Protective recirculation means for heat exchangers

Claim 1

IN COMBINATION: A HEAT EXCHANGER HAVING FIRST AND SECOND FLUID PASSAGES INCLUDING PORTIONS DISPOSED INTERNALLY OF THE EXCHANGER IN HEAT TRANSFER RELATIONSHIP FOR CONVEYING A FIRST, RELATIVELY HOT FLUID AND A SECOND RELATIVELY COLD FLUID, RESPECTIVELY, IN HEAT TRANSFER RELATION TO ONE ANOTHER; SAID FIRST PASSAGE HAVING FIRST AND SECOND FLUID INLETS AND FIRST AND SECOND OUTLETS, SAID FIRST INLET AND SAID FIRST OUTLET BEING ADAPTED FOR CONNECTION TO AN EXTERNAL FLUID CIRCUIT; MEANS DEFINING A RECIRCULATION PASSAGE DIRECTLY COMMUNICATING SAID SECOND OUTLET TO SAID SECOND INLET THROUGH WHICH A PORTION OF SAID FIRST FLUID EXHAUSTING FROM SAID HEAT EXCHANGER AFTER HAVING BEEN COOLED BY SAID SECOND FLUID MAY RECIRCULATE TO MIX WITH AND COOL THE RELATIVELY HOT FIRST FLUID ENTERING THE HEAT EXCHANGER FROM SAID EXTERNAL FLUID CIRCUIT THROUGH SAID FIRST INLET; MEANS FOR INDUCING FLOW OF SAID FIRST FLUID THROUGH SAID RECIRCULATION PASSAGE FROM SAID SECOND OUTLET TO SAID SECOND INLET; TEMPERATURE RESPONSIVE MEANS DISPOSED IN EFFICIENT HEAT TRANSFER RELATION TO SAID FIRST PASSAGE ADJACENT SAID FIRST INLET SO AS TO BE HIGHLY RESPONSIVE TO THE TEMPERATURE OF THE HOT FLUID ENTERING THE HEAT EXCHANGER THROUGH SAID FIRST INLET; AND MEANS IN SAID RECIRCULATION PASSAGE CONTROLLED BY SAID TEMPERATURE RESPONSIVE MEANS FOR REGULATING RECIRCULATION FLOW OF SAID FIRST FLUID THROUGH SAID RECIRCULATION PASSAGE IN SUCH MANNER THAT SAID RECIRCULATION FLOW INCREASES IN RESPONSE TO INCREASING TEMPERATURE OF THE FIRST FLUID ENTERING THE HEAT EXCHANGER AND DECREASES IN RESPONSE TO DECREASING TEMPERATURE OF THE FIRST FLUID ENTERING THE HEAT EXCHANGER, THEREBY TO MAINTAIN THE TEMPERATURE OF THE COMBINED FIRST FLUID FLOWING FROM SAID FIRST AND SECOND INLETS TO SAID INTERNAL PORTION OF SAID FIRST PASSAGE BELOW A PREDETERMINED MAXIMUM TEMPERATURE.