Thermal Analysis of Stratified Storage Tanks

Abstract

This paper presents theoretical and experimental studies on the stratification decay in stratified storage tanks. The effects of the thicknesses of tank wall and thermal insulation were discussed. The experimental results showed that the outside insulation can enhance tank wall axial conduction which tends to degrade the stratification. However, the reduction of heat loss outweighs the enhancement of axial conduction and better stratification is still maintained when compared to a bare wall tank. The axial conduction enhancement is sensitive to the wall thickness for the same thickness of insulation, however, it is not strongly dependent on the insulation thickness for identical thick wall. The addition of inside insulation is helpful in preserving stratification. A two-dimensional laminar flow model was also developed to interpret the temperature and flow fields inside storage tanks and the numerical results were compared with the experimental data.

Transient analysis of energy storage in a thermally stratified water tank

“…The model is compared with the experimental and numerical data of Shyu et al (1989) who used a two-dimensional laminar flow model to interpret the results of temperature and flow fields in a static stratified storage system. They have determined the temperature distribution in the fluid region near the wall by solving the vorticity transport equation, stream function and energy equations in the fluid and the energy equation in the wall.…”

“…Both the present model and the model of Shyu et al (1989) assume that perfectly insulated conditions exist at the top and bottom. The predicted results of the present model are plotted along with the experimental and numerical results of Shyu et al (1989) in Figures 3(a) and 3(b), respectively. The predictions of both the models in the hot fluid region are slightly higher than the experimentally observed values at large intervals of time, though there is good agreement between them at small intervals of time.…”

“…The region below the thermocline region heats up initially due to heat flow from the region above the thermocline, and then gradually decreases because, the heat losses from this region exceed the heat gain with increase in time. The temperatures are predicted, using the present model for a 6 mm bare (uninsulated) cylindrical tank used in the experiments of Shyu et al (1989) for the same experimental conditions and the initial temperature distribution of the water body. Both the present model and the model of Shyu et al (1989) assume that perfectly insulated conditions exist at the top and bottom.…”

“…The temperatures are predicted, using the present model for a 6 mm bare (uninsulated) cylindrical tank used in the experiments of Shyu et al (1989) for the same experimental conditions and the initial temperature distribution of the water body. Both the present model and the model of Shyu et al (1989) assume that perfectly insulated conditions exist at the top and bottom. The predicted results of the present model are plotted along with the experimental and numerical results of Shyu et al (1989) in Figures 3(a) and 3(b), respectively.…”

Study of the influence of inner lining material on thermal stratification in a hot water storage tank

“…In order to diminish the axial heat conduction effect and to preserve or improve stratification, several studies have proposed insulating the inner wall surface by placing insulation material or any low thermal conductivity material compatible with stored fluid [6][7][8][9].…”