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Water cooling assisted laser dissimilar welding with filler wire of nickel-based alloy/austenitic stainless steel
摘要： To clarify the e?ects of water cooling on solidi?cation behavior of pulsed laser welding of Nickel-based alloy/austenitic stainless steel with ?ller wire, and to improve the mechanical properties of laser welded joints, the analyses of morphology, microstructure, anti-peel property and micro-hardness were carried out. The results indicated that adding water cooling increased cooling rate and temperature gradient of the weld. And the addition of water cooling made constitutional supercooling of the weld easier, so that the solidi?cation rate increased with the increase of the temperature gradient. Therefore, the weld grain was re?ned by about 28%, and the average width of unmixed zone decreased by 35%, with a low volume fraction of Mo-rich precipitated phase consisting of p phase and μ phase. The μ phase was discovered in laser welding Nickel-based alloy/austenitic stainless. Both p phase and μ phase had a good coherent relationship with the matrix, which resulted in the low phase boundary energy between precipitated phase and matrix. The coherent relationship is described as [1 4 3] p // [5 3 1] γ between the p phase and the matrix. And the coherent relationship is described as [1 2 0] μ // [2 2 1] γ between the μ phase and the matrix. There are the stacking faults in the μ phase along the direction of [1 1 0], which is one of the slip system in μ phase. At the same time coherent relationship between p phase and matrix is better than that of μ phase. The micro-hardness, load capacity per length, and anti-peel stress were improved by 10.5%, 8.1%, and 11.8%, respectively.
关键词： Ni-based alloy,Precipitated phase,Filler wire,Water cooling assisted,Laser dissimilar welding
更新于2025-09-16 10:30:52
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Investigating the Performance Improvement of a Photovoltaic System in a Tropical Climate using Water Cooling Method
摘要： The performance of a crystalline silicon photovoltaic (PV) system is greatly reduced with the increase of the temperature of the solar panels, especially in the tropics. In this study, a water-film cooling system was installed onto a retrofitted rooftop PV system, which is operating as a distributed generation system. The experiment shows that this method not only can reduce the thermal stress between the front and the back surfaces of the solar panels, it also minimises the non-uniform distribution of temperature across different positions of the solar panels. Besides, the cooling system with an optimal cooling water flow rate of 6 L/min can improve the power output by 32 W per 260-W-rated-PV-module (15% improvement) and with the net energy gain of 0.0178 kWh/hour/panel at 1150 W/m2 solar irradiance. In addition, the collected rainwater from the site is sufficient to cover the water needs for the cooling system. This method justifies that the proposed water-cooling method is technically feasible to provide a positive energy generation for a photovoltaic system.
关键词： temperature reduction,water cooling,distributed generation,photovoltaic performance,tropical climate
更新于2025-09-12 10:27:22
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Underwater laser hardening of bearing steels
摘要： Water can act as an effective cooling agent during processing of materials. This can be beneficial especially for surface hardening of steels whereby a rapid quenching rate is desired to generate a hard martensitic surface layer. In this study, the underwater laser hardening of bearing steels is experimentally investigated using a fiber laser. The study found that underwater laser hardening increases surface hardness by about 3.5 times than that of the base material which is higher than in conventional laser hardening. Surface hardness as high as 900 HV is achieved when processed with a thin layer of water above the steel surface. However, the depth and width of the laser hardened zone are found to be significantly smaller than in conventional laser hardening. Further analysis revealed that irregular hardened track formed at slower scanning speed due to the convective motion of water and shock wave generation.
关键词： Steel,Water cooling,Hardness,Laser hardening
更新于2025-09-11 14:15:04
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[IEEE 2018 International Conference on Computational Approach in Smart Systems Design and Applications (ICASSDA) - Kuching (2018.8.15-2018.8.17)] 2018 International Conference on Computational Approach in Smart Systems Design and Applications (ICASSDA) - Experimental and Simulated Evaluation of Temperature Effect on Panel Efficiency Performance with Front Water Cooling
摘要： The solar photovoltaic (SPV) panel cell’s temperature is the main parameter that gives significant effect on the conversion efficiency of SPV panel. In the present work, simple and efficient front water spraying cooling system in a photovoltaic panel has been designed and developed to introduce active cooling in order to eliminate heat. The performance of the proposed cooling system has been tested and evaluated for the weather climate of a city in Jitra Kedah, Malaysia. The experimental result revealed that with front water cooling system the cell temperature measured at the back of the solar panel can be significantly reduced up to 20-22 ?C. Consequently the electrical efficiency of the SPV panel improves by 10.5% with the introduction of the proposed cooling technique.
关键词： front water cooling,photovoltaic panel,panel efficiency,water spraying
更新于2025-09-10 09:29:36
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Novel Design for Thermal Management of PV Cells in Harsh Environmental Conditions
摘要： The abundance of solar energy is a blessing in the Arabian Peninsula, where more than 2000 kWh/m2 density has been recorded annually. This has resulted in sincere consideration of PV harvesting in the energy matrix and smart grid. However, artefacts such as degradation of PV efficiency due to the high temperature effect have to be addressed. This paper presents a novel design of a PV cooling system using water to mitigate the effect of high temperature. Several experiments have been conducted, and the results have been analyzed. It has been found that the collected water from the panel after 40 min of cooling gained a temperature of 10 ?C approximately, during December 2016. Eventually, the efficiency was improved by 10.35% (without using MPPT) using water at ambient temperature (24 ?C) compared to the non-cooled panel. Moreover, the temperature of the panel during solar peak hours dropped from 64.3 ?C to 32 ?C and from 59 ?C to 27 ?C in 3 min for the back and front surface, respectively. These results, which are the ?rst of their kind in Qatar, constitute good incentives and pave the way for further investigation to enhance PV ef?ciency in harsh environments. This would be of paramount signi?cance, especially for scaling up PV deployment, as is planned in Qatar and GCC countries in their 2030 vision.
关键词： overheating,ef?ciency,photovoltaic,water cooling,heat transfer,renewable energy
更新于2025-09-04 15:30:14