An alternative design for the industrial multitubular shell-side fixed-bed ammonia converter is presented. It can be ran either under cocurrent or countercurrent cooling flow. The behaviour of these two alternatives is compared with that of the existing fully-autothermal co- or countercurrent designs. The comparison among the four cooling schemes is drawn by means of a heterogeneous two-dimensional mathematical model. The results indicate that the cocurrent alternative of the new design is capable of producing a significant increase in the ammonia yield. This higher value could also be obtained al lower maximum temperatures, which would lengthen the catalyst life.