This paper uses finite element analysis software to perform thermal analysis on closed outdoor cabinets and internal equipment. According to different structure modes and different fluid control modes inside the cabinet, the simulation of the fluid movement and temperature field distribution inside the cabinet is carried out, and the changes of the internal flow field and temperature field under different conditions are obtained, thus providing a theoretical support for practical applications. .
I. IntroductionDue to the demand for substation business and the advancement of technology, the integration of primary and secondary equipment in substations and the development of intelligent functions have also resulted in changes in the configuration and installation of intelligent terminal equipment, from the original indoor open layout to outdoor sealing. Place the transition. In the case of outdoor unobstructed, the radiation of the sun and the heat dissipated by the equipment itself may cause the internal temperature of the sealed cabinet to exceed the allowable range of the equipment. If the device is operated under overload for a long time, the performance of the components may be reduced, which may result in Device failures affect the stability of the entire system, so how to control the internal temperature in a sealed outdoor cabinet becomes the key to outdoor cabinet design.
At present, most of the thermal load design analysis of complex systems uses finite element analysis. This paper uses SolidWorks SimulaTIon software to calculate and analyze the flow field and temperature field inside the outdoor cabinet, which provides an intuitive effect for outdoor cabinet thermal simulation and improves the reading power of calculation. In addition, according to the simulation results, the local structure can be easily modified, and the structural design is gradually optimized.
Second, the heat transfer mechanismUsually, there are three ways to transfer heat.
(1) Conduction. Conduction is the primary means of heat transfer in solids. The amount of heat transfer is proportional to the thermal conductivity, temperature difference, and area of ​​the material, and inversely proportional to the length of the passage.
(2) Convection. Convection is the way heat is transferred between a solid surface and a nearby fluid. The amount of heat transfer is proportional to the convection coefficient, surface area, and temperature difference between the surface and the fluid.
(3) Radiation. Thermal radiation is a process in which an object at a certain temperature is emitted outward in the form of electromagnetic waves. The magnitude of the thermal radiation of the object is proportional to the surface area of ​​the object, the surface emissivity of the object, and the fourth power of the temperature.
The heat dissipation design of the sealed outdoor cabinet is to follow the above principle, optimize the cabinet structure, reasonably arrange the internal components, and select a suitable heat dissipation method to achieve the purpose of dissipating heat from the internal components of the device.
Third, establish a mathematical modelControl equation
In the calculation process, the combined effects of fluid and heat transfer should be considered, and the calculation basis is as follows.
In steady state conditions: the continuous equation of the fluid is . Where u, v, and w are velocity components in the x, y, and z directions.
The momentum equation is
Where p is the pressure and is the viscosity coefficient.
The energy equation is .
The simulation calculation is to obtain the distribution of u, v, w and P and T of each point of the fluid at steady state by solving three equations.
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