Exergy Destruction in a Heat Exchanger

This simulator visualises a counterflow heat exchanger from the standpoint of the second law of thermodynamics, not just the first. Adjust the hot and cold inlet temperatures plus the exchanger's effectiveness and capacity ratio, and watch a 3D counterflow core carry hot particles one way and cold particles the other, colour-shifting along their length as heat moves between them. The energy balance always closes perfectly — Q lost by the hot stream equals Q gained by the cold stream — but the entropy-generation and exergy-destruction readouts, computed from the Gouy-Stodola theorem, reveal the usable work that finite-ΔT heat transfer throws away even in a "100% efficient" exchanger, and the second-law efficiency bar shows how design choices like effectiveness and flow matching change that hidden loss.