Investigation of Thermal Performance of Evacuated Tube with Parabolic Trough Collector with and without Porous Media

In this paper a new model has demonstrated that it operates in a moderate performance scale to generate hot water. In its early stage, the preliminary model, which built with double pass water tube inside evacuated tube, was investigated experimentally. The model was tested inside room under different operation conditions in terms of solar radiation 300, 400, 500 and 600 W/m2 and water mass flow rates 0.00305 and 0.0083kg/s. In the first case, there was a problem because of the air gap inside the tube and surrounding the double pass water tube, so In the second stage, two different filling medium inside the evacuated tube was proposed to modify the preliminary model. The mediums cases include porous media (stainless steel wire mesh and Aluminum fiber metallic). The results show that maximum efficiency without porous media was 62.4% at 0.0083 kg/s and heat flux 600 W/m2, but after porous media applied, the efficiency reached 79.4% at 99.997% porosity of Aluminum fiber metallic and heat flux 600 W/m2 with same water mass flow.

3D X-ray Microscopy of Ultrasonically Welded Aluminum/Fiber-Reinforced Polymer Hybrid Joints

Ultrasonically welded hybrid aluminum/fiber-reinforced PEEK joints were analyzed non-destructively with an X-ray microscope. The potential and limitations of the technology as a non-destructive testing method were investigated. For a quantitative evaluation, joints with suitable and unsuitable parameters were compared. For a further comparison, geometric modifications of the joining partners were made, and the influence on the structure and process variation of the resulting hybrid joints was examined on a microscopic level. By using a tool for 3D segmentation of the composition of the joining zone, quantitative information on volume-specific proportions could be obtained and compared in relation to each other.

The effect of metallic fiber geometry and multi-walled carbon nanotubes on the mechanical behavior of aluminum fiber-reinforced composite adhesive joints

The effect of the geometry of metallic fibers on the mechanical response of aluminum fiber-reinforced composite adhesive joints was studied experimentally. Moreover, a combination of multi-walled carbon nanotubes and aluminum fibers was used for reinforcing the composite adhesive joints. Different geometries for the aluminum fibers including straight, twisted and spring-shaped with different pitch lengths were considered. The results indicated that the composite adhesive joints reinforced with a combination of multi-walled carbon nanotubes and aluminum fibers experienced the highest improvement of 171% in the strength compared to the unreinforced specimen. It was found out that the aluminum fiber geometry can significantly influence the adhesive joint behavior. Incorporating the twisted aluminum fibers into the adhesive layer increased, while the spring-shaped fibers decreased the strength of the composite adhesive joints compared to the straight aluminum fibers. The fracture surfaces of the composite adhesive joints were analyzed using scanning electron microscope.