural network architecture for prediction impact energy. These data are taken from Argonne National Laboratories (ANL) in USA that involved impact test results of cast stainless steel after aging between 200 and 400oC for up to 30000 hour. The ANN model exhibited excellent comparison with experimental results of ANL i.e. correlation coefficient (R=0.9451) and mean square error (MSE=1.2*10-5). Since a large number of variables were used during training the ANN model, a reliable and useful predictor for impact energy in thermal aged cast stainless steel was provided.
In this paper, energy and exergy concepts have been carried out on one of the largest gas turbine power plants in Iraq (Rumaila-Basra). Both ISO operating conditions as well as actual operating data recorded for one month in hot season are considered. Results indicate that a lot of heat energy accompanied with remarkable exergy is discharged to the atmosphere. Also, it is found that the combustion chamber has the largest exergy destruction among the plant components. Possibility of cooling the intake air drawn by the compressor and its effects on the plant performance is studied. The required cooling load is found to be in the range 3379 T.R for part load operation to 4723.3 T.R for full load operation.
In this work, both energy and exergy analyses have been carried out on General Electric (GE) gas turbine unit found in Khor Al-Zubair gas turbine power plant located in Basra, Iraq. The analysis covers the ISO (international standards organization) operating conditions in addition to actual operating data recorded for one month in hot season July 2016. The feasibility of adopting a vapor compression cycle (VCC) for cooling the intake air is evaluated. Generally, the study reveals an obvious drop off for most plant performance characteristics while operating during the hot season. Energy and exergy analyses show that adopting the vapor compression cycle to enhance Khor Al-Zubair GE unit could improve the power output by 20% and 27% in case of part-load and full-load conditions respectively. Both of first and second law efficiencies could be improved by 3.5% at part- load and 9% at full load. The expected cooling load needed for the unit is in the range of 2697 to 3024.5 TR according to part- load and full-load operation respectively. Only total irreversibility of the unit is expected to increase in case of adopting VCC and this will not impair the improvement in second law efficiency of the unit. Among the unit components, combustion chamber has the largest computed irreversibility. Further improvement is recommended by utilizing the released heat energy to the atmosphere, which is characterized by significant work potential.
This paper investigates the possibility of recycled aggregate use in concrete slabs with hollow cores. The main variables considered in the experimental study for the slabs were the recycled aggregate percentage and the hollow core number. Six slabs with dimensions of (1000 × 500 × 120) mm was fabricated and tested. The results showed that the addition of recycled aggregate in the concrete slabs affected the ultimate strength, ductility, and energy absorption of the concrete members. An increase of the recycled aggregate percentage to 25 % decreased the ultimate strength capacity by 3.54 %, but the increase of recycled aggregate to 50 % led to a decrease in the ultimate strength of about 6.64%. The existence of a hollow core reduced the cracking and ultimate load capacity of the RCA slabs, and this reduction was according to the core number which the fabrication of more cores caused more decrement. The ductility and energy absorption were decreased when the replacement ratio of the recycled aggregate increased. Also, the core number affected the ductility and energy absorption. The energy absorption was the most property affected by the core number increase which caused an average reduction of 71.5 % when the core number increased from two to three hollow cores.
A household refrigerator represents an essential device for all houses nowadays. The electric energy consumed by the refrigerator and the fluctuation of the temperature inside the fresh food cabin is the main two problems affecting its performance. Incorporating phase change material (PCM) inside the refrigerator is one of the solutions for the previous mentioned problems. In the present study, a water PCM is added to the cabinet of 220-litters double door refrigerator. The PCM (0.5 ml of water) is added at three different locations, touch the front of the evaporator part inside the cabin, touch the rear of the evaporator part in the cabin, and far away from the evaporator part inside the cabin. The location of the PCM determines how much energy is released and stored from the evaporator. The use of phase change material (PCM) touch to the evaporator increases the rate of heat transfer due to the conduction method being used throughout the whole heat transfer process from the evaporator to the phase change material (PCM), which raises the refrigeration system's COP (coefficient of performance). The experimental test period is 24 hours for each day. Firstly, the refrigerator is tested without using PCM, and the power consumption, the temperatures at different points for the refrigerator, suction pressure, discharge pressure, the ambient temperature, and the time on period and time off period of the compressor are measured. Secondly, for same testing period all previous parameters are measured with using PCM at different locations inside the refrigerator. The results show that, adding the PCM (water) behind the evaporator led to increase the COP by 21.97%, increase the compressor off time by 73 minutes, reduction in power consumption of 14.4%, decrease of exergy losses of the system by 8% and temperature fluctuation reduced inside the fresh food cabin, that enhance the quality of stored food. Adding the PCM front the evaporator improve the previous parameters but less than that of the first case. The third location, adding the PCM far away from the evaporator has no improvement on the refrigerator's performance.
In several countries, residential buildings are responsible for high energy consumption. The majority of energy is consumed on air conditioning to ensure maximum indoor comfort. In Iraq, the demand for electricity increases significantly, especially during the summer for cooling purposes. In this paper, two technologies are proposed for buildings to reduce the cooling load. These approaches included the use of phase- changing materials (PCM) in different locations in the walls and roof, in addition to roof shading by galvanized iron. The effects of these proposals were simulated in the latest software tool (designbuilder) and compared with the standard building model. The results were clear when PCM was installed on the outer surface of the wall and roof, which achieved the highest reduction in the cooling load of about 18 %. While the roof shading method using corrugated galvanized iron proved its effectiveness by decreasing the cooling load to 5 % compared to the standard case.
The principle aim of this research is concentrated to analyze the effect of cracks and their propagations on the mechanical behavior of a quasi-brittle material such as concrete. The singularity (stress concentration to infinity at the tip of crack) is avoided by using the principal of fracture energy with the fictitious crack approach. The concrete crack is divided into two major zones; the first one is the fracture zone (a combination of bridging effect and the cohesive microscopic cracking) which obeys a special law permitting the transmission of stress across the two faces of crack, this zone is considered as partially cracked concrete. When the opening of the crack exceeds a specific value, this zone is converted to a real crack (an open crack) and cannot transmit any stress across the two faces of a crack. The program of finite element used in this research is prepared by the researcher using discrete-crack approach with the experimental data obtained from the flexural test on notched beam loaded under three-point bending, where fracture mode I is dominated. The response of the applied load-crack mouth opening displacement (CMOD) with appropriate fracture energy is selected. The results show that the cohesive microscopic cracking zone for the plain concrete is very wide. The cohesive stress distributions across the microcracks with the corresponding crack openings are drawn from the first crack appearance till the beam failure.
