نشریه مهندسی مکانیک تبدیل انرژی
سال هفتم شماره 3 (پیاپی 24، پاییز 1399)

Film Cooling Adiabatic Effectiveness on a Profile of a Gas Turbine blade that Using Holes with 45 Degree Combined Angles to the Flow Direction and Radial Along the Attack Edge as well as 25 Degree Angles to the Flow Direction and Surface Area of the Attack Edge Area and 35 degrees relative to the outlet hole suefaces along stagnation line, Under a specified blowing ratios, using the Reynolds stress approach and the SST turbulence model, have been investigated by using ANSYS FLUENT commercial software. The results show that the film cooling adiabatic effectiveness in the areas near the blade base is strongly affected by these compond angles, while approaching the upper blade areas, the film cooling effectiveness will not be affected by these injection angles.

In this research, optimization of gas microturbine through economic, exergy and environmental analysis has been investigated by the gray wolf algorithm. First, a thermodynamic modeling was performed for each of the above modes, and then using the gray wolf method, optimum points were determined for each system's performance. For modeling, the code written in MATLAB software was used. The results of the study showed that the increase in maximum temperature has a small effect on the increase in the cost of purchasing and installing and maintaining equipment on the micro turbine cycle, which indicates that increasing the combustion temperature to the extent that the metallurgical limit of the cycle allows us to be a good factor in increasing the cycle efficiency with Considering economic issues. As well as increasing the efficiency of the recuperator, the greatest cost is borne by other factors on micro turbines. As the compressor compressor ratio increases, the cost of fuel is increased as shown above. The effect of increasing the turbine input temperature on the cost of exergy damage and the total cost of consuming fuel and purchasing, installation, and maintenance, as well as the matching of input data with the model derived from the gray wolf algorithm related to the total purchase, installation, and maintenance costs In addition, the cost of exergy damage plus fuel consumption is shown.

Nanotechnology is well used in the development and performance improvement of solid oxide fuel cells (SOFCs). The high operating temperature of SOFCs (700-900 ° C) has led to serious shortcomings in their overall performance and durability. Hence, the high operating temperature has been reduced to the average temperature range of approximately 44-700 Celsius, which has improved performance and subsequently commercialized SOFCs as portable energy sources. However, at reduced temperatures, challenges arise such as increasing the internal strength of fuel cell components. Although this may not be as serious as the problems that arise at high temperatures, it still significantly affects SOFC performance. This paper deals with the work of researchers in the field of application of nanotechnology in the construction of SOFC through different methods. These methods have successfully eliminated or minimized internal resistance and shown significant improvements in SOFC energy density at reduced temperatures.

Saving energy is one of the most important challenges of today's world. Reducing electrical energy consumption in compressed air systems is one of the essential requirements for designing these systems. When using domestic air conditioners (dual air conditioners) in very hot areas (Khuzestan) their performance decreases and electric current consumption increases. Therefore, the use of new and renewable energies such as solar energy can play a significant role in reducing energy consumption. In this plan, the plane plate solar collector, which contains PCM, is placed in the compressed air compression and condenser refrigeration compression cycle, and by obtaining the parameters of pressure and temperature at different points of the cycle, and comparing it with the ordinary mode The refrigeration cycle (no collector), compressor work, cooling capacity and performance factor are calculated and investigated. In the same way, the data is synchronized in the normal state and in the solar system at three different times (at 7 am, 15 o'clock, and 23 o'clock). The experimental results show that at the maximum temperature (at 15 o'clock), with a rise ( 6.3° C), the refrigerant temperature of the collector output, the thermodynamic characteristics of the improved system, such that the cooling coefficient from 10.82 to 11.21 and the coefficient of cycle performance From 5 to 5.2 was increased by %3.83 and %3.84 and the compressor power was from 167.2 to 160.2 which decreased by about 0.32%. Moreover, due to the lack of adequate sunlight and proper collector heat absorption in the experiments at 23 o'clock and 7 o'clock, there was little effect on the thermodynamic characteristics of the conventional and solar cycles.

These days With respect to the high importance of energy concept, limitation of natural resources, regulation of environmental issues, and global warming, heat transfer systemschr('39') applications get more attention. In the present paper, the experimental effect of Nano-fluid and turbulator on the heat transfer and pressure drop is investigated. AL2O3-SN300 base oil as nanofluid with weight percentage of 0.05, 0.1, 0.3, and 0.5 are used. To investigate the effect of heat transfer, a steel rotational turbulator was inserted inside the heat exchanger. The experiments were conducted under a constant heat flow rate of 3950 W/m2 and 5280 W/m2 and temperatures of 30, 40, 50, and 60 C. The whole process has been repeated for eight different mass flow rates under the laminar flow condition. The results show a higher heat transfer coefficient of Nano-fluid than the base fluid. Increasing the weight percentage of Nano-fluid caused enhancement of pressure drop in the system. The heat transfer coefficient directly relates to the mass flow rate and increases by raising the Reynolds number. The results reveal that using a turbulator enhances the heat transfer significantly. The experimental results are in reasonable agreement with theory by less than 10 percent mean error.

In the present study, investigated an energy production system using three types of renewable energy: solar, wind and ocean thermal energy with climatic conditions and close to areas with high potential for the OTEC system, Has a good position in terms of wind speed and solar radiation, used them as energy sources. The proposed system is designed and evaluated based on the total daily electricity consumption required by a beach welfare complex. The main components of the system consist of an organic Rankine cycle, turbine, thermoelectric, pump, heat exchanger, wind turbine and a flat plate solar collector. EES software has been used as an engineering tool to model the system and obtain thermodynamic results. The system is designed for an area with good ocean thermal energy, wind energy and solar energy. The most important and effective parameters in these studies are wind speed, solar radiation and Solar heat collector area. Finally, in order to optimize the designed system, the multi-objective genetic algorithm with Non-dominated Sorting Genetic Algorithm-II or NSGA-II algorithm is used to find the best target functions and Pareto chart extraction is used to determine the best values for the target functions. Design variables used for optimization include Solar system area (Ap), output temperature from solar system (T1), turbine inlet temperature (T3), evaporator pinch point (PPeva), thermoelectric parameter (Z_T_M), pump efficiency and turbine efficiency. The two objective functions of this optimization are exergy and system cost rate. After optimization, the Pareto diagram was obtained with a set of optimal points. Finally, the optimal value for exergy efficiency was 14.47% and the cost rate 74.97 ($/h). The introduced systems are suitable for the required applications according to the obtained results. The introduced systems are suitable for the required applications according to the obtained results.