Stratified thermal storage systems utilise the temperature dependence of water density to store both warm return water and cold supply water in a single tank. Manifolds and diffusers at the tank inlets minimise turbulence and mixing in the tank, resulting in a relatively small thermocline between the hot and cold layers. A discrete time step model based on previous work by Wildin and Truman (1985) was developed for implementation in an hourly energy analysis program. The model numerically solves the one-dimensional, time- dependent equation for the tank water temperatures using a Runge-Kutta method. Appropriate time scaling was required to achieve stability. Sensitivity to model and environmental parameters is discussed. The performance of the model is compared to experimental data and a finite difference model.

KEYWORDS: energy storage, tanks, temperature stratification, calculating, research, computer programs, performance, comparing.