Dynamic simulation of outdoor swimming pool solar heating

This paper presents a dynamic model of a “passive” solar heating system composed by horizontal solar flat collectors coupled to an outdoor swimming pool. The numerical model has been developed by using the Matlab/Simulink environment and it allows to predict on a hourly basis the thermal energy collected by the solar panels, the inlet/outlet collector working fluid temperature, the pool water temperature and the system efficiency. As a case study, three different pools characterized by different dimensions and three different flat solar collectors (unglazed, glazed and evacuated collectors) have been considered. The Simulink model allows to estimate the warm-up period of the swimming pool as a function of the characteristics of the pool and of the solar collectors. It has been demonstrated that, by using the model, the designer can make the optimal sizing of the solar heating system in order to obtain a water pool temperature ranging within a fixed interval. The results demonstrate that unglazed collectors are appropriate for this kind of use and evacuated collectors can be useful just in case of very big swimming pools in order to reduce the absorbing area of the solar panels.