Parametric Analysis of Heat Transfer on Multistage Cryogenic Radiator

A theoretical and experimental parametric study of the heat-transfer phenomena on a multistage passive cryo- genic radiatorispresented. Thisinvestigation was performed in theframeof a cooperativeeffort between Clemson University and the Federal University of Santa Catarina. Passive cryogenic radiator technology is under devel- opment at the Satellite Thermal Control Laboratory at the Federal University of Santa Catarina, where two experimental prototypes have been built and ground tested. The mathematical model, developed to predict the temperature distribution on the radiator stages, was used to study the sensitivity coefé cients with respect to the design parameters. The design parameters considered are the radiator stage' s surface emissivity, the multilayer insulation effective emissivity, the radiator support' s global conductance, and the thermal load over the radiator stages. This sensitivity analysis showed that the thermal joint conductance between the stages and the support structure (aluminum-Teè on ®) plays an important role in the temperature distribution of the radiator. An exper- imental study was conducted within the Mechanical Engineering Department of Clemson University to gather thermal conductance data for comparison with the theoretical results. The thermal conductance data were incor- poratedinto an analytical model developed for theprediction ofthetransient temperaturebehavior of a multistage cryogenic radiatorfor spacecraft applications. The data werealso compared with therecently developed model for thepredictionofthermalconductanceofpolymerand metaljoints. Ultimately,conclusionsarepresented aboutthe importance of the thermal conductancebetween the polymer support structure and the passive cryogenicradiator stages in the temperature distribution of the radiator.