The Prediction of Thermal Performance for Outdoor Swimming Pools

Empirical methods and industrial guidelines are conventionally used for arriving at heating needs of outdoor community swimming pools which seldom account for local climatic conditions. This paper presents a comprehensive model to estimate the water temperature of an outdoor swimming pool and then to estimate heating-plant size. The important feature of the present model is that all comprehensible modes of heat and mass transfer and topographic conditions are incorporated. The notables are the heat and mass transfer to/from swimming pools through free and forced convection, radiative cooling to the sky, and climatic changes such as cloud cover and rainfall. The ambient weather conditions and solar contributions are also found to be significant contributors. The consequent predictions of pool-water temperature are evaluated vis-à-vis measurements from an Olympic size open air swimming pool in Perth, Australia. Based on a comparison among some models in the literature, it is found that the present model is able to replicate the measured data to within ±0.5°C for nearly 68% of the results over a three year time frame. The subsequent heating-capacity calculations are found to be satisfied in 82% of the measured values to within ±25 kW.