A heat exchanger (120) includes a core (130) containing inlet manifold (140), outlet manifold (126), interconnecting channels (144) and a heat-transfer surface (128). Each interconnecting channel fluidly communicates at one end with a corresponding inlet manifold and at the other end with the two outlet manifolds located adjacent that inlet manifold. The inlet manifolds are located distal from the heat-transfer surface. The interconnecting channels are configured such that substantially all of the heat collected by a working fluid is collected as the working fluid flows from the inlet manifolds away from the heat-transfer surface in a direction substantially normal to the heat-transfer surface.