Abstract: The efficiency of heat exchangers for cooling exhaust gases from internal combustion engines of stationary plants for the operation of heat pumps or for the combined generation of current and heat, and for the cleaning of the heat exchangers is increased. The heat exchanger, after a liquid secondary heat transfer medium is emptied therefrom, or with the circulation of a gaseous secondary heat transfer medium cut off, is periodically heated by the hot exhaust gases to a temperature which is sufficient for the automatic cleaning of the heat exchanger surfaces.