Temperature stratification in hot-water storage tanks

Experiments have been carried out on a scale model of stratified hot-water storage tanks to study the effects of operating conditions on the thermoclines and on the extraction efficiency. The following parameters were varied: the cold-water temperature (from 30 to 80 °C), hot-water temperature (from 40 to 90 °C), water-flow rate (from 6 to 601/h), and L D ratio (1.56, 2.06, 3.54 and 4.0). Care was taken to keep the total volume and d D ratio the same for all tanks. It was observed that stratification improves with increasing ΔT and water flow rates. L D values between 3 and 4 are optimal. The extraction efficiency has been correlated by an analytical expression. © 1991.