Thermal steam power plants represent the most important and dependable type for supplying the base load of electricity around the world. The thermos-economic analysis is an important tool for improving the performance of thermal steam power plants. In the present study, a thermo-economic analysis of a simple steam power plant for different boiler pressure was performed. The analysis comprises the energy, exergy, entropy, economics, and exergy-economic of a simple cycle steam power plant for different boiler pressure. The analysis was performed for a simple steam power plant with the constant output power of 10 MW and the boiler pressure is varied from 10 bar to 100 bar by a step of 10 bar. For each boiler pressure and constant output power, firstly, the fuel mass flow rate, steam flow rate, energy and exergy efficiency, and cost of electricity were calculated. Secondly, entropy generation, exergy destruction, and exergy efficiency for each component were calculated. Finally, exergy destruction economics for each component of the plant was performed. The results reveal that increasing the boiler pressure from (10 to 100 bar) for constant output power reduces the cost of electricity from (0.135 to 0.1025 $/kWh) due to a decrease in the fuel mass flow rate and an improvement in the thermal cycle and exergy efficiency. Also, when the boiler pressure increases, the exergy destruction for the pump increases, the exergy destruction for the boiler decreases, the exergy destruction for the turbine increases, and the exergy destruction for the condenser decrease.
Solar chimney (SC) together with earth to air heat exchanger (EAHE) is being employed as a low-energy consuming technique to remove undesirable interior heat from a building in the hot seasons. A numerical program "FLUENT 6.3 code" of an earth to air heat exchanger (EAHE) is studied for predicting the outlet air temperature and cooling potential of these devices in Basrah climate. Theoretical analyses have been conducted in order to investigate the ventilation in a solar chimney. The investigation into the viability of Low Energy Earth Pipe Cooling Technology in providing thermal comfort in Basrah. The demand for air-conditioning in buildings in Basrah affects the country escalating energy consumption. Therefore, this investigation was intended to seek for an alternative passive cooling to air-conditioning. The passive technology, where the ground was used as a heat sink to produce cooler air, has not been investigated systematically in hot and humid countries. A sub-soil temperature model adapted for the specific conditions in Basrah is presented and its output compared with CFD modeling. The results have shown that the potential of Earth Pipe is providing lower output temperature of air inlet to the room. We found that the resulting temperature at the buried pipe outlet decreases with increasing pipe length, decreasing pipe diameter, decreasing mass flow rate of flowing air in the pipe and increasing depths up to 4m.
The solar chimney is a natural draft device that uses solar radiation to provide upward momentum to the in-flowing air, thereby converting the thermal energy into kinetic energy through an air turbine which in turn can be converted into electrical energy. The main parts of the solar chimney power plant are a large circular solar collector, a tall chimney, and an air turbine. In this paper, a theoretical study was performed to evaluate the performance of a solar chimney power plant system in Basrah City, where sunny days and solar radiation are high. A mathematical model was developed to study the effect of various parameters on the output power of the solar chimney. I1 was found that the output power depends strongly on the chimney tall and the difference between the collector air temperature and the ambient air temperature as well as the outside heat transfer coefficient, which essentially depends on the wind speed.
In this paper, computation fluid dynamics model (CFD) is used to simulate a turbulence flow fields along the jet ejector. A Steady-state 2-D compressible flow model utilities the standard k- turbulent model has been used. The performance of jet ejector is simulated by FLUENT 6.3 (code) and GAMBIT software, using finite-volume scheme to solve transport NAVIER STOKE equations. The objective of this study is to investigate the high- performance of jet ejector geometry (mass flow and head ratio) nozzle to throat diameter at eight cases (DN/DT) with different initial pressure. Research is performed to optimize jet performance by varying initial pressure and nozzle diameter ratios from (1/8) to (8/8). To increase understanding of the axial velocity distribution at an important regions along the ejector, three regions are chosen, at inlet (1,3), nozzle exit(2) and midpoint of throat(4), with an important different diameters ratio cases 1,2,3,5,7 and 8 respectivly. The comparison of these results is presented by the axial velocity magnitude, mass and head ratio of the ejector at the above cases. Results show that higher pressure ratio and mass ratio (high performance) occur when the nozzle to throat diameter ratio (DN/DT) was (5/8) and (1/8) respectively. Also mass ratio is decreased at all initial pressure when the diameter ratio increased.
In the sustainable dwelling, in all its formations whether at the urban or architectural level, the effects of the surrounding environment are taken into account in the design process, starting from the distribution of residential functions, the form of the dwelling, or even the structural materials used in its formulation, in addition to the technological dimension, not to mention the site and its effects as well as the consumed energy and its effects. The study proceeds with research and analysis to build a comprehensive strategy for the problem related to the harsh climate of the region, and its negative effect on residential formation, by activating ideal solutions to those problems according to the principles of environmental sustainability. The concept of the new healthy dwelling in its proposed form addresses the benefits that sustainable environmental formation can offer in improving the conditions of thermal comfort within architectural spaces and then designing a new form of housing under the name of passive energy bio-climatic formation systems. Its ideas must be subject to the wisdom of the architect through passing over all effective strategies that help create the maximum material comfort and thus reduce high environmental costs.
The present work aims to build mathematical models based on experimental data to estimate the mechanical properties of submerged arc weldment. AISI 1020 low carbon steel plates 16mm thickness were welded according to orthogonal array in order to establish the relationship between input parameters (welding current, Arc voltage and welding speed) and output parameters (ultimate tensile stress, yield stress, impact energy and hardness) by submerged arc welding (SAW) process. The relationship between input and output parameters for the welding process are conducted using two suitable mathematical models the first one based on regression analysis, while the second one based on multi input single output ANFIS model for estimation of some mechanical properties of the welded plates. It was found that ANFIS results are closer to the experimental results than regression results. The optimal parameters (which give a maximum value of ultimate tensile strength (UTS), yield stress and impact energy; 446 MPa, 318 MPa and 213 J) are welding current is (380 Amp), Arc voltage is (25 V) and welding speed is (40 cm/min), while the maximum value of hardness number is (228 HV), when current welding is (380 Amp), Arc voltage is (25 V) and welding speed is (25 cm/min).
