Performance Evaluation of Stratified TES using Sigmoid Dose Response Function

Temperature distribution on the operating stratified thermal energy storage (TES) is commonly available as discrete data. Due to this, it is difficult to conduct performance evaluation based on thermocline profile, because limit points could not be determined accurately. This paper discusses a practical method in determining the performance parameters of stratified TES based on thermocline profile. Non linear regression fitting was adopted to identify the function which could represent temperature distribution profile. The function was used to define performance parameters namely limit points of thermocline, thermocline thickness, lost capacity, integrated capacity, theoretical capacity as well as half cycle of Figure of Merit. Results identified a function which could represent S-curve of temperature distribution, namely Sigmoid Dose Response (SDR) equation. The function was observed to fit the temperature distributions having coefficient determination more than 0.99. Based on evaluations the method was capable to be utilized for evaluation of the performance of the stratified TES. The methods offer an advantage to obtain an exact value of performance parameters.