Can anyone point me in the direction of some information regarding the use of superheated steam in heat exchangers. I know that it reduces the heat transfer rate as the bulk of the heat transfer is obtained by the change of phase, which only occurs after the steam has lost its superheat.

Well, it depends.  If the cold surface is below the saturation temperature of the steam, chances are that a nominal amount of superheat will not make any difference.  The exchanger will operate basically at the saturation temperature.  

However, if there is a LOT (say a few hundred degrees-Instrument Manifolds) of superheat, then it's a different ballgame.  The steam side heat transfer coefficient would then be based on a dry gas in the desuperheating portion of the exchanger, until it reaches a point where the wall temperature is at saturation.  The dry gas coefficient is MUCH lower than the condensing coefficient.  Chances are that the amount of surface required would then be greater than if just condensing the steam, even though the temperature difference in that portion is greater.

The amount of steam required would be slightly less than if just condensing.  It would be a function of the total enthalpy difference between the superheated enthalpy and the saturated liquid enthalpy (assuming that you would be controlling the steam with a simple trap at the outlet).

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