Rotating heat exchanger for a dryer

A compact and lightweight rotary heat exchanger for transferring heat from a hot gas flow to a cold gas flow has a low mass matrix in the form of a wheel. The matrix is rotated at high speed into continuous consecutive contact with the respective hot and cold flows. A fixed splitter runs along a diameter of the inner circumference of the matrix in order to segregate the flows as they pass radially across the matrix. In combination with a domestic clothes dryer, the matrix is rotated directly on the drive shaft for the dryer's blower. The matrix wheel rotates between heated dryer exhaust air and incoming room air to preheat the dryer intake air.