In this proposed study, all environmental factors affecting the aboveground and buried pipes, such as solar radiation and temperature, and soil temperature, have been studied on the characteristics of flow inside the aboveground and underground pipelines by building a mathematical model using MATLAB based on energy balance equations. From the mathematical model, the effect of solar radiation on the aboveground section of the pipeline is significate. During March and an inlet temperature of 34 °C, the pipeline outlet fluid temperature will rise to 50 °C. Other parameters affecting the aboveground section of the pipeline, such as ambient temperature and wind speed, have a much smaller effect on the fluid temperature, and the temperature difference is approximately 4 °C between the highest and lowest pipeline outlet fluid temperature. The result for the underground section of the pipeline showed that the main affecting parameter on the fluid temperature is the burry depth of the pipeline, the deeper the pipeline depth the lower the temperature variation and the lower fluid temperature can be seen, at 1 meter of bury depth the minimum and maximum fluid temperature was 18 °C and 36 °C respectively, and at 5 meters of bury depth, the minimum and maximum fluid temperature was 26 °C and 31 °C respectively. This study also checks different process parameters. Some of these are fluid flow, pipe diameter, and pipe material. The effect of the fluid flow and pipe diameter has a similar impact on the fluid temperature (while fixing all the other parameters), the higher the fluid flow or the smaller the pipe diameter resulted in a better heat transfer and more considerable temperature difference, and vice versa. The final process parameter, pipe material, had little to no effect on the fluid temperature variation.
The solar chimney power plant is one of the modern models studied on the world. This study presents an engineering and numerical analysis of solar chimney with different parameters. Also, it studies the comparison of two collector base shapes(circular and hexagonal) depend on the five storage material types and their effects on the heat transfer, velocity, efficiency, etc. inside the solar chimney system by considering the solar array intensity equations and the energy equation to calculate the heat transferred and stored by applying the laws of CFD. The finite volume method is used to analyze the geometry physical model by applying a commercial Fluent 6.3 code with Gambit 2.3. The obtained results show that the efficiency of solar chimney is increased by increasing the area of solar glassed collector with circular base shape than the others of polygonal or rectangular one because the circular was covered large area of system. So, the circular ground collector shape for thermal storage is the favour because it is the better to increase the velocity of entering air and to increase the efficiency of turbine. In addition to that the black Pebble storage plate is the better material for heat storage which is convected to air passed for operation of turbine than the other types aluminum, tar, copper and steel seriously.
The incorporation of thermal energy storage materials (TESMs) into solar energy systems is a factor that boosts the performance of these systems. In this paper, an experimental study was addressed for enhancing the heat pipe’s thermal performance that works with an Evacuated Solar Tube Collector with Heat Pipe (ETCHP) as a solar water heater system. This is done by adding micro-zinc oxide (ZnO-MP) to the paraffin wax integrated as TESM into the evacuated tube (ET) of the system, where the evaporator section of the heat pipe is completely submerged within the micro-enhanced paraffin wax. Three experimental prototype rigs with one evacuated tube were designed, built, and tested to do the investigation. The most important parameters that have been studied in this study are the thermal resistance and the temperature distribution pattern along the heat pipe. The results show a clear indication of the decrease in the thermal resistance of the heat pipe of the proposed system compared to the system in which pure paraffin wax was incorporated. Also, it was noticed that there is a significant improvement in the temperature distribution along the heat pipe due to the improvement in the conductivity of the micro-enhanced wax compared to the pure wax.
A mathematical model to analysis three–dimensional forced convection turbulent flow in a novel solar air heater integrated with multiple rectangular capsules filled by paraffin wax-based on phase change material PCM was implemented. The investigations were performed under three airflow speed of (0.6, 1.2, and 1.8) kg/min and average solar flux of 625 W/m 2 . The results revealed that the delaying melting time and also lower the melting temperature of PCM by increasing airflow speed during the charging process. As well as, the freezing period is dependent on the airflow speed by inverse relation. Also, the data results represent that the useful energy rate and thermal storage efficiency were a strong dependence on the airflow speed. Moreover, it can be detected that the optimal freezing time and the air temperature rise of the heater were reached about 210 minutes with (12 – 1.5 °C), 150 minutes with (7.5 – 1.4°C), and 120 minutes with (5.5 – 1.5 °C), at airflow speed of 0.6, 1.2, and 1.8 kg/min, respectively, which can be used at night to supply some applications by thermal energy such as heating buildings and drying agricultural crops.
Performance a double slope of the solar still Integrated With or without parabolic trough collector is investigated experimentally. To improve the output of a double slope solar still, a number of initiatives have been undertaken, using wax as a phase change material (PCM) with a parabolic trough collector. A parabolic trough collector (PTC) transfers incident solar energy to the solar still through a water tube connected to a heat exchanger embedded in used microcrystalline wax. Experiments were carried out after orienting the basin to the south and holding the water depth in the basin at 20 mm. According to the results obtained, the solar stills with parabolic trough collector have higher temperatures and productivity than solar stills without parabolic trough collector, as well as the ability to store latent heat energy in solar still, allowing fresh water to condense even after sunset. In addition, the parabolic trough collector with phase change material in the double slope solar improves productivity by 37.3 % and 42 %, respectively.
Human beings are facing an unprecedented rise in temperature rates not recorded for years. HVAC (heating, ventilation, and air conditioning) systems have been created and enhanced to solve this issue. Cooling load must be estimated with accepted methodologies before designing an efficient and effective air conditioning system. Companies, researchers, institutions, and others advise and develop many cooling load calculation methods. Each one of these methods has its advantages and disadvantages and may give a slightly different result for the same case. For each building, whether it was residential or commercial buildings, gyms, or shopping malls, before making the decision on (HVAC) systems to be used, both heating and cooling loads should be obtained as correctly as possible to minimize expenses as possible. Since the HVAC system consumes the most energy in an air-conditioned building, an accurate method of cooling load estimation is necessary. Consequently, an energy-efficient air conditioning system reduces greenhouse gas emissions into the atmosphere while also saving money on electricity. Two cases have been compared and studied, one in Dubai UAE, and the other in Baghdad Iraq. Three different methods, HAP, hand calculation method (CLTD/SCL/CLF), and MS-EXCEL E20 form sheet were used to compare the accuracy of the results for cooling load. Results of E20 and HAP are very close to each other with high accuracy for peak load, the big difference can be found between the CLTD method and the other two methods. The value of the maximum difference percentage was found between CLTD and E20 equals 3.28% and 7.96%, on the other hand, the lowest difference was equals to 0.3% and 1.51% between HAP and E20 results for Baghdad and Dubai respectively. Traditional and local materials came from local factories, used in buildings played a big effect on the results, which may not match those materials stated in the ASHRAE or CARRIER tables, which need to be considered in the results and calculation procedure. However, all methods have a percentage of difference but all results are within the accepted range and are applicable for practical cases. Of course, this percentage is minimal with some methods and maximum with others.
