A heat transfer assembly for transferring heat from a heat generating device (5) to a circulating fluid, said heat transfer assembly comprising - an evaporator device (3) having at least one microchannel (1) formed therein, in thermally conductive contact with said heat generating device (5), - a condenser device (7), - actuating means (8) and manifold means (6) for circulating said fluid between said evaporator device (3) and said condenser device (7), wherein said heat transfer assembly further comprises a bubble generator (10, 100) capable to create bubbles in said at least one microchannel (1) at a controlled frequency.