Heat Transport Section of LM ECS (Part 5, Apollo Control Systems)

Lunar Module ECS (Environmental Control Subsystem) included a section called HTS (Heat Transport Section). Its job was to remove excessive heat from mostly electrical circuits and batteries. It did it by circulating water-glycol through cold plates that were placed under those circuits and sublimated the heat to the space using water sublimators.

Typical cold plate with primary and secondary loop connections

There was a primary and secondary coolant loop. Here are some schematics of the system.

Simplified schematic of the HTS

The following one dates back to year 1966 and might have some differences to later drawings.

HTS year 1966

Maybe more accurate flow diagram.

HTS drawing year unknown

Here is the most detailed schematic from year 1965 showing the whole ECS but there are probably drawing errors in it since for example the primary loop at the lower left corner does not have any output from the cold plates connected to the actual coolant loop.

ECS year 1965

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