Unprotected skin and external surfaces of a spacecraft in earth orbit may experience temperature variations from −50°C to +100°C during exposure to cold space or sun. As a result, thermal management of spacecraft becomes extremely important. One latest trend is to provide flexibility and control in the thermal design that involves variable emittance surfaces consisting of electrochromic (EC) coatings. For investigational purposes, a sample electrochromic device is evaluated for variable emittance in simulated space conditions. A vacuum chamber with a liquid nitrogen circulated blackbody shroud is employed to simulate space conditions. The 63.5 × 63.5 mm test sample supplied by a small business research firm is mounted on an aluminum plate heated by an electrical resistance heater. The sample is thermally insulated by a heat shield from all surroundings excluding the active front surface facing the shroud. The heat shield is uniformly maintained at the sample temperature using an independent circuit of resistance heaters and temperature controllers. A steady state energy balance is applied to the test sample to determine the emittance as a function of temperature and DC bias voltage applied across the anode and cathode. Tests were performed to verify the switchability from high to low emittance states and vice versa. The difference between the high and low emittance values (Δε) obtained in the present calorimetric measurement is compared with the data obtained from FTIR measurements performed by the supplier of the EC sample. Results obtained in the present experiments compare closely with supplier data and prove the effectiveness of the variable emittance sample in space conditions. The validity of the calorimetric experiment is confirmed by testing materials with known emittances, such as black paint and polished metals. Error analysis of the system predicts an emittance accuracy of ±5% at sample temperatures in the range of −50°C to 100°C.


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    Titel :

    Evaluation of an Electrochromic Device for Variable Emittance in Simulated Space Conditions


    Beteiligte:

    Kongress:

    SPACE TECHNOLOGY AND APPLICATIONS INT.FORUM-STAIF 2005: Conf.Thermophys in Micrograv;Conf Comm/Civil Next Gen.Space Transp; 22nd Symp Space Nucl.Powr Propuls.;Conf.Human/Robotic Techn.Nat'l Vision Space Expl.; 3rd Symp Space Colon.; 2nd Symp.New Frontiers ; 2005 ; Albuquerque, New Mexico (USA)


    Erschienen in:

    Erscheinungsdatum :

    06.02.2005


    Format / Umfang :

    9 pages





    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch



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