Stratified Thermal Storage Tank Research Articles

NUMERICAL STUDY OF THE EFFECT OF INLET GEOMETRY ON STRATIFICATION IN THERMAL ENERGY STORAGE

A finite difference computer code incorporating two methods of discretization for the advection terms in the flow governing conservation equations has been developed. These methods are the weighted upwind difference scheme (WUDS) and the second-order upwind difference scheme (SOUDS). Application of the code to a stratified thermal storage showed very good agreement between the experimental and the predicted temperature profiles when using SOUDS as opposed to WUDS. Investigation of the effect of inlet geometry on thermal stratification in a thermal storage tank was carried out using the SOUDS method. Results show that the effect of inlet geometry is negligible for Richardson numbers above 10. Thus a performance criterion for stratified thermal storage tanks with different inlet geometries has been established.

Mass transfer analogy for heat transfer experiments in thermal storage

The analogy between heat and mass transfer in a stratified thermal storage tank was experimentally investigated. The results indicate that it is feasible to utilize mass transfer analogy in reverse to obtain heat transfer information. However, it should be realized that mass transfer experiments tend to show less mixing than the corresponding heat transfer experiments.

A Comparison Study of One-Dimensional Models for Stratified Thermal Storage Tanks

A survey of the stratified thermal storage tank one-dimensional models available in the literature has been conducted. Six of these models were tested and compared against the experimental data obtained at our laboratories and from the literature. Although various factors affecting the performance of a stratified tank can be accounted for by the higher order models, i.e. two- and three-dimensional models, the introduction of empirically-based mixing parameters into the one-dimensional models renders them widely applicable and practical in the simulation of energy systems incorporating thermal storage tanks.

Stratified thermal storage tank inlet mixing characterization

Predictions of thermocline development in thermocline thermal storage tanks can be made by accounting for turbulent mixing at the inlet region. A practical measure for quantifying this mixing is obtained by introducing an effective diffusivity factor in a one-dimensional flow model. Thus, a tool for characterization of turbulent mixing caused by different inlet configurations is now available. This should facilitate the selection of diffusers for achieving a high degree of stratification in thermocline thermal storage tanks.

Abu Dhabi solar distillation plant

In Abu Dhabi (United Arab Emirates), a small seawater solar desalination plant has been designed and constructed as part of a cooperative research program for solar desalination between the Water and Electricity Department (Abu Dhabi) and the New Energy Development Organisation (Japan). The system utilizes the horizontal-tube, thin-film, multi-effect stack (MES) distillation concept and has a design capacity of 120 m 3/d. The thermal energy required by the MES evaporator is provided by a bank of evacuated glass tube collectors. The system uses no auxiliary heat with solar energy representing the only source of thermal energy. The solar collectors have an effective area of 1862 m 2. Three thermally stratified vertical thermal storage tanks with a total capacity of 300 m 3 are utilized to provide thermal energy for the distiller. The plant is designed for continuous operation day and night. This paper describes the plant, reviews its design concept and presents the results of two preliminary performance simulation models.