ECLSS-Thermal Integration 2D: Interface Heat Exchanger

Real spacecraft life-support "integration" is not a slogan — it's a handful of physical components that let independently-designed subsystems talk to each other without ever mixing their fluids. This simulator models the single most important one of those on a station-class vehicle: the Interface Heat Exchanger (IFHX) that couples the cabin's internal water thermal-control loop to the external ammonia loop feeding the radiators. A three-way mixing valve sets what fraction of internal flow is routed through the IFHX, and a real effectiveness–NTU heat-exchanger model plus a first-order thermal-mass energy balance determine whether the loop settles into equilibrium or runs away. This is the 2D schematic sibling of the 3D version: the same physics, rendered as a flat, pannable/zoomable pipe diagram with a live temperature strip-chart, and two coolant loops shown as particle streams meeting only inside the exchanger.