Thermal Control System

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Thermal Control System
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The Three Mechanisms of Heat Transfer

• Conduction - The transfer of heat through a solid
• Heat exchangers
• Cold plates
• Convection - Transfer through fluids both liquids
  and gasses
• Radiation - Transfer through vacuum or empty
  space
• Does not need a vacuum to radiate heat
• Radiators

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System Overview

• Divided into internal and external loops, as well
  as per module
• Divided into 35 and 62 degree loops
• 35 degree loop cools all critical systems
• 62 degree loop cools all non-essential systems
• Maintains a comfortable living and working
  temperature for the station

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Internal TCS system

• Cold plates, LCA, Pumps, Heat exchangers
• All systems use water in case of leaking, as it
  is non toxic, and conducts heat very well.

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Cold Plates

• Aluminum box conducts heat to water piping within
• No power required, all flow is controlled by pump
• Solenoid valve can bypass flow if necessary

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Internal Pump

• Circulates water through the cold plates
• Powered by EPS loads
• Status, Flow rate, Pressure, Temperature,
  Voltage, Amperage

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Loop Crossover Assembly (LCA)

• Allows both 35 and 62 degree loops to be
  connected within a given module
• A single pump can only handle approximately 10
  cold plates continuously at a time
• Valves adjust flow to Heat exchangers

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Heat Exchangers

• Identical internal and external systems
• Intertwined spirals of piping allow heat to
  conduct between the internal water systems, and
  the external ammonium systems
• Ammonium and water never mix as all heat is
  conducted through the walls of the piping
• Sensors will alert crew to any leak of ammonium
  that would possibly contaminate the water system.

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External Thermal Control System

• Heat exchanger, Pump Package Assembly, TRRJ,
  Radiator
• Uses ammonium to prevent damage to pipes from
  extreme temperature differences
• Ammonium has a lower freezing point than water,
  however in higher concentrations can prove toxic
  to the crew

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Pump Package Assembly (PPA)

• Circulates ammonium through external systems
• 5 PPAs share different heat exchangers in all
  modules, but are still divided into 35 and 62
  degree loops
• Powered by EPS loads

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Radiators / TRRJ

• Thermal Radiator Rotation Joint
• Acts as a large loop crossover for PPAs
• Radiators allow heat to radiate into the space
  environment.

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Warning signs of a SOBE

• Red indicator lights on the system wall
• Increase in ambient temperature and or humidity
• Ammonium smell (very obvious)
• Contingency of another SOBE

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Things to check during a SOBE

• Flow Rate
• If no fluid is moving, then no heat is either
• Loads for faulty pump/PPA
• No power No flow
• Ammonium leaks (sensor info)
• Toxic to Crew
• Reduces flow in external system