Results of experimental and numerical investigations of thermal stratification and natural convection in a vertical cylindrical hot water tank during standby periods are presented. The transient fluid flow and heat transfer in the tank during cooling caused by heat loss are investigated by computational fluid dynamics (CFD) calculations and by thermal measurements. A tank with uniform temperatures and thermal stratification is studied. The distribution of the heat loss coefficient for the different parts of the tank is measured by tests and used as input to the CFD model. The investigations focus on the natural buoyancy resulting in downward flow along the tank side walls due to heat loss of the tank and the influence on thermal stratification of the tank by the downward flow and the corresponding upward flow in the central parts of the tank. Water temperatures at different levels of the tank are measured and compared to CFD calculated temperatures. The investigations will gain insight into the natural buoyancy driven flow in the tank. It is elucidated how thermal stratification in the tank is influenced by the natural convection and how the heat loss from the tank sides will be distributed at different levels of the tank for different thermal conditions.
|Title of host publication||ISES Solar World Congress 2009|
|Place of Publication||Johannesburg, South Africa|
|Publication status||Published - 2009|
|Event||29th Biennial Solar World Congress of the International Solar Energy Society - Johannesburg, South Africa|
Duration: 11 Oct 2009 → 14 Oct 2009
|Conference||29th Biennial Solar World Congress of the International Solar Energy Society|
|Period||11/10/2009 → 14/10/2009|