Simplified Modeling of Thermal Storage Tank for Distributed Energy Heat Recovery Applications

A simplified mathematical model was developed to analyze a storage tank containing a stationary fluid with hot and cold heat exchanger coils. The model is to be used as a screening tool for determining tank size and configurations for operation with a given power generation unit in a combined cooling, heating and power (CCHP) system. As such, the model was formulated so that it requires minimal information about the thermo-physical properties of the fluids and design parameters in order to determine the temperature profiles of the stored fluid and the heat transfer fluid for turbulent flow inside the heat exchangers. The presented model is implemented computationally with varying number of nodes, before comparing it with a more detailed model that take into account the variation of thermo-physical properties, as well as the effects of thermal de-stratification and heat loss to the ambient. The simplified model provided accurate temperature predictions that could subsequently be used to design a stratified tank system for a given CCHP application.