A computational fluid dynamics (CFD) model has been developed to simulate the flow and heat transfer near a lower radial inlet diffuser in a cylindrical stratified chilled water storage tank during charging. The model was used to perform parametric simulations of inlet diffuser performance in full-scale tanks during thermocline formation, from which first-order correlation relating thermal performance to tank and diffuser design parameters were derived. Part 1 describes the development of the CFD model and its validation. Part 2 reports the results of the parametric study. The two-dimensional, transient model was implemented in a commercial finite element code. The model has been validated with field-measured data from two full-scale tanks. Laminar analysis predicted field-measured temperature profiles well, even under ostensibly transitional conditions, provided that variations in inlet temperature during the field tests were accurately modeled. These results suggest that turbulence has a secondary effect on the development of thermoclines within the range of parameters considered and that laminar models may be useful for modeling performance of full-scale tanks over a wide range of inlet parameters. The fully developed temperature profile was found to be insensitive to the velocity distribution assumed at the inlet.

Reprinted from the International Journal of Heating, Ventilating, Air-Conditioning and Refrigerating Research, Vol. 7, No.1, January 2001, pp. 31-49.

Units: Dual