Evaporative cooling is a widely used energy-saving and environmentally friendly cooling technology. Evaporative cooling can be defined as a mass and heat transfer process in which the air is cooled by the evaporation of water and as a result a large amount of heat is transferred from the air to the water and thus the air temperature decreases. Evaporative cooling is mainly used in many cooling technologies used in buildings, factories, agricultural in addition to it is used industrially in cooling towers, evaporative condensers, humidification, and humidity control applications. Evaporative cooling is divided into direct evaporative cooling and indirect evaporative cooling, as well as water evaporative cooling and air evaporative cooling. This paper reviews the most important developments and technologies in evaporative cooling that lead to lower energy consumption and provide suitable cooling comfort.
The Atmospheric Water Generator (AWG) is an environmental water recovery that easily dehumidifies water vapor moisture from the air. This article presents an experiment to construct an AWG model using solar energy as a source of power. An experimental and numerical study for a device of (AWG) is performed. The experimental work is performed at Basrah city, located in the south of Iraq, during August and September of 2019 and March of 2020. The theoretical results are calculated by EES and the numerical study has been conducted by the (ANSYS19/CFD/ FLUENT) program. The experimental device is tested for different days with different climate conditions. The Maximum water production obtained is 3.4 L/day from all the testing days, for different hours of operation when the relative humidity in the range of (45 – 95 %) and the temperature range from 17 °C to 45 °C. The results shown that, the water production rate is increased with increasing humidity, temperatures, hours of operation, and model size.
Solar power systems, also known as photovoltaic (PV) systems, are widely used as a clean and sustainable energy source worldwide. However, these systems can be affected by various factors that contribute to dust accumulation, which have been grouped into five categories: module characteristics, environmental factors, climatic conditions, exposure situations, and soiling properties. Dust accumulation can significantly impact photovoltaic modules' efficiency and power output, leading to a decrease in electricity generation. Airborne dust reduces the intensity of solar radiation by scattering and absorbing it, especially in hot and dry regions such as southern Iraq. This study provides an updated overview of the process of dust accumulation on photovoltaic modules south of Iraq. Moreover, it illustrates the methods used to measure dust accumulation and the performance of solar PV under soiling. Furthermore, it exemplifies the sources of the soiling generation. Additionally, it demonstrates the composition and size of dust particles. Finally, future research perspectives are discussed, and a thorough investigation of the impact of dust is suggested in all regions of Iraq and even in all countries of the world, especially those interested in clean energy. This research aims to understand the effect of dust soiling on PV performance. The outcome of this research will help design the PV module system while considering the most effective method to reduce or prevent dust accumulation in specific areas.
In this research, a two – dimensional numerical investigation is conducted to show the ability of the jet-ejector to prepare the air – methane mixture at different equivalence ratio. The basic dimensions (diameters ratio, throat length, angle α , and angle θ ) of the jet-ejector are taken into account on calculating the equivalence ratio. The results showed that the ratio of the diameters has a higher effect than other parameters on preparing a mixture for equivalent ratios including both rich and lean mixture. The rest of the factors did not have a significant effect on the value of the equivalence ratio, and only had a role in preparing an equivalence ratio for rich mixture type.
This research concerns with the fracture behavior of reinforced concrete beams without shear reinforcement numerically. The software ABAQUS is adapted to simulate the crack propagation using the eXtended Finite Element Method (XFEM), taking into account materials nonlinearities using concrete damage plasticity CDP criteria. XFEM is used to solve the discontinuity problems in the simulation. The maximum principal stress failure criterion is selected for damage initiation, and an energy-based damage evolution law based on a model- independent fracture criterion is selected for damage propagation. The traditional nonlinear finite element analysis is used to specify the crack initiation position, which is required to specify the crack location in the analysis of beams using XFEM. Three-dimensional reinforced concrete beam models are investigated subjected to three and four-point loading tests. Simply supported beams under the effect of applied static load are investigated. An elastic perfectly plastic model is used for modeling the longitudinal steel bars. The main variables considered in the study are beam depth and the shear span with beam length. The numerical results are compared with the available experimental results to demonstrate the applicability of the model. The XFEM provides the capability to predict the concrete member fracture behavior.
Modern life makes energy, and the source of it is very important. This renewable energy comes from the Earth-Air Heat Exchanger (EAHE) in the soil employed as an air conditioning device for buildings in the climate conditions in Basrah city, south of Iraq. In the present study, the EAHE buried in the soil is simulated numerically using the finite volume method with a soft package. ANSYS: Fluent 2021/R2. A parametric analysis was carried out to determine the effect of three depths ( Z = 1, 2, and 3 m), taking into account the physical properties of the soil in the area under study, which is in the city of Basrah in southern Iraq, at longitude 47.749° and latitude 30.568°, as well as the data and time of 1/6/2023 at 12 p.m., the diameter of the pipe ( D = 7.62, 10.16, and 15.24 cm), and different velocities ( v = 0.5, 1, and 1.5 m/s). The results are presented as a temperature contour and a velocity contour for the performance of EAHE. The important results showed that when the depth of the buried pipe decreases, the temperature of the air outlet and heat exchanger increases; when the diameter decreases, the air outlet temperature from the EAHE and the soil temperature decrease; when the length of the pipe is about 30 m, after this length, the decrease in temperature is very small; and the maximum temperature difference of about 10 °C between the ambient temperature and the outlet temperature of the EAHE was obtained at a depth of 3 m and a velocity of 1 m/s at a diameter of 7.62 cm.
In this research, the mechanical properties were studied from the experimental, theoretical, and numerical aspects of the sports prosthetic foot for the purpose of providing a sporty prosthetic limb with high performance, easy to use and an appropriate financial cost to use by amputees who have lost their lower limbs (amputation below the knee) in practicing their sports activities and overcoming physical disability. The dimensions of the blades were calculated based on side profiles from European patent specifications. The chosen fibers have high strength, are light in weight, and can be purchased for a lower price than the materials that are used in the production of the sports prosthetic feet that are already on the market and are produced by specialized companies such as Ottobock and Ossur. Six laminates of the composite material consisting of matrix orthocryl lamination 80:20 pro reinforced with different fibers (Kevlar fibers, carbon fibers, glass fibers, and perlon fibers) were fabricated in the form of rectangles using the vacuum system and then cut to the required dimensions using a CNC machine. The density and volume fraction of the samples and the use of the rule of mixtures to calculate the mechanical properties of the laminates were calculated and entered into the ANSYS program. Then the boundary conditions were applied to the athlete's prosthetic foot and the total deformation, and the total strain energy was calculated to find out the best laminates in the athlete's foot industry. It was noticed that the laminates reinforced with carbon fibers were better than the laminates reinforced with glass fibers in terms of Young’s Modulus, as well as deformation. The best laminate obtained is (12 K + 4 C).
