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Go to Editorial ManagerThe 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.
The efficiency of gas turbine units is highly affected by the variation of ambient temperature. Increasing the ambient temperature decreasing the efficiency of gas turbine. Cooling the inlet air to the compressor of the gas turbine units is an essential and economical technique for improving its efficiency. Al-Rumaila gas turbine power plant was located in Basrah city, Iraq, which is characterized by its hot climates for more than six months during the year. A novel upstream inlet air cooling system was applied and tested for Rumaila gas turbine power plant. This article represents a thermo-economic evaluation of applying upstream inlet air cooling system. The analysis is based on the test results for operating single unit of Rumaila gas turbine power plant using upstream inlet air system for cooling. The test was performed during July of 2019 for 90 minutes of operation period with ambient temperature of 45 °C. The evaluation analysis shows that, the power output increased from 217.71 MW to 250.11 MW during the period test with percentage increase in power by 15%. This increase in power output led to net economic gains is approximately 1000 $/h.
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 effect of different dosages of the high range water reducing admixture–additive- (HRWRA), the commercially polymeric material (Plastocrete-N), on the corrosion resistance of embedded steel in concrete exposed to chloride solution in the absence and presence of sulfate ions was studied. In the present study, four levels of polymeric material (Plastocrete-N) (0.125%, 0.250%, 0.375%, and 0.500% by weight of cement) were used to prepare HRWRA treated concrete. The concrete specimens exposed to chloride and chloride–sulfate solutions at concentrations of (3.5% NaCl and 5% Na2SO4), at ambient temperature. The electrochemical behavior of steel in both reference and HRWRA concretes was studied under the effect of corrosive environments using corrosion measurement systems such as: a) half – cell potentials measurement system and b) accelerated corrosion test system. The results showed that a longer time of corrosion initiation (180 day) observed with 0.500% HRWRA containing concrete compared to other different HRWRA percentage including the reference concrete. It was concluded that the use of 0.500% HRWRA provided superior protection to steel reinforcement in concrete that subjected to corrosive environments. Furthermore, the steel with 0.500% HRWRA was subjected to corrosion test by mass loss, it is evident that a reduction in mass loss by about 90.2% and 85.2% in both solutions, respectively.
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.
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.
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.
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 the present research, a Matlab program with a graphical user interface (GUI) has been established for studying the performance of a solar tower power plant (STPP). The program gives the ability for predicting the performance of STPP for different tower dimensions, ambient operating conditions and locations. The program is based on the solution of a mathematical model derived from the heat and mass balance for the tower components. The GUI program inputs are; tower dimensions, solar radiation, ambient temperature, pressure, wind velocity, turbine efficiency, emissivity and absorptivity for collector and ground and thermal conductivity and thickness for ground. However, the GUI program outputs are; temperature and pressure differences across the collector and tower, velocity in the tower, density of air in collector outlet, mass flowrate of air, efficiency for collector and tower, the overall efficiency and output power of STPP. The effect of the geometrical dimensions of STPP and some climatic variables on the plant performance was also studied. The results show that the output power increases with increasing the collector diameter, chimney diameter and solar radiation by an increasing of 0.282 kW/m, 0.204 kW/m and 0.046 kW/(W/m2) respectively.