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The effect of cooling conditions on condensation in the presence of noncondensables

Conference · · Transactions of the American Nuclear Society; (United States)
OSTI ID:6912486
; ;  [1]
  1. Massachusetts Institute of Technology, Cambridge, MA (United States)

In the simplified boiling water reactor nuclear power plant concept during a typical postulated loss-of-coolant accident or steam-line break, a steam/air mixture may flow to the elevated heat exchanger of the passive containment coolant system (PCCS). There, the steam condenses and the condensate drains back to the pressure vessel. Local values of the condensation heat transfer coefficients in the presence of noncondensables are needed for predicting the overall performance of the PCCS and for optimizing the heat exchanger design. To obtain local heat transfer coefficients experimentally, determination of local heat fluxes is necessary. However, doing this involves some difficulties. In most of the experimental work carried out thus far concerning local condensation heat transfer in the presence of noncondensable gases, local heat fluxes were typically obtained in terms of the axial gradients of the measured coolant bulk temperatures. Thus, cooling conditions that may affect the coolant temperature measurement eventually would affect values of the local heat transfer coefficients. Cooling conditions include the cooling-water flow rate, cooling-air flow rate (introduced to promote mixing in the cooling channel), and channel geometry. An example of the channel geometry condition is the step increase of the tube-wall temperature profile in the upper half of the condensing tube observed at both the Massachusetts Institute of Technology and the University of California, Berkeley and termed by the latter as [open quotes]temperature inversion.[close quotes] Understanding the effects of cooling conditions on the local condensation heat transfer coefficients is definitely required for any meaningful comparison of local values of heat transfer coefficients to be made among different groups.

OSTI ID:
6912486
Report Number(s):
CONF-931160--
Journal Information:
Transactions of the American Nuclear Society; (United States), Journal Name: Transactions of the American Nuclear Society; (United States) Vol. 69; ISSN TANSAO; ISSN 0003-018X
Country of Publication:
United States
Language:
English