Next: Appendix #appacronyms#1687>: Glossary Up: CUBIC INSTRUMENT HANDBOOK Previous: Appendix #appelectronics_design#1673>: Electronics

# Appendix #appthermal#1682>: Thermal Analysis

This Appendix presents detailed results of a test run of our 73 node thermal model. The first figure shows the locations of the 73 nodes. It is followed by the program output, which is followed in turn by a plot of the results for about a dozen of the nodes. This model was run for a total of 5 hr.

Our thermal modeling program allows nodes to have one of three characteristics: they can be thermal reservoirs, in which case their temperature is specified and remains constant, but can be changed during the course of the run to a new constant temperature; they can be heat sources or sinks, in which case a specified amount of power is added or removed from the node (heat sources and sinks can be turned on and off at specified times); or the node can be a normal floating node whose temperature is determined by the solution of the differential equations linking it to surrounding nodes. In our models, we have used a simplistic model of the external environment which treats it as a thermal reservoir whose temperature changes during the orbit. The night side of the orbit uses a temperature of -250 C, the day side uses 0 C, and morning and night portions of the orbit use -100 C. We assumed that SAC-B acted as a thermal reservoir with temperature ranging from +35 C to +40 C, and that ISENA was a thermal reservoir at +20 C. Because of the high SAC-B temperature, this run represents a worst case scenario.

The program output lists the detailed model inputs. Most of these are self-explanatory, but not all are completely labeled. The thermal mass, or heat capacitance, of each node is in Joules per degree Celsius. The radiative coupling coefficients that are used are in units of square meters. The conductive coupling constant is in units of Watts per degree Celsius.

The program output consists of a summary table showing the initial and final temperature of each node, plus the minimum and maximum temperature for each. In addition, a file is produced that gives the temperature of each node for each time step. This file was used to produce the plot at the end of this Appendix.

Next: Appendix #appacronyms#1687>: Glossary Up: CUBIC INSTRUMENT HANDBOOK Previous: Appendix #appelectronics_design#1673>: Electronics

David N. Burrows
Thu Oct 24 10:59:06 EDT 1996