Papers by Keyword: Insulation Layer

Abstract: XLPE power cable is widely used in grid system for its series of merits, but the fault become more and more frequent with increase of the use of cable and longer run time. In this paper, the reasons of the fault are introduced and the on-line monitoring technique of XLPE power cables is presented.

Abstract: Space vehicles which enter earth’s atmosphere require a thermal protection system (TPS) to protect them against aerodynamic pressure and heating impact. The use of material with high temperature capability in combination with low thermal conductivity, to limit transfer of heat into interior of the structure, is required of the TPS. Because these requirements cannot be accomplished by a single material layer, two material layers are proposed, and their functions are integrated through the TPS design. Future reentry vehicle’s capabilities will in great extent depend upon the capabilities of the materials used for these layers [1]. This paper is devoted to the protection layer of the TPS, to predict its strength and life under the aerodynamic pressure and heat impact loads.

Abstract: Setting of insulation layer is widely recognized to prevent frost damage for tunnels constructed in cold region. Optimization design of insulation layers, however, still need deeply investigate. In this paper, taking Houanshan tunnel as example, two-dimensional finite element analysis on the optimization design of insulation layers has been carried out by ABAQUS. The tunnel temperature fields due to various thickness and length of insulation layer are numerically analyzed. It shows that ,1)4.85°C increased at backside of insulation layer with thickness of 5cm, while 5.8°C increased for thickness of 7cm;2) frozen depth of surrounding rock decrease with the increase of insulation layer thickness. The farther distance to tunnel portal, the smaller thickness of insulation layer required to prevent the surrounding rock from freezing;3)According to analysis, frost penetration length should be 450~500m before tunnel holing-through ,while 720m~830m after tunnel holing-through.

Abstract: A two-dimensional axisymmetric model was constructed to predict the ablation of the insulation layer in an end burning rocket motor by using the Computational Fluid Dynamics (CFD) software Fluent. The insulation material of graphite was used in the model. The wall surface reactions and discrete phase erosion were applied to simulate the insulation layer ablation. The influence of the burning surface movement was analyzed by using the dynamic mesh method. Numerical results show that the erosion rate increase with the increasing of burning time. The maximum erosion rate occurs at the upstream of the nozzle throat. There has a high erosion rate closing to the burning surface, and it decreases gradually away from the burning surface and becomes zero near the nozzle. It’s found that solid particle deposition appears on the inner surface of combustor closing to the nozzle, and it increases with the increasing of time.

Abstract: The indoor thermal comfort is the basic thing for each and every occupant, not only in tropical areas but also all over the world. It is necessary to make an energy efficient roof design and to improve the indoor condition of the building. This paper is focused on the roof design to develop the ventilation system so as to obtain low attic temperature without effecting the environment and keep the interior of the building cool. In the present study, four identical roof models were fabricated to carry out laboratory tests to evaluate their performances. In the roof models, aluminum (Al) tubes were used as a moving-air path (MAP) which acts as a ventilation channel. These channels allows the natural ventilation to take out hot air to the outside. In addition, an insulation layer and ventilation fans were integrated with the Al tubes to get better performance. For the combination of those features, the results revealed that the attic temperature was reduced remarkably, compared to the ordinary roof model. This comprehensive roof model will be the most suitable to the environment and applicable for its improved performance.

Abstract: The uniformity of thickness of insulation layer on communication cable is an important technique index to guarantee the communication cable has good mechanical and physical properties. Therefore the control method for uniformity of insulation layer on communication cable is desiderated to be researched. In this paper, a control system which took two laser displacement sensors as a detection unit, a CS1G-H PLC of OMRON as a central control unit, two servo drivers and two servo motors of the SMARTSTEP-A series of OMRON as a servo system, a touch screen as a man-machine interface and applied PID and PDFF control algorithms was designed. The system was proved that the operation was reliable and the desired requirements could be achieved based on laboratory simulation and debugging.

Abstract: Soft magnetic powder cores are used for electromagnetic conversion coils, which are essential parts in automotive, home appliance, and other electronics industries. These cores are manufactured through the process of compacting pure iron powder covered with an insulation layer, and are distinguished by high electromagnetic conversion efficiencies. However, soft magnetic powder cores suffer from one problem: their electromagnetic conversion efficiencies drastically decrease when they are subjected to conventional finishing processes. This is directly attributable to the formation of conductive layers on finished surfaces, which significantly reduce the electrical resistance of material surfaces. As a solution to this problem, we developed an electrolytic re-insulation grinding method that finishes materials while applying a current between the material and the grinding wheel. This method regenerates the insulation properties of soft magnetic powder cores through the electrolytic removal of conductive layers formed during finishing, thereby improving electrical resistance. This development enables the finishing of soft magnetic powder cores without compromising their electromagnetic conversion efficiencies.

Abstract: In the previous work, we reported a P/M soft magnetic material with super low core loss value of W10/1k = 68 W/kg which is lower than that of 0.35mm-thick flat rolled soft magnetic laminated steel sheets. But this material lack of strength characteristics due to spherical particles produced by a gas-atomizing method. That is, the value of transverse rupture strength (TRS) was only 20MPa when a non-hygroscopicity resin was used as binder. In order to achieve both low core loss and high strength, the iron powder (shape, surface morphology) and binder strength was improved, and we were able to obtain a material with TRS of 80 MPa and core loss (W10/1k) of 108 W/kg of. Furthermore, by using this binder system, we were able to obtain a TRS of over 50MPa for the material with spherical particles (W10/1k = 81 W/kg).