New methodology for the characterisation of thermal performance in a hot water storage tank during charging

• Published in: Applied thermal engineering 2015-06, Vol.84, p.196-205
• Main Authors: González-Altozano, Pablo, Gasque, María, Ibáñez, Federico, Gutiérrez-Colomer, Rosa Penélope
• Format: Article
• Language: English
• Subjects: Curve fitting; Five-parameter logistic function; Stratification indices; Temperature profile; Thermal energy storage; Thermocline thickness evolution
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2015.03.048

In solar water heating systems, the application of certain stratification indices requires the characterisation of the water temperature distribution profile inside the tank and its evolution. In order to avoid the limitations and drawbacks related to the discrete measures provided by experimental trials, this paper presents a newly developed method, called Virtual TC, which allows the water temperature to be estimated at any depth and at any time in a storage tank during the charge process. The proposed methodology can be very useful for estimating the numerous temperature-dependent indices employed for the characterisation and evaluation of thermal stratification in water storage tanks. As a practical example, it was successfully applied to determine the instantaneous temperature profile and thermocline thickness and its evolution throughout charging. It is concluded that the Virtual TC method gives highly satisfactory results under normal operational conditions for a hot water storage tank during the charge cycle. •Thermal characterisation of a hot water storage tank during charging is performed.•New method to estimate water temperature at any time and depth is proposed.•The developed model adequately fits experimental data and provides reliable results.•Continuous temperature profiles from experimental discrete data can be obtained.•Temperature-dependent stratification indices can be calculated with few data points.