The fabrication of a prototype flat micro heat pipe (FMHP) of a size appropriate for mobile electronics and its performance test results are reported. To ensure reliable operation under repeated thermal loads and to enhance the heat transport capacity, copper is selected as the packaging material considering its high thermal conductivity and good strength. The wick structure of the FMHP consists of fan-shaped microgrooves with a width and depth of about 100 and 200 μm, respectively. The fabrication of microgrooves was done using a laser micromachining technique and water was used as the working fluid. Fan-shaped microgrooves were found to induce a greater capillary pressure than triangular microgrooves of a similar size. Subsequent test results confirmed that despite its small size, 56 mm (L) × 8 mm (W) × 1.5 mm (H), the FMHP had a high heat transport capacity; the maximum heat transfer rate was 8 W under stable operation conditions and 13 W at the dryout point. In addition, the FMHP worked under adverse-gravity conditions with little change in cooling capacity, a key advantage for application in modern mobile electronics.
A high-capacity pump for seawater desalination plant is open to highly corrosive and abrasive environment. To improve anti-corrosion and anti-abrasion properties of pump material, laser modification technology can be applied to the surface of pump material. In this work, experimental results for the laser shock hardening of 2205 duplex stainless steel (22% chromium-5% nickel) for the application to rotating pump parts are reported. The changes in surface hardness and morphology before and after laser shock hardening are investigated for varying process conditions. It is demonstrated that the hardness of duplex stainless steel can be significantly enhanced, up to 30%, by properly controlling the process parameters. The applicability of laser shock hardening for surface treatment of mechanical parts of seawater desalination pumps is discussed.
Generally, vehicle sensor on bracket is installed in engine room to receive sensing signals directly. The brackets in the engine room are exposed to extreme environmental conditions such as high temperature and irregular vibrations. For ease of production, traditional bracket structure has cantilever frame with one leg and two fixed points that is vulnerable to local stress concentration. High local stress in the bracket structure results in malfunctions and shorten life span. From these points, we suggest double legs and two fixed points bracket model with various hinge structures for local stress decreasing. To analysis the stress distribution and working conditions, vibration durability tests are performed for traditional and modified bracket models via finite element method. Impact hammer and grid tests are performed to validate the FEM analysis. Maximum stress conditions are evaluated with resonance frequency vibration analyses. As a result, the maximum stress on double legs bracket with increased thickness and radius of curvature model is reduced to 51.0% compared than traditional single leg bracket model.
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