Solar energy is the most suitable among all renewable energy options for competing with fossil fuels in desalination due to its ability to utilize both heat and power for the process. In this study, the Parabolic Trough Solar Collector (PTSC) for powering a Single Stage Flash (SSF) desalination unit was proposed for Basrah city climate, Iraq. The desalination system comprises two directly coupled sub-systems: the PTSC and the SSF desalination unit. The preheated feed brine water coming from condenser was used as a Heat Transfer Fluid (HTF) for PTSC, which gets heated to a desired temperature referred to as the Top Brine Temperature (TBT). The numerical simulations were performed via EBSILON professional 16.02 (2022) software. The effects of TBT, mass flowrate of feed brine water to get the desired TBT, solar collector area, and vacuum pressure inside flash chamber on the performance of the desalination system was studied. A major finding of the current study can be summarized as follows: The collector efficiency is enhanced eventually as TBT increases. The maximum values of distillate water in June are around 5.5, 4.56, 3.69, 2.75 and 1.85 kg/h for 12.408, 10.434, 8.3472, 6.26, and 4.1736 m² collector area respectively, when TBT 107 °C and vacuum pressure 40 kPa. For 1.598 m² collector area, the total distillate in the 1st of June amounted to 7.9 kg, with an average production rate of around 0.7 kg/h. The solar SSF system's productivity per solar collector unit area at 20 kPa, 15 kPa, and 10 kPa vacuum pressures was 4.7 kg/day/m², 5.3 kg/day/m², and 6.25 kg/day/m², respectively. The average Performance Ratio (PR) values are determined to be 0.694, 0.577, and 0.491 for 10 kPa, 15 kPa, and 20 kPa, respectively. These results are very acceptable when compared with an existing literature.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
In this paper, a new model of beam was built to study and simulate the buckling behavior of function graded beam. All equations of motion are derived using the principal of the minimum total potential energy and based on Euler-Bernoulli, first and high order shear deformation Timoshenko beam theory. The Navier solution is used for simply supported beam, and exact formulas found for buckling load. The properties of material of FG beam are assumed to change in thickness direction by using the power law formula. The dimensionless critical buckling load is calculated analytically by the FORTRAN program and numerically by ANSYS software. In the beginning, the analytical and numerical results are validated with results available in previous works and it is also has very good agreement in comparison with and some researchers. In the present study, the lower layer of the graded beam is made up of aluminum metal. As for the properties of the rest of the layers, they are calculated based on the modulus ratios studied. The effect of length to thickness ratio, modulus ratio, and power law index on the dimensionless critical buckling load of function graded beam calculating by FORTRAN and ANSYS programs are discussed. The numerical analysis of function graded beam offers accurate results and very close to the analytical solution using Timoshenko Beam theory.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
This paper introduces a radial distribution feeder protection scheme based on certain features extraction from current signals measurement at the substation. The features are captured using the discrete wavelet transform (DWT). Two digital signals processing methods are used to introduce those features to the 1) fault detection 2) identification and 3) localization schemes; the first one is the energy method and the second one is the root mean square method. For the purpose of fault type identification, two systems are tested and compared, a Fuzzy Inference System (FIS) and Artificial Neural Network (ANN). Fault location scheme is then built based on ANNs. An effort is made to reduce the computational burden and the speed of detection provided by the fault detection and identification schemes. Since the short circuit faults are the most likely types of faults that can occur in power systems, the ten types of these faults taking into account different fault resistances are simulated in MATLAB environment and the protection scheme is built based on the idea of over current. The power quality disturbances such as switching transient events on the feeder is also taken into account in order to build a reliable and secure protection scheme.
This numerical study aims to enhance the heat transfer efficiency by dissipating the heat Emitted from electronic processors. A jet impingement technique is utilized with porous layer covering a metal fin as a heat sink. Forced convection and normal convection (due to the buoyancy effect) are taken into consideration. The two equations model (Local Thermal Non-Equilibrium LTNE) employed to describe the energy equations of the two phases of the porous surface. Finite Element Method (FEM) used to discretize these equations to obtain the numerical solution. To make this study closest to the reality, constant heat flux boundary condition is applied underneath the metallic heat sink. The geometry comprises of three domains: Free flow channel, Porous layer and Metal fined heat sink. In order to simulate the heat transfer, isotherms; streamlines and Nusselt number have been considered. Investigation has been done by inspecting the effects of the pertinent non- dimensional parameters such as: Reynolds number ( Re = 100-900), Darcy number ( Da = 10 -1 -10 -6 ), Richardson number ( Ri = 0.1-100) and Porosity ( ε = 0.85-0.95). The results show that increasing Re and decreasing ε lead to enhance Nusselt number. Richardson number below 100 has no significant effects on Nu . At Re above 400, Nusselt number proportional with Darcy number. The enhancement of Nusselt number is found to be 250 % by increasing Re from 100 to 900, 290 % by decreasing ε from 0.95 to 0.85 and about 13 % by increasing Darcy number from 10 -6 to 10 -1 .
