Stratified storage tank influence on performance of solar water heating system tested in Beirut

Abstract

This paper presents an experimental and numerical study to evaluate the performance of an active solar water heating system that uses a stratified storage tank in both natural and forced circulation operation modes. A new inlet diffuser design was used in the tank to enhance stratification, and the performance of the solar water heating system was compared to heating systems with other tank inlet designs. A simulation program is used for modeling the thermal behavior of the stratified-tank solar water heating system. Comparison of the resulting calculations with experimental data show good agreement. System efficiencies as high as 60% are observed in the Beirut climate. A substantial increase of up to 20% in the energy delivered is observed when stratification is employed in the storage tank, as compared with the fully mixed tank model. The simulation model is then applied for actual Beirut weather to predict the monthly useful energy gain from using stratified-tank solar water heating systems against the fully mixed tank model.