A heat exchanger includes features for alleviating high pressure drops and controlling the expansion of fluid during freezing. The heat exchanger includes an interface layer in which heat is transferred from a heat source to a fluid. A manifold layer couples to the interface layer. The manifold layer includes a first set of substantially vertical fluid paths for directing the fluid to the interface layer. The manifold layer further includes a second set of substantially horizontal fluid paths, perpendicular to the first set of fluid paths, for removing the fluid from the interface layer. Preferably, the heat exchanger includes an upper layer for circulating the fluid to and from the manifold layer. The upper layer can include at least one of a plurality of protruding features and a porous structure. Preferably, a porous structure is disposed along the interface layer.