In this study a two dimensional, steady state propagation of the laminar premixed flame was numerically and experimental are investigated. The energy, momentum, continuity equations for species and global reaction mechanism with equation of stat for ideal gases were solved. Constant temperature boundary condition is applied on axi – symmetric in y – direction domain. The governing equations were discretized by using computation fluid dynamics (CFD) and finite-volume method - central differencing scheme, then solved using Gauss-Seidel Iteration method on uniformed grid with VISUAL BASIC code. Effects of equivalence ratio and initial temperature of fresh gases (air – fuel mixture) were investigated for three types of fuel Methane, Propane and Butane. Also the flame speed and flame temperature were experimentally measured for air – fuel (Methane, Propane, Butane and LPG) mixtures. The burning velocity was calculated depending on the flame speed and flame temperature measuring. The flame speed and flame temperature were measured by using optical technique. Effects of equivalence ratio and initial temperature of fresh gases (air – fuel mixtures) on flame speed and flame temperature are investigated experimentally. Results were generated for the detailed description of the local fluid flow and heat transfer characteristics including temperature, axial velocity, density and mole fractions profiles. For example the flame speed reached 274.4 cm/s as a maximum value at Ø=1.1 for propane air mixture, and flame temperature comparison give a good agreement between theoretical and experimental results at rich mixtyre
This study presents both experimental and theoretical investigations of an absorption refrigeration system using environmentally friendly working fluids, specifically the acetone–zinc bromide (Acetone/ZnBr₂) pair. The system was designed to operate under outdoor climatic conditions in Hilla City, Iraq, utilizing hot water as the heat source. Performance evaluation was carried out under various operating conditions, including changes in heat source, absorber, condenser, and evaporator temperatures. Experimental testing was conducted during September 2019. The results indicated that the coefficient of performance (COP) of the absorption cooling system ranged from 0.13 to 0.487, with an evaporator temperature drop of approximately 16 °C. Condensation and absorption temperatures remained below 41 °C, while the maximum driving water temperature reached 80 °C. A steady-state theoretical model was developed using the Engineering Equation Solver (EES) program, applying mass and energy balance equations to predict operating parameters such as temperature, pressure, and COP. Model predictions showed good agreement with the experimental measurements. Furthermore, the results confirmed that generator temperature has a significant influence on overall system performance.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
Mixed convection heat transfer of air in a horizontal channel with an open square cavity is studied numerically. At the center of the cavity, it is an insulated rotating circular cylinder for enhancing the efficiency of heat transmission, the location of the inner cylinder is changed vertically along the centerline of the cavity. Heat is applied to the bottom wall of the cavity at a constant temperature, and the other walls are adiabatic. The flow is steady-state, laminar, and incompressible. Using computational fluid dynamics (CFD) and the commercial software program FLUENT 2019 R1, the equations of continuity, momentum, and energy are numerically solved. The angular velocity of the cylinder range is (0 . 5 ≤ ω ≤ 4) rad/sec in a counterclockwise direction, the Richardson number range ( Ri = 0 . 1 , 1 , 10), Reynolds number is 100 and the cylinder location is ( C = 70 , 50 , 30) mm. The airflow Prandtl number is taken as ( Pr = 0 . 7). The effect of various positions of the rotating cylinder has been examined through the visualization of streamline and isotherm contour, as well as the distribution of the average Nusselt number of the heated surface. The results indicate that the flow field and temperature distributions inside the cavity are strongly dependent on the rotating circular cylinder and the position of the inner cylinder.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
Lithium-ion batteries' physical properties classify them as one of the most important sources of clean energy that overcome the need for fuel usage. The rated operating temperature and its uniformity are of the main demands of Lithium-ion batteries. In this survey, several types of studies have been reviewed with the aim of understanding the thermal management systems used to control the temperature of lithium-ion batteries and their uniformity in the battery pack. They are represented by active and passive systems, as well as the hybrid system, which integrates each of the two mentioned systems into a system to obtain the best thermal performance. Active cooling systems were classified due to the type pf coolant used to air and liquid system, meanwhile passive system classified to PCM and heat pipe system. The survey reveals that the air-cooling of lithium-ion battery pack is better than the use of liquids. About 74% of the reviewed works prefer the use of active strategies. The working temperature under normal conditions should be within -20 to 60 °C, meanwhile the optimum range is 15 to 35 °C. The maximum temperature difference between batteries in the pack is preferred to be 5 °C or less.
This work presents a theoretical study on the application of low global warming refrigerants as alternative refrigerant to R 134a in a refrigeration system. The refrigerants investigated are R1234yf, R1234ze, R245fa and R227ea. The performance characteristics of the refrigeration system were predicted using mathematical models running by using EES program under different condenser and evaporator temperatures. The results show that at any working condition the R1234ze give identical performance to R134a and can be used as the best low global warming alternative refrigerant. So the compressor work with R1234ze should be designed with displacement volume more than that of R134a to overcame the reduction in mass flow rate.
The enormous volume of crude oil that needs to be transported results from the growing demand for petroleum. One of the most practical ways to move crude oil is via pipelines. This paper's primary objective is to examine the effects of sulphur, one of the components of crude oil, on welded pipes (API 5L X60, X46, and X42 pipes as well as ASTM A106 pipes). It also aims to show how sulphur content influences different kinds of pipes separately from the other important components of crude oil. The sulphur content of crude oil is determined using the TR-TCXRF equipment. The corrosion rates of welded pipes in four immersion solutions (Different percentages of sulphur content) were computed using weight loss. The samples' corrosion characteristics were assessed morphologically using an optical microscope (OM), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Petroleum welded pipelines' mechanical qualities and resistance to corrosion are significantly impacted by sulphur; an increase in sulphur concentration resulted in a higher rate of corrosion and a decrease in mechanical properties. Among all the welded pipes utilized in the paper, the API 5L X60 welded pipe had the highest corrosion rate, whereas X46 welded pipe was more corrosion-resistant than X46 and X42 in API 5L-type pipes and ASTM A106 pipe.
