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Min J.,Tsinghua University | Zhang B.,China Academy of Space Technology | Zhang B.,Beijing Key Laboratory of Space Thermal Control Technology
Chinese Journal of Chemical Engineering | Year: 2015

Numerical calculations were conducted to simulate the flow and mass transfer in narrow membrane channels equipped with delta winglets, which are often used as longitudinal vortex generators to enhance heat transfer in heat exchanger applications. The channel consists of an impermeable solid wall and a membrane. The delta winglets are attached to the solid wall surface to enhance the mass transfer near the membrane surface and suppress the concentration polarization. The winglet performance was evaluated in terms of concentration polarization factor versus consumed pumping power. Calculations were implemented for NaCl solution flow in a membrane channel having a height of 2.0 mm for Reynolds numbers ranging from 400 to 1000. The delta winglets were optimized under equal pumping power condition, and the results of optimization suggest winglet height of 5/6 of the channel height, aspect ratio of 2.0, attack angle of 30°, and a winglet interval equal to the channel height. The optimal delta winglets were compared with the optimal rectangular winglets we found previously, and it is shown that the rectangular winglets yield a somewhat better performance than the delta winglets. © 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved. Source


Min J.,Tsinghua University | Zhang B.,Beijing Key Laboratory of Space Thermal Control Technology
Chinese Journal of Chemical Engineering | Year: 2014

Numerical calculations were conducted to simulate the flow and mass transfer in narrow membrane channels with and without flow disturbers. The channel consists of an impermeable solid wall and a membrane surface with a spacing of 2.0mm. The flow disturbers studied include rectangular winglets, which are often used as longitudinal vortex generators to enhance heat transfer in heat exchanger applications, as well as square prism, triangular prism, and circular cylinder, which are used here to mimic the traditional spacer filaments for comparison of their abilities in enhancing the convective mass transfer near the membrane surface to alleviate the concentration polarization. The disturber performance was evaluated in terms of concentration polarization factor versus consumed pumping power, with a larger factor meaning a more serious concentration polarization. Calculations were carried out for NaCl solution flow with Reynolds numbers ranging from 400 to 1000. The results show that the traditional flow disturbers can considerably reduce the concentration polarization but cause a substantial pressure drop, while the rectangular winglets can effectively reduce the concentration polarization with a much less pressure drop penalty. The rectangular winglets were optimized in geometry under equal pumping power condition. © 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved. Source


Xiang Y.-C.,China Academy of Space Technology | Xiang Y.-C.,Beijing Key Laboratory of Space Thermal Control Technology | Xiang Y.-C.,Beihang University | Chen J.-X.,China Academy of Space Technology | And 3 more authors.
Yuhang Xuebao/Journal of Astronautics | Year: 2015

According to Jade Rabbit Rover geometry, mission requirements and mission environment, the idea of thermal control system design for Jade Rabbit Rover is put forward; the thermal control system designs for Jade Rabbit Rover during moon day and moon night are described, in which a two-phase fluid loop and a radioisotope heat unit are used to warm Jade Rabbit Rover in moon night. Thermal control system for Jade Rabbit Rover is tested by using the thermal balance tests and flight tests, and the temperature of the equipment meet technical criterion. © 2015, Editorial Dept. of JA. All right reserved. Source


Jian L.,Beijing Key Laboratory of Space Thermal Control Technology | Zhang J.,Beijing Key Laboratory of Space Thermal Control Technology | Zhao X.,Beijing Key Laboratory of Space Thermal Control Technology | Huo Y.,Beijing Key Laboratory of Space Thermal Control Technology
Zhongguo Kongjian Kexue Jishu/Chinese Space Science and Technology | Year: 2014

To study the influence of the void on phase change heat transfer process under microgravity, the void model using temperature sorting algorithm was built based on the enthalpy method, which can simulate the interaction between the void and the temperature distribution. The 2D model of phase change material container was built to study the void migration rule under the periodical heat flux boundary condition. The results show that from the initial time to the 8th period the void disappears gradually in the low temperature region and appears in the high temperature region. The void moves to the high temperature region and diffuses along the isotherms. The void migration increases heat resistance along the heat transfer route and the temperature difference about 3 ℃ between cold and hot boundaries. ©, 2014, Zhongguo Kongjian Kexue Jishu/Chinese Space Science and Technology. All right reserved. Source


Zhang B.,China Aerospace Science and Technology Corporation | Zhang B.,Beijing Key Laboratory of Space Thermal Control Technology | Xiang Y.,China Aerospace Science and Technology Corporation | Xiang Y.,Beijing Key Laboratory of Space Thermal Control Technology | And 6 more authors.
Zhongguo Kongjian Kexue Jishu/Chinese Space Science and Technology | Year: 2016

In the brutal temperature environment in Sinus Iridium with the range between -180℃ to +90℃, it needs to solve camera heat dissipation during lunar daytime and heat preservation in moonlit night without electric energy supply under the complex rotation of YuTu Rover mast. Besides, the uncertainty of lunar dust still results in risks to thermal design. In order to solve the extreme high temperature problem in daytime, the mast rotates to an optimal position for heat dissipation and avoids the camera being too hot, and the proportion of power on and off is optimized. In extremely low temperature at night, the thermal coupling state of the camera and the rover has been changed; the mast is folded into the fence to keep warm by means of heat preservation systems. Based on the analysis of the cause of dust subsidence, the max sun elevation angle for working is restricted to avoid risks by dust. According to the thermal analysis results and in-orbit results, it can be confirmed that the highest temperature decreased 15 degrees by methods of finding optimal position and optimizing the proportion of power on and off. By folding the mast in moon night, cameras have safely undergone the cold night, therefore 4.5 W power generated by RHU has been saved. It indicates that the coupling method between thermal control and posture adjustment can be used to solve the high-low temperature problem of movable cameras on the planet' surface rover, and reduce the rover power demand for RHU. It could provide thermal design reference for the follow-on celestial body surface explorations. © 2016, Editorial Office of Journal of Chinese Space Science and Technology. All right reserved. Source

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