A piston with an integrated heat exchanger comprises a seal, a piston hub and a piston rod. The piston hub is further provided with a coolant reservoir and an outlet nozzle at its lateral surface. The heat exchanger integrated into the piston hub and/or the piston hub include a coolant manifold, a coolant passage communicating thereto, and a plurality of channels connecting to the coolant manifold and extending radially to the annulus. Said heat exchanger provides enhanced efficiencies of heat-exchange and debris-flushing.