The transition to electric vehicles (EVs) is a crucial step towards mitigating climate change and addressing the global energy crisis. The increasing use of lithium-ion batteries in EVs is attributed to their superior power density and efficiency. However, ensuring optimal battery performance and safety necessitates effective thermal management due to the significant heat generated during operation. Current cooling systems face challenges in maintaining the desired temperature range and uniformity. This paper reviews the state-of-the-art techniques in battery thermal management, focusing on phase change material (PCM) cooling and different cooling methods. This study, in accordance with its developments, compares the advantages and limitations of various cooling methods as potential solutions for next-generation EVs. It highlights the potential of method cooling, which, while promising, needs further research to establish its commercial viability and aims to guide future advancements in battery thermal management for next-generation EVs. Under both typical and extreme usage scenarios, direct cooling may enhance the necessary battery performance and serve as an innovative method for managing the temperature of electric vehicle batteries. The primary challenge of this technique lies in its suitability for commercial application. This article is organized to cover the thermal properties of lithium-ion batteries, the main issues associated with lithium-ion battery heat, a discussion of reversible and irreversible heat generation and their effects on battery performance, as well as strategies for preventing and mitigating thermal runaway in battery systems. Finally, it summarizes the key recommendations for future research on battery thermal management.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
In this work, the turbulent buoyancy driven fluid flow and heat transfer in a differentially heated tall rectangular enclosure filled with nanofluid is quantified numerically. The two dimensional governing differential equations (continuity, momentum, energy and low Reynolds number LRN k-ω turbulence equations) are discretized using the finite volume method. SIMPLE algorithm is employed to obtain stabilized solution for high Rayleigh numbers. Two types of nanofluids namely, Al2O3-water and Cu-water, were considered. The effect of Rayleigh number (1010 to 1012), diameter of nanoparticles in the range 25-100 nm, nanoparticle volume fraction in range 0-0.08 and the aspect ratio (30, 40 and 50) on fluid flow and heat transfer are investigated. The present results are compared with previously published work and a qualitative agreement with good validation is obtained. Results show that addition of nanoparticles makes the liquid be more viscous which decreases the vertical velocity component and also decreases the temperature gradient near the walls. Also an announced heat transfer enhancement is obtained with nanoparticle volume fraction reaching a maximum point called optimal volume loading, at which the maximum convective heat transfer is obtained, and then it decreased with further increase of volume fraction.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
Parallel flow microchannel heat exchanger performance was numerically investigated, for laminar, 3-D, incompressible and steady state flow with slip flow and temperature jump conditions. The continuity, Navier-Stokes equations and the energy equations for the hot and cold fluids were solved by using finite volumes method and SIMPLE algorithm method with FORTRAN code to obtain the velocity and temperature distributions for the two fluids and the separated wall between them. The main investigation parameter that affected on the performance and effectiveness of heat exchanger are: Reynolds number Re, thermal conductivity ratio Kr, Knudsen number Kn, thickness of separating wall, heat capacity ratio Cr and aspect ratio α. Increasing of Reynolds number, Knudsen number, thickness of separating wall, heat capacity ratio and aspect ratio each separately leads to decrease the effectiveness while increasing of thermal conductivity ratio up to 10 leads to increase the effectiveness. Also, it is found that friction number and Nusselt number both decreases with increasing Knudsen number.
The thermal performance of an absorption refrigeration system powered by solar pond heat was studied, simulated, and evaluated under the climatic conditions of Basra, Iraq. The simulation used MATLAB to solve the heat and mass transfer equations within the three layers of the solar pond (assuming NaCl as the salinity gradient medium) and linked them via a heat exchanger to the absorption refrigeration system to determine the temperatures supplied to the absorption cycle. The absorption cooling system operates on a lithium bromide-water pair and contains an internal heat exchanger between the generator and absorber with an assumed efficiency of 80%. The simulation was conducted over several months of the year, from March to October, and daily climatic variables such as solar radiation and ambient temperature specific to Basra were considered, allowing the system's performance to be evaluated under realistic climatic conditions. The objective was to evaluate the coefficient of performance (COP) of absorption refrigeration systems and demonstrate the feasibility of using solar ponds as a sustainable heat source for cooling in hot regions. The study demonstrated the feasibility of operating an absorption refrigeration system using the thermal energy stored in the lower layer of the solar pond, while maintaining good thermal stability in that layer throughout the day, especially in areas with high solar radiation, such as Basra. The simulation model was developed entirely in MATLAB using fundamental physical equations that describe each component of the solar pond and absorption refrigeration system, without relying on pre-existing components or tables. This provides greater modeling flexibility and a deeper understanding of system behavior under hot climate conditions.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
This study presents solar chimney power plant integrated with sea water desalination system. A simple mathematical model is based on the conservation of mass and energy. The results show that the integrated system of solar chimney power plant and solar still can achieve simultaneously. The analysis is performed for both summer and winter at latitude 30 o N. It’s noted that, the water layer thickness is of a significant effect on the fresh water productivity while the dimensions of solar chimney and the solar collector are of a minor effect. The productivity of fresh water and output power for summer are the highest. The present work is compared with experimental data of the other work and showed a good agreement.
A numerical study of mixed convection inside a horizontal channel with an open square cavity that includes an adiabatic rotating cylinder. The bottom wall of the cavity is heated at a constant temperature, and the remaining walls are adiabatic. The flow is incompressible, laminar and steady state. The equations of continuity, momentum and energy are solved numerically using computational fluid dynamics (CFD) with the commercial software package FLUENT 2019 R1. Reynolds number values of 50, 100 and 150, the Richardson number (0.1 ≤ Ri ≤ 10) and the angular velocity ( ω ) of cylinder is (0.5 ≤ ω ≤ 4) rad/sec with direction counter clockwise. Prandtl number for air flow is ( Pr = 0.7). The results are presented in terms of streamlines, isotherms, and the average Nusselt value is given over the heated bottom cavity. The combined effects of natural and forced convection in and out of the cavity were obtained. The results showed that at low Richardson values, Ri = 0.1 the effect of buoyancy force is neglected. The effect of increasing the cylinder speed is clearly noticeable at low Reynolds values, Re = 50. Average Nusselt values increase with increasing rotational speed of the cylinder for all Richardson values.
The heat lost from gas turbine power plants with exhaust gases represents the most important source for lowering its thermal efficiency. Also, the gas turbine thermal efficiency affected significantly with the ambient surrounding temperature. Al-Najybia gas-turbine power plant in Basrah, Iraq is choosing as a case study. The power plant consists of four units with a capacity of 125 MW for each unit. In the present study, all the calculations are performed for one unit only. Firstly the thermal impact is studied in terms of energy analysis for Al-Najybia gas turbine power plant (GTPP) for different ambient temperature for twelve months. Also, the economic loss a companied the heat lost with exhaust gases for different ambient temperature are estimated. Secondly, the thermo-economic improvement from coupling the GTPP with a heat recovery system is studied. For gas-steam combined cycle, the performance and economic analysis are performed. The results show that, the output power and thermal efficiency are decreased by 0.97 MW and 0.0726% respectively for each unit temperature rise of the ambient temperature. For the combined gas-steam power plant the percentage increasing of the thermal efficiency is approximately 46.4%. The results indicate the combined cycle power plant (CCPP) is very important to increase electrical capacity. From the economic analysis, the economic gain due to using HRB is 75757 $ per month.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
Wastewater lagoons have proven to be an economically and environmentally beneficial alternative to traditional methods for treating sewage because of their unique properties, which include simplicity of use and inexpensive construction, energy, and maintenance costs. It is a natural wastewater treatment process that exploits the interactions between bacteria, algae, and other microorganisms and their surroundings to remove pathogens, organic matter, suspended particles, phosphates, ammonia, and nitrates. Stabilization lagoons are widely used throughout the world as they have proved to be a perfectly acceptable and satisfactory treatment system, the effluents produced in tertiary lagoons have been used for irrigation and aquaculture in many countries, indicating the high quality achieved during treatment in these units. This aim of this research is to overview the literature on lagoons' classification, design, and historical development. It also includes a set of relevant pilot and laboratory-scale experiments. As well as a comprehensive review of factors affecting lagoon performance, including sun's light, DO, pH, temperature, and nutrients. The relationship between these factors and their use in efficient contaminant removal is also discussed.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
The extended-finite element method (X-FEM) is used for crack analysis of orthotropic and isotropic functionally- graded composite material (FGCM) plate with slanted crack under thermal loadings. The enrichments functions of discontinuity are implemented. Mixed-mode SIFs are calculated in isotropic and orthotropic FGMs. Gaussian technique (Q4) has been applied in numerical calculation of interaction of solution. Thermal effects, fundamental equations, the interaction integral of non-homogeneous cases (M-integral), and proposal numerical integration rule are set to simulate and to debate the accuracy of the present work results in comparing with the results of the references that available in the literature. In addition, the effect of size of crack is studied to discuss the values of energy release rate and stress intensity factors with different crack angles. The present study is implemented by using MATLAB program to present steady state thermo XFEM fracture analysis of isotropic and an isotropic FG plate with inclined center crack.
