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An algorithm for designing a cooling system for photovoltaic panels
摘要： Solar energy is an abundant source of energy for generating electricity. One of the main challenges in using solar energy is that solar photovoltaic (PV) panels are typically used in regions where solar radiation is high; consequently, the temperature of the panels will increase, and the efficiency of the panels will decrease. Adding cooling tubes to the PV panel is a possible approach to cool it down. To design such cooling systems, CFD simulations may be used; however, this approach tends to be time-consuming. In this paper, we report a new algorithm for designing straight cooling tubes. The algorithm can be used to determine important design parameters such as tube center-to-center length, diameter of the tube, and the minimum tube length needed to achieve a desired outlet temperature. The accuracy of the algorithm was tested using real-world data (including various ambient temperatures and solar radiations) and the maximum temperature difference between desired outlet temperature and CFD simulation for the designed cooling system was found to be 1.7oK.
关键词： Solar energy,Conjugated heat transfer,Design algorithm,Renewable energy,PVT,Cooling system
更新于2025-09-12 10:27:22
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Performance Improvement of Trough Concentrating Photovoltaic Thermal System: A Review
摘要： This paper presents an overview on the performance improvement of trough concentrating photovoltaic thermal system by optimizing different components and operating parameters of the system and has been put forwarded. Initially, the performance of four types of solar cell arrays was studied, in that triple junction GaAs cells possessed good performance characteristics. Subsequently the importance of increasing the concentrator reflectivity for improving the performance of TCPV/T system is presented by increasing the mirror reflectivity from 0.69 to 0.92 and consequently the maximum power of the cell array got increased. Then, the role of receiver shape like rectangle and triangle for the maximum utilization of solar radiation is also presented.
关键词： Concentrator reflectivity,GaAs,PV cells,trough collector,Heat transfer
更新于2025-09-12 10:27:22
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Effect of powder feeding rate on heat and mass transfer behaviors during filler powder laser welding
摘要： The heat and mass transfer behavior is the influencing factor of welding quality, during filler powder laser welding. The characteristics of plasma and keyhole can characterize the heat and mass transfer behavior. Experimental platforms were built to observe the effect of powder feeding rate on the heat and mass transfer behavior. The main results of the experiment are as follows. In the process of filler powder laser welding, the keyhole depth and fusion depth were improved by selecting the critical value of powder feeding rate 5 g/min as the welding process parameter. When the powder feeding rate exceeded the critical value, the electron temperature and electron density decreased and increased respectively. The keyhole depth decreased with the increase of the inverse bremsstrahlung absorption coefficient of the keyhole plasma at the top of the keyhole. The keyhole area increased with the increase of plasma pressure at the keyhole opening. The inverse bremsstrahlung absorption of plasma plume and the number of powder particles sprayed into the molten pool were the factors that caused the decrease of the surface temperature and the length of the molten pool.
关键词： Plasma pressure,Inverse bremsstrahlung absorption,Heat and mass transfer behavior,Filler powder laser welding
更新于2025-09-12 10:27:22
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Laser Therapy for the Treatment of Onychomycosis: Best Evidence Based Practice or Not?
摘要： Onychomycosis is a very common condition that accounts for 50% of all nail pathologies. Currently 2–5% of the world population suffers from this disorder. It is primarily caused by dermatophytes, but the infection can also be caused by yeasts and non-dermatophyte moulds. Onychomycosis is a therapeutic challenge and recently there has been an increase in resistance to oral and topical antifungal agents, leading to 20–25% relapse and/or reinfection rate. During the past 5 years, the emergence of laser therapy has been the topic of discussion as a newer, safer modality of treatment. Nail clippings and scrapings are the most common methods of sampling for suspected onychomycosis. The simplest method for detecting fungi is by way of 20% potassium hydroxide (KOH) preparations, but lately show insufficient sensitivity in onychomycosis – as much as 40–68%. Fungi can also be grown in culture form; however a 70% sensitivity detection failure rate is seen. Recently, histological fungal detection – in the form of Periodic Acid-Schiff (PAS) stain – has shown high sensitivity at 92% in the detection of fungal elements. The exact mechanism of action of laser is unknown but it is believed that heat disintegrates fungal structures. One of the most appealing characteristics of laser therapy is its ability to deliver energy to the target tissue and avoid systemic side effects at the same time. In 2009 the United Kingdom (UK) Podiatry magazine Podiatry Now published a letter suggesting laser treatment was “possibly the most radical development in the treatment of onychomycosis our profession has ever seen”, although concerns were raised over the unproven efficacy and investment costs involved. Papers have been published investigating the efficacy of lasers for the treatment of onychomycosis. Even though laser therapy provides an alternative option with rapid procedure duration, conflicting evidence is shown in a variety of papers and studies with longer follow-up periods suggest onychomycosis relapse in those treated with laser, which warrants further investigation.
关键词： Heat,Laser,Effectiveness,Review,1064 nm wavelength,Onychomycosis,Resistance,New treatment
更新于2025-09-12 10:27:22
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Influence of Beam Power and Traverse Speed in Fibre Laser welding of Dual phase steel (590) on Depth of weld zone penetration, Microstructure and Hardness
摘要： The influence of heat input on microstructure, microhardness, and mechanical properties of welded structures of DP 590 (Commercially known as DP 600 grade) grade steel of 1.6 mm thickness sheet has been investigated. The investigation was carried out by using Nd: YAG fibre laser source at a beam power of 1.5 kW and 3.0 kW at a traverse speed of 2 m/min, 4 m/min, and 6 m/min in bead on plate weld configuration. Except at lower beam power and lower traverse speed, at all other combinations of beam power and traverse speed a complete weld penetration has been observed. The weld zone microstructures have been transformed into predominantly martensitic phase due to rapid solidification. The width of the Heat Affected Zone and Weld Zone decreased as the heat input decreased. Hardness values of weld zone has increased to 350 -380 HV from 180-200 HV due to formation of martensite.
