Temperature Profile and Thermocline Thickness Evaluation of a Stratified Thermal Energy Storage Tank

Determination of thermocline thickness requires a
continuous profile of temperature distribution. Difficulty in determining thermocline thickness arises for the case of discrete temperature data, since the profile formed could not be used to estimate the thermocline thickness. This paper discusses a practical method for formulation of thermocline thickness of stratified thermal energy storage. Curve fitting by iterative method was adopted to identify the functions which could represent the S-curve
of temperature distribution. Based on the functions, thermocline
thickness was formulated using functional relationship of
temperature profile. Results identified two functions which could
represent S-curve of temperature distribution, namely sigmoid dose
response (SDR) and four parameter sigmoid (FPS) functions. Both
functions were observed to well fit the temperature distributions
having coefficient determination more than 0.99. Based on
evaluations the formulations were capable to be utilized for
evaluation of thermocline thickness of the stratified TES. The
methods offer an advantage to obtain an exact value of thermocline
thickness.