The LCL Series Resonant Converter (LCL-SRC) type offer nearly load- independent output voltage under some operating conditions. By this way the output voltage can be regulated against a wide load and line variations with a small variation of switching frequency. In this paper a simple method for optimization of LCL-SRC is presented. This method takes the stored energy as a theoretical index to obtain the minimal size of the converter inductors L1 and L2 which contribute significantly to the converter size and weight. The Rac method for the analysis of resonant converter is discussed. This method was found fairly accurate for operation above resonant frequency.
4-Stearoylresorcinol was prepared by acylation of resorcinol with stearoyl chloride in the presence of zinc chloride as catalyst in a batch reactor. The temperature range of reaction was (50-80)°C. The rate of acylation increased with temperature up to (70°C). The conversion of reactants appeared to follow second order kinetic model. The reaction rate constant was (0.0031 1/mol.min) and was higher at higher temperatures. Activation energy was (16.8258 kJ/mol). The optimal catalyst concentration was (2.9936 mol/l). Also, a quantitative relationship was derived to represent the weight of the product as a function to the reaction variables. The quantitative relationship gave mean deviation equal to (5%). The product concentration was measured by UV spectroscopy.
This experimental research depicts the role of coating hot surfaces by graphite and graphene on the process of heat dissipation from these hot surfaces. Three aluminum specimens have been prepared for test, one of theme is coated by graphite, another one by graphene a while the third is left free of coating for comparison purpose. Each specimen is tested separately in a home-made wind tunnel. A plate electrical heater is adhered on the bottom of the specimen to simulate the generated energy by a heat sink. A heat sink composed of high thermal conductivity was applied between the heater plate and the base plate of heat sink to reduce the contact resistance to heat flow. The experiments are conducted with four turbulent Reynolds number. The results reveal that the sample coated by graphene exhibits the best thermal dissipation while the uncoated specimen shows the worst thermal performance.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
Numerical analysis of transient laminar three- dimensional buoyancy-driven convection in an inclined three- dimensional trapezoidal air-filled enclosure was investigated in this paper. The right and left sidewalls of the enclosure are kept at constant cold temperatures. The bottom wall is maintained at a constant hot temperature , while the top wall is considered adiabatic. Numerical investigation is performed for Rayleigh numbers varied as 10 3 ≤ Ra ≤ 10 5 , while the trapezoidal enclosure inclination angle is varied as 0° ≤ ≤ 180°. Prandtl number is considered constant at Pr = 0.71. Flow and thermal fields are presented in both two and three- dimensional pattern. Also, both local and average Nusselt numbers are calculated and discussed. The results show that when the Rayleigh number increases, the flow patterns are changed especially in three-dimensional results and the flow circulation increases. The minimum average Nusselt number inside the trapezoidal cavity corresponds to the highest 180 ].While, the average Nusselt inclination angle [i.e., 30 . Moreover, number reaches its maximum value at when the Rayleigh number increases the average Nusselt number increases as expected.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
In This paper, an experimental study was carried out on a dual channel with perforating “V” corrugated absorber plate of solar air collector which the air flows both in upper channel and lower channel of the absorber plate for increasing heat transfer coefficient and improving thermal performance. The results of experimental procedures for dual channel with perforating “V” corrugated absorber plate of solar collector were compared with the flat plate dual channel of solar collector. Experimental calculations had been performed under Baghdad (33.34° North latitude, 44.4° East longitude) climatic conditions at different values of mass flow rates 0.021 kg/s, 0.027 kg/s and 0.32 kg/s. The results showed that the dual channel with perforating “V” corrugated absorber plate of solar collector is found to perform more efficiently than the flat plate dual channel of solar collector with increased 39% in thermal efficiency. Then, it showed that the efficiency increases with increasing mass flow rates. Also, it showed that the heat removal factor of the dual channel with perforating “V” corrugated absorber plate of solar collector is 36% more than the flat plate dual channel of solar collector. At the last part of the study, the exergy relations were derived for both collectors. The results of this part showed that the flat plate dual channel of solar collector is having largest irreversibility (exergy loss) and the dual channel with perforating “V” corrugated absorber plate of solar collector is having a greatest exergetic efficiency.
The desalination market is gradually growing as a result of the significant water scarcity in various regions throughout the world. Concentrated solar power (CSP) can be used to power distillation, which is an effective method for addressing water shortages in areas where there is both a severe lack of water and abundant direct normal irradiation. CSPs are ideal candidates for the advancement of desalination technologies due to their capacity to produce both thermal and electricity energy. This review article offers a comprehensive of the current status of cutting-edge CSP-desalination systems. The paper reviews previously published studies conducted by researchers in the field of multi-effect desalination using concentrated solar collectors, and they are classified into two main types. Exclusively freshwater generation and freshwater / electricity cogeneration. In addition, the paper reviews conventional desalination. This review illustrates that there are numerous prospective methods for integrating desalination systems into CSPs. Potential areas for future investigation in CSP-desalination systems. In particular, the most significant obstacles to be surmounted are lowering the costs and efficiency improvements of solar repayment and desalination equipment. A potential method to expedite the commercialization of these plants is to develop innovative strategies that optimize thermal efficiency and reduce costs. Environmental factors (solar radiation intensity, ambient temperature and wind speed) and design factors (solar field area, number of mirrors, number of stages, steam temperature, steam quantity and pressure) are the main effective parameters that affect the distilled water production process. In general, the CSP desalination systems are environmentally and technically appealing; however, there remains substantial progress to be made in order for these plants to be commercially viable.