ملخص البحث :

To increase gas turbine power output and thermal efficiency, turbine inlet temperatures can exceed the melting point of component materials. Blade cooling techniques are thus required. This study reviews external cooling methods for gas turbine blade tips. Recent publications on cooling technology improvements were analyzed to enhance turbine blade cooling. The operating conditions and cooling requirements of turbine blades were examined. Air was blown through a duct in the turbine blade at lower temperatures to cool the blade by adjusting the air pressure to match internal pressures. The inlet air pressure was 24,000 Pa. Experiments were conducted by varying the air pressure. At 25,000 Pa, the air flow improved. Increasing the pressure to 30,000, 35,000, and 40,000 Pa resulted in the cooled air flowing away from the blade, causing blockage and reduced inlet air pressure. Reducing the pressure to 24,000 Pa caused the air to be retained, preventing its exit through the holes and increasing blade temperature. The optimal cooling was achieved at 25,000 Pa.

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Compression refrigeration systems include four main parts: compressor, evaporator, expansion valve and condenser. The condenser dissipates heat energy from the refrigerant to the outside air. There are different forms of condenser used in refrigeration systems. The evaporative condenser is one of these types. In this study a comprehensive review of the evaporative condenser will be conducted. The practical and theoretical studies of the evaporative condenser will also be reviewed, including direct and indirect evaporative condensers. A lot of literature are reviewed and summarized carefully in Table No. (1) For the purpose of giving a comprehensive view of the evaporative condenser. We believe that this paper provides a comprehensive description of the latent condenser used in compression refrigeration systems. It also provides an explanation about the nature of the energy spent by the systems and its relationship to the system's performance factors.

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This article examined the effect of central and longitudinal vents on the thermal behavior of the slurry compound Mineral analyzes of the used clays were performed to find the composition of the components for the clay. It was thermal characterization, In a hot cylinder fashion. The thermal transfer analysis, thermal resistance, energy saving and density fraction were extracted in a practical way. This study is important to know the effect of internal gaps on thermal conductivity during the manufacturing process, From the extracted girls, it was found that the central openings dissipate heat and reduce the conductivity, and it is less compared to the longitudinal openings.

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Photovoltaic systems, a clean and renewable energy source, face challenges in optimizing efficiency due to temperature-induced performance loss. This research explores passive cooling strategies using phase change materials, which collect excess heat during peak solar irradiance, store it, and release it during less sunshine or high temperatures. This method efficiently controls panel temperature, enhancing performance and extending lifetime. The choice of cooling technique should be based on the specific requirements and constraints of the photovoltaic system. Solar panels receive 780 W/m2 of incoming solar radiation in summer and peak at noon. Convective heat transfer and air temperature of 25 degrees Celsius allow heat to escape. The stiff material, aluminum fins, and PCM have specific heat of 2000 J/kg.K and thermal conductivity of 0.2 W/m.K, respectively. Temperature distribution reveals significant reduction in surface temperatures with increasing Al2O3 concentrations. The best case was at 0.5wt%, achieving 49.896℃. Electrical efficiency increases with concentration. The distribution of temperatures at different CuO concentrations reveals lower surface temperatures due to increasing concentrations. The optimal concentration was 0.5 wt percent, where temperatures fell to 49.870℃. Increasing electrical efficiency is crucial for temperature improvement, with a peak at 9.26% at 0.5 weight percent mm. Temperature distribution decreases with ZnO concentration, with optimal 0.5wt% concentration, enhancing electrical efficiency with increasing concentrations.

ملخص البحث :

The demand for consumed pure water continues to rise due to the increase in population density. Solar desalination is a process of converting brackish water into potable water. Solar distillation is one of the techniques used in desalination of raw water. Solar stills represent the common method for applying the principle of distillation process for obtained of pure water. Active and passive are the main categories of solar stills. In this study increasing the evaporation process inside the still is experimentally implemented with the help of two type of solar collector (finned tube solar collector and flat plate solar collector) integrating to conventional stills enhance productivity. The results show that the yields of conventional solar still, conventional with flat plate solar collector and conventional with finned tubes solar collector are (2.886, 3.853 and 4.766) L/m2 .day respectively. Hence, the productivity is improved by 65.12 % and 33.49 % when using finned tubes and flat plate solar collectors respectively, as compared to that of conventional solar still. The cost analysis for the three solar still models for 1 Litter of yield is performed and the indication is that the lowest cost is form conventional still with finned tubes collector.

ملخص البحث :

Water that can be consumed is necessary for life to exist. One of the biggest issues that humanity faces globally is access to drinking water, particularly in rural and dry areas. Solar distillation is now the most effective nonconventional and environmentally benign way to filter brackish or marine waters. This experimental work seeks to increase the yield of traditional single-slope solar stills using finned tube solar collectors. Experimental results carried out under the climatic conditions of Najaf, Iraq (32
1 38.5500 N/44
19′ 59.22′ ′E) showed that the maximum basin water temperature of finned tubes solar collector [modify solar still (MSS)] is 64.1
C and for conventional solar still (CSS) is 45.8
C at 14:00 p.m. This behavior is the same for the other temperatures (vapor, inner glass surface, and outer glass surface). Also, the water and inner glass surfaces’ temperature difference (Tw-Tg,in) is 3.9
C for MSS and 1.8
C for CSS. The daily productivity of MSS is 4.766 l/m2 day, with an enhancement of 65.12% as compared with that of CSS. The exergy efficiency increases with time to reach its maximum value of 32.53% at 15:00 p.m. for the MSS and 13.78% at 14:00 p.m. for the CSS. With respect to cost analysis, employing a finned tube collector alongside CSS affords the lowest cost per liter of distillate. Specifically, the cost is equivalent to 0.04 USD.