Thermal Environment

Initial thermal calculations are based on a seven node blackbody analysis (six sides and the insides).

The sun is modelled as a black body.
A node is a finite sub-division of the thermal system so that thermal balance and heat flow may be calculated in unsimilar components.

There are 2 elements to each node, and 3 types of node.
The elements are the Temperature T, which is analogous to potential.
and thermal mass C, or capacitance.

The 3 types are,

Errors that can occur are due to,
Material Thermal Properties
Boundary Conditions
Node Size (smaller the better)
Node Centre Placement
and Time Increment of Dynamic Calculations

-for normal materials
-heat flow in or out of materials
-involves potential, capacitance value, net heat flow, and time.

\begin{align} \Sigma { \delta Q \over \delta t } - {C \Delta T \over t} = 0 \end{align}

-has zero capacitance
-useful for small components, such as bolts, thin films, gas contents of tubes and low-mass insulation
-but should only form a minority of the number of nodes

\begin{align} \Sigma {\delta Q \over \delta t } =0 \end{align}

-has infinite capacitance
-for constant temperature boundaries or heat sinks (such as space)
-it can be used for nodes that have a large thermal capacitance (lots of mass) though this is not realistic for cubesat

\begin{equation} T = constant \end{equation}

Nodes typically sub-divide the main structure into simple volumes that are easy to calculate.
In the case of a simple seven node model each of the solar panels, and the internal components are nodes.

The solar panels are modelled for 3 cases,
-in full sunlight, where the maximum number (3) of panels are illuminated
-in partial sunlight, where only 1 panel is illuminated
-and in shadow, where no panels are illuminated

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