Abstract: The heat exchanger, gas to fluid, consists of a cylindrical wall separating fluid from gas and a helical strip forming secondary exchange surfaces which carry additional heat exchange members forming tertiary heat exchange surfaces to increase the active surface and the heat transfer coefficient in the gas compartment.

Abstract: The invention relates to reciprocating pumps for liquids and gases, especially fluid-solid dispersions containing abrasives. The cylinder is made from material which is harder than the abrasive particles of the fluid. This cylinder rotates around the piston, independent of the number of strokes per minute, so that a lubricating film is formed. This rotation prevents both contact between the piston and the cylinder and freezing of the piston within the cylinder.