Research On Thermal Design Of Stratospheric Electronic Equipment

With the continuous development of near space technology,a new means of communication-stratospheric communication has emerged.However,the special complex thermal environment in the near space has become one of the difficulties faced by the stratospheric communication platform during staying in high altitude.The thermal design of stratospheric electronic equipment is very complicated because it generates a large amount of heat and works directly in the harsh space thermal environment.In order to ensure the normal operation of the stratospheric electronic equipment,the internal and external thermal environment of the equipment is analyzed first in this paper and the atmospheric environment model around the electronic equipment is established.Secondly,a coupling model of convection and radiation is established for calculating the temperature distribution characteristics of the electronic equipment and it considers the convection in the stratosphere,the natural convection inside the equipment,the direct solar radiation,the atmospheric radiation,solar radiation reflection by the ground,the earth’s infrared radiation and the radiation of the equipment itself.The temperature distribution of the stratospheric electronic equipment in the stratosphere 20 km,the ground and the rising process are simulated,considering the effects of different power,different wind speed,different environmental conditions,different altitudes,different launching seasons,different launching speeds on the temperature distribution of electronic equipment.Several thermal control design schemes for stratospheric electronic equipment are proposed,such as opening ventilation holes on the side of the equipment,designing air-cooled cold plate,adding heat dissipation fins on the external surface of the equipment and improving the blackness of the thermal control coating on the external surface of the equipment.The calculation results show that: For the cooling of the stratospheric electronic equipment,both convection heat transfer and radiation heat transfer affect the temperature distribution of electronic equipment.Although the stratospheric atmospheric pressure is low and convection heat transfer is weak,convection heat transfer of the equipment accounts for more than 50% of the total heat dissipation.Convection heat transfer is the main method of equipment heat dissipation.Therefore,in the thermal design of stratospheric electronic equipment,the method of enhanced convection heat dissipation can be considered to control the temperature of the equipment.The heat dissipation method of opening holes or increasing the blackness of the surface can make the temperature of each devices in the electronic device fall more uniformly.Adding a cold plate or a heat dissipating fin can achieve concentrated heat dissipation of a higher temperature device.Several heat dissipation methods should be combined to control the temperature of higher power electronic equipment.Finally,the experimental verification of the stratosphere simulation environment was carried out.The experimental data of the typical operating conditions show that the experimental values are in good agreement with the calculated values,which verifies the correctness of the calculation model.The research in this paper is of great significance for the thermal design of stratospheric electronic equipment.