Abstract: An air-cooled heat exchanger for cooling industrial liquids, particularly such which have a tendency to form deposits at least when the temperature thereof drops below a given level, includes a plurality of externally ribbed hollow cooling sections which are arranged in a plurality of parallel rows each including a multitude of the cooling sections, and a plurality of connecting sections which so communicate the cooling sections with one another as to form at least two separate sets of interconnected sections the cooling sections of which alternate with one another in each of the rows. The sections are so interconnected that the liquid to be cooled will flow through each of the sets in each of the rows and between the rows in a meandering path and in a mutual cross-countercurrent with respect to the flow of cooling air which is advanced by a blower transversely of and past the cooling sections. The throughput rate of the blower may be controlled in dependence on the exit temperature of the cooled liquid.