Due to their small size and other attractive features, nanosatellites are becoming popular in space applications. Experimental investigation of the thermal behavior of such a satellite can be conducted in a laboratory setup using a thermal vacuum chamber to mimic the conditions of outer space. A small, cost effective thermal vacuum system was desired for performing thermal vacuum testing on nanosatellites. Numerical calculations and laboratory testing were performed as part of the design of this thermal vacuum system. A numerical method using the finite element method was employed to determine the amount of heat flux needed to be applied at the bottom plate of a satellite to achieve a certain rate of temperature increase in the plate. The numerical analysis was performed on a 40.5 kg satellite structure to predict the heat rate per unit area through its bottom surface when it was cycled in the temperature range of −40°C to +80°C with a rate of temperature change from 1°C/min to 5°C/min.
A time dependent increase in temperature on the bottom wall was used as a boundary condition. The rest of the satellite walls were assumed to be insulated. Contact resistances between the components of the satellite structure were neglected. Temperature and heat flux distributions on various walls of the satellite were computed and reported in the study. From the numerical results, a maximum heat flux rate of 3,332 W/m2 was calculated on the bottom plate for a temperature increase rate of 1.5°C/min of the plate.
A similar experimental setup was tested under similar conditions as a comparison and as a method to validate the thermal system design. Experimental results indicated a heat flux rate of 17,094 W/m2 through a test satellite. The difference between the numerical and experimental results is attributed to geometric differences between the numerical satellite model and the experimental test structure.