Parametric Study of Charging Inlet Diffuser Performance in Stratified Chilled Water Storage Tanks with Radial Diffusers: Part 1–Model Development and Validation

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.