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ElsevierGonzález Altozano, P.; Gasque Albalate, M.; Ibáñez Solís, F.; Gutiérrez-Colomer, RP. (2015). New methodology for the characterisation of thermal performance in a hot water storage tank during charging. Applied Thermal ABSTRACTIn 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.

ElsevierGasque Albalate, M.; González Altozano, P.; Maurer, D.; Moncho Esteve, IJ.; Gutiérrez-Colomer, RP.; Palau-Salvador, G.; García-Mari, E. (2015). Study of the influence of inner lining material on thermal stratification in a hot water storage tank. Applied Thermal Engineering. 75:344-356. doi:10.1016Engineering. 75:344-356. doi:10. /j.applthermaleng.2014 ABSTRACTThe present study has analyzed the influence of thermal conductivity of the inner lining material on the stratification process in a hot water tank during thermal charge and the later standby period. This analysis has been carried out numerically by a three-dimensional Computational Fluid Dynamics (CFD) model. Experimental measurements of temperature profiles are used to select and verificate the model, and to later validate CFD simulations. With the validated model, temperature over time at several heights, temperature profiles, velocity contours, water streamtraces and temperature contours, are studied and compared for three different inner lining materials. The obtained results confirm that a weak conducting lining material favours energy storage in the tank and the thermal stratification of water during charge and subsequent standby period. The effect of the inner lining material on the energy accumulated in water and on the moment of energy (stratification) is potentially enhanced when the material's thermal conductivity diminishes. The use of insulating paints as inner lining for water storage tanks could be a possible solution to be studied and subsequently adopted in practice to improve the efficient use of energy in stored water. The analysis 2 techniques employed prove most useful and enable the results to be compared and presented in a novel way.

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