A sublimator includes a porous plate having a first surface comprising a low pressure side and a second surface comprising a high pressure side such that refrigerant is configured to move through the porous plate from the high pressure side to the low pressure side. The second surface defines a primary heat transfer surface. The porous plate further includes a plurality of secondary heat transfer surfaces integrally formed on the primary heat transfer surface to facilitate flow and evenly distribute refrigerant across the high pressure side of the porous plate.