
Originally Posted by
fatman57
apparently Sodium sulfate is used in heat storage applications as according to lovely wikipedia...........
"The phase change allows a substantial reduction in the mass of the material required for effective heat storage (83 calories per gram stored across the phase change, versus one calorie per gram per degree Celsius using only water), with the further advantage of a consistency of temperature as long as sufficient material in the appropriate phase is available."
So, with this in mind it is obvious that it should really only be chosen if a phase change is going to be incorporated in the design as that is one of its prime advantages (as I also get to use less of the stuff with high heat energy retained in the different phase) also lowering the specific heat capacity of the working fluid therefore needing less heat to initiate a phase change.
However...................is sodium chloride just as good???
secondly - as far as I am aware a substance with a high specific heat capacity may take longer to warm up but equally have a longer warm down period........is this correct (my first assumption)???? if so then i need to raise the specific heat capacity of the storage medium so long as it gets long exposue to the source of heat to get a longer term of storage?????? - is this ture????
many thanks in advance for any help.