关键词： Dual Phase Steel,microhardness,Laser welding,martensite,heat affected zone
更新于2025-09-12 10:27:22
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Experimental study of observed defects in mini-modules based on crystalline silicone solar cell under damp heat and thermal cycle testing
摘要： In this study, consumer type multicrystalline modules are investigated. To assess the long-term reliability of photovoltaic (PV) multicrystalline modules, extended thermal cycling and damp heat testing were performed. This study focused on four multicrystalline modules. Two modules were subjected to 85 °C/85% damp heat testing at 1000 h and 1300 h, respectively. The other two modules were subjected to thermal cycle test of 55 cycles and 66 cycles, respectively. After testing, all 4 solar panels were investigated with the help of visual inspection, thermography, electroluminescence and IV-curve measurements. The main degradations observed were corrosion, hot spot and delamination.
关键词： Thermal cycle,Degradation,Mini-module,Damp-heat
更新于2025-09-12 10:27:22
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Investigation of Crystallization Process of a Single Crystal Nickel-Based Alloy during the Laser Multilayer Cladding
摘要： The article shows the results of multilayer laser cladding of heat-resistant single crystal nickel-based alloy ZhS32-VI (CSMX-4 analogue). The influence of the main technological parameters on geometry and microstructure formation of deposited beads was investigated. Based on obtained dependencies, the regression equations are compiled for describing the shape of bead and the ratio of directional and equiaxial crystallized sections. The obtained dependencies of regime parameters nomination allow restoring the gas-turbine blades by the method of laser cladding.
关键词： gas-turbine blades,heat-resistant nickel-based alloys,laser cladding,crystallization,single crystal nickel-based alloys
更新于2025-09-12 10:27:22
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Parabolic two-step model and accurate numerical scheme for nanoscale heat conduction induced by ultrashort-pulsed laser heating
摘要： Simulation of nanoscale heat transfer phenomena has attracted great attention, particularly the nano-scale heat conduction induced by ultrashort-pulsed laser heating. In this article, we propose a nanoscale parabolic two-step model and an accurate numerical scheme for thermal analysis of the nanoscale heat conduction induced by ultrashort-pulsed laser heating. To this end, we first introduce the Knudsen number (Kn) into the original parabolic two-step heat conduction equations and couple them with the Kn-dependent and temperature-jump boundary condition. We then develop a fourth-order accurate compact finite difference method for solving the nanoscale model. Stability and convergence of the obtained numerical scheme are analyzed theoretically. We finally test the accuracy and applicability of the nanoscale model and the obtained numerical scheme in three examples. By choosing various values of the Kn and the parameter α in the boundary condition, the simulation could be a tool for analyzing the nanoscale heat conduction induced by ultrashort-pulsed laser heating.
关键词： Nanoscale heat conduction,Convergence,Compact finite difference scheme,Stability,Ultrashort-pulsed laser heating
更新于2025-09-12 10:27:22
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Modeling the Temperature Distribution during Laser Hardening Process
摘要： A mathematical model was developed and is presented here to calculate the temperature distribution on the surface and bulk of a steel plate under the laser hardening process. The model starts from the basic heat equation, is then developed to a volumetric form and is connected to the various solid phases existing. The model is based on three strongly influencing parameters of the laser hardening process: velocity of the laser spot and irradiation time. The results are compared to the available experimental data reported in the literature. The volumetric model provides an assessment of temperature distribution in both the vertical and horizontal axis. Laser irradiation at sufficiently high fluence can be used to create a solid state phase change on the surface. Primary calculations show that the temperature profile has a Gaussian distribution in horizontal x-and y-axis and presents an exponentially decreasing distribution in the horizontal and vertical depth directions.
关键词： Laser hardening,heat treatment,Solid phase transformation,Temporal-temperature profile
更新于2025-09-12 10:27:22
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Laser dimple texturing – applications, process, challenges, and recent developments: a review
摘要： Laser dimple texturing has been a surge in the surface to surface contact applications like the cutting tool/workpiece interaction, piston-cylinder assembly, bearings, prosthetic hip & knee joints, blanking punch- die assembly, etc. to control the friction and wear between the interactions. In this article, the first part presented about a broad literature review on an effect of dimple texture in various industrial applications like bio-implant components and cutting tools. In the second part, detailed information has discussed on a process of laser dimple texturing and influence of laser process parameters such as laser wavelength, laser energy, number of pulses, pulse duration and focal distance on dimple geometry. The third part describes a comprehensive literature review on challenges/limitations of laser dimple texturing process like heat affected zone, tensile residual stresses, bulges around the dimple, etc. Finally, in the fourth part, proper attention has given on recent developments like laser shock peen texturing, laser texturing under water and post-processing techniques to overcome the limitations of laser surface texturing process.
关键词： Friction,Hip & knee joints,Wear,Cutting tool,Laser peen texturing,Heat affected zone,Laser dimple texture
更新于2025-09-12 10:27:22