TO-82-09-1 -- Thermally Stratified Tanks

This paper shows how tanks fail to stratify and describes a new solar collection strategy that allows stratification to be maintained. A theory that models thermally stratified tanks reasonably well is briefly summarized. Tests of tanks fitted with various internal baffle and diffuser configurations are described.

Conclusions are (1) the new collection strategy is essential for maintaining stratification and (2) most tanks can remain stratified in diurnal cycling. Dip tubes and vertical baffles degrade stratification. Tank walls should have low heat capacity compared to that of water. Tanks with a height-to-diameter ratio of about four provide the best stratification without excessive thermal losses. Simple inlet and outlet diffusers provide the best thermal stratification.

Citation: ASHRAE Transactions, Volume 88, Part 2, Toronto, Canada



Product Code(s): D-TO-82-09-1