Abstract: An internal fin tube heat exchanger comprises a cylindrical tube having on its inside a continuous heat exchange member with a plurality of legs branched from a central longitudinal extending member. The heat exchange member can be metal strip cut with a plurality of ribs disposed at an acute angle thereto, so that when the member is pulled into the tube, the ribs do not resist movement in one direction but do resist reverse movement in the opposite direction, which opposite direction is also the direction of flow of the fluid within the tube. Thus the fluid does not dislodge the heat exchange member. The ribs can be cut in various patterns and the strip is rotated when being drawn into the tube so as to impart a twist thereto, thereby to position the ribs all about the periphery of the tube. The ribs can have feet thereon that extend either peripherally of the tube or longitudinally of the tube.

Abstract: The heating means of a greenhouse is combined with a source of waste heat. Preferably, the heating means is a surface heat exchanger placed in the flow path of air which is circulated in the greenhouse while the waste heat source is a mixing condenser of a steam turbine power plant. The condensate from the mixing condenser is cooled down in the surface heat exchanger which warms up the air in the greenhouse. If it has water spray means associated with it which is operated dependent on the moisture content of circulating air, cooling of the condensate and warming up as well as moistening of circulated air is effected by the same system at the expense of waste heat.

Abstract: Steam turbine power plants employ condensers for condensing the dead steam of the turbine. The required cooling in the condenser is obtained by cooling water which is, in case of dry cooling towers, injected into a mixing condenser. Recooling of the cooling water is obtained in surface heat exchangers of the dry cooling tower which carry off the heat by means of air.Where the employment of such system is jeopardised by the hazards of climatic conditions, it is suggested to associate water cooled heat exchangers with the surface heat exchangers and the dry cooling tower of the system. Such water cooled heat exchangers serve as auxiliary means where the cooling effect of the surface heat exchangers of the dry cooling tower fails to ensure a desired low condensation temperature in the mixing condenser.