Process for the thermal treatment of fluids

A process for abruptly increasing fluid temperature from a first to a second temperature, maintaining the fluid temperature at substantially the second temperature for a short period of time and abruptly decreasing the fluid temperature well below said second temperature, comprising:

• (a) passing a fluid at the first temperature and at a predetermined fluid inlet mass flow rate and fluid inlet pressure into and axially through a perforated mixing chamber and into a constricting means of an axial nozzle having a passage means
• (b) passing a vapor through an annular chamber extending around said mixing chamber and injecting said vapor from said annular chamber into said mixing chamber perpendicularly to said fluid flow in said mixing chamber, at an inlet temperature superior to said second temperature, at a vapor inlet mass flow rate and at a vapor inlet pressure superior to the fluid inlet mass flow rate and the fluid inlet pressure, respectively, at least partially mixing the vapor with the fluid and at least partially condensing said vapor so as to raise said fluid temperature from said first temperature,
• (c) passing a stream of said fluid, said vapor and the vapor-fluid mixture thus obtained, at a mass flow rate corresponding to the sum of said fluid and vapor mass flow rates, through and out from said mixing chamber, into said constricting means and then through said passage means in axial extension with said constricting means for producing complete condensation of said vapor in said stream entering said passage means so as to increase said fluid temperature up to said second temperature, thereby generating cavitation in the vicinity of a point of maximum constriction of said stream located inside said passage means to produce a critical flow therein, and
• (d) conveying said stream exiting from said passage means into a pressure release enclosure under reduced pressure for abruptly evaporating said condensed vapor from said stream, thus separating said vapor from said stream and abruptly cooling said fluid.