Process engineering apparatuses are often equipped with complex structures inside to intensify the heat and mass transfer. This heat transfer enhancement at the same time also results in an increase in pressure drop. Therefore, structures are usually used that only cause a moderate increase in this. One such class of structures, which has been the subject of much discussion in recent years, is highly porous network structures that are permeable to fluids on all sides. These can be composed of irregular and stochastically distributed cells (sponges) or of regular unit cells (periodic open cellular structures, POCS). In principle, it is always desirable to have the most generally valid correlations possible for determining the heat and momentum transport (pressure drop) for the design of process engineering apparatus. Within this contribution, a heat transfer and a pressure drop correlation is given for sponges, based on findings from experimental and numerical work on different sponges. In contrast to sponges, POCS have the enormous advantage that they can be fabricated by means of additive manufacturing specifically according to requirements with regard to the dimensions of the installation space, geometric characteristics and cell geometry. This contribution therefore focuses on a methodology for the determination of heat transport and pressure drop of POCS, which is based on a superposition approach. There, the unit cell is decomposed into its smallest structural elements. Characteristic strut arrangements are created, for which the heat transport and pressure drop are determined by means of numerical simulations. The data determined in this way is then summed up to derive a heat transfer or pressure drop correlation for the corresponding POCS. The advantage of this methodology is that it is applicable for various types of unit cells.