Heat Recirculation Induced by Thermal Diffusers

by Joseph H.W. Lee, Asst. Prof.; Univ. of Delaware, Newark, Del.,
Donald R.F. Harleman, (M.ASCE), Prof. of Civ. Engrg.; Mass. Inst. of Tech., Cambridge, Mass.,
Gerhard H. Jirka, (A.M.ASCE), Asst. Prof.; School of Civ. and Environmental Engrg., Cornell Univ., Ithaca, N.Y.,

Serial Information: Journal of the Hydraulics Division, 1979, Vol. 105, Issue 10, Pg. 1219-1231

Document Type: Journal Paper


A unidirectional multiport thermal diffuser discharges large quantities of condenser cooling water in the form of a line of turbulent heated jets near the bottom of the receiving waterbody. The large momentum input induces a large mixed flow compared with the discharge flow, causing rapid temperature reduction within a relatively small area. This paper presents the results of an experimental study which demonstrates that under certain conditions the large back entrainment demand coupled with momentum dissipation (due to bottom friction) of the diffuser plume may generate recirculation of the mixed flow back into the near field, leading to temperatures significantly higher than previously predicted. Length and time scales of recirculation are estimated: the transient maximum temperature rise is correlated with the length scale of recirculation and the sink strength.

Subject Headings: Diffusion (thermal) | Temperature effects | Thermal pollution | Water discharge | Field tests | Cooling (wastewater treatment) | Turbulent flow | Entrainment

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