What does this equation mean?

Heat reuse imposes a real constraint back onto the cooling-loop design, and it is a direct consequence of the $\dot{Q}$ = $\dot{m}$ $c_p$ $\Delta$ T relation above: a district heating network needs delivery water above some useful temperature (often 60–90°C depending on the network), which is far above what a direct-to-chip loop returns on its own. A heat pump bridges that gap, but every heat pump has a coefficient of performance that degrades as the temperature lift it must perform increases — so a datacenter operator sizing for heat reuse has a genuine incentive to run its internal coolant loop at a higher return temperature than a pure cooling-efficiency design would choose, trading some cooling-loop pumping efficiency for a smaller, cheaper temperature lift on the heat-pump side. This is a real engineering trade-off with public precedent, not a hypothetical.