Identification of UA Using the Locus Curve on a Schumann Plot
MARSHALL, RICHARD; MARSHALL, RICHARD; Solar Energy Unit, University College
Журнал:
International Journal of Solar Energy
Дата:
1985
Аннотация:
Testing a thermal storage device accurately for its characteristic parameters requires a large amount of time. Of the six or so key parameters which characterise a thermal store it is the determination of the overall fluid to storage material heat transfer coefficient, UA, and the “ degree of stratification” which consumes the most time, e.g. six different flow rate tests about ambient temperature. Therefore, shortcut methods based on theory are desirable to reduce the experimental effort. Presented herein is the idea of establishing the upper and lower limits on UA by assuming a perfectly mixed and perfectly stratified response respectively. The latter requires the use of a Schumann plot of the exit temperature at one fill period. Such a subset of the general Schumann plots is called a “ Locus Curve” The derivation of the locus curve is given together with an indication of how it is used for the identification of UA from a step response test.
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